西湖凹陷某构造花港组致密砂岩储层的渗流特征

摘要

This paper studies the seepage flow characteristics of the tight sandstone reservoirs in Oligocene Huagang Formation in a certain structure of the Xihu depression in East China Sea Basin in order to provide some guiding advices for the highly-effective development of this gas pool. Based on the casting thin sections materials and the scanning electron microscopy materials using the experimental techniques such as physical property test, NMR, mercury pressure, water drive gas, etc. , it studies the pore structure, the gas-water seepage flow characteristics in cores and the influencing factors of in Huagang Formation in a certain structure in the Xihu depression. The results show that most pores of the cores are intergranular pores in the tight sandstone of Huagang Formation. The radius of the pore throat is tiny, the gradation of the pore throat radius is poor, and its pressure is high. The irreducible water saturation of the tight sand stone reservoir is high and the scope of two-phase (gas and water) seepage flowing is narrow. The gas phase relative permeability is lower and it decreases sharply after water increased. The residual gas saturation is higher, the ultimate recovery is low and the recovery at the water-free stage accounts to a large percentage of the ultimate recovery. As a result, great attention should be paid to the recovery at the water-free stage. The percolation characteristics of the reservoir is affected by the physical property, the pore structure, the original water saturation, the wettability, etc. . Among them, the pore structure is the greatest impact.%研究西湖凹陷某构造渐新统花港组致密砂岩储层的渗流特征,旨在为该气藏的高效开发提供指导性意见.利用铸体薄片、扫描电镜资料,综合分析物性测试、压汞、核磁共振、水驱气等实验数据,研究西湖凹陷某构造花港组致密砂岩储层的孔隙结构、气水渗流特征及其影响因素.该区致密砂岩储层孔隙类型以粒间溶孔为主,孔喉半径细小,且孔喉分选性差,排驱压力高；致密砂岩储层束缚水饱和度高,两相渗流区窄,气相相对渗透率较低,且见水后急剧下降,残余气饱和度较高,最终采收率低,且无水期采收率占最终采收率的比例很大,应充分重视储层见水前的天然气开采.储层渗流特征受物性、孔隙结构、原始含水饱和度以及润湿性等多种因素的影响,其中孔隙结构影响最大.