Abstract: This disclosure relates to a direct drive pumping unit having a reciprocator for reciprocating a sucker rod string and a sensor for detecting position of a polished rod. The reciprocator includes a tower for surrounding a wellhead. The polished rod is connectable to the sucker rod string and has an inner thread open to a top thereof and extends along at least most of a length thereof. A screw shaft extends into the polished rod and interacts with the inner thread. A motor is mounted to the tower, torsionally connected to the screw shaft, and operable to rotate the screw shaft relative to the polished rod.

Abstract: Methods and apparatus for operating a rod pumping unit for a wellbore are provided. One example method includes measuring vibration data in the time domain using at least one sensor coupled to a housing for a moving component of the rod pumping unit; converting the vibration data in the time domain to vibration data in the frequency domain; determining that: (1) at least one frequency component of the frequency-domain vibration data in a first frequency band has a power above a first threshold; or (2) a number of frequency components of the frequency-domain vibration data in a second frequency band having power above a second threshold is above a third threshold; and outputting an indication based on the determination.

Abstract: A long-stroke pumping unit includes a tower, a counterweight assembly movable along the tower, and a crown mounted atop the tower. A sprocket is supported by the crown and rotatable relative thereto. The counterweight is coupled to a belt. The pumping unit further includes a motor having a stator mounted to the crown and a rotor torsionally connected to the sprocket. A sensor is used to detect a position of the counterweight assembly. The pumping unit may include a dynamic control system for controlling a speed of a motor.

Abstract: Methods and apparatus for operating a rod pumping unit for a wellbore are provided. One example method includes measuring vibration data in the time domain using at least one sensor coupled to a housing for a moving component of the rod pumping unit; converting the vibration data in the time domain to vibration data in the frequency domain; determining that: (1) at least one frequency component of the frequency-domain vibration data in a first frequency band has a power above a first threshold; or (2) a number of frequency components of the frequency-domain vibration data in a second frequency band having power above a second threshold is above a third threshold; and outputting an indication based on the determination.

Abstract: An artificial lift system has a surface pump operated by a prime mover powered by a variable speed drive. A jet pump disposed downhole in tubing receives pressurized power fluid from the surface pump, mixes the power and production fluid and delivers the product uphole. A controller disposed at surface adjusts the artificial lift system relative to a set value based on a measured discharged pressure or a measured flowrate and trends a change in the other of the measured flowrate or the measured discharged pressure over time. The controller can also trend an operating condition (intake pressure vs. production rate) to determine changes relative to cavitation conditions. Based on the trended changes, the controller initiates an operation in the artificial lift system, such as adjusting the discharge pressure, initiating an alarm condition, etc.

Abstract: A pumping method can include displacing a rod string with pressure applied to an actuator by a pressure source including an accumulator and a separate gas volume in communication with the accumulator. A sensor indicates whether a fluid is in the gas volume. A pumping system can include an actuator, a pump connected between the actuator and an accumulator, a hydraulic fluid contacting a gas in the accumulator, a separate gas volume in communication with the accumulator, and a sensor that detects the hydraulic fluid in the gas volume. Another pumping system can include an actuator, a pump connected between the actuator and an accumulator that receives nitrogen gas from a nitrogen concentrator assembly while a hydraulic fluid flows between the pump and the actuator, a separate gas volume in communication with the accumulator, and a sensor that detects a presence of the hydraulic fluid in the gas volume.

Abstract: A method of balancing a beam pumping unit can include securing counterweights to crank arms, thereby counterbalancing a torque applied at a crankshaft at a maximum torque factor position due to a polished rod load and any structural unbalance. A well system can include a beam pumping unit including a gear reducer having a crankshaft, crank arms connected to the crankshaft, a beam connected at one end to the crank arm and at an opposite end to a rod string polished rod, and counterweights secured to the crank arms, and in which a torque applied at the crankshaft at a maximum torque factor position due to weights of the crank arms, the counterweights and wrist pins equals a torque applied at the crankshaft at the maximum torque factor position due to a load applied to the beam via the polished rod and any structural unbalance.

Abstract: A method of balancing a beam pumping unit can include securing counterweights to crank arms, thereby counterbalancing a torque applied at a crankshaft at a maximum torque factor position due to a polished rod load and any structural unbalance. A well system can include a beam pumping unit including a gear reducer having a crankshaft, crank arms connected to the crankshaft, a beam connected at one end to the crank arm and at an opposite end to a rod string polished rod, and counterweights secured to the crank arms, and in which a torque applied at the crankshaft at a maximum torque factor position due to weights of the crank arms, the counterweights and wrist pins equals a torque applied at the crankshaft at the maximum torque factor position due to a load applied to the beam via the polished rod and any structural unbalance.

Abstract: A method of balancing a beam pumping unit can include securing counterweights to crank arms, thereby counterbalancing a torque applied at a crankshaft at a maximum torque factor position due to a polished rod load and any structural unbalance. A well system can include a beam pumping unit including a gear reducer having a crankshaft, crank arms connected to the crankshaft, a beam connected at one end to the crank arm and at an opposite end to a rod string polished rod, and counterweights secured to the crank arms, and in which a torque applied at the crankshaft at a maximum torque factor position due to weights of the crank arms, the counterweights and wrist pins equals a torque applied at the crankshaft at the maximum torque factor position due to a load applied to the beam via the polished rod and any structural unbalance.

