摘要
鄂尔多斯盆地南缘延长组裂缝发育程度高,对致密油成藏富集具有重要控制作用。综合利用露头、岩心、分析化验、地球物理及生产动态资料,系统分析鄂南地区长8油层组致密砂岩储层裂缝发育特征、控制因素及与油气富集关系,取得如下主要认识:(1)研究区裂缝具有“多类型、多尺度、多组系”特点,以高角度构造剪切缝为主,NEE向和NW向裂缝发育程度高,为燕山期NWW—SNN向挤压应力作用下形成的一组共轭剪切缝;(2)泥质隔夹层面、钙质隔夹层面、河道冲刷面、韵律岩性变化面是研究区限制裂缝纵向扩展的4种主要岩石力学层面类型,地质统计与数值模拟结合,构建了岩石力学性质、岩层厚度、构造应力三大因素共同作用下的裂缝纵向生长模式;(3)裂缝平面展布受控于不同级次断层,断层规模越大、距离断层越近,裂缝发育程度越高,断层长度与对应裂缝带宽度呈较好线性函数关系;(4)裂缝是控制研究区长8致密油富集与高产的关键因素,水平井钻遇裂缝带规模与单井产量呈极好正相关性,断缝带是成藏期主要油气运移通道与优势聚集部位,也是现今油气富集区。
Fractures in the Yanchang Formation at the southern margin of the Ordos Basin are highly developed and play a crucial controlling role in the accumulation and enrichment of tight oil.By comprehensively using outcrop data,core data,analytical and laboratory test data,geophysical data,and production dynamic data,this study systematically analyzed the fracture development characteristics,controlling factors,and relationship with oil and gas enrichment of the Chang 8 tight sandstone reservoir in the southern part of the Ordos Basin(the southern Ordos Basin for short),and obtained the following main conclusions:(1)Fractures in the study area have the characteristics of“multiple types,multiple scales,and multiple sets”,with high-angle structural shear fractures as the main type.NEE-trending and NW-trending fractures are highly developed,which are a set of conjugate shear fractures formed under the NWW-SNN-trending compressive stress during the Yanshanian period;(2)Mudstone interbedding surfaces,calcareous interbedding surfaces,river channel erosion surfaces,and rhythmic lithological change surfaces are the four main types of rock mechanical layers that restrict the vertical expansion of fractures in the study area.By combining geological statistics with numerical simulations,a verticalgrowth model of fractures under the combined action of three factors—rock mechanical properties,rock layer thickness,and tectonic stress—has been constructed;(3)The planar distribution of fractures is controlled by faults of different orders;the larger the fault scale and the closer the distance to the fault,the higher the degree of fracture development.The fault length shows a good linear functional relationship with the width of the corresponding fracture belt;(4)Fractures are the key factor controlling the enrichment and high production of tight oil in the Chang 8 reservoir in the study area;the scale of fracture belts encountered by horizontal wells shows an excellent positive correlation with single-well production.Fault-fracture belts are the main oil and gas migration channels and preferential accumulation sites during the hydrocarbon accumulation period,and also the current oil and gas enrichment areas.
作者
伍岳
夏东领
郭秀娟
WU Yue;XIA Dongling;GUO Xiujuan(SINOPEC Petroleum Exploration and Production Research Institute,Beijing 100083,China)
出处
《现代地质》
北大核心
2025年第5期1282-1292,共11页
Geoscience
基金
中国石化重点科技攻关项目(P23174)。
关键词
裂缝
致密储层
致密油
长8
鄂尔多斯盆地
fracture
tight reservoir
tight oil
Chang 8 reservoir
Ordos Basin
作者简介
伍岳,男,高级工程师,1989年出生,主要从事非常规油气地质综合研究工作。Email:wuyue.syky@sinopec.com。
