Abstract: A thread structure in accordance to one or more embodiments includes a thread extending helically along a portion of a bit body in spaced thread turns, the thread having a crest extending between a first flank and a second flank and a root extending between the thread turns, the root having a curvature defined by a portion of an ellipse tangentially adjoining the first and second flank at respective flank transition points, the ellipse having a major axis extending parallel to the axis and a minor axis extending perpendicular to the major axis and through a root bottom.

Abstract: Inductive coupler assemblies for controlling the stray magnetic fields of an inductive coupler to reduce the associated losses are disclosed. This results in reduced attenuation (increased efficiency) of the inductive coupler even in the presence of gaps. The assembly includes an inductive coupler having a housing, a biasing element, and a retention mechanism. The assembly further includes a wire surrounded by a ring of flux channel material disposed in the housing. In some embodiments, the retention mechanism is adapted for removal of the inductive coupler from a pipe joint end. The biasing element may be a circumferential spring disposed between the housing and the pipe joint end. The retention mechanism may be a retention snap ring, press fit, or threaded, to removably couple the housing to the pipe joint end.

Abstract: A thread structure in accordance to one or more embodiments includes a thread extending helically along a portion of a bit body in spaced thread turns, the thread having a crest extending between a first flank and a second flank and a root extending between the thread turns, the root having a curvature defined by a portion of an ellipse tangentially adjoining the first and second flank at respective flank transition points, the ellipse having a major axis extending parallel to the axis and a minor axis extending perpendicular to the major axis and through a root bottom.

Abstract: A thread structure in accordance to one or more embodiments includes a thread extending helically along the cylindrical member in spaced thread turns, the thread having a crest extending between a first flank and a second flank and a root extending between the thread turns, the root having a curvature defined by a portion of an ellipse tangentially adjoining the first and second flank at respective flank transition points, the ellipse having a major axis extending parallel to the axis and a minor axis extending perpendicular to the major axis and through a root bottom.

Abstract: Inductive coupler assemblies for controlling the stray magnetic fields of an inductive coupler to reduce the associated losses are disclosed. This results in reduced attenuation (increased efficiency) of the inductive coupler even in the presence of gaps. The assembly includes an inductive coupler having a housing, a biasing element, and a retention mechanism. The assembly further includes a wire surrounded by a ring of flux channel material disposed in the housing. In some embodiments, the retention mechanism is adapted for removal of the inductive coupler from a pipe joint end. The biasing element may be a circumferential spring disposed between the housing and the pipe joint end. The retention mechanism may be a retention snap ring, press fit, or threaded, to removably couple the housing to the pipe joint end.

Abstract: A thread structure in accordance to one or more embodiments includes a thread extending helically along the cylindrical member in spaced thread turns, the thread having a crest extending between a first flank and a second flank and a root extending between the thread turns, the root having a curvature defined by a portion of an ellipse tangentially adjoining the first and second flank at respective flank transition points, the ellipse having a major axis extending parallel to the axis and a minor axis extending perpendicular to the major axis and through a root bottom.

Abstract: A drilling system includes a downhole sampling tool configured to be placed in a wellbore of a subterranean formation and configured to pump formation fluid from the subterranean formation into the downhole sampling tool. The downhole sampling tool includes internal components configured to route the formation fluid through the downhole sampling tool and drill collars configured to hold the internal components of the downhole sampling tool. The downhole sampling tool also includes at least one coupon made from a material that is optically reactive to hydrogen sulfide (H2S). The coupon is disposed in a location that is exposed to the formation fluid that is pumped into the downhole sampling tool, and the location of the coupon is accessible from outside the downhole sampling tool without removing the internal components from the drill collars.

Abstract: Subsurface formation evaluation comprising, for example, sealing a portion of a wall of a wellbore penetrating the formation, forming a hole through the sealed portion of the wellbore wall, injecting an injection fluid into the formation through the hole, and determining a saturation of the injection fluid in the formation by measuring a property of the formation proximate the hole while maintaining the sealed portion of the wellbore wall.

Abstract: Subsurface formation evaluation comprising, for example, sealing a portion of a wall of a wellbore penetrating the formation, forming a hole through the sealed portion of the wellbore wall, injecting an injection fluid into the formation through the hole, and determining a saturation of the injection fluid in the formation by measuring a property of the formation proximate the hole while maintaining the sealed portion of the wellbore wall.

