砾岩油藏化学驱微观孔隙剩余油分级动用机理--以克拉玛依油田砾岩油藏K7区块为例  

Study on graded production mechanism of remaining oil in micro-pores of chemical flooding in conglomerate reservoirs:A case of conglomerate reservoir in Block K7,Karamay Oilfield,Xinjiang

作　　者：谭龙[1] 聂振荣[1] 熊志国 王晓光[1] 程宏杰[1] 陈丽华[1] 朱桂芳[1] TAN Long;NIE Zhenrong;XIONG Zhiguo;WANG Xiaoguang;CHENG Hongjie;CHEN Lihua;ZHU Guifang(Research Institute of Petroleum Exploration and Development,Xinjiang Oilfield Company,PetroChina,Karamay,Xinjiang,834000,China;Fengcheng Operation Area,Xinjiang Oilfield Company,PetroChina,Karamay,Xinjiang,834000,China)

机构地区：[1]中国石油新疆油田分公司勘探开发研究院,新疆克拉玛依834000 [2]中国石油新疆油田分公司风城作业区,新疆克拉玛依834000

出　　处：《油气地质与采收率》2021年第4期107-112,共6页Petroleum Geology and Recovery Efficiency

基　　金：中国石油科技重大专项“新疆油田已开发水驱油藏二三结合提高采收率技术研究与应用”(2017E-04-06);国家科技重大专项“化学驱提高采收率技术”(2016ZX05010-004)。

摘　　要：砾岩油藏的储层非均质性强、孔隙结构复杂,微观渗流体系呈现稀网状-非网状特征。化学驱常规注入开采极易造成化学剂沿高渗透层突进,中、低渗透层难以动用,波及体积有限,驱油效率低。通过对克拉玛依油田砾岩油藏K7区块探索研究,提出了梯次注入、分级动用的采油方法,采收率大幅度提高。该方法结合油层渗流理论和岩心分析,首先建立受储层非均质性影响的井间压力梯度递减率的计算模型;其次确定化学剂介质渗流阻力的主要影响因素,建立基于储层微观孔隙结构参数、聚合物溶液质量浓度及聚合物相对分子质量的渗流阻力计算公式。在此基础上,依据驱替压力梯度大于渗流阻力时驱油介质才能在油层中流动的理论,在注采井距和注入速度一定的前提下,高阻力的化学剂体系只能进入大孔喉渗透层;随着体系不断推进,驱替压力梯度快速下降,化学剂体系会滞留堵塞大喉道渗透层,此时可梯次降低体系质量浓度,减小阻力系数,使化学剂体系依次进入不同孔喉级别的渗透层,对不同微观孔隙空间的剩余油分级动用。该理论在K7区块的矿场试验中取得了良好的应用效果,油藏化学驱阶段采出程度达15.9%。Conglomerate reservoirs are strongly heterogenous and complex in pore structures,and the microscopic percola⁃tion system presents sparse network-non-network characteristics.Conventional chemical flooding can easily cause chemi⁃cal agents to protrude along high-permeability layers and the medium-and low-permeability layers are difficult to exploit,leading to limited swept volume and low oil displacement efficiency.Through the explorative research in a conglomerate res⁃ervoir in Block K7,Karamay Oilfield,Xinjiang,an oil recovery method of“cascaded injection and graded production”is proposed,dramatically enhancing oil recovery.This method combines the reservoir percolation theory and core analysis.Firstly,a calculation model of the decline rate of inter-well pressure gradients is constructed,which is affected by reservoir heterogeneity.Secondly,the major influencing factors of the percolation resistance to the chemical agent medium are deter⁃mined,and a calculation formula of percolation resistance is created on the basis of the microscopic pore structure parame⁃ters of the reservoir,the mass concentration of polymer solution,and the polymer molecular weight.According to the theory that oil displacement media can flow in reservoir only when the displacement pressure gradient is greater than percolation resistance,the high-resistance chemical agent system can only enter the large pore-throat permeable layer at a constant in⁃jection rate and a fixed injection-production well spacing.As the system continues to advance,the displacement pressure gradient plummets and the chemical agent system can stay and block the large pore-throat permeable layer.At this time,the mass concentration of the system can be reduced in a cascaded manner,and the resistance coefficient can be lowered,so that the system can enter permeable layers at different pore throat levels sequentially,and the remaining oil in different microscopic pore spaces can be produced in grades.This theory has achieved good application effects in th

关 键 词：砾岩油藏 化学驱 渗流阻力 压力梯度 分级动用 剩余油挖潜 

分 类 号：TE357.46[石油与天然气工程—油气田开发工程]