A Monte Carlo modelling approach for including fault seal and fault reactivation risk in trap evaluation is described. The model reduces the problem to a 1D analysis using a structural description depth-referenced to the crest of the prospect. Both juxtaposition and membrane fault seal are calculated, and any potential hydrodynamic effects on fault seal also included. A complementary geomechanical model is used to evaluate fault reactivation and mechanical top seal failure risk. The impact of both fault seal and fault reactivation on trapped column height is calculated and compared in a roll-up of results that also includes the potential columns constrained by capillary and mechanical top seals. The output is a predicted hydrocarbon column height distribution for a trap. The technique additionally offers insight into the potential fluid phase fractionation that may occur due to the active leakage mechanisms, thereby enabling gas vs oil column heights and their respective controls to be included in the prospect evaluation. This latter feature offers an update of the Seal Strength-Trap Closure approach championed by John Sales, by demonstrating how faults impact both the trapped hydrocarbon column and fluid phase partitioning.


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