CPC Definition - Subclass E21B

Last Updated Version: 2020.05
EARTH DRILLING, e.g. DEEP DRILLING (mining, quarrying E21C; making shafts, driving galleries or tunnels E21D); OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
Definition statement

This place covers:

Earth drilling, e.g. deep drilling;obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells. This subclass also includes drilling at shallow depths but over extended distances, such as drilling for laying a pipeline under surface obstacles.

References
Limiting references

This place does not cover:

Mining, quarrying

E21C

Making shafts, driving galleries or tunnels

E21D

Percussion drilling (drives used in the borehole E21B 4/00)
Definition statement

This place covers:

Machines and methods in which the drilling action is done principally by percussion.

The percussive drive is placed outside of the borehole, and the drilling can be for any depth, including drillholes and mining applications:

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Relationships with other classification places

When classifying in groups E21B 1/12 - E21B 1/38, a symbol from one of the following main groups of B25D should also be given:

B25D 9/00 Portable percussive tools with fluid-pressure drives

B25D 11/00 Portable percussive tools with motor drive

B25D 16/00 Portable percussive machines with superimposed rotation

B25D 17/00 Details of, or accessories for, portable power-driven percussive tools

References
Limiting references

This place does not cover:

Drives for drilling, used in the borehole

E21B 4/00

Informative references

Attention is drawn to the following places, which may be of interest for search:

Drives for combined percussion and rotary drilling

E21B 6/00

Portable drilling rigs

E21B 7/20

Derricks, masts

E21B 15/00

Rotary drilling machines in general

B23B

Rotary drilling (drives used in the borehole E21B 4/00; rotary drilling machines in general B23B)
Definition statement

This place covers:

Machines and methods in which the drilling action is done principally by rotation:

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References
Limiting references

This place does not cover:

Drives for drilling, used in the borehole

E21B 4/00

Informative references

Attention is drawn to the following places, which may be of interest for search:

Drives for combined percussion and rotary drilling

E21B 6/00

Portable drilling rigs

E21B 7/20

Derricks, masts

E21B 15/00

Rotary drilling machines in general

B23B

Special rules of classification

Reference B23B is non-limiting in the main group E21B 3/00. CPC will be corrected once this inconsistency is resolved in IPC.

{movably mounted on the drilling structure or platform (derricks adapted to be moved on their substructure E21B 15/003)}
References
Limiting references

This place does not cover:

Derricks adapted to be moved on their substructure

E21B 15/003

Informative references

Attention is drawn to the following places, which may be of interest for search:

Supports for the drilling machine specially adapted for underwater drilling

E21B 15/02

Drives for drilling, used in the borehole
Definition statement

This place covers:

Drives located inside the borehole for powering drilling units:

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References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Rotary-piston machines or pumps

F04C 2/00

Moineau motors

F04C 2/107

Arrangements for handling mechanical energy structurally associated with the machine, e.g. structural association with mechanical driving motor or auxiliary dynamo-electric machine

H02K 7/00

{Bearing, sealing, lubricating details (for roller bits E21B 10/22)}
References
Limiting references

This place does not cover:

Bearing, lubrication or sealing details for roller bits

E21B 10/22

Informative references

Attention is drawn to the following places, which may be of interest for search:

Bearings in general

F16C

Sealing in general

F16J

Lubricating in general

F16N

{Mechanical motion converting means, e.g. reduction gearings (E21B 4/10 takes precedence)}
References
Limiting references

This place does not cover:

Continuous unidirectional rotary motion of shaft or drilling pipe effecting consecutive impacts

E21B 4/10

Informative references

Attention is drawn to the following places, which may be of interest for search:

Gearings in general

F16H

Down-hole impacting means, e.g. hammers (percussion drill bits E21B 10/36; boring rams E21B 11/02; releasing-jars E21B 31/107)
References
Limiting references

This place does not cover:

Percussion drill bits

E21B 10/36

Releasing-jars

E21B 31/107

Informative references

Attention is drawn to the following places, which may be of interest for search:

Boring rams

E21B 11/02

Special rules of classification

Looping references between E21B 11/02 and E21B 4/06 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: Reference E21B 11/02 is non-limiting in the subgroup E21B 4/06. CPC will be corrected once this inconsistency is resolved in IPC.

Drives for drilling with combined rotary and percussive action (drives used in the borehole E21B 4/00; portable percussive machines with superimposed rotation B25D 16/00)
Definition statement

This place covers:

Drives outside the borehole for combined percussion and rotary drilling:

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References
Limiting references

This place does not cover:

Drives for drilling, used in the borehole

E21B 4/00

Informative references

Attention is drawn to the following places, which may be of interest for search:

Drives for combined percussion and rotary drilling

E21B 6/00

Portable drilling rigs

E21B 7/20

Derricks, masts

E21B 15/00

Methods or apparatus for generating mechanical vibrations of infrasonic, sonic or ultrasonic frequency

B06B 1/00

Portable percussive machines with superimposed rotation

B25D 16/00

Special rules of classification

Reference B25D 16/00 is non-limiting in the main group E21B 6/00. CPC will be corrected once this inconsistency is resolved in IPC.

Special methods or apparatus for drilling
Definition statement

This place covers:

Drilling methods and apparatus characterised by any aspect that differs from those of conventional drilling, which is understood as drilling a vertical borehole with a roller or drag type bit, using a derrick or mast.

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Rotary or percussion drill bits

E21B 10/00

Derricks or masts

E21B 15/00

Drilling rods or pipes

E21B 17/00

Setting of casings when not simultaneous with drilling of the borehole

E21B 43/10

Details of, or accessories for, portable power-driven percussive tools

B25D 17/00

Vehicles adapted to transport or to comprise special loads

B60P 3/00

Underwater drilling for submerged foundations

E02D 27/52

Erecting posts for fences

E04H 17/263

Machines for drilling and setting anchoring bolts

E21D 20/003

Details of hydraulic circuits

F15B

{combined with a bucket-type container}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Bailers with helical conveying means

E21B 27/04

{Drilling by use of explosives (underwater drilling using explosives E21B 7/1245)}
References
Limiting references

This place does not cover:

Underwater drilling using explosives

E21B 7/1245

Informative references

Attention is drawn to the following places, which may be of interest for search:

Setting-tools actuated by explosives

E21B 23/04, E21B 23/065

Cutting or destroying objects in boreholes by explosives

E21B 29/02

Freeing objects using explosives

E21B 31/1075

Gun or shaped-charge perforators

E21B 43/116

Fracturing by explosives

E21B 43/263, E21B 43/248

Taking samples using explosives

E21B 49/04

{With a rotary table, i.e. a fixed rotary drive for a relatively advancing tool}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Rotary tables

E21B 3/04

Directional drilling {(derricks or masts specially adapted therefor E21B 15/04)}
Definition statement

This place covers:

Directional drilling in the general sense of producing a borehole in a direction other that vertical. The drilling direction can be essentially horizontal, such as for laying a pipe under an obstruction or in an urban environment.

