中江气田沙溪庙组致密砂岩气藏地层水微观赋存状态及产出特征

Microscopic Occurrence and Production Characteristics of Formation Water in Shaximiao Formation Tight Sandstone Gas Reservoir in Zhongjiang Gas Field

开展地层水微观赋存状态研究,可为有利区优选和气井生产制度优化提供参考和依据。利用铸体薄片、扫描电镜、压汞、核磁共振、两相渗流实验、测井以及生产动态资料,开展中江气田沙溪庙组致密砂岩气藏的孔隙结构、地层水赋存状态及产出特征研究。结果表明,中江气田沙溪庙组Ⅰ、Ⅱ、Ⅲ类储层中值喉道半径平均为0.30、0.16和0.04μm。地层水以自由水、毛细管水和薄膜水的形式赋存于储层中,薄膜水普遍存在,毛细管水主要存在于喉道半径小于0.100μm的喉道中,断砂配置较差及构造相对低部位储层可见自由水。气井产水来源主要为凝析水、毛细管水和薄膜水,整体表现为产水量小、矿化度低、水气比低且后期增大的特征。相对高含水饱和度区的评价和开发应以Ⅰ、Ⅱ类储层为主要目标,产水气井生产过程中应适当控制生产压差。

The study of the microscopic distribution of formation water can provide reference and basis for the optimization of favorable zone selection and gas well production system.Using thin section,scanning electron microscope,mercury injection,nuclear magnetic resonance,two-phase flow experiment,logging,and production dynamic data,the study of the pore structure,reservoir water distribution state,and production characteristics of the tight sandstone gas reservoir in the Shaximiao Formation of Zhongjiang Gas Field was conducted.The results show that the average median pore throat radius of Class Ⅰ,Ⅱ,and Ⅲ reservoirs in the Shaximiao Formation of Zhongjiang is 0.30,0.16 and 0.04m,respectively.Formation water exists in the form of free water,capillary water,and thin film water in the reservoir.Thin film water is widely distributed,capillary water mainly exists in the throats with a radius less than 0.100μm,and free water can be seen in reservoir with poor matching relationship between fault and sand body and low structural position.The main source of water production in gas wells is condensate water,capillary water,and thin film water,with the overall characteristics of low water production,low mineralization,low water-gas ratio,and an increase in the latter.The evaluation and development of high water-saturated areas should primarily target Ⅰ and Ⅱ reservoirs,and production pressure differentials should be appropriately controlled during production of water-gas wells.