| US 7,530,407 B2 | ||
| Rotary coring device and method for acquiring a sidewall core from an earth formation | ||
| Borislav Tchakarov, Humble, Tex. (US); Bahadur Sagoo, Houston, Tex. (US); Quan Phan, Houston, Tex. (US); and David Ashcraft, Katy, Tex. (US) | ||
| Assigned to Baker Hughes Incorporated, Houston, Tex. (US) | ||
| Filed on Aug. 30, 2005, as Appl. No. 11/215,271. | ||
| Prior Publication US 2007/0045005 A1, Mar. 01, 2007 | ||
| Int. Cl. E21B 44/02 (2006.01) | ||
| U.S. Cl. 175—20 [175/27; 175/58; 175/78] | 18 Claims |
| 1. A rotary coring device for acquiring at least one sidewall core from an earth formation adjacent a wellbore, comprising:
a coring tool comprising a rotary coring bit;
a direct-current electrical motor configured for rotating the rotary coring bit at one of a plurality of rotational speeds
wherein the direct-current electrical motor is electrically coupled to a controller configured to generate commutation signals
for controlling operation of the direct-current motor;
a variable reluctance position sensor operably coupled to a rotor of the electrical motor and electrically coupled to the
controller, the position sensor generating position signals indicative of a rotational position of the rotor; and
a hydraulic actuator configured to move the rotary coring bit in a first direction away from the tool toward the earth formation.
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