OIL TRANSPORT BY SOLITARY WAVES IN ELASTIC POROUS MEDIA: A CASE STUDY OF THE EUGENE ISLAND FIELD, GULF OF MEXICO BASIN
A two-dimensional numerical model of the formation of the Eugene Island field incorporating the deposition and compaction of its sediments, the generation of oil and methane from kerogen, the transport of heat, and the flow and pressure evolution of oil, water, and gas indicated pore pressure in the source sediments to increase at an average rate of 30 Pa/yr. A further one-dimensional model of an oil-saturated vertical flow path indicated that solitary waves could form in the hydrocarbon source region but only within a narrow window of very low permeability between 10−24 and 10−25 m2 and at high degrees of overpressuring between 91 and 93% of lithostatic. Solitary waves were able to reach velocities on the order of 10−3 m/yr, several orders of magnitude greater than the background Darcian flow, but were only able to ascend 1-2 km before dissipating to ambient fluid pressure and porosity. Thus, solitary waves are unlikely to have played a significant role in charging any but the deepest reservoirs at Eugene Island based on a model of steady pressure increase and diffusive pressure change. This model for oil transport by solitary waves could be more important in fields where hydrocarbon source sediments and reservoirs are separated by less than one kilometer.