A mud motor includes a rotor and a stator. Drilling fluid received by cavities of the mud motor drives the rotor to rotate within the stator. The rotor includes one or more rotor lobes extending helically and defining a rotor pitch. The stator includes two or more stator lobes extending helically and defining a stator pitch. The rotor and the stator together define a tapered profile of the mud motor that varies proceeding from a top end of the mud motor to a bottom end of the mud motor. At least one of the rotor pitch or the stator pitch vary as proceeding from the top end of the mud motor to the bottom end of the mud motor.

An apparatus includes a base, including two motors and a mechanical coupling mechanism, and a cartridge shaped to define two stators and respective pairs of ports in fluidic communication with the stators. The cartridge is removably insertable into the base and includes two rotors disposed, respectively, within the stators. The mechanical coupling mechanism is configured to mechanically couple the rotors to the motors, respectively, such that, following insertion of the cartridge into the base, the motors rotate the rotors, thereby pumping fluid through the pairs of ports. Other embodiments are also described.

A multi-pump apparatus can include a pump unit including two or more motorized pumps, wherein each of the two or more motorized pumps can include a stator and a stator exit. The multi-pump apparatus can further include a plurality of stator exits including each stator exit of each stator of the two or more motorized pumps, and a group of adjustable hoses, wherein the two or more motorized pumps of the pump unit are operable to inject a dense fluid from the plurality of stator exits through the group of adjustable hoses.

A progressing cavity pump has: a stator; a rotor; the rotor having a first axial operating position within the stator in which a first axial part of the rotor aligns with a first axial part of the stator to form an active pump section adapted to generate a pumping force on rotation of the rotor in the stator; the rotor having a second axial operating position within the stator in which the first axial part of the rotor aligns with a second axial part of the stator to form an active pump section adapted to generate a pumping force on rotation of the rotor in the stator. A related method is disclosed.

A progressing cavity pump has: a stator; a rotor; the rotor having a first axial operating position within the stator in which a first axial part of the rotor aligns with a first axial part of the stator to form an active pump section adapted to generate a pumping force on rotation of the rotor in the stator; the rotor having a second axial operating position within the stator in which the first axial part of the rotor aligns with a second axial part of the stator to form an active pump section adapted to generate a pumping force on rotation of the rotor in the stator. A related method is disclosed.

The invention relates to a progressive cavity pump, comprising at least: a stator (1); a rotor (2), which rotates in the stator (1); a drive (3); a pump housing (4), which is connected to the stator (1) and has at least one inlet opening or outlet opening for the medium to be conveyed; a connecting shaft (9), which is driven by the drive and rotates centrally about an axis (R) in ideal operation of the pump; a coupling rod (10), which is arranged, for example, in the pump housing (4), is articulated at the drive-side end to the connecting shaft (9) and is articulated at the rotor-side end to the rotor (2), and produces an eccentric motion of the rotor end (7) when the connecting shaft (9) rotates centrally. Said pump is characterized in that at least one sensor (15, 16) is arranged in the region of the connecting shaft (9) in order to detect or measure a deviation from true running, which sensor determines a motion profile of the connecting shaft (9) at a specified angular position of the connecting shaft by virtue of the fact that the distance of the surface of the connecting shaft (9) from the sensor (15, 16) is measured.

The invention relates to a progressive cavity pump, comprising at least: a stator (1); a rotor (2), which rotates in the stator (1); a drive (3); a pump housing (4), which is connected to the stator (1) and has at least one inlet opening or outlet opening for the medium to be conveyed; a connecting shaft (9), which is driven by the drive and rotates centrally about an axis (R) in ideal operation of the pump; a coupling rod (10), which is arranged, for example, in the pump housing (4), is articulated at the drive-side end to the connecting shaft (9) and is articulated at the rotor-side end to the rotor (2), and produces an eccentric motion of the rotor end (7) when the connecting shaft (9) rotates centrally. Said pump is characterized in that at least one sensor (15, 16) is arranged in the region of the connecting shaft (9) in order to detect or measure a deviation from true running, which sensor determines a motion profile of the connecting shaft (9) at a specified angular position of the connecting shaft by virtue of the fact that the distance of the surface of the connecting shaft (9) from the sensor (15, 16) is measured.

A stator segment is provided for a helical gear device. The stator segment includes a stator tube and modular stator inserts. The stator tube has an inner profile with at least two internal sides that extend longitudinally along an interior of the stator tube. The modular stator inserts each have an outer profile that substantially matches and fits within the inner profile of the stator tube. The modular stator inserts also each have an interior helical profile that defines a central opening. The modular stator inserts are configured to be removably inserted longitudinally into the stator tube along the inner profile of the stator tube. The inner profile aligns the modular stator inserts to form a continuous helical chamber and prevents rotation of the modular stator inserts relative to the stator tube.

Rotary positive displacement machines based on trochoidal geometry, that comprise a helical rotor that undergoes planetary motion within a helical stator are described. The rotor can have a hypotrochoidal cross-section, with the corresponding stator cavity profile being the outer envelope of the rotor as it undergoes planetary motion, or the stator cavity can have an epitrochoidal cross-section with the corresponding rotor profile being the inner envelope of the trochoid as it undergoes planetary motion. In some embodiments, the geometry is offset in a manner that provides structural and/or operational advantages in the rotary machine.

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.