确定气水同产水平井流入动态关系的新方法

气水两相渗流过程中,气体从水中逸出,或水从气体中析出会改变气藏渗流特征。针对这一现象,基于渗流力学的基本理论,结合保角变换数学方法,将水平井三维流动简化成水平面和垂直面的两个平面流动,同时考虑地层中气水相互溶解和挥发的过程,推导出水平井气水两相渗流的数学模型,建立了水平井气水两相产能方程,并结合相对渗透率辅助方程及水驱气藏的物质平衡压降方程,建立了气水同产水平井综合渗流模型。利用自动拟合方法,通过对气井产气量、产水量、油套压的自动拟合分析,求取气水同产水平井综合渗流模型参数,同时得到气水两相产能方程、气水相渗曲线、单井控制储量与水侵强度。该方法摆脱了确定气井产能必须依靠现场试井的局限,为气水两相流井的产能及动态分析提供了一种新的理论方法。

A new method for ascertaining the influx dynamic relation in water-gas producing horizontal wells

For the two phases flow of gas and water, gas will escape from the water or water will evolve from the gas, which both changes the gas reservoir flow characteristics. Based on the basic theory of permeation flow mechanics and the conformal transformation mathematical method, the 3D flow in horizontal wells is simplified into the flow in horizontal and vertical planes. Simultaneously, considering the process that the gas and water mutually dissolve and volatilize in the formation, the gas-water two phase flow mathematical model for horizontal well is inferred, and the gas-water productivity equation for horizontal wells is established. By referencing the auxiliary equation of relative permeability and the equation of material balance pressure drop of water-drive gas reservoirs, the comprehensive flow model for gas-water producing horizontal wells is built. By automatic fitting analysis of gas production, water production, tubing and casing pressure of gas wells, the integrated flow model parameters of gas-water producing horizontal wells can be obtained, and the gas-water productivity equation, gas-water flow curves, probable reserves in individual wells and water cut intensity can also be obtained. This new method avoids the limitation of relying on field test to determine the gas well productivity and provides a new theoretic method for deliverability and dynamic analysis for gas-water flow wells.