低渗气藏多次应力敏感测试及应用

低渗透气田在我国已开发气藏中占有相当大比例，应力敏感性对气田开发的影响已逐渐引起人们重视。针对目前大多数低渗透气田应力敏感测试仍然采用定内压变围压测试方式所存在的与实际气田开发过程中内压变化上覆压力恒定的变化规律不一致的问题，研究提出了变内压定围压测试方法，采用该方式测试低渗透岩芯在净上覆压力六升六降过程中应力敏感性,并应用测试的应力敏感曲线对低渗透气井试井特征及单井生产动态进行研究。结果表明：变内压定围压测试方法更接近于气田实际压力变化过程；（不）考虑应力敏感试井分析两者在试井特征曲线第II阶段相差较大，五开五关试井分析表明渗透率应力敏感效应的存在对气藏的开发是不利的；应力敏感对单井模拟井底流压影响很大，考虑应力敏感时，气井生产压差明显增大。因此，在低渗透气田开发过程中，必须注意应力敏感对气田开发的影响。

Test and Application of Multiple Stress Sensitivity of Low Permeability Gas Reservoir

Low permeability gas reservoirs take up a quite large percentage in the developed gas reservoirs in China, the influence of stress sensitivity on gas field development is drawing great attention. Aiming at such problems as in most low permeability gas reservoirs, the stress sensitivity test is done by the way of fixing inner pressure and changing confining pressure, and in practical production, inner pressure changes but the overburden pressure is constant, a test way changing inner pressure and fixing confining pressure is put forward. The way is used to test the stress sensitivity of low permeable cores in the process of net overburden pressure rising and lowering six times respectively. The stress sensitivity curves are used to study the characteristics of low permeable gas well test and single well production performance. Result shows that the way of changing inner pressure and fixing confining pressure is more similar to reservoir practice, in the stage Ⅱ on well test curve, there is big difference while considering and not considering stress sensitivity well test, the well test analysis of closing and opening well five times respectively indicates the existence of permeability stress sensitivity effect is unfavorable for gas reservoir production, stress sensitivity impacts single well simulation bottom hole flowing pressure greatly, considering stress sensitivity, the pressure difference of gas well production increases apparently. So, in the process of low permeability gas field production, the influence of stress sensitivity on gas field production must be taken into consideration.