南海西部A油田ZJ_(1)Ⅱ_(下)油组沉积微相及砂体展布研究

Study on the Micro-facies and Sandbody Distributions of ZJ_(1)Ⅱ_(下) LOil Group A Oilfield in the West of South China Sea

A油田生产层位为ZJ_(1)Ⅱ_(下)油组,平面上分为A1、A2两个井区生产。在过去的研究中,普遍认为ZJ_(1)Ⅱ_(下)油组属于一套临滨砂坝沉积。随着油田的开发生产,A1井区和A2井区在生产动态特征上表现出较大差异,用原先的沉积模式已经不能进行合理解释。通过古生物分析、FMI成像测井分析、岩心观察和地震相分析,提出了新的沉积模式认识:ZJ_(1)Ⅱ_(下)油组沉积时期属于浅海沉积环境,A1井区属于滨外滩坝沉积、A2井区属于滩砂沉积,两套砂体为不同期次的沉积物,因此并不连通。该认识不仅解释了之前沉积模式无法解释的种种矛盾,更为油田后续挖潜提供了有力的地质依据。

A oilfield consists of Block A1 and Block A2,and its production zone is ZJ1ⅡL oil group.In the previous researches,it is generally believed that ZJ1ⅡL oil group belongs to shore face sandbar deposits.However,oil wells in Block A1 and Block A2 began to present different production features since its production.Therefore,it is difficult to explain this phenomenon by using traditional depositional mode.Through comprehensive analysis of paleontology,FMI image logging,core observation and seismic facies,a new depositional mode is put forward that ZJ1ⅡL oil group belongs to shallow sea deposits,and Block A1 belongs to offshore bar deposits while Block A2 belongs to offshore beach deposits;these two sandbodies are deposited in different sedimentary phrases,thus,not inter-connected.The new recognition not only reasonably explains the controversies of the performance features in two blocks,but also provides support for the potential tapping in the future.