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US 10,294,781 B2Granted
Compensator, thrust bearing and torsion bar for servo-driven mud pulser
AssigneeGordon Technologies, LLC
InventorsBenjamin G. Frith, Terrence G. Frith
Life of this patent
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Abstract
A pressure compensator assembly is deployed in a servo-driven mud pulser. The assembly includes a generally tubular compensator sleeve that expands and contracts in a radial direction in order to compensate for pressure differentials across the compensator sleeve. A thrust bearing arrangement is also deployed in a servo-driven mud pulser, the thrust bearing arrangement designed to protect the servo motor from reactive energy caused by servo motor stalls as the motor changes direction of rotation. A torsion bar is deployed in a drill string to protect fragile components and electronics in the drill string by absorbing and smoothing out torsion spikes in the drill string arising from stick-slip events.
Claims16
A compensator assembly in a downhole servo motor assembly, the compensator assembly comprising:
- a servo motor including a rotor and a motor housing, the servo motor received inside an elongate and tubular screen housing;
- a pulser shaft also received inside the screen housing, wherein rotation of the rotor in alternating directions causes corresponding reciprocating motion of the pulser shaft parallel to a longitudinal axis of the screen housing;
- a seal base also received inside the screen housing, the seal base received over the pulser shaft and affixed rigidly and sealingly to an interior wall of the screen housing;
- a compensator sleeve also received inside the screen housing, the compensator sleeve received over the pulser shaft;
- a seal cap also received inside the screen housing, the seal cap received over the pulser shaft, a dynamic seal also received over the pulser shaft and interposed between the seal cap and the pulser shaft such that the dynamic seal permits sealed sliding displacement between the seal cap and the pulser shaft;
- wherein a first end of the compensator sleeve is affixed sealingly to the seal base and a second end of the compensator sleeve is affixed sealingly to the seal cap such that an annular space is created between the compensator sleeve and the interior wall of the screen housing;
- wherein an oil chamber is bounded at least in part by the compensator sleeve and the seal cap, wherein oil in the oil chamber is sealed from commingling with at least (1) drilling fluid in the annular space, and (2) drilling fluid in a cavity sealed off from the oil chamber by the dynamic seal;
- wherein, responsive to pressure differential across the compensator sleeve between oil in the oil chamber and drilling fluid in the annular space and the cavity, the compensator sleeve contracts and expands in a radial direction perpendicular to the longitudinal axis of the screen housing;
- and
- wherein, responsive to said contraction and expansion of the compensator sleeve, the seal cap displaces along the pulser shaft while the oil chamber remains sealed during said seal cap displacement by the dynamic seal.
7 more elements
A drill string section, the drill string section including a drill collar, the drill string further comprising:
- measurement-while-drilling (MWD) equipment;
- a servo motor including a rotor and a motor housing, the servo motor received inside an elongate and tubular screen housing;
- a pulser shaft also received inside the screen housing, wherein rotation of the rotor in alternating directions causes corresponding reciprocating motion of the pulser shaft parallel to a longitudinal axis of the screen housing;
- a seal base also received inside the screen housing, the seal base received over the pulser shaft and affixed rigidly and sealingly to an interior wall of the screen housing;
- a compensator sleeve also received inside the screen housing, the compensator sleeve received over the pulser shaft;
- a seal cap also received inside the screen housing, the seal cap received over the pulser shaft, a dynamic seal also received over the pulser shaft and interposed between the seal cap and the pulser shaft such that the dynamic seal permits sealed sliding displacement between the seal cap and the pulser shaft;
- wherein a first end of the compensator sleeve is affixed sealingly to the seal base and a second end of the compensator sleeve is affixed sealingly to the seal cap such that an annular space is created between the compensator sleeve and the interior wall of the screen housing;
- wherein an oil chamber is bounded at least in part by the compensator sleeve and the seal cap, wherein oil in the oil chamber is sealed from commingling with at least (1) drilling fluid in the annular space, and (2) drilling fluid in a cavity sealed off from the oil chamber by the dynamic seal;
- wherein, responsive to pressure differential across the compensator sleeve between oil in the oil chamber and drilling fluid in the annular space and the cavity, the compensator sleeve contracts and expands in a radial direction perpendicular to the longitudinal axis of the screen housing;
- wherein, responsive to said contraction and expansion of the compensator sleeve, the seal cap displaces along the pulser shaft while the oil chamber remains sealed during said seal cap displacement by the dynamic seal;
- and
- an elongate and tubular torsion bar inserted in the drill string, the torsion bar having (a) a length, (b) an external diameter, and (c) an internal diameter, the torsion bar further comprising at least one feature from the group consisting of:
- (1) the torsion bar comprises a softer material than used to form the drill collar;
- and
- (2) the torsion bar's length provides a reduced diameter portion thereof, the reduced diameter portion having a reduced external diameter.
12 more elements
Dependencies are inferred from the claim text.