Integration of geology and geophysics through geostatistical inversion: a case study

Geostatistical inversion of seismic data can be used to build highly detailed reservoir models with integration of information from diverse sources. A key to successful integration is the solution for facies during the inversion, provided that the facies definition is meaningful in the elastic, petrophysical, geological, and reservoir engineering domains. This case study from a field offshore Vietnam shows that the seismic data are only able to constrain the vertical distribution of facies when the beds are close to or above seismic resolution. Prior facies probability trends are required to ensure that the detailed vertical distributions of facies are consistent with geological and reservoir engineering expectations. However, even when below seismic resolution and when the probability trends are laterally invariant, the lateral variations of facies are driven by the seismic data.