Method for estimating and/or reducing uncertainty in reservoir models of potential petroleum reservoirs

A method for estimating and/or reducing uncertainty in reservoir models of potential petroleum reservoirs, the method comprising the steps of:

• (a) receiving the results of a stochastic seismic inversion which provides output ensembles in respect of a plurality of properties on the basis of imaged seismic data obtained at points on an imaged seismic input grid over a region to be modelled, the output ensembles including information regarding the values of the plurality of properties at points on the input grid for a sequence of model layers, including means and covariances for the properties,
• (b) assembling information regarding an observed fault structure in the region,
• (c) assembling well log data in respect of one or more properties, obtained from well locations within the region,
• (d) modifying the geometry of the input grid to form an output grid for each layer, based on the observed fault structure and the seismic inversion results,
• (e) interpolating the values of the plurality of properties from the points on the input grid onto the output grid,
• (f) spatially smoothing the means and covariances of the output ensembles to produce a smooth trend map for each property and a smooth inter-property trend covariance,
• (g) performing a kriging adjustment of the property trends on the basis of the well log data so that the trends pass through the well log data,
• (h) simulating a set of spatially correlated random fields on the output grid for each property, and generating a set of realisations for each property on the basis of the random fields, the smooth inter-property trend covariance and the property trend maps, which honour inter-property and inter-layer correlations from the seismic inversion and measured well data, and
• (i) using the generated realisations in a reservoir model to conduct flow simulation and/or volumetric calculations in respect of the region.