References
Limiting references

This place does not cover:

Derricks or masts specially adapted therefor

E21B 15/04

Deflecting the direction of boreholes
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Directional window cutting

E21B 29/06

Deflecting the direction of fishing tools

E21B 31/14

from floating support with independent underwater anchored guide base
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Guide line systems

E21B 41/10

Drilling by use of heat, e.g. flame drilling
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Drilling by use of explosives

E21B 7/007

Drilling by liquid or gas jets, with or without entrained pellets (E21B 7/14 takes precedence; hydraulic monitors E21C 45/00)
References
Limiting references

This place does not cover:

Drilling by use of heat

E21B 7/14

Methods of hydraulic mining; Hydraulic monitors

E21C 45/00

Informative references

Attention is drawn to the following places, which may be of interest for search:

Obtaining a slurry of minerals from wells

E21B 43/29

Driving or forcing casings or pipes into boreholes, e.g. sinking; Simultaneously drilling and casing boreholes (surface means for applying to-and-fro rotation movements to the casing E21B 3/025; placing piles E02D 7/00; sinking shafts while moving the lining downwards E21D 1/08 {; making galleries by forcing prefabricated elements through the ground E21D 9/005})
Definition statement

This place covers:

Methods in which the drilling action takes place simultaneously with the installation of a casing or of the pipe to be installed, with the borehole being horizontal or not.

References
Limiting references

This place does not cover:

Surface means for applying to-and-fro rotation movements to the casing

E21B 3/025

Placing piles

E02D 7/00

Sinking shafts while moving the lining downwards

E21D 1/08

Making galleries by forcing prefabricated elements through the ground

E21D 9/005

Informative references

Attention is drawn to the following places, which may be of interest for search:

Pushing means outside of the borehole

E21B 19/08

{with helical conveying means}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Drilling with helical conveying means

E21B 7/005

Augers

E21B 10/44

Drilling rods or pipes with helical structure

E21B 17/22

{using down-hole drives}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Down-hole drives per se

E21B 4/00

{using down-hole drives}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Down-hole drives per se

E21B 4/00

{using down-hole drives (E21B 7/203 and E21B 7/206 take precedence)}
References
Limiting references

This place does not cover:

Using down-hole drives in combination with helical conveying means

E21B 7/203

Using down-hole drives without earth removal

E21B 7/206

Informative references

Attention is drawn to the following places, which may be of interest for search:

Using down-hole drives per se

E21B 4/00

Enlarging drilled holes, e.g. by counterboring (drill bits for enlarging the borehole E21B 10/26)
Definition statement

This place covers:

Vertical or horizontal drilling, in which means are provided for enlarging a borehole made previously, which borehole may have been made by the same machine carrying out the enlargement, or by a different machine or in a previous operation:

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References
Limiting references

This place does not cover:

Drill bits for enlarging the borehole

E21B 10/26

Drill bits (specially adapted for deflecting the direction of boring E21B 7/064; with means for collecting substances E21B 27/00)
Definition statement

This place covers:

Drill bits for any application in earth drilling, be it deep drilling for oil and gas or rock drilling for mining or for use in an underground space.

References
Limiting references

This place does not cover:

Drill bits specially adapted for deflecting the direction of boring

E21B 7/064

Drill bits with means for collecting substances

E21B 27/00

Informative references

Attention is drawn to the following places, which may be of interest for search:

Manufacture of articles from metal powder

B22F

Special treatment of metallic powder, e.g. to facilitate working, to improve properties

B22F 1/00

Cutting tools of which the bits or tips are of special material

B23B 27/14

Drill bits for stone or stone-like material

B28D 1/00

Alloys containing diamond

C22C

Bulkheads, piles specially adapted to foundation engineering

E02D 5/00

Glossary of terms

In this place, the following terms or expressions are used with the meaning indicated:

Arrangement of teeth or other cutting elements: placement or number of elements on a bit body

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Wear resisting parts: materials on the body of the bit adapted for withstanding wear caused by the flow of drilling fluid having cuttings entrained therein

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Chisel or button type inserts:

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Preformed cutting elements mounted on a distinct support:

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Core bits (characterised by wear resisting parts E21B 10/46; obtaining undisturbed cores E21B 25/00)
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Drill bits characterised by wear resisting parts

E21B 10/46

Apparatus for obtaining undisturbed cores

E21B 25/00

Special rules of classification

Reference E21B 10/46 is non-limiting in the subgroup E21B 10/02. CPC will be corrected once this inconsistency is resolved in IPC.

Looping references between E21B 25/00 and E21B 10/02 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: Reference E21B 25/00 is non-limiting in the subgroup E21B 10/46. CPC will be corrected once this inconsistency is resolved in IPC.

{percussion type, e.g. for masonry}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Percussion drill bits in general

E21B 10/36

characterised by wear resisting parts, e.g. diamond inserts
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Drill bits with self-renewable cutting edge

E21B 10/006

the bit being of core type
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Saw cylinders having their cutting rim equipped with abrasive particles for drilling stone or glass

B28D 1/041

with preformed cutting elements (inserts per se E21B 10/56, E21B 10/58)
Definition statement

This place covers:

Rotary drag type bits with blades having preformed cutting elements mounted on a distinct support, e.g. polycrystalline inserts.

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Inserts per se

E21B 10/56, E21B 10/58

Special rules of classification

References E21B 10/56 and E21B 10/58 are non-limiting in the subgroup E21B 10/55. CPC will be corrected once this inconsistency is resolved in IPC.

characterised by conduits or nozzles for drilling fluids (for roller bits E21B 10/18; for percussion drill bits E21B 10/38)
References
Limiting references

This place does not cover:

Roller drill bits characterised by conduits or nozzles for drilling fluids

E21B 10/18

Percussion drill bits characterised by conduits or nozzles for drilling fluids

E21B 10/38

Informative references

Attention is drawn to the following places, which may be of interest for search:

Mining picks with arrangement of fluid-spraying nozzles

E21C 35/187

characterised by parts, e.g. cutting elements, which are detachable or adjustable (E21B 10/64 takes precedence; for roller bits E21B 10/20; for augers E21B 10/44)
References
Limiting references

This place does not cover:

Roller bits characterised by detachable or adjustable parts

E21B 10/20

Augers with leading portion or with detachable parts

E21B 10/44

Drill bits characterised by the whole or part thereof being insertable into or removable from the borehole without withdrawing the drilling pipe

E21B 10/64

Informative references

Attention is drawn to the following places, which may be of interest for search:

Rotary drag type drill bits

E21B 10/42

characterised by the whole or part thereof being insertable into or removable from the borehole without withdrawing the drilling pipe (retrievable core receivers E21B 25/02)
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Retrievable core receivers

E21B 25/02

Special rules of classification

Looping references between E21B 25/02 and E21B 10/64 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: Reference E21B 25/02 is non-limiting in the subgroup E21B 10/64. CPC will be corrected once this inconsistency is resolved in IPC.

Other drilling tools
Definition statement

This place covers:

Other drilling tools different from the drill bits of E21B 10/00

Accessories for drilling tools
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Connecting and disconnecting drill bit and drilling pipe

E21B 19/18

Sharpening stone drill bits

B24B 3/33

Supports for the drilling machine, e.g. derricks or masts
Definition statement

This place covers:

Drilling derricks or masts having such dimensions that require considerable complication for assembling and disassembling them, so that they cannot be considered as "movable" or "portable" units:

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References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Drill rigs with movable understructures

E21B 7/02

Floating drilling platforms

B63B 35/44

Drilling platforms on legs

E02B 17/00

{adapted to be moved on their substructure, e.g. with skidding means; adapted to drill a plurality of wells}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Derricks or masts specially adapted for directional drilling, e.g. slant hole rigs

E21B 15/04

specially adapted for underwater drilling (E21B 15/04 takes precedence; floating drilling platforms B63B 35/44; drilling platforms on legs E02B 17/00)
References
Limiting references

This place does not cover:

Derricks or masts specially adapted for directional drilling, e.g. slant hole rigs

E21B 15/04

Floating drilling platforms

B63B 35/44

Drilling platforms on legs

E02B 17/00

Informative references

Attention is drawn to the following places, which may be of interest for search:

Derricks or masts adapted to be moved on their substructure, e.g. with skidding means

E21B 15/003

specially adapted for directional drilling, e.g. slant hole rigs
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Derricks or masts adapted to be moved on their substructure, e.g. with skidding means

E21B 15/003

Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; {Cables;} Casings; Tubings (rod couplings in general F16D; tubes or tube couplings in general F16L)
Definition statement

This place covers:

Pipes for use in wellbores, for drilling but also for subsequent operations, such as casings or risers. Couplings between pipes. Centralisers and other accessories for pipes.

