Study On Calculation Method Of Reservoir Reformation Volume In Fuling Shale Gas Field

The basic characteristics of shale gas reservoir in Jiaoshiba of Fuling area are studied in this paper, based on the theory of fluid mechanics, crack propagation theory, rock failure criterion, a mathematical model for evaluating stimulated reservoir volume (SRV) in shale gas fracturing was established. The model contains hydraulic fractures propagation calculation, reservoir fluid pressure field calculation, interference stress field calculation and failure criterion of natural fractures. Then the numerical solving processes of the model was presented in this paper, and the SRV computing program has been compiled with MATLAB.Based on the mathematical model, the influence factors of SRV, including several critical engineering parameters, were quantitatively analyzed. According to the parameters sensitivity analysis, it shows that the SRV is influenced by the natural fracture dip angle and approach angle, the horizontal stress difference, the pump rate, the total fracturing-fluid volume and the perforation cluster spacing.Combined with the reservoir characteristic of shale gas reservoir in Jiaoshiba and fracturing parameters on field, the SRV mathematical model was applied to Fuling shale gas reservoir, the SRV of JY A-1HF Well, B wells factory JY B-1HF, JY B-2HF, JY B-3HF were calculated. The SRV calculation results show that:in the horizontal wells fracturing process, reservoir fluid pressure surrounding hydraulic fractures significantly increase, stress interference effect is evident, so that natural fractures are vulnerable to be activated and turn into reservoir stimulated volume. Single-stage SRV mainly ranges between 0.86? 1.99×106m3; Single-well SRV ranges between 22.9?34.5×106m3.Finally, the SRV model calculation results of B well factory was compared with microseismic monitoring data on field, it shows that the geometrical dimensions (length, width and height) of SRV calculated by mathematic model agree well with microseismic monitoring data, but calculated SRV total volume is generally less than microseismic monitoring results.