页岩油储层裂缝对CO_(2)吞吐效果的影响及孔隙动用特征  

The Influence of Fractures in Shale Oil Reservoirs on CO_(2) Huff and Puff and Its Pore Production Characteristics

作　　者：李凤霞[1] 王海波[1] 周彤 韩玲 LI Fengxia;WANG Haibo;ZHOU Tong;HAN Ling(Sinopec Petroleum Exploration and Production Research Institute,Beijing,102206,China;Research Institute of Petroleum Engineering,Sinopec Jianghan Oilfield Company,Wuhan,Hubei,430035,China)

机构地区：[1]中国石化石油勘探开发研究院,北京102206 [2]中国石化江汉油田分公司石油工程技术研究院,湖北武汉430035

出　　处：《石油钻探技术》2022年第2期38-44,共7页Petroleum Drilling Techniques

基　　金：中国石化科技攻关项目“陆相页岩油地球物理与储层改造关键技术”(编号:P20049-2)资助。

摘　　要：为了分析页岩水力压裂后产生的裂缝对CO_(2)吞吐效果的影响,采用低场核磁共振测试技术,开展了不同渗透率级别页岩CO_(2)吞吐试验,研究了裂缝对不同渗透率储层CO_(2)吞吐效果的影响。研究发现,裂缝显著提高了CO_(2)吞吐初期的采油速度和采收率;但随着渗透率升高和吞吐次数增多,裂缝对采收率的影响程度逐渐降低;渗透率对裂缝岩心的吞吐效果影响明显小于无裂缝岩心,表明裂缝能够降低渗透率对CO_(2)吞吐采收率的影响;随着吞吐次数增多,裂缝提高大孔隙原油采出程度的幅度减小,而提高小孔隙原油采出程度的幅度增大,但大孔隙仍是原油的主要产出部位。研究结果表明,大孔隙原油的产出主要靠体积膨胀和溶解气驱,速度快且产量大;而小孔隙中原油的产出主要靠抽提和传质方式,过程缓慢且产量小。研究结果为评价裂缝性油藏的产油特征、改善生产动态提供了理论依据。To study the influence of fractures from shale hydraulic fracturing on the CO_(2) huff and puff,low-field nuclear magnetic resonance was adopted in CO_(2) huff and puff experiments with shales of different permeabilities,and the influence of fractures on the CO_(2) huff and puff effect in reservoirs of different permeabilities was investigated.Experimental results show that fractures significantly improve the oil production rate and recovery at the initial stage of the CO_(2) huff and puff operations.However,the influence of fractures on the recovery gradually decreases as huff and puff continues and the permeability increases.The influence of permeability on huff and puff of fractured cores is much lower than that of unfractured cores,which indicates that fractures may reduce the influence of permeability on recovery by CO_(2) huff and puff.With continuing huff and puff,the increase rate in the degree of reserve recovery of crude oil from macropores contributed by fractures declines while that of crude oil from micropores increases.Despite this finding,macropores continued to be the main contributor of crude oil production.The results indicate that the quick and high production of crude oil from macropores mainly depends on volume expansion and dissolved gas drive.In contrast,the slow and low production of crude oil from micropores is primarily brought by extraction and mass transfer.The results of this study have provided a theoretical basis for evaluating the characteristics of oil production from fractured reservoirs and improving production performance.

关 键 词：页岩油 裂缝 CO_(2)吞吐 动用特征 核磁共振 

分 类 号：TE357.45[石油与天然气工程—油气田开发工程]