Abstract: An apparatus and method to control the rotation of a downhole drill bit are disclosed. A pair of spaced-apart measuring or survey instruments at the drill string provide data that is analyzed to determine relative rotation between the instruments so that drag affecting the drill bit may be reduced.

Abstract: A method of manufacturing composite parts for an apparatus handling abrasive fluids and an apparatus for handling abrasive slurries, for example, a centrifugal pump. Portions of the composite parts are cast in a two-stage process. Portions to be machined are cast in a material suitable for machining and portions exposed to abrasive slurries are cast in a material that is wear-resistant.

Abstract: An apparatus and method to control the rotation of a downhole drill bit are disclosed. A pair of spaced-apart measuring or survey instruments at the drill string provide data that is analyzed to determine relative rotation between the instruments so that drag affecting the drill bit may be reduced.

Abstract: The invention relates to antenna configurations for electromagnetic logging tools. The antennas have one or more electrical conductors disposed on a dielectric core. The conductor is formed on the core through plating or deposition processes and arranged such that the antenna has a first magnetic dipole moment substantially perpendicular to a longitudinal axis of the core. One embodiment includes an antenna adapted for mutual balancing using interleaved conductive paths or disks to alter the magnetic dipole moment to mutually balance the antenna system. The invention also relates to a method for producing such antenna structures.

Abstract: Techniques are presented for determining the drift of a clock adapted for subsurface disposal. Seismic signals are transmitted through the subsurface medium from an uphole location at selected times, acoustic signals associated with the transmitted seismic signals are received with acoustic sensors at identified downhole locations. First and second transit times for acoustic signals received at an identified downhole reference location are determined using the clock. A time difference between the first and second signal transit times at the reference point is calculated to determine the clock drift.

Abstract: A method and apparatus is provided to determine downhole pressures, such as annular pressure and/or pore pressure, during a drilling operation. A bottom hole assembly (BHA) of a downhole tool includes one or more pressure equalizing assemblies capable of registering the pore pressure when the BHA is at rest and in contact with the wellbore, and annular pressure of a wellbore when it is not. Wellbore fluid is permitted to enter the pressure equalizing assembly and register an annular pressure measurement. Once the BHA comes into contact with the wellbore and to rest, fluid communication is established between the pressure equalizing assembly and the formation to generate a pore pressure measurement. The pressure equalizing assembly includes a sliding valve selectively moveable between an open and closed position in response to operation of the BHA so that the desired pressure measurement may be taken.

Abstract: Techniques are presented for determining the drift of a clock adapted for subsurface disposal. Seismic signals are transmitted through the subsurface medium from an uphole location at selected times, acoustic signals associated with the transmitted seismic signals are received with acoustic sensors at identified downhole locations. First and second transit times for acoustic signals received at an identified downhole reference location are determined using the clock. A time difference between the first and second signal transit times at the reference point is calculated to determine the clock drift.

Abstract: A method and apparatus is provided to determine downhole pressures, such as annular pressure and/or pore pressure, during a drilling operation. A bottom hole assembly (BHA) of a downhole tool includes one or more pressure equalizing assemblies capable of registering the pore pressure when the BHA is at rest and in contact with the wellbore, and annular pressure of a wellbore when it is not. Wellbore fluid is permitted to enter the pressure equalizing assembly and register an annular pressure measurement. Once the BHA comes into contact with the wellbore and to rest, fluid communication is established between the pressure equalizing assembly and the formation to generate a pore pressure measurement. The pressure equalizing assembly includes a sliding valve selectively moveable between an open and closed position in response to operation of the BHA so that the desired pressure measurement may be taken.

Abstract: The invention relates to antenna configurations for electromagnetic logging tools. The antennas have one or more electrical conductors disposed on a dielectric core. The conductor is formed on the core through plating or deposition processes and arranged such that the antenna has a first magnetic dipole moment substantially perpendicular to a longitudinal axis of the core. One embodiment includes an antenna adapted for mutual balancing using interleaved conductive paths or disks to alter the magnetic dipole moment to mutually balance the antenna system. The invention also relates to a method for producing such antenna structures.