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 a motor at the surface, and a rod string operatively moved by the motor reciprocates the downhole pump in the wellbore. A downhole card 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 card for upstrokes and downstrokes of the downhole pump, and calculated fluid load lines for from the strokes are determined from load values distributed on the downhole card.
Abstract:
A pump drive assembly (10) including a driver (18), a pump drive member (36) driven by the driver (18), and a decoupler (20a) that decouples the drive member (36) from the driver (18) when a force acting upon the drive member (36) exceeds a threshold force. The pump drive member (36) can be a piston rod (36), and the decoupler (20a) can be a magnet (20a) attached to the piston rod (36) and coupled to a magnetically attracted plate (22) driven by the driver (18). When a force resisting movement of the piston rod (36) exceeds the magnetic force coupling the magnet (20a) to the plate (24), the magnet (20a) decouples from the plate (24), and the pumping operation ceases.
Abstract:
A method and system for pumping unit with an elastic rod system is applied to maximize fluid production. The maximum stroke of the pump and the shortest cycle time are calculated based on all static and dynamic properties of downhole and surface components without a limitation to angular speed of the prime mover. Limitations of structural and fatigue strength are incorporated into the optimization calculation to ensure safe operation while maximizing pumped volume and minimizing energy consumption. Calculated optimal prime mover speed is applied to the sucker rod pump by means of beam pumping, long stroke or hydraulic pumping unit by controlling velocity, acceleration and torque of the electric prime mover or by controlling pressure and flow rate in hydraulically actuated sucker rod pumping system.
Abstract:
Techniques and apparatus are provided for improved diagnostics of downhole dynamometer data for control and troubleshooting of reciprocating rod lift systems. A method for pump fillage determination for a reciprocating rod lift system is provided. The method generally includes measuring downhole data during a pump cycle, wherein the downhole data comprises a first plurality of data points associated with an upstroke of the pump cycle and a second plurality of data points associated with a downstroke of the pump cycle, each data point comprising a rod position value and an associated rod load value; converting the data points to non-dimensional data points, calculating non-dimensional slope values between non-dimensional data points; and determining pump fillage based, at least part, on the calculated non-dimensional slope values.
Abstract:
Methods and apparatus to determine operating parameters of a pumping unit for use with wells are disclosed. An example apparatus includes a housing and a processor positioned in the housing. The processor is to determine a rate at which to operate a motor of a pumping unit to enable a load imparted on a polished rod of the pumping unit to be within a threshold of a reference load or to enable a speed of the polished rod to be within a threshold of a reference speed.
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.