Pump-off detection, and actions to avert a pump-off event from occurring, are described that may be implemented in a wireline control system while performing a pump-down operation to position a downhole tool within a wellbore. As part of the pump-down operation, the downhole tool is attached to a wireline coupling the tool to a wireline control device located at the surface above the wellbore.

An example mud pulse telemetry method includes positioning an external acoustic or vibration sensor on or near a pump to collect acoustic or vibration data during operation of the pump. The method also includes monitoring a pressure of fluid in a tubular, the fluid conveying a data stream as a series of pressure variations. The method also comprises processing the monitored pressure to demodulate the data stream. The processing uses a pump noise estimate obtained at least in part from analysis of the acoustic or vibration data.

An example mud pulse telemetry method includes positioning an external acoustic or vibration sensor on or near a pump to collect acoustic or vibration data during operation of the pump. The method also includes monitoring a pressure of fluid in a tubular, the fluid conveying a data stream as a series of pressure variations. The method also comprises processing the monitored pressure to demodulate the data stream. The processing uses a pump noise estimate obtained at least in part from analysis of the acoustic or vibration data.

A control system for operating a beam pumping unit includes a strain gauge and a beam pumping unit controller. The strain gauge is coupled to a Samson post of the beam pumping unit, and is configured to measure a Samson post strain. The beam pumping unit controller is coupled to the strain gauge and is configured to operate the beam pumping unit to induce a variable load on a rod of the beam pumping unit. The beam pumping unit controller is further configured to receive the Samson post strain from the strain gauge and compute the variable load based on the Samson post strain.

A control system for operating a beam pumping unit includes a strain gauge and a beam pumping unit controller. The strain gauge is coupled to a Samson post of the beam pumping unit, and is configured to measure a Samson post strain. The beam pumping unit controller is coupled to the strain gauge and is configured to operate the beam pumping unit to induce a variable load on a rod of the beam pumping unit. The beam pumping unit controller is further configured to receive the Samson post strain from the strain gauge and compute the variable load based on the Samson post strain.

An engine piston is provided. A first sealing structure, including a first sealing rubber ring and a first annular groove, is provided at a head of the engine piston. The first sealing rubber ring has a U-shaped section with a reserved space at the top of the first sealing rubber ring, and a gap for circulating hydraulic oil is provided between a ring bank, above the first sealing rubber ring, of the engine piston and a simulated cylinder liner of a fatigue testing apparatus for an engine piston. In a case that the hydraulic oil is introduced into the fatigue testing apparatus for the engine piston to simulate pressure loading under a high-explosion pressure, when the hydraulic oil enters into the reserved space from the gap for circulating the hydraulic oil, an inner wall of the reserved space is squeezed and the first sealing rubber ring is deformed.

A method and apparatus to reduce the intrusion of ambient air into an open-crankcase compressor. The method employs recycle control to reduce the magnitude of vacuum inside the compressor relative to ambient air pressure, and thereby eliminate the intrusion of said ambient air into said compressor.

A method and apparatus to reduce the intrusion of ambient air into an open-crankcase compressor. The method employs recycle control to reduce the magnitude of vacuum inside the compressor relative to ambient air pressure, and thereby eliminate the intrusion of said ambient air into said compressor.

A pump including one or more pumping chambers, one or more drive mechanisms for driving the one or more pumping chambers and a logic arrangement. The first pumping chamber of the one or more pumping chambers has a first inlet check valve, a first outlet check valve and a first temperature sensor. The logic arrangement is configured to identify a leak by applying logic to at least resistance-data indicative of a resistance of the first pumping chamber to the driving and temperature-data at least based on output from the first temperature sensor.

A pump including one or more pumping chambers, one or more drive mechanisms for driving the one or more pumping chambers and a logic arrangement. The first pumping chamber of the one or more pumping chambers has a first inlet check valve, a first outlet check valve and a first temperature sensor. The logic arrangement is configured to identify a leak by applying logic to at least resistance-data indicative of a resistance of the first pumping chamber to the driving and temperature-data at least based on output from the first temperature sensor.