Abstract: A long stroke pumping unit includes a tower, a counterweight assembly movable along the tower, a crown mounted atop the tower, and a drum supported by the crown and rotatable relative thereto. A belt has a first end connected to the counterweight assembly and a second end connectable to a rod string, and the belt extends over the drum. A linear electromagnetic motor is used to reciprocate the counterweight assembly along the tower. The linear electromagnetic motor includes a traveler mounted to an exterior of the counterweight assembly and a stator extending from a base of the tower to the crown and along a guide rail of the tower. The pumping unit further includes a sensor for detecting position of the counterweight assembly.

Abstract: A long stroke pumping unit includes a tower; a counterweight assembly movable along the tower; a crown mounted atop the tower; a belt having a first end connected to the counterweight assembly and having a second end connectable to a rod string; a prime mover for reciprocating the counterweight assembly along the tower; a sensor for detecting position of the counterweight assembly; a load cell for measuring force exerted on the rod string; a motor operable to adjust an effective weight of the counterweight assembly during reciprocation thereof along the tower; and a controller in data communication with the sensor and the load cell and operable to control the adjustment force exerted by the adjustment motor.

Abstract: A direct drive pumping unit having a reciprocator for reciprocating a sucker rod string and a sensor for detecting position of a polished rod. The reciprocator having a tower for surrounding a wellhead; the polished rod connectable to the sucker rod string and having an inner thread open to a top thereof and extending along at least most of a length thereof; a screw shaft for extending into the polished rod and interacting with the inner thread; and a motor mounted to the tower, torsionally connected to the screw shaft, and operable to rotate the screw shaft relative to the polished rod.

Abstract: A hydraulic pumping system for use with a subterranean well can include an actuator with a displaceable actuator member, a magnet device that displaces with the actuator member, the magnet device including at least one permanent magnet positioned between low magnetic permeability elements, and a sensor that senses a magnetic flux propagated from the magnet device. The actuator can include a cylinder, and the sensor can include an outer tube, with materials of the cylinder and outer tube having substantially a same magnetic permeability. An enclosure can be positioned exterior to the cylinder, with the sensor being positioned at least partially in the enclosure. The enclosure can be configured to focus the magnet flux, so that it propagates to the sensor.

Abstract: A reservoir analysis method can include transmitting a signal from a downhole pump in a wellbore, receiving the signal at another wellbore, and determining a reservoir characteristic from the received signal. A reservoir analysis system can include a downhole pump positioned in a wellbore and a sensor positioned at another wellbore. The downhole pump selectively transmits a signal, and the sensor receives the signal. Another reservoir analysis method can include selectively changing a reciprocating displacement of a rod string connected to a downhole pump in a wellbore, transmitting a signal from the downhole pump in response to the changed reciprocating displacement, receiving the signal at another wellbore, and determining a reservoir characteristic from the received signal.

Abstract: A long-stroke pumping unit includes a tower; a counterweight assembly movable along the tower; a crown mounted atop the tower; a sprocket supported by the crown and rotatable relative thereto; and a belt. The unit further includes a motor having a stator mounted to the crown and a rotor torsionally connected to the sprocket; and a sensor for detecting position of the counterweight assembly. The pumping unit may include a dynamic control system for controlling a speed of a motor.

Abstract: A method for operating rod pumping unit for a wellbore includes measuring a parameter of the rod pumping unit at a first location; measuring the parameter of the rod pumping unit at a second location; and subtracting the measured parameters at the second location from the measured parameter at the first location.

Abstract: A reciprocating rod pumping unit includes a tower; a counterweight assembly movable along the tower; and a drum connected to an upper end of the tower and rotatable relative thereto. The unit also includes a belt having a first end connected to the counterweight assembly, extending over the drum, and having a second end connectable to a rod string. The unit further includes a prime mover for reciprocating the counterweight assembly along the tower; a sensor for detecting a condition of the pumping unit; a brake system for halting movement of the counterweight assembly; and a controller in communication with the at least one of the sensors and operable to activate the brake system in response to detection of the faulty condition of the pumping unit.

Abstract: A long-stroke pumping unit includes a tower; a counterweight assembly movable along the tower; a drum connected to an upper end of the tower and rotatable relative thereto. The unit also includes a belt having a first end connected to the counterweight assembly, extending over the drum, and having a second end connectable to a rod string. The unit further includes a prime mover for reciprocating the counterweight assembly along the tower; a sensor for detecting sudden acceleration of the counterweight assembly due to failure of the rod string; and a controller in communication with the sensor and operable to activate the braking or arrestor system in response to detection of the sudden acceleration. The unit further includes at least one of a braking system for halting free-fall of the counterweight assembly; and an arrestor system for absorbing kinetic energy of the falling counterweight assembly.

Abstract: A system can include an actuator with a piston rod that displaces in response to pressure in the actuator, a seal assembly that seals about the piston rod and includes seal cartridges, each including a dynamic seal sealingly engaging the rod, and each including a static seal sealingly engaging a seal assembly housing, and a port providing communication between a housing exterior and a housing interior between adjacent static seals. A method can include preventing leakage from a well with a seal assembly about a piston rod of a hydraulic actuator, the seal assembly including seal cartridges, each including a dynamic seal that sealingly engages the rod, and each including a static seal that sealingly engages a seal assembly housing, enabling communication through a housing sidewall to a housing interior between adjacent static seals, and reciprocably displacing the rod in response to pressure variations in the actuator.

Abstract: A well pumping system can include an actuator that reciprocates a rod string, and a rod rotator including at least one helical profile and at least one engagement device. The rod string may rotate in response to longitudinal displacement of the rod string while the engagement device is engaged with the helical profile. A method of rotating a rod string in a well can include rotating a rod in a rotary direction, in response to displacement of the rod in a longitudinal direction, and preventing rotation of the rod in an opposite rotary direction, in response to displacement of the rod in an opposite longitudinal direction.