榆林气田山_2~3亚段低渗砂岩气藏流动单元精细划分

Fine division of flow units in Shan_2~3 sub-member for the low permeability sandstone gas reservoir in Yulin Gasfield

鄂尔多斯盆地榆林气田下二叠统山西组二段(以下简称山2段)为一套辫状河三角洲沉积,储集岩主要为石英砂岩、岩屑石英砂岩,储层渗透率低、非均质性强,是典型的低渗岩性气藏。自2001年建产以来,气田采取滚动开发方式,已投入开发16年,自然稳产期13年,目前已处于稳产末期。随着气田不断开发,由于气井或井区投产时间不一,各井区的地层压力下降不均衡、部分区域储量动用程度低,如何调整开发对策、保持气田持续稳产是亟待解决的问题。根据气田开发实际情况,通过描述储层宏观和微观特征,分析影响天然气开发效果的动、静态因素,首先从地质角度初步划分山_2~3亚段气藏流动单元,再应用泄流半径、井间干扰分析等动态方法进一步验证气藏连通性,动静结合,精细划分流动单元。在精细划分流动单元内部,运用FZI、多参数综合分析法进一步划分不同类型储层,搞清了气藏储层物性差异,为气藏下一步针对性开发管理、开发调整部署提供了技术支撑。

The second member of Shanxi Formation （＂Shan-2 Member＂） of Lower Permian in Yulin Gasfield of Ordos Basin is a set of braided river delta deposit. The reservoirs are mainly composed of quartz sandstones and lithic quartz sandstone, which is low per- meability and strong heterogeneity. It is a typical low-permeability lithologic gas reservoir. Yulin Gasfield has been put into develop- ment in the pattern of progressive development for 16 years since it was initially constructed in 2001. Its naturally stable production lasts 13 years, and it is now at the late stage of stable production. With its constant development, the formation pressure of different well blocks in this gas field drops unevenly and the reserve producing degree of some zones is low, because gas wells or well blocks were put into production in different time. It is urgent to figure out how to adjust the development strategies and maintain the stable production continuously. According to the actual development performance of Yulin Gasfield, the dynamic and static factors which influence the development effects of natural gas were analyzed by describing the macro and micro characteristics of reservoirs. Firstly, the flow units in Shan2^3 gas reservoir were preliminarily divided from the geological point of view. Then, gas reservoir connectivity was verified further by using the dynamic methods, e.g. the discharge radius method and the inter-well interference analysis method. And finally, the flow units were divided precisely by using static and dynamic methods comprehensively. These precisely divided flow units were subdivided further into different types of reservoirs by using FZI and multi-parameter comprehensive analysis method and the differences of reservoir physical properties were figured out. It provides the technical support for the targeted development man- agement, adjustment and deployment in the following steps.