长岩心CO_(2)非混相驱中注气速率对重力超覆的影响  

Effect of Gas Injection Rate on Gravity Segregation during CO_(2) Long Cores Immiscible Flooding

作　　者：赵凤兰[1,2] 宋黎光 冯海如 王强[1,2] ZHAO Fenglan;SONG Liguang;FENG Hairu;WANG Qiang(College of Petroleum Engineering,China University of Petroleum(Beijing),Beijing 102249,P R of China;Key Laboratory of Petroleum Engineering(Ministry of Education),Beijing 102249,P R of China;Jidong Oilfield Branch Company,PetroChina,Tangshan,Hebei 063000,P R of China;Offshore Oil Engineering Company Ltd,Tianjin 300451,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]石油工程教育部重点实验室,北京102249 [3]中国石油冀东油田分公司,河北唐山063000 [4]海洋工程股份有限公司,天津300451

出　　处：《油田化学》2021年第2期273-278,295,共7页Oilfield Chemistry

基　　金：十三五国家科技重大专项课题“低渗-致密油藏高效提高采收率技术”(项目编号2017ZX05009-004);中石油战略合作科技专项“注气提高单井产量技术研究”(项目编号ZLZX2020-02-04-04)。

摘　　要：针对室内难以模拟真实油气运移中重力超覆的问题,课题组自主研制了一种二维高温高压气驱超覆物理模型,通过上下层产出流体差异对超覆程度进行表征,开展不同注气速率下长岩心CO_(2)非混相驱实验,利用岩心上、下层气体突破时采收率比值、最终采收率及岩心剖面剩余油分布等评价重力超覆程度,并分析注气速率对重力超覆的影响机理。研究结果表明,以0.1 mL/min的低注入速率注入时,岩心下层几乎不产油,上层采收率所占比重高达97.5%,岩心整体波及效率低,最终采收率仅为49.49%,重力超覆严重;注气速率逐渐增加至1 mL/min,岩心上层采收率所占比重由97.5%逐渐降至50.9%,最终采收率高达60.26%,岩心剖面剩余油随注气速率增加而减少,重力超覆减弱。随注气速率的增加,CO_(2)水平黏性力增大,对油气密度差引起的垂向重力抑制作用增强,重力超覆减弱,岩心整体波及效率得到改善。实验结果可为低渗油藏CO_(2)驱注气参数优化提供理论依据。图11表1参15.Aimed at the problem that it is difficult to simulate the gravity segregation in real reservoir condition by indoor experiments,the gravity segregation physical model in high temperature and high-pressure gas flooding that can stimulated the gravity segregation under reservoir conditions was developed independently.the gravity segregation physical model in high temperature and high pressure gas flooding that can stimulated the gravity segregation under reservoir conditions was developed and gravity segregation was characterized by the produced fluid difference of upper and lower layers,CO_(2) immiscible flooding using long cores was conducted to study gravity segregation at different injection rates,the gravity segregation degree was evaluated through oil recovery proportion at upper and lower layers of core when gas breakthrough,final recovery and core displacement profiles,and the mechanism that how gas injection rate affected gravity segregation was also analyzed.The results showed that,the gravity segregation was serious that oil recovery of lower layer was nearly zero and oil recovery of top reached up to 97.5%when gas injection rate was at low value of 0.1 mL/min,resulting in the whole sweep efficiency of core was so poor that final oil recovery was only 49.49%.The oil recovery proportion of upper layer reduced to 50.9%as gas injection rate increased from 0.1 mL/min to 1 mL/min,and the final oil recovery even reached up to 60.26%.The residual oil of core displacement profiles decreased since gas injection rate increased,indicated that the gravity segregation degree got weaken.With increasing gas injection rate,CO_(2) level viscous force increased,the suppression of vertical gravity caused by oil-gas density difference was enhanced,the core sweep efficiency was improved as gravity segregation declined.Experimental results can provide theoretical basis for optimization of CO_(2) flooding gas injection parameters in low permeability reservoirs.

关 键 词：长岩心 CO_(2)非混相驱 注气速率 重力超覆 

分 类 号：TE357.7[石油与天然气工程—油气田开发工程]