低渗透油气藏应力敏感性评价实验新方法

为了研究地层压力的变化对低渗透油气藏孔隙度和渗透率的影响程度，采用室内实验与理论研究相结合的方法，对中原文东油田天然岩心进行了地面条件和地层条件应力敏感性实验。实验结果表明：孔隙度对应力不敏感；渗透率变化结果差别较大，地面条件实验所得的渗透率损害率约为地层条件的2—4倍，说明地面条件下的实验结果不能真实再现油气藏的应力敏感性，以往实验中单纯乘以系数0．61的处理方法不合理。低渗透油气藏应力敏感性评价实验应采用新方法，即模拟地层条件，将实验岩心加上围压（模拟上覆压力）和回压（辅以形成油层压力），通过改变内压（模拟油层压力），来达到改变净覆压的目的，测定不同内压下的渗透率，判断应力敏感性。

The new experiment method of stress sensitivity evaluation in the low permeability 0il-gas reservoirs

To study the effect of the change in formation pressure on porosity and permeability in the low permeability oil-gas reservoirs,the lab experiment together with theoretical method is used to study the stress sensitivity of the natural cores from Wendong,Zhongyuan Oilfield at both surface and formation conditions.The results have indicated that the porosity isn' t sensitive to the stress.The permeability differs greatly,that is,the permeability damage ratio at surface condition is about two to four times that at formation conditions,which implies that the experiment result at the surface can't reproduce the stress sensitivity of the real oil-gas reservoirs,and the old method by multiplying a factor of 0.61 is not precise.The stress sensitivity experiment for the low permeability oil-gas reservoirs should adopt this new method,that is,simulating the formation condition by applying confining pressure(simulating the overburden pressure) and back-pressure(help to form formation pressure) with the experiment cores,changing the net overburden pressure by changing the internal pressure(simulating reservoir pressure),then measuring the permeability in different internal pressure and determining the stress sensibility.