Stochastic Fault Seal Analysis and Reservoir Simulation for Fields with Thin Layers and Many Faults (Best of EAGE)

Shang, B.Z¹, H.D. Yang², S.A. Bourgeois² (1) Marathon Oil, N/A, NV (2) Marathon Oil, N/A,

Traditional fault seal analysis requires deterministic structural and stratigraphic models and significant fluid flow data for transmissibility calibration. For multi-faulted reservoirs with large structural and stratigraphic uncertainties and little dynamic data, traditional method fails to capture the range of production scenarios. This paper proposes a new method to capture the range of possibilities via stochastic analysis in juxtaposition, shale gouge ratio, and fluid flow. First, we gather the stratigraphic and structural information and to generate the parameter ranges, such as reservoir layer thicknesses, net-to-gross ration, number of layers, etc. Then, many juxtaposition realizations are created from these parameters. When reservoir zone thickness is greater than the fault throw, the shale gouge ratio is reduced to a function of net-to-gross ratio alone. Afterward, we construct the probability distribution function of cross-fault transmissibility by combining juxtaposition, shale gouge ratio and dynamic data. Finally, the transmissibility probability is provided to the simulator for reservoir performance simulation. This procedure has been applied to the appraisal of an offshore oil field that has many faults and subseismic reservoir layers. The procedure is demonstrated in 1 D but can be expanded into 3D by allowing the controlling parameters to vary with location.