含水气藏合理产能新方法研究

NEW WAY TO DETERMINE REASONABLE PRODUCTIVITY OF WATER-BEARING GAS RESERVOIR

在现场生产中很难获知气井线性临界流速的大小,致使常规气井产能方程的应用有一定的局限性。含水气藏由于产水会使气井的产能降低,若积液不能被及时带出,严重时会造成气井水淹。在其它条件相同或相近的情况下,产水气井的产能比纯气井产能小。文章在气水同产井含水气藏两相渗流理论研究的基础上,考虑表皮系数和非达西效应的影响,建立了在地层中气水两相渗流含水气藏的合理产能方程,这为确定含水气藏的合理产能和气水同产井动态分析提供了理论基础。方程中所涉及的参数可通过气藏PVT物性试验、产水气井的测试资料获取,再用数值积分方法求解两相拟压力函数。建立的产能方程可应用于分析气水同产井流入动态关系,确定合理产量,求出产水气井最大无阻流量。现场情况分析表明,产能方程对合理配产提供了科学的依据。

The application of the productivity equation is limited for conventional gas wells because it is very hard to acquire the critical linear flow rate in real operation, The productivity of water-bearing gas reservoirs will decrease since water producing. If the cumulative water in the bottom-hole is not discharged timely it may cause watered out of gas wells. The productivity of water-producing gas wells is lower than that of pure gas wells under the same or similar conditions. Based on the percolation theory of gas/ water bi-phase flow for both gas and water producing wells of water-bearing gas reservoirs, considering the influence of skin factor and non-Darcy effect, the reasonable productivity equation of water-bearing gas reservoirs is set up for gas/water, bi-phase percolation, which provides the theoretical basis to determine the reasonable productivity of water-bearing gas reservoirs and conduct the performance analysis of both gas and water producing wells. The parameters concerned in the equation can be acquired by PVT test of the gas reservoir and the testing date of the water-producing gas wells, and the bi-phase pseudo-pressure function can be solved with numerical integral method. The productivity equation can be used to analyze the flowing performance of both gas and water producing wells, determine the reasonable production, and cal- culate the maximum open (low rate of water-producing gas wells. The analysis of field situation shows the productivity equation provides the scientific basis for reasonable production allocation.