WENDEBOURG, JOHANNES, Stanford University, Department Applied Earth Sciences, Stanford, CA

ABSTRACT: Simulating Hydrocarbon Migration Using 3-D Geologic Process Modeling

Secondary hydrocarbon migration is a dynamic process that affects

both migrating fluids and carrier beds. During migration, the composition of hydrocarbon fluids may change due to changes in pressure and temperature. Simultaneously, carrier beds may undergo changes due to compaction and diagenetic alterations. Furthermore, tectonic displacement may affect carrier beds and form structural traps, while primary depositional features may have already created stratigraphic traps. It is important, therefore, to characterize carrier bed properties as time-dependent features, in contrast to procedures for characterizing reservoirs of producing fields, where reservoir properties usually do not change.

With numerical modeling, the evolution of hydrocarbon fluids and carrier beds through time can be simulated. A 3-D simulator system developed at Stanford known as SEDSIM creates carrier beds whose sediment distribution is provided by depositional process modules. The resulting three-dimensional lithostratigraphic record can be transformed to its petrophysical equivalents with functions that relate grain-size distributions in clastic sediments, fluid pressures, and hydrocarbon saturations, to porosity, permeability, capillarity, and relative permeability. SEDSIM's migration module is a fully implicit multi-phase flow simulator that tracks hydrocarbon saturations through geologic time as a function of source rock expulsion and three-dimensional carrier bed heterogeneities. The simulator has been applied to the Tulare Formation of Quaternary age at South Belridge oil field in Kern County, California. Data for the Tulare Formation include grain-size distributions, porosities, permeabilities, and oil saturations, all of which have been correlated with primary depositional environment using suites of well logs.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.