4D SEISMIC RESEVOIR SIMULATION: AN ALTERNATIVE APPROACH TO IMPROVE THE PERMEABILITY FIELD THROUGH THE USE OF TIME-LAPSE SEISMIC DATA

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Abstract

Field data from a producing field was used to correlate changes in pressure and saturation with changes in seismic attributes from 4D seismic. The correlations explored how the seismic responses and the distribution of rock properties (i.e.: permeability, pressure and saturation) are related to the changes caused by the production from a reservoir. An extended approach for estimating horizontal permeability was developed through an integrated approach involving multiple disciplines and an initial permeability model including 4D seismic and field production data. The development of the approach involved the use of mathematical, numerical and computer modelling techniques through partial differential equations and computer software to solve these equations. The robustness, applicability and accuracy of the approach were tested on the Dalia field for which a 3D static reservoir model was built for extraction of the numerical data. The static model of the Dalia field was populated with up-scaled reservoir properties of the field in addition to information obtained from wells logs (5 oil producers and 3 water injector wells); in addition to the well data, 4D seismic data (consisting of 2 seismic volumes shot at T0 and T1), completion data, well trajectories, time-depth laws, horizon information, geological and geophysical information were also used. A single 2D layer model was produced by averaging reservoir properties in the vertical direction from the 3D model. The permeability estimation approaches proposed by this project were successfully implemented by building computer programs that used equations derived by the numerical analysis; the input data for the computer programs was the data quantitatively extracted from the average 2D single layer model of the Dalia field. The approach made use of an initial log-derived permeability, saturation models in addition to reservoir dynamic and rock properties. Results produced by the approach show permeability estimates that honour the input data by displaying patterns correlatable to the initial permeability model, while revealing detailed features that can be interpreted as a better distribution of the channels. Therefore, the approach has proven possible to generate detailed permeability information using 4D seismic and production data. Permeability estimation approaches using 4D seismic have been developed before (Vasco, et al., 2004; MacBeth & Al-Maskeri, 2006). Compared to the previous work, the approach here proposed poses the advantage of being adaptable to different physical and production scenarios – oil-gas-water production and oil and water production. In essence, the method can have different applications estimating reservoir properties, updating simulation models or used as a tool that takes advantage of the advances in the computer imaging developments by making more quantitative use of the seismic data to use in parallel with traditional techniques. The uncertainty and limitations of the approach were explored and minimized where possible. The permeability estimated using the approach is dependent on the initial permeability model, the spatial distribution of the rock properties, pressure, saturation, flow properties - all related to changes in the seismic attribute.

Keyword(s)

3D modeling; 4D seismic reservoir simulation; Fluid characterization; Petrophysical modeling; Reservoir modeling & characterization; Reservoir simulation; Stochastic modeling

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