Geostatistical Reservoir Characterization in Barracuda Field, Campos Basin: A case study

Deterministic seismic inversion methods have been successfully used in many exploration and production projects in the petroleum industry. Some of the benefits of these methods are: the inverted impedances are rock properties tightly calibrated with well data; the seismic inversion process itself attenuates the wavelet effects, reduces side-lobes and tuning effects and enables quantitative predictions of reservoir properties, all of which are advantages to improving the understanding of the reservoir geology and better management of the drilling programs. However, when the reservoir is below the resolution of the seismic and/or has thinner low permeability barrier layers (compartments), estimating the reservoir volume and/or evaluating the connectivity in the reservoir geobodies from deterministic seismic inversion become less accurate and in many cases unfeasible. In such cases, the geostatistical seismic inversion method provides more accurate reservoir volumes and the uncertainty associated with the 3D models can be assessed and quantified. For the work described in this paper, we used a stochastic inversion methodology, which simulates many possible scenarios, to better discriminate the thickness of the sand/shale layers and the areal extent the layers in the Oligocene reservoir in the Barracuda Field, Campos Basin, offshore Brazil.