A Unified Dynamic Model of Subsurface Fluid Systems (The Λ Framework)

This study presents a unified dynamic framework for subsurface fluid systems, integrating hydrocarbon reservoirs and hydrothermal systems within a single physical model. Traditional approaches treat these systems separately and often as static accumulations, limiting their explanatory and predictive capabilities. The proposed model introduces a dimensionless governing parameter, Λ, defined as the ratio between fluid pressure and total geological resistance, including rock strength, external pressure, and capillary forces. This parameter determines the system regime: stable reservoirs (Λ 1). The framework incorporates fundamental physical processes such as pressure-driven flow (Darcy’s law), capillary resistance, multiphase fluid interactions, and geomechanical seal behavior. A complete 13-phase dynamic model is introduced to describe the evolution from deep fluid generation to reservoir formation. The study demonstrates that hydrocarbon reservoirs and hydrothermal systems are not fundamentally different in origin, but represent different states of the same underlying physical system controlled by pressure–resistance balance. Case studies including Ghawar, Iceland, and the North Sea support the model’s applicability. This work provides a shift from static to dynamic understanding of subsurface systems and offers a foundation for predictive modeling in energy, geology, and geothermal sciences.This work introduces a novel unified parameter (Λ) for describing subsurface fluid systems. Feedback and collaboration are welcome