盐池地区长8和长9油层油气富集的差异性分析

The difference analysis on oil accumulation of Chang8 and Chang9 reservoir in Yanchi Area

为研究构造和沉积对天环凹陷构造带盐池地区长8和长9油层油气组富集差异的控制作用,通过对研究区构造、沉积和储层特征的深入刻画,对2个油层的油气成藏主控因素进行了对比分析。结果表明,研究区长8和长9油层组断层、鼻隆构造发育,断层自下而上断穿延长组,主要发育于研究区东南部,其次为北部和东部;鼻隆构造多呈东西向或北东东向成排分布,具有良好继承性,是原油初次运移进入储层的优势通道。两沉积期均发育辫状河三角洲平原亚相,储层砂体主要以主河道和分流河道为主,但两者储层砂体组合特征宏观差异明显;微观上,长8储层以致密砂岩为主体,原油富集主要受沉积相带和物性控制,河道厚度大,高孔渗区带原油富集程度高,为致密砂岩岩性油藏;长9储层以中孔、低渗-特低渗以及低孔、超低渗储层为主,整体连续性及物性较好,原油富集主要受到浮力控制。优质储层在鼻隆上倾方向和梁部配置区原油富集程度高,在两翼边部和低部位边底水活跃,油藏类型为构造-岩性油藏。

In order to study the control of structure and sedimentation on the oil and gas enrichment difference of Chang8 and Chang9 oil groups in Yanchi Area of Tianhuan Sag tectonic zone,the main controlling factors of oil and gas accumulation in the two oil layers are compared and analyzed through in-depth description of the structure,sedimentation and reservoir characteristics of the study area.The results show that the faults and nose-shaped of Chang8 and Chang9 oil-bearing formations are developed in the study area,and the faults break through the Yanchang Formation from bottom to top.The faults are mainly developed in the southeast of the study area,followed by the north and east.The nose uplift structures are mostly distributed in rows in the EW or NEE direction,with good inheritance,and are the dominant channels for the primary migration of crude oil into the reservoir.Braided river delta plain subfacies were developed in both sedimentary periods,and the reservoir sand bodies were mainly formed by main channel and distributary channel,but the macroscopic difference of reservoir sand body combination characteristics between them was obvious;At the microscopic level,Chang8 reservoir is dominated by dense sandstone,and the enrichment of crude oil is mainly controlled by sedimentary facies and physical properties,the channel is thick and the oil enrichment degree is high in the high porosity and permeability zone,which is a tight sandstone lithologic reservoir;Chang9 reservoir is mainly composed of medium porosity,low permeability-ultra-low permeability,low porosity and ultra-low permeability reservoirs,with good overall continuity and physical properties,the enrichment of crude oil is mainly controlled by buoyancy.The high-quality reservoir and nose uplift upward dip direction,the beam configuration area have a high degree of crude oil enrichment,and the edge and bottom water jump at both wings and low parts.The reservoir type is a structural lithologic reservoir.