“BP has developed a one-dimensional stochastic inversion method (ODiSI) for jointly estimating reservoir properties and facies, and also, importantly, the associated uncertainties. ODiSI generates a large number of pseudo-wells consistent with the input prior information (well data and seismic horizons) at each trace location. It then generates a synthetic seismic trace for each pseudo-well, compares these traces to one or more colour-inverted seismic angle stacks and selects the ones that give the best match. These best match pseudo-wells are then analysed to provide estimates of the reservoir properties and associated uncertainty. No low-frequency model is required, and no lateral constraints imposed.

This paper will discuss briefly how the pseudo-wells are constructed and how the matching process is implemented. We will look at the results of the first application of ODiSI to a carbonate reservoir — the Mishrif interval of the Rumaila field, Iraq — and compare the ODiSI outputs to measured porosity logs.”