Reservoir characterisation by direct probabilistic inversion

There is an infinite number of subsurface facies and fluid configurations that can give rise to any given seismic response. Traditional reservoir characterisation workflows struggle to discriminate between facies with extremely elastically similar properties. Facies that are elastically extremely similar may have very different petrophysical properties.

As beds become thinner the seismic response, and hence the response in any elastic AVO inversion, becomes that of the package response. The package response can be thought of as some type of average response for all the facies within a given interval where this interval is based on the bandwidth of the input data.

This poster describes a technique that uses an innovative prior framework and inversion formulation. The inversion is one step, it takes data directly from the reflected amplitude domain to the facies domain. The key advantages of this approach are that it is robust in the presence of noise, there is a rigorous data driven provision of confidence in the results, it is able within certain limits to classify facies at sub-seismic resolution and that it can discriminate between elastically ambiguous facies.