A method of actuating a double-action pump assembly with a reciprocating plunger includes signaling the reciprocating plunger to stop for a changeover period; while the pump is stopping, signaling the first inlet and outlet valves to close; while the first inlet and outlet valves are closing, signaling the second inlet and outlet valves to open, such that the second inlet and outlet valves begin to mechanically open at least a dwell period after the first inlet and outlet valves have entirely closed; and signaling the reciprocating plunger to begin moving while the second inlet and outlet valves are closing.

A monitoring system may include at least a strain gauge and a computing device for determining a bulk modulus of a fluid system of a pressure pump using strain measurements. The strain gauge may determine strain in a chamber of the pressure pump. The computing device may receive a strain signal generated by the strain gauge and may correlate the strain signal to pressure to determine a change in pressure during a period in which fluid is isolated in the chamber. The computing device may use the change in pressure during this period to determine a bulk modulus of the fluid system.

A monitoring system may include a strain gauge, a position sensor, and a torque sensor. The strain gauge may measure strain in a chamber of the pressure pump and generate a strain signal representing the strain measurement. The position sensor may measure a position of a rotating member and generate a position signal representing the position measurement. The torque sensor may measure torque in a component of the pressure pump and generate a torque signal representing the torque measurement. The torque measurement may be used with the strain measurement and the position measurement to determine a condition of the pressure pump.

A pump monitoring system for use in wellbore operations includes a strain gauge that can be positioned on a fluid end of a pump and at least one pressure transducer to measure relative pressure. A computing device can be connected to the strain gauge and the pressure transducers. The computing device executes programming instructions to identify failures of specific valves by correlating the strain signal to an actual pressure associated with the specific valve in the pump section. The processor then determines whether a pump pressure corresponds to the actual pressure associated with the specific valve, and if so, displays an indication that the specific valve in the pump section has failed.

According to an embodiment, an apparatus for detecting a characteristic of a pump includes: a housing having a first planar surface and a second planar surface opposite the first planar surface, a mount structure located on the second planar surface, wherein the mount structure is configured to facilitate attachment of the apparatus on an external surface of the triplex pump, and wherein the mount structure avoids penetrating an inside surface of the triplex pump. Advantageously, apparatus is a non-invasive device and does not involve modifications to the pump nor opening the lid of the pump.

A reciprocating compressor-expander according to the present invention comprises a cylinder, a piston, a crankshaft connected to the piston, a first valve for a low pressure compressible fluid, a second valve for a high pressure compressible fluid, and a valve drive mechanism for driving the first valve and the second respectively such that, during a compression process, the low-pressure compressible fluid is sucked into the cylinder from the first valve in synchronization with the rotation of the crankshaft and the high-pressure compressible fluid compressed in the cylinder is discharged from the second valve, and that, during an expansion process, the high-pressure compressive fluid is introduced from the second valve into the cylinder, and the low-pressure compressible fluid expanded in the cylinder is discharged from the first valve.

A monitoring system for a plurality of pressure pumps may include, for each pump, a strain gauge, a position sensor and a pressure transducer. A strain gauge may be positionable on each pump to generate a strain measurement corresponding to strain in each pump. A position sensor may be positionable on each pump to generate a position measurement corresponding to a position of a rotating member corresponding of each pump. A pressure transducer is positionable on each pump to generate a boost pressure measurement that is usable with the strain measurement and the position measurement to determine a cavitation threshold for each pump.

An analysis system may determine a discharge pressure or a suction pressure using a single measurement sensor coupled to a computing device. The measurement sensor may include a pressure sensor or a strain sensor. In some aspects, the pressure sensor may generate a pressure signal representing the total pressure in a chamber of the pressure pump. The computing device may apply an envelope filter to the pressure signal to determine the discharge or suction pressure in the chamber from the pressure signal. In other aspects, the strain sensor may generate a strain signal representing the strain in the chamber. The computing device may determine the discharge or suction portions of the strain signal and may correlate the portions with a predetermined internal pressure for the pressure pump to determine the discharge or suction pressure in the chamber.

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.

A monitoring system may include a position sensor, a strain gauge, and a computing device for determining the condition of a valve in a chamber of a pump using strain measurements. The strain gauge may determine strain in the chamber. The position sensor may determine the position of a crankshaft coupled to a plunger in the chamber. The computing device may receive signals generated by the strain gauge and the position sensor related to the strain in the chamber and the position of the crankshaft, respectively, and may process the signals to determine delays in the actuation of the valves.