Abstract: Tapered stator designs are engineered in a positive displacement motor (PDM) power section to relieve stator stress concentrations at the lower (downhole) end of the power section in the presence of rotor tilt. A contoured stress relief is provided in the stator to compensate for rotor tilt, where the taper is preferably more aggressive at the lower end of the stator near the bit.

Abstract: A rubber compound for use in a stator. The stator may be deployed in a positive displacement motor. The rubber compound includes a fiber reinforcement, wherein fibers in the fiber reinforcement create a grain direction in which “with the grain” is generally orthogonal to “across the grain”. In some embodiments, the rubber compound has a first value for 25% tensile Modulus across the grain and a second value for 25% tensile Modulus with the grain, wherein the first value is at least 10% lower than the second value. In such embodiments, the fiber reinforcement may further include a fiber loading of greater than 1.0 phr of fibers. In such embodiments, the rubber compound may further have a 25% tensile Modulus of greater than 400 psi across the grain and a 50% tensile Modulus of greater than 700 psi across the grain.

Abstract: Unlaminated bearings (or Torque Transfer Elements, or TTEs) are disposed to slide and displace within pockets (or “housing cavity receptacles”) provided in the internal periphery of a housing in which an articulating shaft is received. As the shaft “tilts” about its untilted axial centerline during misaligned rotation, convex curved bearing surfaces on shaft pins slidably rotate against corresponding concave curved bearings surfaces on the T as received in the housing cavity receptacles. Further, substantially flat surfaces on the TTEs are disposed to slidably displace against corresponding bearing surfaces on the housing cavity receptacles as the shaft tilts and the convex curved bearing surfaces on the shaft pins slidably rotate against the concave curved bearing surfaces on the TTEs. The sliding displacement of TTEs with respect to the housing cavity receptacles during articulated rotation is in a direction generally parallel to the shaft's untilted axial centerline.

Abstract: A stator for use in a positive displacement motor or a progressing cavity pump. The stator comprises an elastomer mix preferably including rubber and a fiber reinforcement. The fiber reinforcement includes a plurality of fibers. The elastomer mix is formed into a stator via an injection molding process. The injection molding process includes a shear flow step in which shear flow is induced in the elastomer mix while the elastomer mix is in an uncured state. The shear flow modifies the orientation of the fibers into an advantageous modified fiber orientation. Shear flow is induced preferably via differential rotation of injection mold assembly elements during the injection molding process. Methods of manufacturing the stator are also disclosed.

Abstract: Tapered stator designs are engineered in a positive displacement motor (PDM) power section to relieve stator stress concentrations at the lower (downhole) end of the power section in the presence of rotor tilt. A contoured stress relief (i.e. a taper) is provided in the stator to compensate for rotor tilt, where the taper is preferably more aggressive at the lower end of the stator near the bit.

Abstract: An adapted elastomer compound, in which the adaptation is based at least in part on load performance data of a rotor/stator test coupon as evaluated on a test apparatus. The test coupon's stator section includes the original elastomer compound before adaptation thereof. The test apparatus includes a motor, a brake, and at least one sensor disposed to evaluate load performance data of the test coupon. The load performance data is the product of the process comprising the steps of: (a) rotating either the rotor section or the stator section on the test apparatus, wherein such rotation section actuates corresponding rotation of the other of the rotor section and the stator section; (b) applying a braking torque to the actuated rotor section or stator section; and (c) responsive to step (b), evaluating load performance data of the test coupon.

Abstract: A ball-CV style transmission suitable for use in a Positive Displacement Motor (PDM). A shaft provides shaft wings received into housing receptacles on a housing. A ball and a Torque Transfer Element (TTE) is interposed between each shaft wing and housing within each housing receptacle, with the ball received into opposing recesses preferably on the shaft wing and the TTE. The TTEs float within their corresponding housing receptacles so as to maintain torque transfer contact between all thrust surfaces during articulated rotation of the shaft with respect to the housing. The TTEs preferably float generally radially towards the shaft centerline as angular deflection increases during articulated rotation.

Abstract: The dynamic fatigue and hysteresis performances of fiber reinforced rubber compounds are compared using different plasticizers. Fiber reinforced rubber compounds including a non-linear functionalized fatty acid ester, preferably a trimellitate, and more preferably Tris (2-Ethylhexyl) Trimellitate (TOTM) are shown to demonstrate greatly improved dynamic fatigue and hysteretic performance as compared to reference fiber reinforced rubber compounds including conventional reference plasticizers such as Di-isodecyl phthalate (DIDP).

