A rotor and/or stator dampening system includes a stator and/or rotor with a liner selected of one or more materials to achieve a desired dampening effect. In one implementation, a progressive cavity motor or pump includes a stator with an internal axial bore therethrough. The stator has a liner along an axial length thereof with an inwardly facing surface defining the internal axial bore therethrough. The liner has a plurality of axial sections with at least two of the plurality of axial sections being constructed of different materials. A compression resistant mechanism, such as a spring or spring-like device, is disposed within at least one of the axial sections of the liner. The progressive cavity motor or pump also includes a rotor that is disposed and is rotatable within the internal axial bore of the stator to form a moving chamber between the rotor and the stator.

A method, system, and computer-readable medium related to control of mud motors in drilling systems, of which the method includes measuring an eccentricity of rotation of a rotor in a stator of a mud motor using a rotor-position sensor, determining a torque of the mud motor based in part on the eccentricity, and selecting a fluid flow rate, a pressure, or both of fluid delivered downhole, through the mud motor, based in part on the determined torque.

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.

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.

A semi-rigid stator is provided for a helical gear device. The stator includes a stack of rigid rings, a deformable layer, and a rigid housing. Each of the rigid rings has a central opening and an exterior surface. The rigid rings are aligned along a common centerline and rotated slightly relative to each other such that the stack of rigid rings forms a helically convoluted chamber. Each of the rigid rings is secured within the rigid stator housing by the deformable layer disposed between the exterior surface of each of the rigid rings and the rigid housing. The deformable layer bonds the rigid rings together as the ring stack and permits movement of the rigid rings relative to each other.

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.

A stator for a helical gear device includes a first section having first helically convoluted chamber with a set of radially inwardly extending lobes and a second section adjacent to the first section. The second section includes a stack of cutter disks. Each cutter disk includes a front surface, a rear surface, an interior surface defining a central opening extending from the front surface to the rear surface, a forward cutting edge, and a rearward cutting edge. The interior surface forms a same number of lobes for the central opening as the set of radially inwardly extending lobes in the first section. Each cutter disk is aligned along a common centerline, and each cutter disk is rotated slightly relative to each other to form a second helically convoluted chamber with a same pitch as the first helically convoluted chamber. The second helically convoluted chamber exposes, to materials passing through, portions of the forward cutting edge or the rearward cutting edge of each cutter disk.

The present invention aims to provide a long-life stator and a uniaxial eccentric screw pump provided with the stator, which enable a comparatively extended period of use by preventing damage of the stator due to repeating of attachment and removal to/from the uniaxial eccentric screw pump. A stator 20 includes an outer cylinder 30, and a stator main body 42 having flange-shaped gasket parts 46 and 47. The stator 20 includes fixing areas 24 and 25 to which the gasket parts 46 and 47 and the outer cylinder 30 are adhered. One or both of the outer cylinder 30 and the gasket parts 46 and 47 has a derricking part penetrating or being dented in axial directions X and made into such a shape where at least part of one of the outer cylinder and the gasket parts is fitted into the other.

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.

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.