克拉玛依油田冲积扇岩石相特征及储层质量分析

研究冲积扇储层内部结构,为开发后期井网调整和剩余油挖潜提供更准确的地质依据,以克拉玛依油田六中区为例,通过对密闭取心井岩心及野外露头的观察,将研究区岩石相划分为砾岩相、砂岩相及泥岩相三大类若干亚类,对不同岩石相沉积特征及成因机制进行了分析。在此基础上,依据实验室化验分析数据及铸体薄片等资料,结合不同岩石相物性及孔隙微观特征,将冲积扇岩石相按储层质量归为三大类,其中,粗砂—细砾岩相以剩余粒间孔为主,物性好,孔喉分选较好,含油性好,为研究区一类储层;中砾岩和中砂岩物性相对较差,孔隙喉道相对较小,含油性较差,为研究区二类储层;细粒沉积物性最差,孔隙喉道窄,含油性差,为非储层。依据不同类储层地质渗流差异,结合实际开发状况,发现不同类储层剩余油分布形式是不同的。一类储层物性好,注入水推进速度快,容易形成水窜,剩余油相对较少,一般分布在储层的上部;二类储层物性较差,水淹程度低,剩余油相对富集。该方法不仅对研究区储层深入研究具有一定指导意义,而且对于类似油田储层研究具有借鉴作用。

Lithofacies characteristics and quality analysis of alluvial fan reservoir in Karamay Oilfield

In order to provide more accurate geological basis for the well pattern adjustment and the potential tapping of remaining oil in the later development stage,the internal structure of alluvial fan reservoir is further researched.Taking Liuzhong Area of Karamay Oilfield as an example and by observing the cores from sealing coring wells and field outcrops,the lithofacies in the study area are divided into three major categories including conglomerate facies,sandstone facies and mudstone facies,and a number of sub-categories,and the sedimentary characteristics and formation mechanism of different lithofacies are analyzed.On this basis,the alluvial fan facies are classified into three categories by reservoir quality according to the laboratory test analysis and casting thin sections data,and combined with the physical properties and the microscopic characteristics of pores of different lithofacies.Among them,the coarse sand-fine gravel lithofacies is mainly remaining intergranular pores with good physical properties,sorted pore throats and oiliness quality,which is I type reservoir in the study area.The medium conglomerate and sandstone lithofacies has relatively poor,small pore throats and poor oiliness quality,which is II type reservoir.The fine-grained sediment has the worst physical properties,narrow pore throats and poor oiliness quality,which is non-reservoir.Based on the differences of geological seepage of different type reservoirs,it is found that the distribution of remaining oil is different.The remaining oil of I type reservoir is relatively less and the remaining oil of II type reservoir is relative rich.This method not only has guiding significance for further studying the reservoir,but also can provide a reference for the study of similar reservoirs.