Abstract: CIRF.B: Fully Coupled Water-Rock Interactions and Basin Evolution Simulator

Anthony Park, Miles Maxwell

A basin scale simulator CIRF.B (Chemical Interaction of Rock and Fluid, Basin model) is used to simulate the coupled chemical compaction (pressure solution), fluid flow, and mass transport processes occurring in a sedimentary basin. Using sedimentation histories based on sequence stratigraphic analysis of modern day basins, the simulator predicts the evolution of diagenetic seals and overpressured zones for petroleum exploration purposes. Predictions of the simulator on porosity-depth curves can be used to characterize the reservoir property of the lithologies in the basin; the predicted history of basin scale fluid flow patterns can be used to deduce petroleum migration pathways.

The unique phenomenology used for CIRF.B allows the fully coupled interaction between all minerals present in the system and solutes in pore water as a function of temperature, fluid pressure, tectonic stresses, and pore water composition. A new phenomenology accounting for pressure solution in multimineralic systems is introduced that accounts for potential differences in pressure solution between different type of mineral contacts as well as for free face grain coatings. As a result the processes of mineral dissolution, authigenic mineral precipitation, and subsequent modifications to porosity and permeability and the generation of overpressured zones can be comprehensively simulated.

Simulations of typical sandstone, shale and carbonate shale sequences show the development of overpressured compartments within a single bed and illustrate the potential for diagenetic enhancement of original sedimentary nonuniformity leading to observed reservoir heterogeneity. Mineralogic and textural controls on basin scale diagenetic seals and abnormal pressure are illustrated with examples from the Anadarko Basin.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994