鄂西渝东区飞三段鲕滩储层及控制因素

Ef_3 Oolitic Shoal Reservoirs and Their Control Factors in Western Hubei-Eastern Chongqing Area

分析了储层岩石学特征、储集空间类型、储层孔渗特征及孔隙度与白云岩含量的关系,认为研究区飞三段储层主要岩类为鲕粒灰岩与鲕粒白云岩,主要的储集空间类型为粒间溶孔、粒内溶孔、晶间孔、晶间溶孔,鲕粒白云岩储层为区内最优储层。将飞三段划分为3个四级层序,认为鲕滩主要发育于每个四级层序的高位体系域中,纵向上发育3期鲕滩,具有由南西向北东抬升迁移的规律性;古地理位置的不同造成鲕滩储层储渗能力的差异,第1、2期鲕滩发育于缓坡部位,为鲕粒灰岩储层;第3期鲕滩发育于陡坡部位,发育优质鲕粒白云岩储层;认为白云岩与滩体暴露有关,为混合水成因,分布于建南北高点及东北方向,由南西-北东呈间断叠瓦状排列分布,并具有逐渐增厚的趋势。针对鄂西渝东区储层分布规律,提出建南构造南高点及西南方向的区域,以滚动扩边,打斜井提高单井产能为主;建南构造北高点及东北方向的区域,应以寻找优质白云岩储层为主。

The reservoir rock property,reservoir space type,its pore property and the relationship between porosity and dolomite content were analyzed,it was considered that oolitic limestones and dolomites were dominated in Ef3 reservoirs and reservoir types were mainly of intergrain dissolution pores,intragrain dissolution pores,intercrystalline pores and intercrystalline dissolution pores.The oolitic dolomites were the most excellent reservoirs.Ef3 reservoirs were divided into 3 fourth grade sequences.It was considered that oolitic shoals were mainly developed in the high position of each fourth grade sequence,oolitic shoals of 3 stages were vertically developed,which were uplifted and transformed from SW to NE.The difference of palaeogeographic location resulted in difference of permeable ability.In StageⅠand Ⅱ oolitic shoals were developed in gentle slope,which were oolitic limestone reservoirs;Stage III oolitic shoals were grown in steep slope,which were excellent oolitic dolomitic reservoirs.It was believed that the dolomites were related to the exposed shoals of mixed water origin,they were distributed on the north high points of the Jiannan Structure and in the NE direction,discontinuously imbricated and tended to be thickened in SW-NE.Based on the distribution of the reservoirs in the Western Hubei-Eastern Chongqing Area,it is suggested that rolling extension of production,drilling deviated wells to enhance the single well production on the south high point and in the southwest of Jiannan Structure;and find excellent dolomitic reservoirs on the north high point and in the northeast of the structure.