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Connecting flow lines to offshore structures

E21B 43/0107

Connecting flow lines to an underwater wellhead

E21B 43/013

Expansible tubulars

E21B 43/103

Details of, or accessories for, portable power-driven percussive tools

B25D 17/00

Rod couplings in general

F16D

Tubes or couplings in general

F16L

Subsea flow lines

F16L 1/00

Pipeline systems

F17D 1/00

Special rules of classification

References F16D and F16L are non-limiting in the main group E21B 17/00. CPC will be corrected once this inconsistency is resolved in IPC.

{Devices for subsurface connecting or disconnecting by rotation}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Connecting or disconnecting pipe couplings or joints

E21B 19/16

Fishing tools for frozen rods, casings, ropes, bits or the like

E21B 31/00

{Arrangements for fixing cables or wirelines to the outside of downhole devices}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Protectors and centralisers for cables and control lines

E21B 17/1035

Threaded
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Releasing-joints between rod or the like and bit or between rod and rod or the like

E21B 17/06

Telescoping joints for varying drill string lengths; Shock absorbers (heave compensators in the derrick E21B 19/09; releasing-jars E21B 31/107)
References
Limiting references

This place does not cover:

Heave compensators in the derrick

E21B 19/09

Releasing-jars

E21B 31/107

Informative references

Attention is drawn to the following places, which may be of interest for search:

Shock-absorbers in general

F16F

{with articulated arms or arcuate springs}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Measuring diameter of boreholes or wells

E21B 47/08

Pipes provided with plural fluid passages ({E21B 17/203 takes precedence;} circulation of drilling fluid by means of such pipes E21B 21/12)
References
Limiting references

This place does not cover:

Flexible or articulated drilling pipes with plural fluid passages

E21B 17/203

Circulation of drilling fluid by means of such pipes

E21B 21/12

Informative references

Attention is drawn to the following places, which may be of interest for search:

Joints or fittings for double-walled or multi-channel pipes or pipe assemblies

F16L 39/00

Flexible or articulated drilling pipes {, e.g. flexible or articulated rods, pipes or cables}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Risers

E21B 17/01

Swivel joints between rod or the like and bit or between rod and rod or the like

E21B 17/05

{with conductors, e.g. electrical, optical}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Hoses with electrically conducting means in general

F16L 11/127

Rods or pipes with helical structure (drill bits with helical conveying portion E21B 10/44)
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Drill bits with helical conveying portion

E21B 10/44

Special rules of classification

Looping references between E21B 10/44 and E21B 17/22 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: Reference E21B 10/44 is non-limiting in the subgroup E21B 17/22. CPC will be corrected once this inconsistency is resolved in IPC.

Handling rods, casings, tubes or the like outside the borehole, e.g. in the derrick; Apparatus for feeding the rods or cables (surface drives E21B 1/02, E21B 3/02)
Definition statement

This place covers:

Machines or methods performed in the surface for assembling pipes, hoisting pipes, pushing pipes into a borehole, storing pipes and similar. The application is typically for drilling, i.e. vertical, horizontal, deep drilling, mining or other earth drilling, but can also be for well treatment or other.

References
Limiting references

This place does not cover:

Surface percussion drives

E21B 1/02

Surface rotary drives

E21B 3/02

{specially adapted for underwater drilling (E21B 19/09, E21B 19/143 take precedence)}
Definition statement

This place covers:

Handling and supporting of tubulars in relation to underwater drilling operations other that feeding the drill string into the borehole or controlling the weight on bit:

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References
Limiting references

This place does not cover:

Apparatus specially adapted for drilling underwater for feeding the rods or cables, increasing or decreasing the pressure on the drilling tool or counterbalancing the weight of the rods

E21B 19/09

Racks, ramps, troughs or bins, for holding the lengths of rod singly or connected, specially adapted for drilling

E21B 19/143

Informative references

Attention is drawn to the following places, which may be of interest for search:

Risers with buoyancy elements

E21B 17/012, E21B 17/015

{Winding units, specially adapted for drilling operations}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Cathead actuated pipe wrenches or spinners

E21B 19/162

Capstans, winches

B66D

Rod or cable suspensions (load-engaging elements for hoisting or lowering purposes in general B66C 1/00; crown blocks or pulley blocks B66D; cable guides B66D 1/36)
Definition statement

This place covers:

Apparatus for suspension by rods or cables that have normally no capacity of applying rotation. A spinner or other rotary drive may be suspended from the suspension apparatus.

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References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Load-engaging elements for hoisting or lowering purposes in general

B66C 1/00

Crown blocks or pulley blocks

B66D

Cable guides

B66D 1/36

Special rules of classification

References B66C 1/00, B66D and B66D 1/36 are non-limiting in the subgroup E21B 19/02. CPC will be corrected once this inconsistency is resolved in IPC.

Apparatus for feeding the rods or cables (E21B 19/22 takes precedence; automatic feed E21B 44/02; hoisting drums B66D); Apparatus for increasing or decreasing the pressure on the drilling tool; Apparatus for counterbalancing the weight of the rods
Definition statement

This place covers:

Apparatus for pushing drilling tools into the borehole. All kinds of earth drilling tools are classified in these groups, such as deep drilling tools, rock drills for mining, horizontal drills or coiled tubing:

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References
Limiting references

This place does not cover:

Handling reeled pipe or rod units

E21B 19/22

Automatic control of the tool feed

E21B 44/02

Informative references

Attention is drawn to the following places, which may be of interest for search:

Hoisting drums in general

B66D

Special rules of classification

Reference B66D is non-limiting in the subgroup E21B 19/08. CPC will be corrected once this inconsistency is resolved in IPC.

specially adapted for drilling underwater formations from a floating support using heave compensators supporting the drill string (drilling-pipe telescoping joints E21B 17/07 {; heave compensators for supporting a riser E21B 19/006})
Definition statement

This place covers:

Feeding the drill string for underwater drilling:

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References
Limiting references

This place does not cover:

Heave compensators for supporting a riser

E21B 19/006

Informative references

Attention is drawn to the following places, which may be of interest for search:

Drilling-pipe telescoping joints

E21B 17/07

Special rules of classification

Looping references between E21B 17/07 and E21B 19/09 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: reference E21B 17/07 is non-limiting in the subgroup E21B 19/09. CPC will be corrected once this inconsistency is resolved in IPC.

Slips; Spiders {; Catching devices (rotary tables with master bushing or kelly bushing E21B 3/04)}
References
Limiting references

This place does not cover:

Rotary tables with master bushing or kelly bushing

E21B 3/04

Informative references

Attention is drawn to the following places, which may be of interest for search:

Slip-type elevators

E21B 19/07

Casing heads with slips

E21B 33/0422

Rope clamps {; Rod, casings or tube clamps not secured to elevators} (rope clamps in general F16G 11/00)
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Rope clamps in general

F16G 11/00

Special rules of classification

Looping references between E21B 19/12 and F16G 11/00 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: Reference F16G 11/00 is non-limiting in the subgroup E21B 19/12. CPC will be corrected once this inconsistency is resolved in IPC.

