High-resolution Geostatistical Inversion of a Seismic Data Set Acquired In a Gulf of Mexico Gas Reservoir.

Kelly, Michael C. (The University of Texas at Austin) | Torres -Verdín, Carlos (The University of Texas at Austin) | Schile, Charles A. (UNOCAL Corporation)



Geostatistical inversion is applied on a Gulf-of-Mexico, 3D post-stack seismic data set to improve the vertical resolution of reservoir parameters yielded by trace-based inversion. Results are derived in the form of a set of equally probable realizations of acoustic impedance that honor both the well logs and the seismic data. Petrophysical analysis reveals two prospective gas-bearing sands. We focus our analysis to the determination of lateral and vertical resolution properties of the thicker of the two sands. Geostatistical inversion yields stochastic realizations of acoustic impedance and bulk density with vertical resolutions of 4 and 1 ms. Inversion of bulk density follows from the enforcement of a statistical relationship with acoustic impedance validated with wellbore data. In turn, bulk density lends itself to a relatively simple procedure to obtain high-resolution simulations of total porosity andabsolute permeability.