Water-Cut Forecasting and Permeability Inversion From Time-Lapse Seismic using a Stream-Line Technique

摘要

In this paper, we describe an algorithm, which predictsrnsaturation development through the a-priori unknownrnpermeability field using the saturation history of the field.rnFurthermore, the algorithm allows estimation of thernunderlying permeability field. The field’s saturation history isrnderived from time-lapse 3-D seismic data. Time-lapse seismicrnis used to monitor the reservoir during production. Assumingrnseismic repeatability, it is possible to couple seismic changesrnto dynamic reservoir properties changes induced byrnproduction. Successive seismic data set give direct informationrnover the speed at which the saturation front propagatesrnthrough the a-priori unknown permeability field. Thernpropagation speed of the saturation front contains usefulrninformation about the fluid flow velocity field in the observedrnmedium. It enables us to forecast the development of thernsaturation contours in time, which is easily translated intornwater-cut profiles. In addition, a relation between the velocityrnmap and desired reservoir parameters (e.g. permeability) canrnbe established using an inversion technique.rnA streamline technique is used to verify that eachrnsimulated saturation contour matches the a-priori knownrncontour it is based on. In a number of test cases we createdrnrandomly exponential correlated heterogeneous permeabilityrnfields. We verified the algorithm by comparing the forecastedrnresults with the real simulated results. A sensitivity analysisrnwas performed to study the number of saturation fronts (i.e.rnrepeat 3D surveys) required to yield reliable results. Thernproposed approach offers the advantage of invertingrnpermeability via a rather simple, but reliable method usingrntime-lapse seismic data.