The representation of structural complexities in numerical reservoir simulations is cumbersome and often over-simplified. The introduction of leak paths across faults is particularly subjective, because patterns of fault sealing are generally not described by the geologist.

A procedure is presented here which models fault sealing capacity, and allows potential leak, paths to be located, ranked and incorporated into the simulation model. The procedure involves the semi-quantitative modelling of fault sealing assuming clay smear and shale juxtaposition to be the primary sealing mechanisms. The capacity for sealing along faults cutting representative reservoir sequences is described on clay smear ‘type panels’. Information from the type panels is used to map out variations in fault sealing capacity along individual fault planes, allowing potential leak paths to be located and ranked.

The reservoir simulation employs a coarse, curvilinear grid, designed to honour the structural configuration of the reservoir but facilitate fast processing times. Ranked leak paths are introduced into the simulation model during history matching to constrain cross-flow between reservoir

sub-compartments. This leads to a matched simulation model, and also provides a calibration of the fault seal model against production data.

The procedure of combining the reservoir simulation and fault seal models illustrates the benefits of an integrated production geology/reservoir engineering approach to reservoir modelling.

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