摘要:
碳酸盐岩地层在湿热气候条件下可形成典型的裂缝-溶洞系统。塔里木盆地奥陶系碳酸盐岩存在3大构造隆起,与上覆志留系、石炭系地层存在沉积间断,具备了岩溶缝洞形成的基础条件;在泥盆纪、志留纪时塔里木古陆位于低纬度地区,具有与现代中国南方相似的热带、亚热带湿热海洋性气候条件,岩溶作用强烈,为大型岩溶缝洞储层的形成提供了水热条件。为了更好地揭示塔河油田岩溶缝洞储层的发育和分布规律,文章基于对塔北露头区古岩溶的调查分析,结合地震、岩心、测井等资料,并与我国西南岩溶区现代岩溶研究成果相比较,总结了古今湿热气候条件下典型碳酸盐岩缝洞系统的空间结构和发育特征,将其划分为地下河、岩溶洞穴、溶蚀孔洞、溶蚀缝等4种缝洞类型,地下河又细分为单支管道、多支管道、廊道型管道3个亚类,洞穴细分为厅堂型、溶洞型和竖井型洞穴3个亚类,分别建立了这些缝洞类型的地质结构模式,并对其发育特征和地球物理响应特征进行了归纳,为深入认识岩溶缝洞储层油气富集规律和油田地质建模提供科学依据。
Abstract:
Carbonate rocks can form typical crack-cave systems under warm and humid climate conditions. The Ordovician carbonate rocks has three tectonic uplifts in the Tarim basin,resulting in depositional break between Ordovician and Silurian,Carboniferous strata.The ancient Tarim land was located in low latitudes during the Devonian and Silurian,and had a tropical or sub-tropical climate which was favorable to generate large karst crack-cave systems.The Tarim area in Devonian and Silurian had the similar climate characteris-tics to the modern South China,and experienced intense karstification.Based on outcrops investigation and analysis of cores,seismic and logging data,combined with the modern karst theory,this work makes a com-parative study and summarizes spatial structural characteristics of carbonate fracture-cave systems.Such typ-ical systems under warm and humid climate conditions are divided into 4 types:underground rivers,karst ca-ves,karst pores,karst seams.Furthermore,the underground river is subdivided into 3 sub categories of sin-gle pipe,multi pipe and corridor pipeline,and the cave is subdivided into the hall type,cave type and vertical type.Then eight corresponding structural models are established,and their characteristics are summarized. This will help to reveal the pattern of development and distribution of crack-cave systems in Tahe oil field, and provide a reliable basis for oil geological modeling.
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