At present, the major problems of stripper-type wells in Chinese market are commonly low submergence and insufficient liquid supply, so it is particularly important to develop small-displacement subsurface oil-well pump which can match the capacity of oil-well supply. Based on the conclusion of the advantages and disadvantages of the 4 kinds of oil-well pumps, a small-displacement oil-well pump for diameter 25mm with gas-liquid exchange device is developed. The leakage rate of pump is studied by CFD simulation technology, and the reasonable length of exchange device is determined. Meanwhile, the variation of discharge coefficient of this pump with stroke, strokes and submergencepressure is studied via the controlling variable method after establishing the sucker rod pumping indoor test system, and the influence of swabbing parameters on pump performance is analyzed. Additionally, combining with the field tests, the rationality and practicability of small displacement pump are proved. The analysis of field test data shows that the average pump efficiency after test increases relatively at least 7.3% points than before test, and it can be more than 70% after reasonable adjustment of swabbing parameters. Up to July 2018, the performance of small displacement pumps become excellent after testing six wells on the site. As the data shows that average daily fluid production is 2.2m3/d, average pump setting depth is 1171m, average pump efficiency is 53.6%, average repair free period is 725 days, satisfying the lifting requirements of oil wells within the range of 5m3/d displacement and 1500m lift. The pump developed in this paper can meet the production needs of low-yield wells, and provide the references for the popularization of small displacement pumping technology. © 2020, Springer Nature Singapore Pte Ltd.

Polished rod load is an important basis for the design and selection of pumping units. Due to the elastic action of slender sucker rods, the maximum and minimum values of the suspension load increase and decrease, resulting in the increase of the power of pumping units or the increase of pumping units. Firstly, the mathematical model of suspension dynamic load of beam pumping unit is established, the mechanism of damping on suspension dynamic load is analyzed; a metal spring suspension is designed and hysteresis characteristic test is carried out. The laboratory experiment of metal spring suspension is carried out on the pumping unit test bench. The results show that the maximum polished rod load and dynamic load are reduced by adding metal rubber element. The maximum load reduction rate is about 10%. With the increase of the relative density of metal rubber, the maximum polished rod load decreases and the dynamic load reduction rate decreases under the same pumping stroke. Therefore, the elastic damped suspension can effectively reduce the maximum suspension load and alternating load, which has important engineering practical significance for energy-saving exploitation and improving the operation conditions of pumping units, and provides a new idea for the application of pumping units in deep wells. © 2020, Springer Nature Singapore Pte Ltd.

On-line measurement of oil well multi-phase flow split-phase content is of great significance to the analysis of oil well production dynamics. This paper proposes an online measurement model of oil-well multi-phase flow split-phase measurement based on multi-sensors of differential pressure device and radio frequency device, and conducts experiments. This paper explores the close relationship between the pressure fluctuation signal of the gas-liquid two-phase flow and the parameters of the two-phase flow, such as the flow pattern, gas phase content and other parameters, analyzes the characteristic values of the differential pressure fluctuation signal, and establishes a number of dimensionless parameters and gas phase The relationship model of the content rate; considering the influence of temperature, fluid state, salinity and other factors on the radio frequency moisture content measurement, an optimized support vector machine moisture content data fusion measurement model is established. A gas-liquid measurement sample is obtained through a laboratory multi-phase flow verification and calibration device, and multiple linear regression correction is performed on the differential pressure method flow test data to obtain a correlation with better measurement accuracy. Experimental research shows that the oil volume multi-phase flow split-phase metering model established in this paper has a liquid volume error of less than 5%, a water cut error of less than 2%, and a gas volume error of less than 10%, which improves the application range and measurement accuracy of oil well multi-phase flow measurement. © 2020 ACM.