Study On The Technology Of Downhole Gas-water Separation And Reinjection System

This paper presents application of downhole gas-water separation technology can be output of water directly into the same well water recharge in gas well production. In this paper, put forward the use of spiral hydrocyclone for underground gas and water separation by the first time. Original design of a set of spiral hydrocyclone used to inject water and gas separation process with the well water system layer. The result shows that:First of all, the paper bring forward that using spiral cyclone separator for downhole gas-water separation is reasonable combination of conventional gas-well processes. The paper make the pitch of spiral separator, the number of spiral,as well as liquid flow and gas flow as the basic structure parameters impacting the performance and efficiency of separation in the first time.Second, the formula of droplet coalescence is derived by gas-liquid separation of flow field from the actual flow field. At the same time, the paper attempt to put forward the diagnosis of effusion of natural gas wells and the preparation of the wellbore fluid prediction software. Combination of underground conditions at the actual situation, it determines the pitch of spiral separator and the number of spiral under different acceleration of diameter of particle and founds the theoretical basis of spiral separator.Third, the paper analyzes the Reynolds Stress Model (RSM) as the most suitable model for the numerical simulation of turbulence. For 11 models parameters, respectively, it uses FLUENT software to simulate the single-phase of gas flow field and gas-liquid of two-phase flow field, and detailed study the relationship: the changes of structural parameters of spiral separator and the turbulent gas flows as well as the impact of separation efficiency factors. Results are obtained that the pitch, the number of spiral has relationship with separator pressure drop, cross-section pressure drop, velocity's distribution and separation efficiency. As pressure drop is the important parameter of hydrocyclone energy consumption, so the structural parameters and the the pressure drop's relationship is focused on the paper. The result shows that: when the speed of entrance and the number of spiral are fixed,the smaller the pitch, the greater the pressure drop with gas go through the separation; the greater the pitch, the smaller the pressure drop. When the pitch is fixed, the speed of entrance is greater, the pressure drop that gas pass the separator is greater. On the other hand when the pitch is not changed, the number of spiral is greater, the pressure drop is greater. At the same time, the law of pressure drop in cross-section is same with the whole separator by the simulation results. Also by the simulation results it can be seen that the velocity of entrances has greater impact on the velocity distribution in cross-section. The simulation study of gas-liquid separator and structure parameters and operating parameters of the relationship found that the number of spiral is more ,particles in the separator to isolate the time longer, higher separation efficiency when the pitch, particle diameter are under the same conditions. Under the structure in the same conditions, diameter of particles is larger, gas-liquid separated is more easily. According to single-phase of gas and gas-liquid two-phase analysis of simulation results, while overall energy consumption efficiency and separation factors, the paper obtains the best structure of Case1, that is, pitch for D1, the number of spiral for N1.This article also design spiral hydrocyclone laboratory frame, combined with the actual parameters of the production and results of numerical simulation, through experiments, confirmed the pitch for D1, the number of spiral for N1 has a good gas - water separation efficiency that the separation efficiency is more than 90%.Finally, the paper give the success of the design of the first: spiral hydrocyclone combination of helical screw pump, respectively, spiral hydrocyclone combination of electric submersible pump.With the combination of the two sets of downhole gas-water separation devices, it design software of underground gas-water separation and injection. At the same time, the paper select a wells in Shengli Oilfield, the use of gas-liquid separator with spiral frame and helical screw pump injection in field test, it achieved remarkable results.