Feasibility Study on Downhole Gas–Liquid Separator Design and Experiment Based on the Phase Isolation Method

Yuntong Yang,Wancun Liu,Gang Deng,Lianfu Han,Zhaoyu Jiang,Xingbin Liu

doi:10.3390/app112110496

Abstract

As oil exploitation enters its middle and late stages, formation pressure drops, and crude oil degases. In production profile logging, the presence of the gas phase will affect the initial oil–water two-phase flowmeter’s flow measurement results. In order to eliminate gas-phase interference and reduce measurement costs, we designed a downhole gas–liquid separator (DGLS) suitable for low flow, high water holdup, and high gas holdup. We based it on the phase isolation method. Using a combination of numerical simulation and fluid dynamic measurement experiments, we studied DGLS separation efficiency separately in the two cases of gas–water two-phase flow and oil–gas–water three-phase flow. Comparative analysis of the numerical simulation calculation and dynamic test results showed that: the VOF model constructed based on k−ε the equation is nearly identical to the dynamic test, and can be used to analyze DGLS separation efficiency; the numerical simulation results of the gas–water two-phase flow show that when the total flow rate is below 20 m3/d, the separation efficiency surpasses 90%. The oil–gas–water three-phase’s numerical simulation results show that the oil phase influences separation efficiency. When the total flow rate is 20 m3/d–50 m3/d and gas holdup is low, the DGLS’s separation efficiency can exceed 90%. Our experimental study on fluid dynamics measurement shows that the DGLS’s applicable range is when the gas mass is 0 m3/d~15 m3/d, and the water holdup range is 50%~100%. The research presented in this article can provide a theoretical basis for the development and design of DGLSs.

Highlights

As one of the world’s three major energy sources, oil reserves and production have an effect on many countries’ economic development
We studied the change in the downhole gas–liquid separator (DGLS)’s gas separation efficiency when gas phaserange efficiency within the range of 20 m3/d~30 m3/d, and its error is within thethe allowable increases.to As in Figure the gas thethe water (according theshown conditions (e)). 5, With the holdup increaseisin10%, flowand rate, gas holdup holdupisin90%
We designed a DGLS for the oil–gas–water multiphase flow of lowproduction liquid and high-water combine with the phase isolation method

Summary

Introduction

As one of the world’s three major energy sources, oil reserves and production have an effect on many countries’ economic development. With the increase in demand, petroleum reserves will decrease year by year. The efficient development of petroleum resources has become a crucial research direction in many countries. Oil production in China is dependent on the exploitation of onshore oilfields. Fluid production profile logging technology [1,2] is a key link in oilfield production. Providing oil–water stratified production is integral to the efficient development of oilfields. During the high water-cut development period, formation pressure declines, natural gas is freed from the oil, and the wellbore is a three-phase flow of oil, gas, and water

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Conclusion