Understanding the Impact of Hydrodynamics Using Petroleum System Modeling

Abstract

The impact of hydrodynamic mechanism on hydrocarbon accumulations is being discussed since the 1950s. Its role in tilting the oil-water contact is documented but it has been under debate. Explorationists have been modeling the hydrodynamic mechanism using the pressure gradients caused by topographic elevation difference between hinterland and basinal areas. The pressure gradient causes the flow of water from high to low hydraulic head which provides the source of hydrodynamic force for fluid flow. The tilt of a hydrocarbon contact is mainly influenced by pressure gradient and the fluids density. In addition to the traditional understanding of gravitational flow, which is commonly observed in the Arabian plate due to structural tilt, the OWC tilt can be created by fluid flow from deeper overpressured layers to shallower normally pressured layers. This paper illustrates the impact of hydrodynamics on hydrocarbon accumulations using the petroleum system modeling. The petroleum system modeling based workflow demonstrate the tilted hydrocarbon contacts resulted from pressure gradient and fluid densities. A three-dimensional dynamic basin model was built with hypothetical source rock and related reservoirs. For the purpose of workflow demonstration, the source rock was positioned at the depth where both oil and gas are being generated so the model can predict the variable tilts for OWCs, GOCs and GWCs. The model incorporates scenarios of hydrodynamic impact due to the variation in parameters such as a recent structural deformation, changes in fluid density, changes in facies and thickness of the aquifer. This modeling approach can be used predictively to understand the tilted OWCs in the fields to explore for upside potential beyond the discovered fields limits.

AAPG Datapages/Search and Discovery Article #90364 © 2019 AAPG Middle East Geoscience Technology Workshop, Integrated Emerging Exploration Concepts: Challenges, Future Trends and Opportunities, Dhahran, Saudi Arabia, December 2-4, 2019