Experimental Study on Stress Sensitivity Considering Time Effect for Tight Gas Reservoirs

Stress sensitivity is a crucial engineering problem in the process of tight gas reservoir development. In this work, the experiments about tight gas reservoirs are performed by confining pressure for a long time to simulate tight gas reservoirs under pressure for a long time during production process. The cores used in the test were from Ordos Basin, which is a typical tight gas reservoir. The results show that the stress sensitivity is increasing with compression time extended. Evaluation method for stress sensitivity about tight reservoirs was established based on time scale. The stress sensitivity for tight gas reservoirs was divided into two feature segments from time scale, which were named instantaneous stress sensitivity and delayed stress sensitivity. The conventional evaluation method for stress sensitivity about tight reservoirs has only considered the instantaneous stress sensitivity, and the delayed stress sensitivity has been ignored. The new method can more accurately simulate the stress sensitivity for tight gas reservoir, which has great guiding significance in rational development for tight gas reservoir.