Finding ways to accelerate the effective development of tight sandstone gas reservoirs holds great strategic importance in regard to the improvement of consumption pattern of world energy. The pores and throats of the tight sandstone gas reservoir are small with abundant interstitial materials. Moreover, the mechanism of gas flow is highly complex. This paper is based on the research of a typical tight sandstone gas reservoir in Changqing Oilfield. A strong stress sensitivity in tight sandstone gas reservoir is indicated by the results, and it would be strengthened with the water production; at the same time, a rise to start-up pressure gradient would be given by the water producing process. With the increase in driving pressure gradient, the relative permeability of water also increases gradually, while that of gas decreases instead. Following these results, a model of gas-water two-phase flow has been built, keeping stress sensitivity, start-up pressure gradient, and the change of relative permeability in consideration. It is illustrated by the results of calculations that there is a reduction in the duration of plateau production period and the gas recovery factor during this period if the stress sensitivity and start-up pressure gradient are considered. In contrast to the start-up pressure gradient, stress sensitivity holds a greater influence on gas well productivity.

中文翻译：

---

产水致密砂岩气藏产能影响因素

寻找加快致密砂岩气藏有效开发的途径，对改善世界能源消费格局具有重要战略意义。致密砂岩气藏孔喉细小，填隙物质丰富。此外，气体流动的机理非常复杂。本文基于对长庆油田典型致密砂岩气藏的研究。结果表明致密砂岩气藏具有较强的应力敏感性，且随采水而增强；同时，制水过程会导致启动压力梯度上升。随着驱动压力梯度的增加，水的相对渗透率也逐渐增加，而气体的相对渗透率反而下降。根据这些结果，建立了考虑应力敏感性、启动压力梯度和相对渗透率变化的气水两相流模型。计算结果表明，在考虑应力敏感性和启动压力梯度的情况下，高原生产期持续时间和采气率均有所降低。与启动压力梯度相比，应力敏感性对气井产能的影响更大。计算结果表明，在考虑应力敏感性和启动压力梯度的情况下，高原生产期持续时间和采气率均有所降低。与启动压力梯度相比，应力敏感性对气井产能的影响更大。计算结果表明，在考虑应力敏感性和启动压力梯度的情况下，高原生产期持续时间和采气率均有所降低。与启动压力梯度相比，应力敏感性对气井产能的影响更大。