非线性渗流地层水平气井二项式产能方程

水平井是开发低渗透气藏最有效的方法之一,而低渗透气藏存在着启动压力梯度效应以及高速非达西渗流时的紊流效应。通过建立和求解包含水平气井井身结构参数、近井区高速非达西渗流条件下气体紊流因素以及启动压力梯度效应的水平气井渗流模型,推导出描述水平气井产能的二项式产能方程。在此基础上,依据理论推导和计算,对水平气井和直井的产能进行对比,研究启动压力梯度以及非达西渗流对水平气井产能的影响。结果表明启动压力梯度对水平气井产量影响呈一线性下降关系,非达西流动引起水平气井产能的降低,并且非达西流动对水平井的影响小于对直井的影响。

A binomial deliverability equation for horizontal gas wells in formations with nonlinear seepage flow features

A horizontal well is one of the most effective methods for developing low-permeability gas reservoirs which are characterized by the effects of start-up pressure gradient and turbulent flow under high-speed non-Darcy flow.A seepage flow model was established and solved for horizontal gas wells.It involves well-bore structure parameters,turbulent gas flow under high-speed non-Darcy flow in near-wellbore area and start-up pressure gradient.A binomial deliverability equation for horizontal gas wells was derived.Based on strict theoretical derivation and calculation,deliverability of horizontal and vertical wells was compared to understand the influences of start-up pressure gradient and non-Darcy flow on the deliverability of horizontal gas wells.The results indicate that the start-up pressure gradient is in negative linear relationship with the deliverability,the non-Darcy flow decreases the deliverability of horizontal gas wells and its influence on horizontal gas wells is smaller than that on vertical gas wells.