致密储层不同二氧化碳注入方式下的沥青质沉积特征及其对渗透率的影响  

Asphaltene Deposition Characteristics and Their Effects on the Permeability of Tight Reservoirs under Different CO_(2) Injection Modes

作　　者：杨明洋 黄世军[1,2] 赵凤兰[1,2] 孙浩月 陈新阳 YANG Mingyang;HUANG Shijun;ZHAO Fenglan;SUN Haoyue;CHEN Xinyang(College of Petroleum Engineering,China University of Petroleum(Beijing),Beijing,102249,P R of China;National Key Laboratory of Petroleum Resources and Engineering(China University of Petroleum(Beijing)),Beijing,102249,P R of China)

机构地区：[1]中国石油大学(北京)石油工程学院,北京102249 [2]油气资源与工程全国重点实验室(中国石油大学(北京)),北京102249

出　　处：《油田化学》2024年第1期85-92,共8页Oilfield Chemistry

基　　金：国家自然科学基金面上项目“页岩油注CO_(2)过程中重有机质沉积机理表征及预测”(项目编号52174039);中国石油天然气集团有限公司-中国石油大学(北京)战略合作科技专项“鄂尔多斯盆地致密油-页岩油油藏工程方法及关键技术研究”(项目编号ZLZX2020-02-04)。

摘　　要：注CO_(2)引起的原油沥青质沉积对致密储层造成的伤害严重影响其开发效果。为明确不同CO_(2)注入方式下的沥青质沉积特征及其对储层渗透率的影响,对致密岩心分别进行了CO_(2)驱替和吞吐两种注入方式的实验,通过核磁共振和扫描电镜等,分析了两种注入方式下的沥青质沉积特征、原油采出程度以及对致密岩心渗透率的影响。结果表明,两种CO_(2)注入方式下的致密岩心均会产生沥青质沉积,且主要以膜状吸附的方式沉积在孔隙表面。受CO_(2)与原油相互作用时间的影响,吞吐方式下的沥青质沉积量大于驱替方式,且吞吐方式下的沉积孔径范围高于驱替方式。沥青质沉积对致密岩心渗透率的伤害程度与原油的产出方向有关。驱替方式下沥青质沉积对岩心正向(CO_(2)注入方向)渗透率的伤害程度较大,而吞吐方式下沥青质沉积对岩心逆向渗透率的伤害程度较大。在围压为10、5 MPa时,CO_(2)驱替和吞吐方式下的沥青质沉积对岩心正向渗透率的伤害程度(正向渗透率平均降幅)分别为7.05%和1.67%,对岩心逆向渗透率的伤害程度(逆向渗透率平均降幅)分别为0.41%和2.66%。受注采模式和流动机制的影响,CO_(2)吞吐方式下的采出程度低于驱替方式。研究结果对于致密储层CO_(2)驱沥青质沉积不同方向上储层伤害程度的认识及注入方式的优选具有一定的指导意义。The asphaltene deposition of crude oil caused by CO_(2) injection will damage the tight reservoir and seriously affect the ultimate recovery.In order to clarify the characteristics of asphaltene deposition and the influence on reservoir permeability under different CO_(2) injection methods,the experiments of CO_(2) flooding and CO_(2) huff-n-puff were carried out.The characteristics of asphaltene deposition,the performance of oil recovery,and the influences on the permeability of tight cores under different injection methods were analyzed by nuclear magnetic resonance(NMR)and scanning electron microscope(SEM).The results showed that the asphaltene deposition occurred in the tight cores under both of CO_(2) flooding and huff-n-puff,which was mainly deposited on the pore surface by membrane adsorption.Influenced by the interaction time between CO_(2) and crude oil,the amount of asphaltene deposition under CO_(2) huff-n-puff was greater than that under CO_(2) flooding.Moreover,the pore size range of asphaltene deposition under CO_(2) huff-n-puff was higher than that of CO_(2) flooding.The damage of asphaltene deposition to core permeability was related to the direction of crude oil production.Asphaltene deposition had greater damage to the forward(CO_(2) injection direction)core permeability under CO_(2) flooding,while that had greater damage to the reverse core permeability under CO_(2) huff-n-puff.When the confining pressure was 10 MPa and 5 MPa,the damage of asphaltene deposition under CO_(2) flooding and CO_(2) huff-n-puff to the forward core permeability(average decrease of forward permeability)was 7.05%and 1.67%,while the damage degree of the reverse core permeability(average decrease of reverse permeability)was 0.41%and 2.66%,respectively.Due to the influence of injection-production mode and flow mechanisms,the recovery of CO_(2) huff-n-puff was lower than that of CO_(2) flooding.The research results were significant in understanding the damage caused by asphaltene deposition in different directions and selec

关 键 词：致密储层 CO_(2)驱替 CO_(2)吞吐 沥青质沉积 渗透率 

分 类 号：TE341[石油与天然气工程—油气田开发工程]