致密油气藏二氧化碳焖井置换效率实验  

Experimental study on replacement efficiency of carbon dioxide in tight oil and gas reservoirs

作　　者：赵祺楠 江厚顺[1,2] 孟伟 汪杰[1,2] 王长权[1,2] 续化蕾 ZHAO Qi-nan;JIANG Hou-shun;MENG Wei;WANG Jie;WANG Chang-quan;XU Hua-lei(School of Petroleum Engineering,Yangtze University,Wuhan 430100,China;Unconventional Oil and Gas Co-construction Cooperative Innovation Center of Yangtze University,Wuhan 430100,China;Exploration Division of Changqing Oilfield Company,PetroChina,Xi’an 710018,China)

机构地区：[1]长江大学石油工程学院,湖北武汉430100 [2]长江大学非常规油气省部共建协同创新中心,湖北武汉430100 [3]中国石油长庆油田分公司勘探事业部,陕西西安710018

出　　处：《天然气地球科学》2021年第5期718-726,共9页Natural Gas Geoscience

基　　金：国家科技重大专项“大型油气田及煤层气开发”子课题“高效深部液流转向与调驱和精细分层注采技术”(编号:2011ZX05010-003)资助.

摘　　要：CO_(2)干法压裂后气体进入致密砂岩气藏,通过焖井方式与储层油气进行置换,既可以提高油气藏采收率,又可以解决CO_(2)封存问题,减少其排放量,对环境保护和提高油田产量具有双重效益。油气藏中CO_(2)焖井置换宏观效益显而易见,但焖井置换过程中CO_(2)对储层微观孔喉侵蚀作用研究较少。基于长庆油田C7、C8油藏和H8、S2气藏在室内设计驱替置换实验,研究CO_(2)焖井置换驱替油气效率,并结合XRD和SEM扫描结果研究CO_(2)置换过程对储层矿物成分及微观孔喉结构的影响。结果表明:油藏中CO_(2)置换驱油效率普遍较低,约为25.27%,且受岩心渗透率影响较大,而焖井时间对其置换效率影响相对较小;气藏中CO_(2)置换甲烷气效率较高,约为76.50%,且受岩心渗透率影响较小,但焖井时间对其置换效率影响相对较大。XRD结果表明,CO_(2)对储层黏土矿物产生微弱溶蚀作用并造成岩心中方解石含量降低;SEM结果表明,CO_(2)侵蚀后岩心孔喉表面产生少量的蚀变产物附着于岩石颗粒表面,使得岩石矿物颗粒形态、边界及孔隙结构变得略微模糊,且焖井时间越长,固相表面侵蚀越严重。After CO_(2) dry fracturing,the gas enters the tight sandstone gas reservoir and is replaced with reservoir oil and gas through the method of simmering wells,which can improve the oil and gas reservoir recovery rate and solve the problem of CO_(2) storage,reduce its emissions,and protect the environment. And increasing oilfield production has double benefits. The macro benefits of CO_(2) simmering well replacement in oil and gas reservoirs are obvious,but there are few studies on the micro-erosion effect of CO_(2) on reservoir pore throats during simmering well replacement. In this paper,based on the indoor design displacement experiments of C7 and C8 reservoirs and H8 and S2 gas reservoirs in PetroChina Changqing Oilfield Company,the efficiency of CO_(2) replacement and displacement of oil and gas in stewed wells is studied,and the effects of CO_(2) replacement process on the mineral composition of the reservoir are studied by combining XRD and SEM scanning results and the influence of microscopic pore throat structure. The results show that in oil reservoirs,CO_(2) displacement oil displacement efficiency is generally low(25.27%),and it is greatly affected by core permeability,while the time of simmering well has relatively little influence on its displacement efficiency;in gas reservoirs,CO_(2) displacement methane gas displacement efficiency is higher(76.50%),and the core permeability is less affected,but the simmering time has a relatively large impact on its replacement efficiency;XRD results show that CO_(2) has a weak dissolution effect on the clay minerals of the reservoir;SEM results show that after CO_(2) erosion,a small amount of alteration products on the surface of the core pore and throat are attached to the surface of the rock particles,making the shape,boundary and pore structure of the rock mineral particles slightly blurred,and simmering;the longer the well time,the more serious the solid surface erosion.

关 键 词：二氧化碳 焖井置换 置换效率 矿物组成 微观孔喉结构 

分 类 号：TE37[石油与天然气工程—油气田开发工程]