Racks, ramps, troughs or bins, for holding the lengths of rod singly or connected; Handling between storage place and borehole (E21B 19/20, E21B 19/22 take precedence)
Definition statement

This place covers:

Storage of rods and to handling of rods between storage and a position where the rods can be connected or disconnected.

References
Limiting references

This place does not cover:

Combined feeding from rack and connecting

E21B 19/20

Handling reeled pipe or rod units

E21B 19/22

Informative references

Attention is drawn to the following places, which may be of interest for search:

Storing elongated articles in general

B65G 1/0442

Connecting or disconnecting pipe couplings or joints (E21B 19/20 takes precedence; pipe wrenches or the like B25B)
Definition statement

This place covers:

Method or apparatus for connecting or disconnecting the rods:

media15.jpg

References
Limiting references

This place does not cover:

Combined feeding from rack and connecting

E21B 19/20

Informative references

Attention is drawn to the following places, which may be of interest for search:

Pipe wrenches or the like in general

B25B

Special rules of classification

Reference B25B is non-limiting in the subgroup E21B 19/16. CPC will be corrected once this inconsistency is resolved in IPC.

Combined feeding from rack and connecting, e.g. automatically
Definition statement

This place covers:

The combination of feeding from rack and connecting:

media16.jpg

Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor (freeing objects stuck in boreholes by flushing E21B 31/03; well drilling compositions C09K 8/02)
Definition statement

This place covers:

Control of circulation and pressure of fluids in a borehole, typically drilling fluids, tools for filling a borehole, treatment of drill cuttings, various types of drilling fluids.

References
Limiting references

This place does not cover:

Freeing objects stuck in boreholes by flushing

E21B 31/03

Well drilling compositions

C09K 8/02

Informative references

Attention is drawn to the following places, which may be of interest for search:

Cementing

E21B 33/13

Enhanced recovery methods

E21B 43/16

Fracturing formations

E21B 43/26

Destroying or transforming solid or contaminated waste into something useful or harmless

B09B 3/00

Floating drilling platforms, e.g. carrying water-oil separating devices

B63B 35/4413

Arrangements for handling drilling fluids or cuttings outside the borehole, e.g. mud boxes (arrangements for treating drilling fluids E21B 21/06 {; waste disposal systems E21B 41/005})
References
Limiting references

This place does not cover:

Arrangements for treating drilling fluids

E21B 21/06

Waste disposal systems

E21B 41/005

Informative references

Attention is drawn to the following places, which may be of interest for search:

Swivel joints in hose-lines

E21B 21/02

Swivel joints in hose-lines
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Hose connections in general

F16L 31/00, F16L 33/00

Valve arrangements in drilling-fluid circulation systems (valves in general F16K)
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Valves in general

F16K

Special rules of classification

Reference F16K is non-limiting in the subgroup E21B 21/10. CPC will be corrected once this inconsistency is resolved in IPC.

using drilling pipes with plural fluid passages, e.g. closed circulation systems (pipes with plural fluid passages E21B 17/18)
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Pipes provided with plural fluid passages

E21B 17/18

Special rules of classification

Looping references between E21B 17/18 and E21B 21/12 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: Reference E21B 17/18 is non-limiting in the subgroup E21B 21/12. CPC will be corrected once this inconsistency is resolved in IPC.

Apparatus for displacing, setting, locking, releasing, or removing tools, packers or the like in the boreholes or wells (setting of casings, screens or liners E21B 43/10)
Definition statement

This place covers:

Actuators for installing tools used for any application in a borehole, wherein the way of installation is more relevant than the function of the tool as such.

References
Limiting references

This place does not cover:

Setting of casings, screens or liners

E21B 43/10

Informative references

Attention is drawn to the following places, which may be of interest for search:

Borehole thrusters

E21B 4/18, E21B 44/005

Fishing for or freeing objects in boreholes or wells

E21B 31/00

Special rules of classification

If a document discloses specific details of actuation or installation according to the meaning of E21B 23/00, and the actuation is done by elements incorporated in the tool, then those details are also classified in E21B 23/00.

The tool in question may in addition be classified in the group that corresponds to its function or construction.

for anchoring the tools or the like (E21B 23/02 - E21B 23/06 take precedence; anchoring of drives in the borehole E21B 4/18)
References
Limiting references

This place does not cover:

Anchoring of drives in the borehole

E21B 4/18

Apparatus for locking the tools or the like in landing nipples or in recesses between adjacent sections of tubing

E21B 23/02

Apparatus for setting the tools into, or removing the tools from, laterally offset landing nipples or pockets

E21B 23/03

Apparatus operated by fluid means

E21B 23/04

Apparatusfor setting packers

E21B 23/06

Informative references

Attention is drawn to the following places, which may be of interest for search:

Introducing or running tools by fluid pressure, e.g. through-the-flow-line tool systems (special provisions on heads therefor E21B 33/068; cementing plugs E21B 33/16; scrapers operated by fluid pressure E21B 37/04)
References
Limiting references

This place does not cover:

Special provisions on heads therefor

E21B 33/068

Cementing plugs

E21B 33/16

Scrapers operated by fluid pressure

E21B 37/04

Informative references

Attention is drawn to the following places, which may be of interest for search:

Tool diverters

E21B 23/12

Tool diverters
Definition statement

This place covers:

Tool diverters, e.g. for through-the-flow line tool systems or for wire-line tools

References
Application-oriented references

Examples of places where the subject matter of this place is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Tool diverters for drilling

E21B 7/06

Tool diverters for setting the tools into, or removing the tools from, laterally offset landing nipples or pockets

E21B 23/03

for displacing a cable or cable-operated tool, e.g. for logging or perforating operations in deviated wells (by fluid pressure E21B 23/08; provision on well heads for introducing or removing cable-operated tools E21B 33/072, E21B 33/076)
References
Limiting references

This place does not cover:

Introducing or running tools by fluid pressure

E21B 23/08

Provision on well heads for introducing or removing cable-operated tools

E21B 33/072, E21B 33/076

Informative references

Attention is drawn to the following places, which may be of interest for search:

Side entry subs for connecting cables or wirelines to downhole devices

E21B 17/025

Control line protectors for plural rods, pipes or lines

E21B 17/1035

Apparatus for obtaining or removing undisturbed cores, e.g. core barrels, core extractors (core bits E21B 10/02; using explosives or projectiles in boreholes E21B 49/04; side-wall sampling or coring E21B 49/06)
Definition statement

This place covers:

Tools for receiving, preserving, transporting etc. a core:

media17.jpg

References
Limiting references

This place does not cover:

Using explosives or projectiles in boreholes

E21B 49/04

Side-wall sampling or coring

E21B 49/06

Informative references

Attention is drawn to the following places, which may be of interest for search:

Core bits

E21B 10/02

Special rules of classification

Looping references between E21B 10/02 and E21B 25/00 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: reference E21B 10/02 is non-limiting in the main group E21B 25/00. CPC will be corrected once this inconsistency is resolved in IPC.

the core receiver being insertable into, or removable from, the borehole without withdrawing the drilling pipe (retrievable drill bits E21B 10/64)
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Retrievable drill bits

E21B 10/64

Special rules of classification

Looping references between E21B 10/64 and E21B 25/02 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: reference E21B 10/64 is non-limiting in the subgroup E21B 25/02. CPC will be corrected once this inconsistency is resolved in IPC.

