苏里格气田苏14井区盒8段河流相砂体展布与演化规律研究

Fluvial sand bodies distribution and evolution of He 8 member in Su 14 block of Sulige Gas Field

河流相砂体横向相变快,连续性和连通性差,储层非均质性强,严重影响了河流相储层的开发效果。依据储层沉积学的研究方法,对苏里格气田苏14井区盒8段河流相砂体展布与演化规律进行了研究。结果表明:苏14井区盒8段属于早期辫状河沉积向晚期曲流河沉积逐渐转化的沉积背景,其主要沉积微相包括河道滞留沉积、心滩、边滩、决口扇、天然堤、河漫砂及泛滥泥。受基准面升降与沉积物供应的共同作用,该区河流相砂体演化呈阶段性变化,大致经历了辫状河繁盛发育期、辫-曲共存转化发育期及曲流河繁盛发育期3个阶段,其中辫状河繁盛发育期的心滩砂体与辫-曲共存转化发育期的心滩及边滩砂体是主力含气储层。研究区优质储集砂体的发育受沉积微相展布与基准面旋回的控制。

The fluvial sand bodies are characterized by rapid lateral facies variation, weak continuity and connectivity and strong reservoir heterogeneity, which seriously affect the development of the fluvial reservoir. Based on the study of the reservoir sedimentology, the fluvial sand bodies distribution and evolution of He 8 member in Su 14 block were studied. The result shows that the sedimentary background in the He 8 member is gradual transition from the early braided river deposition to the later meandering river deposition, and the sedimentary microfacies mainly includs channel lag deposits, channel bars, point bars, crevasse splays, natural levees, overbank sand and mud deposits. By the influence of the interaction between the base level and the sediment supply, the fluvial evolution experienced three stages, which are the braided river prosperous development stage, the braided river and meandering river coexistence and transforming stage and the meandering river prosperous development stage. The sand bodies of channel bar and point bar in the stage of the braided river prosperous development and the braided river and meandering river coexistence and transformingare the main gas-bearing reservoirs. The development of favorable gas-bearing sand bodies is controlled by sedimentary microfacies and base level cycles.