低渗透无边、底水气水同产气藏产水原因分析

REASONS OF PRODUCING WATER IN THE LOW-PERMEABILITY GAS/WATER RESERVOIRS WITHOUT EDGE/BOTTOM WATER

低渗透无边、底水气藏生产井出现气、水同产问题,产水的原因及其对开发的影响受到油藏工程师的关注。为此,分析了两个低渗透碳酸盐岩气、水同产气藏,通过对生产资料统计分析、理论分析和判断方法的研究,解释了无边、底水气藏的产水原因:孔隙毛细管力作用导致的气水同层,存在气水过渡带;在非均质条件下,气水界面并非水平界面或斜面,而是呈不规则起伏的界面,在此界面之下的气水过渡带高度不同,相同含水饱和度对应的高度也不同;处于低渗透气水过渡带的生产井在大生产压差作用下地层水开始流动,生产井产水量与产层部位水的饱和度有关。研究表明,尽管存在气、水同产,但产水规模不会对气田整体开发造成大的影响,应采取合理的措施避免生产井井底积液,以提高该类气藏的开发效果。

The problems of producing gas and water usually occur in the production well of the low-permeability gas reservoir without edge/bottom water.Reasons of producing water and its affections on the gas development have been paid close attention by reservoir engineers.Therefore,by means of analyzing two low-permeability carbonate gas water reservoirs and through statistic analysis of production data,theory analysis,and studies on judging methods,this paper interpreted the reasons of producing water in the gas reservoir without edge/bottom water,i.e.,gas and water reside in the same layer by the action of capillary force and gas/water transition zone exists;under the heterogeneous conditions,the interface of gas and water is not a horizontal surface or a slope,but an irregular and fluctuate surface,where the height of gas/water transition zone is different,the corresponding height of the same water saturation is also different;the formation water can flow under the pressure difference in the production well of low permeability gas/water transition zone and the water yield of production well is related to the water saturation of pay formation's location.The results showed that despite the existence of the gas/water producing,water production will not cause great influence to the development of gas fields;however,reasonable measures should be adopted to avoid the liquid loading of the production wells,so as to enhance the development in this kind of gas reservoir.