Containers for collecting or depositing substances in boreholes or wells, e.g. bailers, {baskets or buckets} for collecting mud or sand; Drill bits with means for collecting substances, e.g. valve drill bits
Definition statement

This place covers:

media18.jpg

Vibration generating arrangements for boreholes or wells, e.g. for stimulating production (for drilling E21B 7/24; {for fishing for or freeing objects E21B 31/005;} for transmitting measuring-signals E21B 47/14; for geophysical measurements G01V 1/02)
Definition statement

This place covers:

The vibration is normally generated by tools inside the borehole:

media19.jpg

References
Limiting references

This place does not cover:

Vibration for drilling

E21B 7/24

Vibration for fishing for or freeing objects

E21B 31/005

Vibration for transmitting measuring-signals

E21B 47/14

Vibration for geophysical measurements

G01V 1/02

Informative references

Attention is drawn to the following places, which may be of interest for search:

Vibrating earth formations

E21B 43/003

Cutting or destroying pipes, packers, plugs, or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows (perforators E21B 43/11); Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground {(by enlarging drilled holes or counterboring E21B 7/28)}
Definition statement

This place covers:

Cutting or deforming methods and apparatus for pipes, lines etc. inside the wellbore.

References
Limiting references

This place does not cover:

Reconditioning of well casings while in the ground by enlarging drilled holes or counterboring

E21B 7/28

Perforators

E21B 43/11

Informative references

Attention is drawn to the following places, which may be of interest for search:

Shear-type blow-out preventers

E21B 33/063

Expanding tubulars

E21B 43/103

Cutting windows, e.g. directional window cutters for whipstock operations ({E21B 29/005 and} E21B 29/08 take precedence)
References
Limiting references

This place does not cover:

Cutting a pipe with a cutter rotating along the circumference of the pipe with a radially-expansible cutter rotating inside the pipe

E21B 29/005

Cutting or deforming pipes to control fluid flow

E21B 29/08

Informative references

Attention is drawn to the following places, which may be of interest for search:

Whipstocks

E21B 7/061

Fishing for or freeing objects in boreholes or wells (provisions on well heads for introducing or removing objects E21B 33/068; locating or determining the position of objects in boreholes or wells E21B 47/09)
References
Limiting references

This place does not cover:

Provisions on well heads for introducing or removing objects

E21B 33/068

Locating or determining the position of objects in boreholes or wells

E21B 47/09

{Destroying the objects to be fished, e.g. by explosive means}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Cutting by explosive

E21B 29/02

{using vibrating or oscillating means}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Vibration generating arrangements for boreholes or wells

E21B 28/00

using impact means for releasing stuck parts, e.g. jars (telescoping joints E21B 17/07)
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Telescopic joints

E21B 17/07

Special rules of classification

Looping references between E21B 17/07 and E21B 31/107 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: reference E21B 17/07 is non-limiting in the subgroup E21B 31/107. CPC will be corrected once this inconsistency is resolved in IPC.

Sealing or packing boreholes or wells
Definition statement

This place covers:

Apparatus and methods for sealing, both at the surface and in the interior of a borehole

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Apparatus or methods for producing mixtures of cement with other substances, e.g. slurries, mortars, porous or fibrous compositions

B28C 5/00

Special rules of classification

Pitless wells are also classified in E21B 33/00

Surface sealing or packing
Definition statement

This place covers:

Apparatus for sealing a wellbore and placed outside the wellbore, be it at the surface or subsea, such as wellheads, casing or tubing hangers,

Christmas trees or blow-out preventers:

media20.jpg

{Corrosion protection means}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Corrosion protection means in general

C23F

{electrical connectors}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Underwater electrical connections in general

H01R 13/523

{a suspended tubing or casing being gripped by a slip or an internally serrated member}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Slips in rotary table

E21B 19/10

Blow-out preventers {, i.e. apparatus closing around a drill pipe, e.g. annular blow-out preventers (rotating blow-out preventers E21B 33/085)}
References
Limiting references

This place does not cover:

Rotating blow-out preventers

E21B 33/085

Informative references

Attention is drawn to the following places, which may be of interest for search:

Valve arrangements for boreholes or wells

E21B 34/00

{for shearing drill pipes (cutting of wireline E21B 29/04)}
References
Limiting references

This place does not cover:

Cutting of wireline

E21B 29/04

Informative references

Attention is drawn to the following places, which may be of interest for search:

Cutting pipes

E21B 29/08

Packers; Plugs (used for cementing E21B 33/134, E21B 33/16)
Definition statement

This place covers:

Packers, tools lowered with a reduced diameter and expanded by various means to establish an annular seal between an outer tubular or wall and an inner tubular:

media21.jpg

References
Limiting references

This place does not cover:

Bridging plugs for cementing

E21B 33/134

Using plugs for isolating cement charge

E21B 33/16

Application-oriented references

Examples of places where the subject matter of this place is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Locking packers or plugs in landing nipples

E21B 23/02

Methods or devices for cementing, for plugging holes, crevices, or the like (dump bailers E21B 27/02; chemical compositions therefor C09K 8/00)
Definition statement

This place covers:

Tools for plugging the bore or a well, and to methods for cementing parts of a wellbore, for cementing a casing in the wellbore and similar:

media22.jpg

References
Limiting references

This place does not cover:

Dump bailers

E21B 27/02

Chemical compositions therefor

C09K 8/00

Informative references

Attention is drawn to the following places, which may be of interest for search:

Methods or apparatus for grouting offshore structures

E02B 17/0008

Bridging plugs
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Plastering the borehole wall; Injecting into the formation {(packers E21B 33/12)}
References
Limiting references

This place does not cover:

Informative references

Attention is drawn to the following places, which may be of interest for search:

Consolidation of loose sand or the like round the wells without excessively decreasing the permeability thereof

E21B 43/025

Compositions for plastering the borehole wall

C09K 8/56

for cementing casings into boreholes {(control of cementation quality or level E21B 47/005)}
References
Limiting references

This place does not cover:

Control of cementation quality or level

E21B 47/005

Informative references

Attention is drawn to the following places, which may be of interest for search:

Compositions for cementing

C09K 8/42

Valve arrangements for boreholes or wells (in drilling fluid circulation systems E21B 21/10; blow-out preventers E21B 33/06; oil flow regulating apparatus E21B 43/12; valves in general F16K)
Definition statement

This place covers:

Constructive details of valves specifically adapted for use at the surface of a wellbore or in the interior of a wellbore:

media23.jpg

References
Limiting references

This place does not cover:

Valve arrangements in drilling fluid circulation systems

E21B 21/10

Blow-out preventers

E21B 33/06

Oil flow regulating apparatus

E21B 43/12

Gas lift valves

E21B 43/123

Informative references

Attention is drawn to the following places, which may be of interest for search:

Tool diverters

E21B 23/12

Valves in general

F16K

Special rules of classification

Reference F16K is non-limiting in the main group E21B 34/00. CPC will be corrected once this inconsistency is resolved in IPC.

Methods or apparatus for preventing or extinguishing fires (cutting or deforming pipes to control fluid flow E21B 29/08; controlling flow of fluid to or in wells E21B 43/12; fire fighting in general A62C, A62D)
References
Limiting references

This place does not cover:

Cutting or deforming pipes to control fluid flow

E21B 29/08

Controlling flow of fluid to or in wells

E21B 43/12

Informative references

Attention is drawn to the following places, which may be of interest for search:

Fire fighting in general

A62C, A62D

Prevention of fires in mines or tunnels

E21F 5/00

Special rules of classification

References A62C and A62D are non-limiting in the main group E21B 35/00. CPC will be corrected once this inconsistency is resolved in IPC.

