成岩作用对豫西北马家沟组三段遗迹化石充填物孔隙发育的影响  

Diagenesis and Effect of Trace Fossil Fillings on Pore Development in Lower Ordovician Majiagou Member-3 Limestone in the Northwest of Henan

作　　者：董小波[1] 牛永斌[1,2] 

机构地区：[1]河南理工大学资源环境学院 [2]河南省生物遗迹与成矿过程重点实验室

出　　处：《海相油气地质》2015年第3期17-27,共11页Marine Origin Petroleum Geology

基　　金：国家自然科学基金"豫西奥陶系碳酸盐岩中生物遗迹组构与储层改造效应"(编号:41102076)和"海相碳酸盐岩储层中增强储集性能遗迹组构的属性表征及制约机制"(编号:41472104);"构造与油气资源"教育部重点实验室开放基金"豫西北奥陶系碳酸盐岩储层生物改造机理研究"(TPR-2011-34);河南理工大学博士基金(编号:B2011-046)联合资助

摘　　要：豫西北奥陶系马家沟组三段碳酸盐岩的野外露头观察和室内测试分析结果表明,马家沟组三段的岩性以泥晶灰岩为主,岩石中具有典型的遗迹化石充填特征。遗迹化石充填物经历了白云石化、胶结、溶蚀、压实/压溶、去白云石化等成岩作用,其中溶蚀作用对充填物孔隙发育具有建设性,压实作用和去白云石化作用具有破坏性,而白云石化作用、胶结作用和压溶作用则具有建设性和破坏性的双重影响。潜穴充填物的孔隙类型主要以白云石晶间孔、晶间次生溶孔和晶内次生溶孔为主。随着成岩环境的变化,孔隙度经历了降低—升高—降低—升高的反复演化过程。早成岩阶段的白云石化作用对于潜穴充填物孔隙的发育贡献最大,此后充填物孔隙度的提升主要依赖于表生环境下大气淡水的淋滤溶蚀,而遗迹化石充填物经成岩改造后对提高宿主岩层的储层物性具有促进作用。According to observation to the rock samples from 6 outcrops of Lower Ordovician Majiagou Member-3 carbonate rock in the northwest of Henan province, the Majiagou Member-3 mostly consists of micritic limestone full of typical burrow fillings associated with trace fossils. Based on analysis to burrow fillings, diagenesis experienced mainly is dolomitization, cementation, dissolution, compaction-pressolution and dedolomitization during four periods of diagenesis. It is known that dissolution plays a constructive role in filling pore development and compaction and dedolomitization play a destructive role while dolomization, cementation and pressolution do dual influence. Intercrystalline pores, intercrystalline dissolution pores and intracrystal secondary dissolution pores are the main types of burrow fillings pores. The porosity of burrow fillings experienced twice evolutions from lower to higher as diagenetic environments changed. The dolomitization had done the best contribution for pore development during early diagenetic stage and subsequent increase of porosity mainly depended on leaching and dissolution of atmospheric fresh water in supergene environment. It is proved that diagenetic reformation to burrow fillings in trace fossils can finally improve the reservoir property of host rock.

关 键 词：河南省西北部 早奥陶世 马家沟组 石灰岩 遗迹化石 成岩作用 

分 类 号：TE122.23[石油与天然气工程—油气勘探]