关键词: 裂缝性气藏, 应力敏感性储层, 渗透率模量, 有限元法, 试井模型, 数值试井解释软件

Abstract: On the basis of the experimental data of stress-sensitive reservoir and well test theories, the dual media numerical well test model was established in consideration of stress sensitive permeability. The concept of permeability module was introduced to the model. The numerical well test interpretation software was developed by finite element method. The typical curves were gained and analyzed with the software. The dual logarithmic curve consists of three periods. In the first period,it has the similar characteristics as conventional gas reservoir, showing as a straight line at slope of 1.0.In the transition period,the length is controlled by permeability modulus under condition of the same storage factor and crossflow factor, the smaller the permeabitity modulus, the longer the transition period length. In the third period, the pressure of reservoir shows a semi-log straight line, and the value of derivative pressure is a constant less than 0.5. In the log-log plot, the distance of pressure curve to the pressure derivative curve of pressure sensitive reservoir is larger than that of the normal reservoir.The interpretation result of skin factor will be abnormal positive for the sensitive data interpreted by the traditional software. A field example analysis with the new numerical simulator shows that the numerical well test analysis can accurately identify the formation parameters and evaluate the acidization effectiveness of the ultra-high stress-sensitive gas reservoir contrasting the normal well test software.

Key words: naturally fractured reservoir, stress-sensitive reservoir, permeability modulus, finite element method, well test model, numerical well test interpretation software