Validation of fault seal mechanisms in the Timor sea : an outcrop and subsurface perspective

When risking faulted structures, across-fault juxtaposition and or membrane seal are key issues. Generally, this work is done on a “best-guess” model. The application of SGR methods in reservoir / seal systems that have moderate Vshale values artificially increases predicted column heights. In a risking processes these large columns are discounted through other geologic risk factors. Faults in Miri, Sarawak, have been systematically mapped in outcrop in great detail to measure the strike variability of fault rocks. This work greatly helps to understand the limitation of membrane seal algorithms. To illustrate the implications to subsurface risking, a validation will be presented in which observed hydrocarbon water contacts are compared with probabilistic models for both juxtaposition and SGR. A comprehensive review of a set of fields in The Timor Sea shows that probabilistic juxtaposition models more accurately predict hydrocarbon water contacts than calibrated SGR single “best” technical models