Joint Inversion Method of Rock Physics Based on Hunger Games Search Correction and Bidirectional Long-Short-Term Memory Network

Petrophysics estimates reservoir parameters are based on formation reflections, but generally neglect porosity heterogeneity. In the Berryman theory, the pore aspect ratio is considered in petrophysical modeling. As we cannot acquire the pore aspect ratio directly, a fixed value is set empirically without considering the heterogeneity of the reservoir. We propose pore aspect ratio correction through Hunger Games Search (HGS). HGS quickly develops the optimal solution space for pore aspect ratio by simulating the way social animals forage. The revised pore aspect ratio improves the accuracy of forward modeling. In the new rock physics modeling with revised pore aspect ratio, the correlation coefficient for P-wave velocity improved from 0.843 to 0.924, and for S-wave velocity from 0.784 to 0.857. We added the revised pore aspect ratio to the petrophysical inversion process. A bidirectional long-short-term memory network is established to realize the joint inversion of multiple reservoir parameters considering the heterogeneity of porosity. The proposed scheme was applied in a tight sandstone reservoir. The results show that the physical parameters and pore space structure can be effectively inverted.