低渗致密砂岩气藏提高采收率实验研究

针对我国典型的低渗致密砂岩气藏，通过大量岩心实验和露头剖面精细取心测试分析，研究了应力作用对储层渗透率的影响、储层非均质性以及储层含水饱和度等特征，选用有代表性的岩心，开展了系统的单相气体渗流，含水条件下的气相渗流以及气、水两相渗流实验，分析了低渗致密砂岩储层单相气体渗流形态，含水饱和度变化对气相渗流能力的影响以及气、水两相渗流特征；在此基础上，采用气藏开发物理模拟实验技术，模拟研究了气藏衰竭开采过程中储层渗透率、含水条件、配产与废弃条件、纵向储层渗透率差异、平面非均质(储层砂体间存在阻流带)等多种因素对低渗致密砂岩气藏采收率的影响，根据权重分析对这5类影响因素进行了排序，结果表明储层物性和储层含水饱和度对采收率的影响最大，权重分别占到0.24和0.38，为进一步提高气藏采收率奠定了基础。

Enhanced Gas Recovery of the Low Permeability and Tight Sandstone Gas Reservoir

The effect of stress on the reservoir permeability and the features of reservoir heterogeneity and formation water saturation were analyzed by means of a huge number of core experiments and test analyses of outcrop section fine coring in the typical low permeability tight sandstone gas reservoirs.With some representative samples,we analyzed the single-phase gas seepage state of low permeability sandstone reservoir,the impact of water saturation on gas permeability and gas water two phase percolation characteristics by conducting systematically single-phase gas seepage experiments,gas percolation experiments under aquiferous condition and seepage tests of gas-water two-phase.On this basis,we studied the impact of various factors such as reservoir permeability,aquiferous conditions,proration and abandoned conditions,longitudinal reservoir permeability differences and the lateral heterogeneity-blocking zone between reservoir sand bodies on the recovery efficiency of low permeability tight sandstone gas reservoir in the process of depletion-drive development by using the physical simulation experimental techniques for gas reservoir development.Then,these five kinds of factors were sorted according to the weight analysis.The results show that reservoir property and reservoir water saturation have the largest effect on the recovery efficiency,whose weight accounted for 0.24 and 0.38,respectively.This study laid a solid foundation for further improving gas reservoir recovery efficiency.