非线性流下井筒压降影响的水平井产能分析

 大量研究表明,气体渗流受到启动压力梯度、滑脱效应、应力敏感等因素影响,针对气藏的特征,基于稳定渗流理论,在考虑气体高速非达西渗流的基础上,通过气藏渗流与井筒流动耦合,推导建立同时考虑滑脱效应、启动压力梯度、应力敏感等因素共同影响的气藏-水平井井筒耦合模型,并通过实例分析研究了各因素对井筒流量分布的影响.研究结果表明：非线性流特征对井筒流量在井筒跟端分布影响较大;井筒管径越小,绝对粗糙度越大,在靠近水平井的趾端部分井筒流量减小幅度越大,而在靠近水平井的跟端部分井筒流量上升幅度越大;非均质性越强,水平井长度越长,井筒中流量减小幅度越大.

Effect of well bore Pressure Drop on the Horizontal Well Productivity with Non-linearSeepage

A lot of research results indicate that the main factors affecting percolation features of gas flow include the start-up pressure gradient, slippage effect, and stress sensitivity. And the researchers have found that the start-up pressure gradient, slippage effect, and stress sensitivity have an effect on the productivity of the gas well in the low-permeability gas reservoirs. On the other hand, the low-permeability is often applied to the horizontal well technology in order to enhance the production of the gas well. In view of the characteristic of low permeability gas reservoirs, based on the steady seepage theory and the high speed non-Darcy, by using the coupling of formation percolation and wellbore flow of the horizontal well, taking the influence of the start-up pressure gradient, slippage effect, and stress sensitivity into account, a coupling model of formation percolation and wellbore flow is established, and the distribution of the shaft flow for the horizontal well is discussed by analyzing and calculating examples. The results indicate that the non-linear seepage characteristics have a big effect on the distribution of the shaft flow at the heel of horizontal well. The smaller the wellbore diameter is, and the larger the absolute roughness is, the bigger the decreasing extent of the shaft flow at the toe of horizontal well is, while the bigger the obvious increasing extent of the shaft flow at the heel of horizontal well is. The stronger the heterogeneity is, and the longer the length of the horizontal well is, the larger the decreasing extent of the shaft flow of horizontal well is.