Heating, cooling, insulating arrangements for boreholes or wells, e.g. for use in permafrost zones (drilling by use of heat E21B 7/14; secondary recovery methods using heat E21B 43/24)
Definition statement

This place covers:

Equipment for generating heat at the surface or in the wellbore, for transmitting heat into a wellbore, or for cooling wellbores.

Heating or cooling in the wellbore of fluids produced or of treatment fluids

media24.jpg

References
Limiting references

This place does not cover:

Drilling by use of heat

E21B 7/14

Secondary recovery methods using heat

E21B 43/24

Special rules of classification

If a document describes the extension of the heating action into a reservoir or formation for enhanced recovery, then this operation is classified in E21B 43/24.

Methods or apparatus for cleaning boreholes or wells (E21B 21/00 takes precedence; {bailers E21B 27/00;} cleaning pipes in general B08B 9/02)
Definition statement

This place covers:

Methods or apparatus for cleaning boreholes or wells; Cleaning by physical or chemical action:

media25.jpg

References
Limiting references

This place does not cover:

Flushing of wellbores

E21B 21/00

Bailers

E21B 27/00

Informative references

Attention is drawn to the following places, which may be of interest for search:

Inhibition of corrosion

E21B 41/02

Cleaning pipes in general

B08B 9/02

Special rules of classification

Looping references between E21B 37/00 and B08B 9/02 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: reference B08B 9/02 is non-limiting in the main group E21B 37/00. CPC will be corrected once this inconsistency is resolved in IPC.

operated by fluid pressure, e.g. free-piston scrapers (operating other tools by fluid pressure E21B 23/08)
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Operating other tools by fluid pressure

E21B 23/08

Special rules of classification

Looping references between E21B 23/08 and E21B 37/04 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: Reference E21B 23/08 is non-limiting in the subgroup E21B 37/04. CPC will be corrected once this inconsistency is resolved in IPC.

Well swabs
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Pistons in general

F16J 1/00

Tubing catchers, automatically arresting the fall of oil-well tubing {(preventing small objects from falling into the borehole E21B 41/0021)}
Definition statement

This place covers:

Tubing catchers, automatically arresting the fall of oil-well tubing

References
Limiting references

This place does not cover:

Preventing small objects from falling into the borehole

E21B 41/0021

Informative references

Attention is drawn to the following places, which may be of interest for search:

Slips, spiders

E21B 19/10

Equipment or details not covered by groups E21B 15/00 - E21B 40/00
Definition statement

This place covers:

  • Equipment as specified in the subgroups of E21B 41/00.
  • Equipment specifically adapted for use in earth drilling and not covered by other groups of E21B or by the subgroups of E21B 41/00.
  • Timers and actuators.
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Power stations, adaptations for drilling wells

F03B 13/00

Fuel cells; Manufacture thereof

H01M 8/00

Special rules of classification

The technical field E21B is an application field, wherein many different tools performing various functions find use. Care should be taken not to classify in E21B 41/00 documents describing methods or apparatus marginally related to oil and gas drilling and production for which no suitable class in E21B can be found. Such documents should instead be classified in the groups corresponding to their specific function.

{Apparatus or methods for multilateral well technology, e.g. for the completion of or workover on wells with one or more lateral branches}
References
References out of a residual place

Examples of places in relation to which this place is residual:

Tool diverters

E21B 23/12

Cutting casing windows

E21B 29/06

Informative references

Attention is drawn to the following places, which may be of interest for search:

Whipstocks

E21B 7/061

Specific well pattern

E21B 43/30

{Waste disposal systems}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Collecting oil or the like from a submerged leakage

E21B 43/0122

{Nozzles used in boreholes (drilling by liquid or gas jets E21B 7/18; drill bits with nozzles E21B 10/60; perforators using direct fluid action E21B 43/114; obtaining a slurry of minerals using nozzles E21B 43/29)}
References
Limiting references

This place does not cover:

Drilling by liquid or gas jets

E21B 7/18

Drill bits with nozzle

E21B 10/60

Perforators using direct fluid action

E21B 43/114

Obtaining a slurry of minerals using nozzles

E21B 43/29

Informative references

Attention is drawn to the following places, which may be of interest for search:

Nozzles in general

B05B

{Adaptations of electric power generating means for use in boreholes}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Generation of electric power per se

H02

in situ inhibition of corrosion in boreholes or wells (dump bailers E21B 27/02; chemical compositions therefor C09K 8/54; inhibiting corrosion in general C23F)
References
Limiting references

This place does not cover:

Compositions for in situ inhibition of corrosion in boreholes or wells

C09K 8/54

References out of a residual place

Examples of places in relation to which this place is residual:

Dump bailer

E21B 27/02

Informative references

Attention is drawn to the following places, which may be of interest for search:

Inhibiting corrosion in general

C23F

Special rules of classification

Reference C23F and E21B 27/02 are non-limiting in the main group E21B 41/02. CPC will be corrected once this inconsistency is resolved in IPC.

Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells (applicable only to water E03B; obtaining oil-bearing deposits or soluble or meltable materials by mining techniques E21C 41/00; pumps F04)
Definition statement

This place covers:

Methods and equipment for completion of wellbores and control and improvement of production.

References
Limiting references

This place does not cover:

Production methods applicable only to water

E03B

Installations for obtaining or collecting drinking water or tap water from underground

E03B 3/06

Obtaining oil-bearing deposits or soluble or meltable materials by mining techniques

E21C 41/00

Informative references

Attention is drawn to the following places, which may be of interest for search:

Survey of wellbore pump systems

E21B 47/008

Pumps

F04

Multiphase pumps

F04D 31/00

Jet pumps

F04F 5/00

Special rules of classification

Enhanced recovery methods (E21B 43/16), methods for stimulating production (E21B 43/25) and methods of fracturing (E21B 43/26) are sometimes carried out on the basis of specific chemical compositions. In these cases, the use of those compositions is seen as a method carried out by chemists, and therefore classified respectively in C09K 8/58, C09K 8/60 and C09K 8/62.

Reference F04 is non-limiting in the main group E21B 43/00. CPC will be corrected once this inconsistency is resolved in IPC.

{Vibrating earth formations}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Vibration generating arrangements for boreholes or wells

E21B 28/00

{Production of coal-bed methane (E21B 43/243 takes precedence)}
References
Limiting references

This place does not cover:

Enhanced recovery methods for obtaining hydrocarbons using heat with combustion in situ

E21B 43/243

Informative references

Attention is drawn to the following places, which may be of interest for search:

Methods or devices for drawing-off gases for safety purposes in mines

E21F 7/00

specially adapted for obtaining from underwater installations (underwater well heads E21B 33/035)
Definition statement

This place covers:

Methods specially adapted for obtaining from underwater installations;

Subsea production equipment:

media26.jpg

References
Limiting references

This place does not cover:

Underwater well heads

E21B 33/035

Subsoil filtering (E21B 43/11 takes precedence; chemical compositions for consolidating loose sand or the like around wells C09K 8/56)
Definition statement

This place covers:

  • Subsoil filtering;
  • Production screens and gravelling.

media27.jpg

References
Limiting references

This place does not cover:

Perforators; Permeators

E21B 43/11

Chemical compositions for consolidating loose sand or the like around wells

C09K 8/56

{Consolidation of loose sand or the like round the wells without excessively decreasing the permeability thereof}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Sealing borehole walls

E21B 33/138

Screens or liners {(expandable screens or liners E21B 43/108)}
References
Limiting references

This place does not cover:

Expandable screens or liners

E21B 43/108

Informative references

Attention is drawn to the following places, which may be of interest for search:

Obtaining drinking water using well filters

E03B 3/18

Setting of casings, screens, liners {or the like} in wells (driving or forcing casings into boreholes, simultaneously drilling and casing boreholes E21B 7/20; setting of tools, packers or the like E21B 23/00; suspending casings in well heads E21B 33/04)
Definition statement

This place covers:

Setting of casings, screens, liners or the like in wells;

Running in and installation of tubulars, expandable tubulars:

media28.jpg

References
Limiting references

This place does not cover:

Driving or forcing casings into boreholes, simultaneously drilling and casing boreholes

E21B 7/20

Suspending casings in well heads

E21B 33/04

Informative references

Attention is drawn to the following places, which may be of interest for search:

Setting of tools, packers or the like

E21B 23/00

Special rules of classification

Looping references between E21B 23/00 and E21B 43/10 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: reference E21B 23/00 is non-limiting in the subgroup E21B 43/10. CPC will be corrected once this inconsistency is resolved in IPC.

