志丹油田长2段沉积微相特征及其控油规律

Sedimentary microfacies characteristics of the second member reservoir of Yanchang Formation and its controlling rule on oil distribution in Zhidan Oilfield

根据岩心观察和薄片鉴定结果,以及测井资料和粒度分析,并综合前人研究成果,明确指出志丹油田长2油层组为三角洲沉积,主要的沉积微相类型包括分流河道微相、天然堤微相、沼泽微相、决口扇微相和河漫滩微相。其中,分流河道微相和天然堤微相是主要的油气富集相带,长2油层由下而上的沉积具有一定的继承性;沉积相对长2油层下段的油藏分布起主要控制作用;沉积微相对志丹油田长2油层的分布及其油井产量有重要控制作用,但非唯一控制因素,局部低幅的鼻状隆起构造也有重要控制作用。

According to the results of core observations and identification of petrographic thin section,as well as logging data and grain size analysis,and combined with the comprehensive results of previous studies,this paper points out clearly that the second member oil layer group of Yanchang Formation in Zhidan Oilfield is delta deposit.The main microfacies types include distributary channel facies,natural levee facies,swamp facies,crevasse splay and overbank facies.Among them,the distributary channel and the natural levee facies are the main zones of oil and gas accumulation.Form bottom to top of the second member reservoirs of Yanchang Formation,sediments have certain continuity.Sedimentary facies play a major control on oil distribution of lower interval of second member oil layer of Yanchang Formation.The sedimentary microfacies play a major control role on distribution and oil-gas production of the second member reservoirs,but it is not the only controlling factor.The local low-amplitude and nose-like uplifts also play an important role in controlling.