Volume 45: Energy Transitions toward Carbon Neutrality: Part VIII

Study on reasonable production allocation method of CO2 assisted gravity flooding in low permeability reservoir considering pressure sensitivity effect Wenkui Huang, Leng Tian, Zechuan Wang, Cong Yang, Mingliang Li, Zhangjun Hou

Abstract

There is a large amount of residual oil in the high part of the reservoir and the recovery rate is low when the high dip angle and low permeability reservoir is developed by water flooding. The use of CO2 assisted gravity flooding can make full use of the geological characteristics of high dip angle and effectively improve the recovery degree of this kind of reservoir. However, because the influence of CO2 on the physical properties of crude oil is much greater than the influence of water on the physical properties of crude oil, the seepage process of fluid in the process of CO2 flooding is more complex, so it is necessary to study the reasonable production allocation optimization of CO2 gravity flooding in low permeability reservoirs. Firstly, according to the relationship between the pressure at any point in the reservoir and the minimum miscible pressure (MMP), the miscible and immiscible models of CO2 gravity flooding in low permeability reservoirs considering the pressure sensitivity effect are established respectively. Secondly, Python is used to solve the model, and the influence of pressure sensitivity coefficient, formation dip angle, injection- production well spacing and gas injection speed on reservoir allocation is analyzed. Finally, combined with the existing work system method and the production increase multiple method, compared with the calculation results of this model, the tNavigtor software is used to predict the recovery rate of the three methods. The results show that this method has a good development effect on the reasonable production allocation of the reservoir, and the recovery rate of the reservoir is relatively high. The research results have a good reference for the development of this kind of low permeability reservoir.

Keywords high dip and low permeability reservoir, CO2 displacement, filtration theory, pressure sensitivity effect, reasonable production allocation