Perforators; Permeators
Definition statement

This place covers:

Perforators and guns used to create apertures in casing or formation in order to establish a fluid communication with the reservoir for the production of oil or gas. Included are details about construction, ignition, communication and placement.

media29.jpg

Gun or shaped-charge perforators
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Projectiles with shaped or hollow charge

F42B 12/10

{Dropping perforation guns after gun actuation}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Releasing-joints between rod or the like and bit or between rod and rod or the like

E21B 17/06

Methods or apparatus for controlling the flow of the obtained fluid to or in wells (E21B 43/25 takes precedence; valve arrangements E21B 34/00)
Definition statement

This place covers:

Production pumps, lifting wellbore fluids, production chokes:

media30.jpg

References
Limiting references

This place does not cover:

Methods for stimulating production

E21B 43/25

Informative references

Attention is drawn to the following places, which may be of interest for search:

Valve arrangements for boreholes or wells

E21B 34/00

Special rules of classification

Looping references between E21B 34/00 and E21B 43/12 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: reference E21B 34/00 is non-limiting in the subgroup E21B 43/12. CPC will be corrected once this inconsistency is resolved in IPC.

Enhanced recovery methods for obtaining hydrocarbons (fracturing E21B 43/26; obtaining slurry E21B 43/29; reclamation of contaminated soil in situ B09C {; chemical compositions therefor C09K 8/58})
Definition statement

This place covers:

Increasing the fraction of original oil recovered in place in a reservoir, including waterflooding, chemical flooding, gas injection, and thermal methods:

media31.jpg

References
Limiting references

This place does not cover:

Fracturing

E21B 43/26

Obtaining slurry

E21B 43/29

Reclamation of contaminated soil in situ

B09C

Chemical compositions therefor

C09K 8/58

using heat, e.g. steam injection (heating, cooling or insulating wells E21B 36/00 {; in combination with organic material C09K 8/592})
References
Limiting references

This place does not cover:

Compositions for enhanced recovery methods for obtaining hydrocarbons used in combination with generated heat

C09K 8/592

Informative references

Attention is drawn to the following places, which may be of interest for search:

Heating, cooling or insulating wells

E21B 36/00

Special rules of classification

Looping references between E21B 43/24 and E21B 36/00 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: reference E21B 36/00 is non-limiting in the subgroup E21B 43/24. CPC will be corrected once this inconsistency is resolved in IPC.

{by means of nuclear energy}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Nuclear reactors

G21

Methods for stimulating production (dump bailers E21B 27/02; vibration generating arrangements E21B 28/00; {by vibrating earth formations E21B 43/003;} chemical compositions therefor C09K 8/60)
Definition statement

This place covers:

Treatment to restore or enhance the permeability of a well, typically hydraulic fracturing treatments and matrix treatments (acidizing):

media32.jpg

References
Limiting references

This place does not cover:

Dump bailers

E21B 27/02

Vibration generating arrangements

E21B 28/00

Methods for stimulating production by vibrating earth formations

E21B 43/003

Chemical compositions therefor

C09K 8/60

{by means of nuclear energy}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Peaceful applications of nuclear explosive devices in general

G21J 3/00

Dissolving minerals other than hydrocarbons, e.g. by an alkaline or acid leaching agent (E21B 43/241 takes precedence)
Definition statement

This place covers:

Production of minerals other than hydrocarbons by dissolving them in situ with a dissolving agent:

media33.jpg

References
Limiting references

This place does not cover:

Enhanced recovery methods for obtaining hydrocarbons using heat combined with solution mining of non-hydrocarbon minerals

E21B 43/241

Informative references

Attention is drawn to the following places, which may be of interest for search:

Using steerable or laterally extendable nozzles

E21B 43/292

{using heat}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

heating, cooling or insulating wells

E21B 36/00

Gasification of minerals, e.g. for producing mixtures of combustible gases (E21B 43/243 takes precedence)
Definition statement

This place covers:

Obtention of combustible gas from mineral bodies, usually from coal underground.

media34.jpg

References
Limiting references

This place does not cover:

Enhanced recovery methods for obtaining hydrocarbons using heat, the combustion being in situ

E21B 43/243

Glossary of terms

In this place, the following terms or expressions are used with the meaning indicated:

Coal underground

A method for exploiting poor-quality mineral and thin seams by burning the mineral in place to produce combustible gas which can be burned to generate power or processed into chemicals and fuels

Arrangements for separating materials produced by the well (separating apparatus per se, see the relevant subclasses)
Definition statement

This place covers:

Separation of materials produced by the well:

media35.jpg

Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems (for non-automatic drilling control, see the operation controlled; automatic feeding from rack and connecting of drilling pipes E21B 19/20; controlling pressure or flow of drilling fluid E21B 21/08); Systems specially adapted for monitoring a plurality of drilling variables or conditions (means for transmitting measuring-signals from the well to the surface E21B 47/12)
Definition statement

This place covers:

Methods and devices such as sensors for monitoring drilling operations and for controlling the drilling operation in response to the information obtained:

media36.jpg

References
Limiting references

This place does not cover:

Automatic feeding from rack and connecting of drilling pipes

E21B 19/20

Controlling pressure or flow of drilling fluid

E21B 21/08

Means for transmitting measuring-signals from the well to the surface

E21B 47/12

Informative references

Attention is drawn to the following places, which may be of interest for search:

Control systems in general

G05

Arrangements for automatic stopping when the tool is lifted from the working face
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Arrangements for automatic stopping for portable percussive tools

B25D 9/265

Survey of boreholes or wells (monitoring pressure or flow of drilling fluid E21B 21/08)
Definition statement

This place covers:

  • Sensors or devices for obtaining data relative to the wellbore itself.
  • Means for sending information from the well to the surface or from the surface into the well.
Relationships with other classification places

E21B 47/00 includes a wide range of measurements of very different nature. In case the disclosure relates to the specific construction or functioning of a sensor or measuring method, classification in one of the subclasses of G01 as specified in the subgroups should be considered.

Measurements of fluid properties as they flow into the wellbore are classified in E21B 47/10, but devices and methods for obtaining fluid samples are classified in E21B 49/08.

Telecommunication techniques used in an oilfield but other than between wellbore and surface, such as to communicate data from a plurality of producing wells to a centralised location, should not be classified in E21B 47/12, but in the corresponding group relative to its specific application, in this example oil production, if they have an influence in the operation of the production control. If a document mentions only the application to an oilfield or the like, and no specific application in an oilfield operation, but only the details of a communications system are disclosed, that document should be classified in H04L.

References
Limiting references

This place does not cover:

Monitoring pressure or flow of drilling fluid

E21B 21/08

Informative references

Attention is drawn to the following places, which may be of interest for search:

Testing of formations and obtaining samples of fluids or of borehole walls

E21B 49/00

Geophysical logging

G01V

Details, e.g. power supply systems for well logging instruments

G01V 11/002

Special rules of classification

Documents are classified in E21B 47/00 if they disclose a specific application in a downhole environment.

