埕岛东斜坡馆上段断-砂输导能力定量评价

Quantitative Evaluation of Fault-Sandstone Transport Capacity of Upper Member of Guantao Formation in Chengdao East Slope

以埕岛东斜坡馆上段断-砂输导体系为研究对象,从断-砂配置类型分析入手,分别对影响砂体和断层油气成藏动力的地质要素进行归类计算,确立断-砂输导体系油气运聚方式判识方法。研究表明:埕岛东斜坡发育反向正断层、顺向正断层和“屋脊式”正断层3种断-砂配置类型。其中,反向断-砂垂向运移输导体系分布最广,其上盘砂体是有利的侧向运移介质。只有当砂体物性显著好于断层物性时,在油气初始运移阶段才存在砂层运移区和砂层运移优势区,其余情况均为断层运移占主导地位。决定断-砂输导体系运移方式的地质要素包含砂岩倾角α、断层倾角β、砂岩泥质体积分数V_(sh)和断裂带内泥质体积分数S_(GR)。以sinβ/sinα为纵坐标、以V_(sh)/(S_(GR)·cosβ)为横坐标建立断-砂输导体系油气运聚方式定量判识模版,选取与反向正断层上盘相交的65个砂体断-砂输导体系运移方向进行判别,与实际钻探结果吻合效果较好,说明利用断-砂输导体系油气运聚方式定量判识模版判别埕岛东斜坡馆上段断-砂配置油气运移路径是可行的。

Taking the fault-sandstone hydrocarbon transport system in the upper member of Guanshan formation on Chengdao east slope as the research object,starting with the analysis of the types of fault-sandstone configuration,the geological factors affecting the hydrocarbon migration and accumulation power in sandstone and faults are classified,and the identification method of hydrocarbon migration and accumulation modes in the fault-sandstone transport system is established.The results show that there are three types of fault-sandstone configuration in Chengdao east slope:reverse normal fault-sandstone,forward normal fault-sandstone and"roof ridge"normal fault-sandstone.Among them,the reverse fault-sandstone vertical migration transport system is the most widely distributed,and its hanging wall sandstone is a favorable lateral migration medium.There are sandstone migration areas and sandstone migration dominant areas in the initial stage of hydrocarbon migration only when the physical properties of sand bodies are significantly better than those of faults,and fault migration is dominant in other cases.The geological factors determining the hydrocarbon migration mode of fault-sandstone transport system include dip angleαof sandstone,dipβof fault,shale volume fraction V SH of sandstone and shale volume fraction S_(GR)in the fault zone.Taking sinβ/sinαas longitudinal ordinate,V_(sh)/(S_(GR)·cosβ)as horizontal ordinate,the quantitative identification chart of hydrocarbon migration and accumulation modes of fault-sandstone transport system is established.The hydrocarbon migration direction of fault-sandstone transport system in which the hanging wall of reverse normal fault intersects with 65 sandbodies is identified,the result is in good agreement with the actual drilling result,indicating that it is feasible to use the quantitative identification chart to identify the hydrocarbon migration path in the fault-sandstone configuration in the upper member of Guantao formation on Chengdao east slope.