胜利油田低渗透油藏CO2混相驱合理注采井距研究  

Reasonable well spacing for CO2 miscible flooding in low-permeability reservoirs of Shengli Oilfield

作　　者：李金志 LI Jinzhi(Oil and Gas Development Management Center,Shengli Oilfield Company,SINOPEC,Dongying City,Shandong Province,257001,China)

机构地区：[1]中国石化胜利油田分公司油气开发管理中心,山东东营257001

出　　处：《油气地质与采收率》2020年第3期64-69,共6页Petroleum Geology and Recovery Efficiency

基　　金：国家科技重大专项“渤海湾盆地济阳坳陷致密油开发示范工程”(2017ZX05072);中国石化重大示范工程课题“低丰度特低渗滩坝砂油藏CO2驱技术研究与示范”(P18088-2)。

摘　　要：针对利用组分数值模拟优化井距复杂、常规技术极限井距计算方法不能考虑储层非均质性和CO2驱原油黏度随空间变化的问题,通过大量室内实验,回归得到胜利油田低渗透油藏启动压力梯度与储层空气渗透率的关系式;基于非达西渗流理论,考虑储层非均质性、CO2降低原油黏度、对流、扩散、吸附等特性,建立了CO2混相驱直线井排注采压差数学模型,进而建立了临界流动井距和产量合理井距的确定方法。以胜利油田某低渗透油藏为例,计算其临界流动井距。研究结果表明,当空气渗透率增大到一定值后,随着渗透率的增大,启动压力梯度逐渐减小,且变化平稳,当空气渗透率减小到一定值后,随着渗透率的减小,启动压力梯度急剧增大。对于胜利油田某低渗透油藏,随着注采压差的增大,产量合理井距逐步增大,计算的产量合理井距与实际注采井距较为吻合,验证了本文计算方法的可靠性。Considering the complexity of optimizing well spacing with component numerical simulation,and the insufficiency of capturing reservoir heterogeneity and oil viscosity changing with space in CO2 flooding with conventional well spacing calculation methods,through a large number of experiments,the relationship between the threshold pressure gradient(TPG)and the permeability of low-permeability reservoir in Shengli Oilfield is obtained by regression.Based on the non-Darcy theory and considering the reservoir heterogeneity,reduced viscosity of crude oil by CO2 flooding,convection,diffusion and adsorption,a mathematical model of injector-producer pressure difference of line well pattern in CO2 miscible flooding is established,and methods to determine the critical flow well spacing and the reasonable production well spacing are proposed.Taking a low-permeability reservoir in Shengli Oilfield as an example,the critical flow well spacing for CO2 miscible flooding is calculated.The results indicate that when the permeability increases to a certain value,TPG stably decreases with the increase of permeability.When the apparent permeability decreases to a certain value,TPG sharply increases with the decrease of permeability.For the low-permeability reservoirs in Shengli Oilfield,with the increase of injector-producer pressure difference,the reasonable production well spacing gradually increases,and the calculated reasonable production well spacing is consistent with the actual injector-producer well spacing,which verifies the reliability of the calculation method in this paper.

关 键 词：低渗透油藏 启动压力梯度 CO2驱 混相驱 注采井距 

分 类 号：TE357.45[石油与天然气工程—油气田开发工程]