Commonplace measurements such as temperature or pressure should only be classified in E21B 47/06 if specific measurement techniques are disclosed, or if the temperature or pressure data is relevant for the execution of another operation.

Glossary of terms

In this place, the following terms or expressions are used with the meaning indicated:

Borehole

An unlined shaft drilled into the ground, typically for the purposes of extracting water, crude oil or natural gas. This is often referred to as the wellbore.

by visual inspection
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Photographing internal surfaces, e.g. of pipes

G03B 37/005

Closed circuit television systems

H04N 7/18

Determining well or borehole volumes (determining depth E21B 47/04; diameter E21B 47/08)
References
Limiting references

This place does not cover:

Measuring depth of borehole or well

E21B 47/04

Measuring diameter of borehole or well

E21B 47/08

Informative references

Attention is drawn to the following places, which may be of interest for search:

Measuring volumes in general

G01F

Monitoring or checking of cementation quality or level
Definition statement

This place covers:

Processes or apparatus for tracking or examining the extent or integrity of the plugging or consolidating material.

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Measuring temperature at borehole or well

E21B 47/07

Devices for supporting measuring instruments on drill bits, pipes, rods or wirelines; Protecting measuring instruments in boreholes against heat, shock, pressure or the like
Definition statement

This place covers:

Devices for mounting a data collection instrument upon a boring tool, boring tool string or cable-carried tool; Devices for shielding down-hole data collection instruments from damage.

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Flexible or expansible centering means per se

E21B 17/1014

Setting or locking tools in boreholes or wells

E21B 23/00

Protecting measuring instruments
Definition statement

This place covers:

Processes or apparatus for shielding the data collection device against thermal effect, vibration, pressure, debris or the like.

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Cooling or insulating arrangements for boreholes or wells

E21B 36/00

{Cooling arrangements}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Cooling or insulating arrangements for boreholes or wells

E21B 36/00

Determining slope or direction
Definition statement

This place covers:

Processes or apparatus for measuring the inclination or orientation of boreholes or wells.

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Clinometers or direction meters in general

G01C

of penetrated ground layers
Definition statement

This place covers:

Processes or apparatus for measuring the inclination (i.e. dip) or orientation (i.e. strike) of a drilled stratum, e.g. by using a specially adapted compass (e.g. a Brunton compass).

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Apparatus for obtaining oriented cores

E21B 25/16

Formation testing

E21B 49/00

Measuring depth or liquid level
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Measuring depth in general

G01B 7/26

Measuring liquid level in general and telerecorders for level of liquids

G01F

Measuring temperature or pressure
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Measuring temperature in general; Telerecorders for temperature

G01K

Measuring pressure in general; Telerecorders for pressure

G01L

Measuring diameters or related dimensions at the borehole
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Measuring diameter in general

G01B

Locating or determining the position of objects in boreholes or wells {, e.g. the position of an extending arm}; Identifying the free or blocked portions of pipes
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Measuring depth at borehole or well

E21B 47/04

Measuring borehole or well diameter

E21B 47/08

by detecting magnetic anomalies
Definition statement

This place covers:

Processes or apparatus for determining the whereabouts or position of objects in a borehole or well using magnetic attraction/repulsion force irregularities.

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Investigating materials by investigating magnetic variables

G01N 27/72

Locating fluid leaks, intrusions or movements {(using impression packers E21B 47/098)}
Definition statement

This place covers:

Processes or apparatus for determining if the pipes are sufficiently fluid-tight to prevent leakage or ingress of liquid or gas.

Processes or apparatus for detecting unwanted fluids flowing from the formation into the borehole.

Processes or apparatus for detecting the presence and properties of production fluids in the borehole.

Processes or apparatus for determining well debit or flow rate.

References
Limiting references

This place does not cover:

Locating or determining the position of objects in boreholes or wells using impression packers

E21B 47/098

Informative references

Attention is drawn to the following places, which may be of interest for search:

Flow measurement in general

G01F

Examining density and leaking in general

G01M

Detecting leaks, e.g. from tubing, by pressure testing
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Investigating fluid-tightness of structures by using fluid or vacuum

G01M 3/02

Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
Definition statement

This place covers:

Processes or apparatus in which an information or control signal is sent to or from equipment located in the borehole over an information transmission link, for the purpose of measuring while boring.

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Remote signaling in general

G08C

using earth as an electrical conductor (E21B 47/13 takes precedence)
Definition statement

This place covers:

Processes or apparatus in which the transmission link is through the ground.

References
Limiting references

This place does not cover:

Means for transmitting measuring-signals or control signals from the well to the surface or from the surface to the well by electromagnetic energy

E21B 47/13

Informative references

Attention is drawn to the following places, which may be of interest for search:

Magnetic or electric prospecting

G01V 3/00

Electronic transmission systems in which the earth is the medium

H04B 13/02

by electromagnetic energy, e.g. radio frequency
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Magnetic or electric prospecting

G01V 3/00

Electronic transmission in general

H04B

using light waves, e.g. infrared or ultraviolet waves
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Light guides, e.g. optical fibres

G02B 6/00

Optical transmission in general

H04B 10/00

Storing data down-hole, e.g. in a memory or on a record carrier
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Recording in connection with measuring in general

G01D

Recording seismic data

G01V 1/24

Recording data of measuring magnetic field characteristic of the earth

G01V 3/36

Information storage in general

G11

Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells (sampling in general G01N 1/00)
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Sampling in general

G01N 1/00

Special rules of classification

Reference G01N 1/00 is non-limiting in the main group E21B 49/00. CPC will be corrected once this inconsistency is resolved in IPC.

{Testing the nature of borehole walls or the formation by using drilling mud or cutting data}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Investigating chemical or physical properties of materials per se

G01N

{Measuring wall stresses in the borehole}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Investigation of mechanical properties of foundation soil

E02D 1/022

{by injection test; by analysing pressure variations in an injection or production test, e.g. for estimating the skin factor (measuring pressure E21B 47/06)}
References
Limiting references

This place does not cover:

Measuring pressure of boreholes or wells

E21B 47/06

Informative references

Attention is drawn to the following places, which may be of interest for search:

Obtaining fluid samples or testing fluids

E21B 49/08

by mechanically taking samples of the soil (apparatus for obtaining undisturbed cores E21B 25/00; investigation of foundation soil in situ E02D 1/00)
References
Limiting references

This place does not cover:

Apparatus for obtaining undisturbed cores

E21B 25/00

Informative references

Attention is drawn to the following places, which may be of interest for search:

Investigation of foundation soil in situ

E02D 1/00

Special rules of classification

Looping references between E02D 1/00 and E21B 49/02 have been identified. Until this inconsistency is resolved in IPC, the current classification practice in CPC is as follows: reference E02D 1/00 is non-limiting in the subgroup E21B 49/02. CPC will be corrected once this inconsistency is resolved in IPC.

{of underwater soil, e.g. with grab devices}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Underwater coring

E21B 25/18

using explosives in boreholes; using projectiles penetrating the wall
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Drilling by use of explosives

E21B 7/007

Gun or shaped charge perforators

E21B 43/116

Obtaining fluid samples or testing fluids, in boreholes or wells
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Packers

E21B 33/12

Valve arrangements for boreholes or wells

E21B 34/00

Analysing pressure variations in an injection or production test

E21B 49/008

{determining specific fluid parameters}
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Locating fluid leaks, intrusions or movements

E21B 47/10