Abstract - We summarise methodological advances towards more flexible, realistic and accurate representations of fault rock and fault zone petrophysical and geometrical properties in conventional flow simulation models. These advances have been included in the TransGen fault modelling software package, developed to its current level through an ITF-associated project, and are illustrated using a range of synthetic reservoir models.
Since each reservoir has been the subject of a specific characterisation program and is geologically unique, it will have specific levels of parameter uncertainty and may require subtly or totally different approaches to fault and fault property modelling than other reservoirs. These requirements are at odds with most geological fault property modelling packages which offer a limited suite of black-box solutions, and is better achieved with dedicated fault property software allowing both a wide range of fault-related flow effects to be represented in the simulation model stochastically and deterministically, and complete user flexibility in both the choice and detailed application of work-flow used.
Novel fault-related flow effects for which full solutions have been derived and included in the software include both the effects of two-phase fault rock properties (i.e. relative permeability and capillary pressure curves of fault rock) and of fault segmentation (i.e. fault relay zones, paired slip surfaces etc); in each case appropriately up-scaled to the resolution of the flow model in which fault are represented as planar discontinuities between grid-blocks. User flexibility includes basic choices such as the fault property predictor (e.g. SGR, CSP, SSF, user-defined) to use or whether or not (and if so, how) to include stochastic components within the algorithms, as well as more fundamental choices such as uncertainties in the displacement on (and hence juxtapositions across) specific faults or portions of faults, inclusion of deterministic sub-resolution faults not included explicitly in the geometry of the simulation model, effects of geological fault drag or effects on vertical permeability as well as on across-fault transmissibility of fault damage zones.
Abstract of poster presented at:
Structurally Complex Reservoirs, Geological Society of London, February 2006.