US 9,810,028 B2
EM gap sub assembly
Vadim Minosyan, Conroe, TX (US); and Peter Harvey, Tampa, FL (US)
Assigned to Canrig Drilling Technology Ltd., Houston, TX (US)
Filed by NABORS DRILLING TECHNOLOGIES USA, INC., Houston, TX (US)
Filed on Jan. 26, 2015, as Appl. No. 14/605,445.
Claims priority of provisional application 61/931,901, filed on Jan. 27, 2014.
Prior Publication US 2015/0211307 A1, Jul. 30, 2015
Int. Cl. E21B 17/00 (2006.01); E21B 17/02 (2006.01); E21B 17/042 (2006.01); E21B 47/12 (2012.01)
CPC E21B 17/003 (2013.01) [E21B 17/028 (2013.01); E21B 17/042 (2013.01); E21B 47/122 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A gap sub assembly comprising:
a generally cylindrical housing having an interior connecting surface including right- and left-handed helical grooves;
a generally cylindrical mandrel having an outer connecting surface inserted into the housing to form a gap between the interior surface of the housing and the outer surface of the mandrel, the outer connecting surface including right- and left-handed helical grooves;
an electrically isolating medium filling the gap between the housing and the mandrel, the electrically isolating medium mechanically coupling the housing and the mandrel while maintaining electrical isolation between the housing and the mandrel;
wherein the right-handed and left-handed grooves on the housing and mandrel surfaces have clearing diameters so that the mandrel can be inserted into the housing without any longitudinal rotation of the mandrel relative to the housing, and
wherein, when the housing and mandrel are connected, the region having right-handed helical grooves formed on the outer surface of the mandrel corresponds to the left-handed helical grooves formed on the interior surface of the housing and/or the region having left-handed helical grooves formed on the outer surface of the mandrel corresponds to the right-handed helical grooves formed on the interior surface of the housing.