鄂尔多斯盆地富县地区碳酸盐岩储层风化裂缝成因类型及其对油气富集的影响  

Genetic types of weathering-induced fractures in carbonate reservoirs in Fuxian area of Ordos Basin and their impact on hydrocarbon enrichment

作　　者：毛金昕 何建华 解馨慧 邓虎成[1,2] 王瑕 曹峰 邢梓萌 MAO Jinxin;HE Jianhua;XIE Xinhui;DENG Hucheng;WANG Xia;CAO Feng;XING Zimeng(College of Energy,Chengdu University of Technology,Chengdu City,Sichuan Province,610059,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu City,Sichuan Province,610059,China;College of Geophysics,Chengdu University of Technology,Chengdu City,Sichuan Province,610059,China;Xianhe Oil Production Plant,Shengli Oilfield Company,SINOPEC,Dongying City,Shandong Province,257068,China)

机构地区：[1]成都理工大学能源学院,四川成都610059 [2]油气藏地质及开发工程全国重点实验室,四川成都610059 [3]成都理工大学地球物理学院,四川成都610059 [4]中国石化胜利油田分公司现河采油厂,山东东营257068

出　　处：《油气地质与采收率》2025年第2期25-35,共11页Petroleum Geology and Recovery Efficiency

基　　金：国家自然科学基金青年基金项目“前陆盆地湖相页岩储层纤维状方解石脉体结构形成机制与时空演化序列”(42402148);“颗粒排列结构对页岩储层剪切模量的控制机制”(42402169)。

摘　　要：鄂尔多斯盆地下古生界碳酸盐岩具有沉积厚度大、分布范围广的特点,其储层岩石致密,具有低孔、低渗透的特征,碳酸盐岩储层中裂缝与孔洞组成的储渗空间对天然气的富集与运移有着不可忽视的作用。利用岩心、薄片观察等测试结果,结合生产资料分析了鄂尔多斯盆地富县地区马家沟组风化裂缝成因类型及其对油气富集的影响。结果表明:研究区碳酸盐岩储层风化裂缝受岩性、岩溶古地貌和断裂规模影响,可划分为岩溶崩塌裂缝、风化淋滤裂缝和陡坎拉张裂缝3类。岩溶崩塌裂缝易发育在残丘上可溶性较好的膏云岩和膏盐岩中;坡地及阶地的灰质白云岩发育风化淋滤裂缝;陡坎拉张裂缝发育在不整合面坡度较大位置的白云石含量较低的云质灰岩中。3种风化裂缝中岩溶崩塌裂缝形成的有效缝网对碳酸盐岩储层孔渗的改善作用明显;陡坎拉张裂缝有效性较好,但难以形成复杂缝网,仅对改善渗透率起重要作用;风化淋滤裂缝多为机械充填,对碳酸盐岩储层孔渗的改善作用最差。结合生产动态将研究区碳酸盐岩储层划分为岩溶崩塌裂缝型、陡坎拉张裂缝型、风化淋滤裂缝型和基质无效型4类。The Lower Paleozoic carbonate rocks in the Ordos Basin are characterized by substantial depositional thickness and extensive distribution,with reservoirs exhibiting tight lithology,low porosity,and low permeability.The accumulation and migration of natural gas in these carbonate reservoirs are significantly influenced by storage and flow space composed of fractures and pores.Based on analytical results from core samples,thin-section observations,and production data,this study investigated the genetic types of weathering-induced fractures in Majiagou Formation of Fuxian area and their impact on hydrocarbon accumulation. The results demonstrate that weathering-induced fractures in the carbonate reservoirs are controlled by lithology, paleokarst geomorphology, and fault scale, and they can be classified into three types: karst-collapse fractures, weathering-leached fractures, and scarp related tensile fractures. Karst-collapse fractures predominantly develop in soluble gypsum-bearing dolomites and evaporites within residual hills;weathering-leached fractures occur in dolomitic limestones on slopes and terraces;scarp-related tensile fractures form in dolomite-poor argillaceous limestones at steep unconformity surfaces. Among these fracture types, karst-collapse fractures create effective fracture networks that enhance reservoir porosity and permeability. Scarp-related tensile fractures exhibit moderate effectiveness, primarily improving permeability but failing to form complex fracture networks. Weathering-leached fractures, often mechanically filled, contribute minimally to reservoir porosity and permeability. According to production dynamics, the carbonate reservoirs in the study area are categorized into four types: karst-collapse fracture-dominated, scarp-related tensile fracture dominated, weathering-leached fracture-dominated, and matrix-ineffective reservoirs.

关 键 词：天然裂缝 发育特征 富集成藏 马家沟组 鄂尔多斯盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]