Efficiency research of the reducing the gas pressure in the annulus

UDK: 622.276.34
DOI: 10.24887/0028-2448-2019-11-134-138
Key words: production well, annular gas pressure, optimization, three-phase stationary flow, gas factor, volume fraction of gas at the inlet, compressor flow
Authors: V.V. Belozerov (BashNIPIneft LLC, RF, Ufa; Ufa State Petroleum Technical University, RF, Ufa) R.U. Rabaev (Ufa State Petroleum Technical University, RF, Ufa), V.A. Molchanova (Ufa State Petroleum Technical University, RF, Ufa)

One of the key factors affecting the operating efficiency of producing wells, especially with a high gas content in the product, is to maintain the optimum annular gas pressure. The accumulation of petroleum gas in the annulus in the process of oil extraction by the mechanized method, in particular by sucker-rod pumping units, leads to a decrease in depression on the reservoir, the influx of formation fluid and other negative consequences. The above determines the relevance of the use of various methods and technologies for pumping gas from the annular space of producing wells.

The article investigates the problem of optimizing the annular gas pressure and evaluating the effectiveness of its reduction by calculating the potential increase in well flow rate. As optimization criteria, the joint implementation of the following conditions was proposed: ensuring the permissible volume fraction of gas at the inlet, minimum pump immersion under the dynamic level, and maximizing the flow rate of the well. A two-stage algorithm for calculating the parameters of an optimal well operation mode was developed, based on a mathematical model of a three-phase steady-state fluid flow in a wellbore, taking into account phase transitions, hydraulic losses, and the effect of oil and gas slippage. A study was made of the influence of the gas factor and the water content of the product on the effectiveness of reducing gas pressure in the annulus of producing wells. Simulation has shown that the optimal annular gas pressure increases with increasing gas factor and decreasing water cut, and in the natural gas separation mode at the intake it can reach up to 4.0 MPa. It was proposed to use gas separators and anchors as part of a shafts system, which, all other things being equal, would reduce the optimal annular pressure of gas and ultimately increase well production and operating efficiency. Calculations show that pumping gas from the well annular space allows, under favorable geological and technical conditions, to obtain a significant inease in fluid flow rate — up to 15–20 m3/day.


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