塔北哈拉哈塘奥陶系岩溶储层类型与特征及控制因素

近年来,塔北哈拉哈塘奥陶系碳酸盐岩油气勘探开发取得了重要发现。综合露头、钻井、岩心、地震等资料进行分析,明确哈拉哈塘地区奥陶系岩溶储层包括大型溶洞、溶蚀孔洞、溶蚀裂缝3种类型,将研究区内桑塔木组尖灭线南北划分成剥蚀区和覆盖区。通过地震解释资料分析发现,桑塔木组尖灭线以北的剥蚀区的岩溶储层主要受到风化壳的影响,风化壳发育的范围和强度影响岩溶储层的规模;建立研究区断裂控制岩溶模式分布图,并分析井漏数据与断裂系统叠合关系,得出断裂系统及其对所控制的层间岩溶作用,是桑塔木组尖灭线以南覆盖区岩溶储层发育的主要控制因素;明确了加里东中期Ⅰ幕、Ⅱ幕、Ⅲ幕3个不同岩溶发育时期,受断裂控制的明河、暗河对研究区岩溶储层的叠加改造作用。

CHARACTERISTICS AND ORIGINS OF ORDOVICIAN KARST RESERVOIR IN HALAHATANG AREA,NORTHERN TARIM BASIN

Recently, big progresses have been made in oil and gas exploration and development in the Ordovician carbonate reservoir in the Halahatang area, northern Tarim Basin. Integration of the data from outcrops, drilling cores and seismic profiles indicates that there are three kinds of karst reservoirs in the Halahatang area, i.e. large Karst caves, dissolution pores and dissolution fractures. With the pinchout line of the Sangtamu Formation as the boundary, the study area is divided into two parts:the northern denudated area and the southern covered area.Seismic data suggest that karst reservoir in the northern denudated area is mainly affected by weathering crust,the coverage and intensity of the weathering process affect the scale of the karst reservoir.On the other hand, the distribution pattern of fractures is another factor which controls karst development. The superimposed relationship between circulation loss and fault system suggests that the fault system and its effect on the interlayer karstification is the main control factor over the karst reservoir developed in the southern area of the pinchout line of the Sangtamu Formation.There are three development stages responding toⅠ,Ⅱand Ⅲepisodes of the middle Caledonian respectively in this region. The ground and underground rivers under the control of faults played significant role on development of the karst reservoirs in the study area.