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: Techniques and apparatus are provided for stress calculations for sucker rod pumping systems. A method is provided for determining stress along a sucker rod string disposed in a wellbore. The method generally includes receiving, at a processor, measured rod displacement and rod load data for the sucker rod string, wherein the sucker rod string comprises a plurality of sections; and calculating stress values at a plurality of finite difference nodes for at least one of the plurality of sections based, at least in part, on the measured rod displacement and rod load data.

Abstract: A pump apparatus has a downhole pump disposed in a wellbore and has a motor at the surface, and a rod string operatively moved by the motor reciprocates the downhole pump in the wellbore. Downhole data indicative of load and position of the downhole pump is generated using surface measurements and a wave equation model having an upstroke damping factor and a downstroke damping factor. Actual fluid load lines are determined from the downhole data for upstrokes and downstrokes of the downhole pump, and calculated fluid load lines for from the strokes are determined from the distribution of the load values in the downhole data. The actual fluid load lines are compared to the calculated fluid load lines to determine if the downhole card is over or under-damped. Then, at least one of the upstroke or downstroke damping factors of the wave equation model is adjusted so that new downhole data can be generated with appropriate damping.

Abstract: A pump apparatus has a downhole pump disposed in a wellbore and has a motor at the surface, and a rod string operatively moved by the motor reciprocates the downhole pump in the wellbore. Downhole data indicative of load and position of the downhole pump is generated using surface measurements and a wave equation model having a damping factor. Actual fluid load lines are determined from the downhole data for upstrokes and downstrokes of the downhole pump, and calculated fluid load lines for from the strokes are determined from the distribution of the load values in the downhole data. The actual fluid load lines are compared to the calculated fluid load lines to determine if the downhole data is over or under-damped. Then, the damping factor of the wave equation model can be adjusted so that new downhole data can be generated with appropriate damping.

Abstract: Diagnosing a pump apparatus having a downhole pump disposed in a deviated wellbore characterizes axial and transverse displacement of a rod string with two coupled non-linear differential equations of fourth order, which include axial and transverse equations of motion. To solve the equations, derivatives are replaced with finite difference analogs. Initial axial displacement of the rod string is calculated by assuming there is no transverse displacement and solving the axial equation. Initial axial force is calculated using the initial axial displacement and assuming there is no transverse displacement. Initial transverse displacement is calculated using the initial axial force and the initial axial displacement. Axial force and friction force are calculated using the initial displacements, and the axial displacement at the downhole pump is calculated by solving the axial equation with the axial force and the friction force. Load at the downhole pump is calculated so a downhole card can be generated.

Abstract: A pump apparatus has a downhole pump disposed in a wellbore and has motor at a surface of the wellbore, and the downhole pump is reciprocated in the wellbore by a rod string operatively moved by the motor. A card indicative of load and position of the downhole pump is generated using surface measurements and a wave equation model having a damping factor or two damping factors. Actual fluid load lines are determined from the downhole card for upstroke and downstroke of the downhole pump, and calculated fluid load lines from the load distribution of the downhole data. The actual fluid load lines are compared to the calculated fluid load lines so that at least one parameter of the pump apparatus can be modified based on the comparison. For example, the damping of the wave equation model can be adjusted so that another downhole card can be generated.