Modeling Scale Up of Steamflood in a Heterogeneous Reservoir
- Kaveh Dehghani (Chevron Petroleum Technology Co.) | W.M. Basham (Chevron Petroleum Technology Co.) | L.J. Durlofsky (Chevron Petroleum Technology Co.) | K.E. Tucker (Chevron Petroleum Technology Co.)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Engineering
- Publication Date
- November 1995
- Document Type
- Journal Paper
- 237 - 246
- 1995. Society of Petroleum Engineers
- 3 in the last 30 days
- 223 since 2007
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In the numerical modeling of a steamflood process in a highly stratified,thick reservoir with thin interbedded discontinuous permeability barriers, thevertical grid size must be comparable to the length scale of permeabilityvariation in the vertical direction. In a thick reservoir, the smaller lengthscale of vertical heterogeneities results in an impractically large number oflayers for the modeling of a computationally intensive process such assteamflooding.
In the first part of this study a series of simulation runs were conductedfor different geostatistically derived cross sectional models to study thedegree of heterogeneity that is required to properly model steamfloods in thepresence of thin diatomite barriers in both the dipping and non-dippingsections of a heavy oil, thick reservoir. These cross sectional models each hada different number of layers and were developed by sequential indicatorsimulation of log traces. The most detailed models contained 300 layers.
In the second part of this work we applied different methodologies forcoarsening the most detailed model while still capturing the effects of thegeologic features. Two different methods were examined to coarsen the detailedmodels. In one method, we maintained the impermeable layers and coarsened thesands by averaging each 10 sand layers. In the other method, the 300 layermodels were coarsened using a general scale up method. In this method thedominant flow paths in the cross section are first identified through solutionof a single phase flow problem. This information is then used to selectivelyscale up the reservoir properties, leaving detail in regions where required andcoarsening in other regions.
The results show that the coarse models developed directly from thesequential indicator simulation underpredict the recovery in the non-dippingcross sections and overpredict the recovery in the dipping cross sections.
The results also show that the scaled up coarse models predict recoveries ingood agreement with the detailed model in both the dipping and non-dippingsections of the reservoir. The results also show that the coarse models whichwere developed by keeping the shale and averaging the sand layers only provideaccurate results in the non-dipping section of the reservoir.
As heat and reservoir management become more important in steamfloodoperations improved engineering tools are required to cost-effectively managesteam injection projects. Application of reservoir simulation as a tool forsteamflood management is growing. However, many steamflood reservoirs have ahigh amount of geologic heterogeneities, which may impact both actual andsimulated project performance.
The importance and impact of heterogeneities on the performance predictionof steamflood processes in highly stratified systems have been recognized inthe literature.
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