Welltest Of Condensate Gas Reservoir In Consideration Of Variable Wellbore Storage

The development of condensate gas reservoir plays a significant role in China's oil & gas industry. Thanks to the complexity of condensate gas reservoir, condensate gas welltest turns into a difficulty and emphasis point in welltesting. Previous studies only took the factor that affected wellbore storage into account, but neglected conditions of variable wellbore storage. However, in view of characteristic of condensate gas, variable wellbore storage has a remarkable influence on the pressure and differential of pressure. If variable wellbore storage is disregarded, the result of the analysis will be imprecise. Base on the features of condensate gas reservoir welltest, in this paper I presented mathematical models of homogeneous condensate gas reservoir,double porosity condensate gas reservoir and triple porosity condensate gas reservoir in concern of the effects of skin coefficients, as well as variable wellbore storage, and adopted analysis method and numerical method to solve them respectively. Besides, I also edited program to draw Pressure Behavior curves under different parameters, analyzed the impact of each parameter on the pressure and differential of pressure, studied the application of non-linear regression of M—L automatic fitting method. And finally I integrated the theory achievements into gas welltesting interpretation software, which gains great fit effects during practical application.