摘要
为实现特低渗油藏注CO2后形成混相驱,通过渗流力学和油藏工程方法研究特低渗油藏CO2混相驱注采压力系统保压设计方法。首先,利用等值渗流阻力法,考虑特低渗油藏压裂后储层渗透率分布的“四台阶”特性,建立特低渗油藏CO2混相驱渗流阻力数学模型;其次,考虑CO2注入地层后溶解于原油所引起的驱替滞后效应,引入CO2驱迟滞因子,对传统前缘推进方程进行修正。在此基础上,建立特低渗油藏CO2混相驱注采压力系统保压设计方法,并从注采压差、注采井距、水井近井渗透率、油井近井渗透率四个方面进行单因素影响程度分析;最后,绘制M油藏在不同注采压差条件下注入速度与CO2混相驱驱替前缘位置的关系图版。结果表明:注采压差对各项保压设计参数影响最大;纯油相区渗流阻力与混相区渗流阻力的比值仅与注采压差有关,与其他因素和驱替前缘位置无关;注入速度是CO2混相驱保压设计的关键,在合理施工参数范围内,注CO2无法实现全程混相驱,驱替前缘极限位置约在油水井距的3/4位置处。研究结果为特低渗油藏CO2混相驱注采压力系统保压设计提供了理论依据和技术指导。
In order to form miscible flooding after CO 2 injection in extra-low permeability reservoir,the pressure maintaining design method of injection-production pressure system in CO 2 miscible driving of extra-low permeability reservoir was studied through seepage mechanics and reservoir engineering methods.Firstly,the seepage resistance mathematical model of CO 2 miscible flooding in extra-low permeability reservoirs was established by using equivalent seepage resistance method with considering the four steps characteristics of reservoir permeability distribution after fracturing in extra-low permeability reservoirs.Secondly,considering the displacement hysteresis effect caused by the dissolution of CO 2 in crude oil after injection into the formation,the CO 2 displacement hysteresis factor was introduced to modify the traditional front-edge displacement equation.On this basis,the pressure maintaining design method of injection-production pressure system in CO 2 miscible driving of extra-low permeability reservoir was established.The influence degree of single factor was analyzed from the following aspects as injection-production pressure difference,injection-production well spacing,near-well permeability of injection well and near-well permeability of production well.Finally,the diagram between the CO 2 injection speed and displacement front position in M reservoir under different injection-production pressure differential conditions were drawn.The results show that the injection-production pressure difference has the greatest influence on the pressure maintaining design parameters.The ratio of seepage resistance in the pure oil zone and the CO 2 miscible zone is only related to the injection-production pressure difference,and has no relationship with the other factors or the displacement front.The CO 2 injection speed is the key parameter for the pressure maintaining design of CO 2 miscible driving.And within the reasonable construction parameters,it is unable to achieve miscible driving in the whole distance.The l
作者
刘同敬
赵习森
任允鹏
第五鹏祥
刘睿
LIU Tong-jing;ZHAO Xi-sen;REN Yun-peng;DIWU Peng-xiang;LIU Rui(The Unconventional Oil and Gas Institute,China University of Petroleum-Beijing(CUPB),Beijing 102249,China;Shanxi Yanchang Petroleum(Group)Co.,Ltd.,Xi an 710075,China;Research Institute of Geosciences,Shengli Oilfield Co.,Ltd.,Sinopec,Dongying 257015,China)
出处
《科学技术与工程》
北大核心
2020年第6期2237-2245,共9页
Science Technology and Engineering
基金
北京市自然科学基金(2173061)
国家科技重大专项(2018YFB060550102,2018YFB060550501)。
关键词
特低渗油藏
CO2混相驱
渗流阻力
驱替前缘
保压设计
extra-low permeability reservoir
CO 2 miscible driving
seepage resistance
displacement front
pressure maintaining design
