Inversion of reservoir fluid mobility from frequency-dependent seismic data - A case study of gas-bearing reservoirs

Reservoir fluid mobility is by definition the ratio of rock permeability to fluid viscosity. This attribute can be applied to reservoir physical property and permeability evaluation. Thus far, the only means of obtaining the reservoir fluid mobility over a large range of exploration areas is based on the extraction method. However, the location of high fluid mobility obtained by the extraction method is close to the reservoir interface. To obtain fluid mobility in the middle of the reservoir, an approximate inversion method of reservoir fluid mobility from frequency-dependent seismic data is proposed. First, we have calculated the reservoir fluid mobility coefficient using well data according to the relationship of fluid parameters. Then, we establish an inversion equation based on the low-frequency reflection coefficient and the reservoir fluid mobility. Taking the reservoir fluid mobility coefficient calculated from well data as an a priori constraint, the low-frequency model is subsequently constructed and applied with the inversion equation to obtain an inversion objective function. Next, the inversion equation is solved by the basis pursuit algorithm. Finally, the proposed reservoir fluid mobility inversion method is applied to synthetic and real data of gas-bearing reservoirs. The real data processing results show that the proposed reservoir fluid mobility inversion method can estimate the fluid mobility in the actual position of the reservoir more effectively.