异常高压气藏岩石应力敏感性及其对产能的影响

STRESS SENSITIVITY OF ROCK AND ITS INFLUENCE ON PRODUCTIVITY FOR GAS RE SERVOIRS WITH ABNORMAL HIGH PRESSURE

文章具体实测了克拉2异常高压气藏岩样不同覆压下的渗透率,根据其实测结果拟合出渗透率的应力敏感性幂函数表达式,总结了岩石渗透率随气藏压力或有效覆压的变化规律。考虑渗透率变化对气藏产能的影响,推导出新的产能方程。研究表明:克拉2气藏岩样应力敏感性高于大庆油田岩样,具有异常高压气藏岩石欠压实的特点。岩样的应力敏感性使产能降低,在克拉2 气藏的条件下,考虑应力敏感时的绝对无阻流量是渗透率为常数时的70%左右。该研究对深入了解异常高压气藏的产能及预测异常高压气藏的开发动态和采收率有一定意义。

The permeability of rock samples is measured under different overburden pressure for Kela-2 gas reservoirs with abnormal high pressure. According to the measured results, the power function expression of stress sensitivity of permeability is derived. The changing law of the rock permeability is summed up as the gas reservoir pressure or the effective overburden pressure changes. Considering the influence of permeability changing on the productivity of the gas reservoir, a new productivity equation is developed. The study shows the stress sensitivity of rock samples for Kela-2 gas reservoirs is bigger than that for Daqing oilfield, which is the no-compacted characteristic of rocks of gas reservoirs with abnormal high pressure. The stress sensitivity of rock samples makes the productivity decreasing. Under the conditions of Kela-2 gas reservoirs, considering the stress sensitivity, AOF is about 70% of that when the permeability is constant. The study provides reference to deeply understand the productivity of gas reservoirs with abnormal high pressure, predict the production performance and the recovery factor of gas reservoirs with abnormal high pressure.