Abstract:

Multi-parameter inversion of fractured reservoirs is affected by coupling between fracture and fluid parameters, while the limited seismic bandwidth makes conventional log-derived models difficult to use as stable initial constraints. Here we derive decoupled PP-wave reflection coefficients and azimuthal elastic impedance from a solid-liquid-fracture decoupling theory, and construct extended azimuthal elastic impedance (EAEI) through an auxiliary-angle transformation. We then establish an initial fluid factor model by selecting the EAEI with the highest correlation with the fluid factor and treating it as a pseudo-fluid phase. Tests on a Marmousi model and field seismic data show that EAEI reproduces the variation of fluid factor; The correlations between inverted and logging fluid parameters are 0.91 and 0.89 for Wells C and D, respectively, compared with 0.74 and 0.87 for the corresponding fracture parameters.

Key words: fracture-type reservoirs')">

fracture-type reservoirs, solid-liquid-fracture decoupling, azimuthal seismic data, expanded azimuthal elastic impedance, fluid parameters