A high-pressure and low-flow core displacement pump based on rock laboratory experiments

Abstract

The invention discloses a high-pressure low-flow rock core displacement pump based on a rock laboratory experiment. A servo motor is connected with the high-speed end of a harmonic gear reducer, and the low-speed end of the harmonic gear reducer is connected with a screw rod through a torque limiter. A bearing sleeve is installed between the screw rod and a shell body. A nut is installed on the screw rod in a sleeving mode, and a piston is installed on the nut in a sleeving mode. The shell body is provided with a long-strip-shaped guiding hole. A cam bearing is arranged between the piston and the shell body. The screw end of the cam bearing is fixedly connected to the piston. The roller end of the cam bearing is located in the long-strip-shaped guiding hole. A sealing sleeve is installed on a piston rod in a sleeving mode. One end of the piston rod is fixedly connected with the piston, and the other end of the piston rod is located in a cylinder body. The shell body is fixedly connected with the cylinder body through the sealing sleeve. Sealing rings are installed between the shell body and the sealing sleeve as well as between the cylinder body and the sealing sleeve. The cylinder body is provided with a low-pressure liquid suction opening and a high-pressure liquid discharging opening which both communicate with an inner cavity of the cylinder body. The high-pressure liquid discharging opening is connected with a pressure sensor. The servo motor conducts feedback control through pressure data sensed by the pressure sensor.

Description

technical field [0001] The invention belongs to the technical field of rock chamber experiments, in particular to a high-pressure and low-flow rock core displacement pump based on rock chamber experiments. Background technique [0002] At present, for the petroleum industry, unconventional natural gas industry (such as shale gas exploitation, etc.), and the development of hot dry rock heat sources, it is necessary to conduct rock laboratory experiments, especially to test the permeability of tight rock matrix through rock laboratory experiments. [0003] Since the porosity of the rock core is very small and its permeability can reach the Nadarcy level, the requirements for experimental precision are very high. The current mainstream rock laboratory experiments include indoor triaxial experiments and indoor true triaxial experiments. The relevant permeability tests of rock samples are completed by combining displacement pumps in rock laboratory experiments. [0004] However,...

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Problems solved by technology

[0004] However, with the continuous improvement of experimental precision requirements, the traditional displacement pump has become more and more difficult to meet the experimental requirements. In the actual use process, it is found that there is a certain degree of micro-leakage in the cylinder seal of the traditional displacement pump. Moreover, this kind of micro-leakage is uncertain, and it will show nonlinearity with the change of experimental pressure and temperature. Due to the existence of micro-leakage, the operation accuracy of traditional displacement pumps will be reduced; moreover, the gears used in traditional displacement pumps Reducer, due to the gear gap, there will be start-up hysteresis and start-up shock when the motor is started in the forward or reverse direction, which makes it difficult for the traditional displacement pump to ensure the stability of the pressure and flow during operation, and its operation stability is poor; In addition, the traditional displacement pump is limited by its own structure, and its output pressure is low, generally not exceeding 70MPa, which is difficult to meet the permeability test under higher pressure conditions

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