碳酸盐岩地层断裂结构特征及油气地质意义——以青州云门山地区下古生界断裂为例

Fault structure characteristics of carbonate strata and petroleum geological significance:a case study of Lower Paleozoic fault in Yunmenshan area of Qingzhou

为明确济阳坳陷下古生界碳酸盐岩地层断裂结构对油气成藏的控制作用,文中选取青州云门山地区碳酸盐岩露头断裂进行野外地质考察,利用岩心、野外露头、分析化验等资料,对碳酸盐岩地层断裂结构及其控藏作用进行系统研究,建立了多期方解石胶结、泥质充填和“三元”断裂结构,揭示了3种断裂结构差异化控藏作用。研究认为:多期方解石胶结断裂结构对油气具有垂向输导和横向封堵双重作用,控制油气沿大型油源断层两侧断块圈闭选择性成藏;泥质充填断裂结构对潜山油气成藏具有明显的封堵作用,控制油气在不同的断层-不整合油藏中大规模富集成藏;“三元”断裂结构具有破碎带和裂缝带输导、角砾岩带封堵的双重作用,控制油气主要沿油气来源方向的断层下盘呈梳状富集成藏。断裂结构差异化控藏模式将为济阳坳陷下古生界碳酸盐岩潜山油气勘探提供理论依据。

In order to clarify the controlling effect of fracture structure of Lower Paleozoic carbonate strata on hydrocarbon accumulation in Jiyang Depression,the Lower Paleozoic carbonate outcrop in Yunmenshan area of Qingzhou was selected for field geological investigation.Combined with core,field outcrop and testing data,the fracture structure of carbonate strata and its reservoir controlling effects were sysmatically studied.Three types of fault structure models,including multi-stage calcite cementation,clay filling and"ternary"fault structure,are established to reveal the different controlling effect of the three fault structures on hydrocarbon accumulation.The research shows that the multi-stage calcite cemented fault structure has dual functions of vertical transportation and horizontal sealing on oil and gas,which controls the differential enrichment of oil and gas along the fault block traps on both sides of large oil source faults;the clay filling fault structure has obvious sealing effect on the oil and gas enrichment in the buried hill,which controls the large-scale accumulation of oil and gas in different fault-unconformity reservoirs;the"ternary"fault structure has dual functions of rupture zone and fracture zone transport and breccia zone sealing,which controls the comb-shaped accumulation of oil and gas mainly along the footwall of oil source fault.Differential reservoir-controlling model of fault structure will provide a theoretical basis for oil and gas exploration in the Lower Paleozoic carbonate buried-hill in Jiyang Depression.