低渗气藏产水气井产能评价

PRODUCTIVITY EVALUATION OF WATER-PRODUCING GAS WELLS IN LOW-PERMEABILITY GAS RESERVOIRS

随着我国大批低渗气藏的相继发现,低渗透气田的开发引起了极大的关注.对此类气藏产能的准确评价成为了合理、高效开发的关键.从渗流力学角度来讲,低渗产水气藏的渗流规律不同于常规气藏,气体渗流时,存在一个启动压力梯度,且气井产水后,出现了气、水两相流动,如果仍用常规方法来分析气井产能就会得出错误的结果.为此,针对气藏低渗、产水的特点,推导了低渗产水气井产能预测公式,并通过实例分析了产水及启动压力梯度对气井产能的影响,这对于气、水同产井的管理及生产动态预测都具有重要的意义.

With the successive discoveries of a large number of low-permeability gas reservoirs in China, the development of such reservoirs has attracted great attention and moreover the accurate productivity evaluation of this kind of gas reservoirs has become the key to their reasonable and high-efficiency developments. In the viewpoints of fluid mechanics, the percolation laws in low-permeability gas reservoirs with water production are distinct from the ordinary ones because there is a threshold pressure gradient when gas flow happens and furthermore two phase flows of both gas and water will appear after water produced in gas wells. If the traditional methods are still used to analyze the productivity of thus low-permeability gas wells, wrong results will occur. Therefore this paper derives a predic- ting fommla for the productivity of above low-permeability water-producing gas reservoirs, and then analyzes the influences of water production and threshold pressure gradient on gas well productivity. All above achievements possess a great significance to the management and production performance prediction for those gas ＆ water producing wells.