Abstract: A rubber compound for use in a stator in a positive displacement motor. The rubber compound includes a fiber reinforcement, wherein fibers in the fiber reinforcement create a grain direction in which “with the grain” is generally orthogonal to “across the grain”. In some embodiments, the rubber compound has a first value for 25% tensile Modulus across the grain and a second value for 25% tensile Modulus with the grain, wherein the first value is at least 10% lower than the second value. In such embodiments, the fiber reinforcement may further include a fiber loading of greater than 5.0 phr of fibers. In such embodiments, the rubber compound may further have a 25% tensile Modulus of greater than 400 psi across the grain and a 50% tensile Modulus of greater than 700 psi across the grain.

Abstract: Tapered stator designs are engineered in a positive displacement motor (PDM) power section to relieve stator stress concentrations at the lower (downhole) end of the power section in the presence of rotor tilt. A contoured stress relief (i.e. a taper) is provided in the stator to compensate for rotor tilt, where the taper is preferably more aggressive at the lower end of the stator near the bit.

Abstract: A rubber compound for use in a stator in a positive displacement motor. The rubber compound includes a fiber reinforcement, wherein fibers in the fiber reinforcement create a grain direction in which “with the grain” is generally orthogonal to “across the grain”. In some embodiments, the rubber compound has a first value for 25% tensile Modulus across the grain and a second value for 25% tensile Modulus with the grain, wherein the first value is at least 10% lower than the second value. In such embodiments, the fiber reinforcement may further include a fiber loading of greater flan 1.0 phr of fibers. In such embodiments, the rubber compound may further have a 25% tensile Modulus of greater than 400 psi across the grain and a 50% tensile Modulus of greater than 700 psi across the grain.

Abstract: A torque transmission comprising input and output shaft adapters. Pins disposed on an outer surface of the input shaft adapter. Each pin provides a curved pin portion oriented generally perpendicular to the input shaft adapter's longitudinal axis. The output shaft adapter provides a recess with a plurality of receptacles (or “notches”) formed in the recess's periphery, wherein the recess is shaped and sized such that when the input shaft adapter is received inside the recess, each pin is received into a corresponding notch. The torque transmission further comprises torsional bearings interposed between the pins and the notches, each torsional bearing providing a curved laminate portion such that the curved laminate portions contact the curved pin portions when the pins are received into their corresponding notches. The torsional bearings may further provide flat laminate portions that contact the notch when the pins are received into the notches.

Abstract: A method for evaluating load performance of a rotor/stator test coupon tested within a sealable test chamber containing test fluid. The test coupon preferably includes at least a partial length of a PDM stage. Alternatively, the test coupon may include a splined rotor/stator. The method includes rotating either the rotor section or the stator section in order to actuate corresponding rotation of the other of the rotor section and the stator section. Non-linear torque in the form of an acceleration torque and/or a braking torque may be applied to either the rotor section or the stator section. Downhole stall conditions may be simulated by selectively engaging and disengaging a second motor and flywheel to vary rotational torque applied to the test coupon. Load performance of the test coupon may be evaluated over time in such simulated stall conditions.

Abstract: A method for evaluating load performance of a rotor/stator test coupon, advantageously within a sealable test chamber comprising test fluid. In some embodiments, the test coupon comprises at least a partial length of a PDM stage, and in others the test coupon comprises a splined rotor/stator. The method includes rotating either the rotor section or the stator section, wherein such rotation actuates corresponding rotation of the other of the rotor section and the stator section. A braking torque is applied to the actuated one of the rotor section and the stator section such that load performance of the test coupon may be evaluated. Embodiments include selectively applying non-linear torque to load the test coupon, and evaluating load performance of the test coupon with reference to relative angular positions of the rotor section and the stator section over time.

Abstract: A method for measuring load performance of a positive displacement motor (PDM) test coupon. The test coupon comprises a partial length of a PDM stage and is received inside a sealable test chamber. In some embodiments, the test coupon may be cut from a failed PDM stage. The test chamber is filled with test fluid. In some embodiments, the test fluid may be drilling fluid sampled from a live well. Rotation of the rotor on the test coupon actuates rotation of the stator. A braking torque is applied to the stator rotation, enabling evaluation of, for example, fatigue load performance of test coupon. Additional embodiments comprise the rotor axis and the stator axis being offset in order to simulate rotor/stator eccentricity in a full size PDM stage.