The Seepage Mechanism And Productivity Analysis In Tight Gas Reservoir

Tight gas reservoir with poor reservoir physical property and complicated development well,testing time long,caused great difficulty for the capacity analysis and productivity prediction served an important part as a development plan.Therefore,it is necessary to establish a suitable for tight gas reservoir capacity test and analysis method considering the tight gas reservoir percolation characteristics.So that the tight gas reservoir can be developed comprehensively and efficiently.Analysis based on the domestic and foreign papers of tight gas reservoir,optimization of main control factors,the percolation mathematical model is set up in line with the tight reservoir layer characteristics.The new model considered the threshold pressure gradient,stress sensitivity and high-speed non-darcy.Considering the difference of the tight gas reservoir,the slow pressure wave speed,long test period,in the full analysis of the existing test method,a series of short-term production test method is established innovatively and the deliverability test time is greatly shortened.Nonlinear well test interpretation mathematical model is established based on homogeneous gas reservoir and dual porosity medium.The boundary contains infinite boundary,closed boundary and constant pressure boundary.The well types are horizontal well and fractured horizontal well.The wellbore storage and skin factor is introduced in the model.By using the point source function,the model is solved.Via drawing the curves of pressure and pressure derivative,the influence of different parameters on the well test curve are analyzed.Considering the characteristics of tight gas reservoir,using elliptic seepage theory,horizontal wells and fractured horizontal wells nonlinear steady productivity prediction methods are established with the consideration of starting pressure gradient and stress sensitivity.In addition to,based on the establishment of well test interpretation model,by using the perturbation theory and numerical inversion of the Laplace transform,the unsteady productivity method is built considering the nonlinear factors.The main parameters of horizontal well and fractured are analyzed.According to the above research results,the tight gas reservoir well test interpretation and productivity analysis software is compiled.Combined with a certain gas reservoir capacity test data for example,the software application is vertified.Compared with the Darcy model,the calculation results of seepage model with nonlinear factors are much closer to the field practice,which can guide the development of tight gas reservoir.