Abstract
In the practical petroleum exploration, there appears to be some issues and confusions when the concept of fluid potential of Hubbert (1953) and England (1987) is applied. If the four kinds of energy in a fluid potential (e.g. buoyancy, stratigraphic pressure, capillary pressure and hydrodynamic forces) are simply added together, it will confuse the relationship between the mechanisms of different forces that cause petroleum to migrate and accumulate while neglect the differences caused by the different forces that control the hydrocarbon accumulation, and thus mix the contributions of different forces to hydrocarbon pooling. The causes to these issues include human factors such as inadequate understanding and/or over simplification of the practical problems and misunderstanding of Hubbert's original formula. To make the fluid potential concept more useful and powerful in the practical petroleum exploration further revision and perfection to the conceptual model of fluid potential is required. Fluid potential can be expressed as the potential energy of a unit volume of fluid within a sedimentary basin. For the convenience of discussion, it is here expressed as the work that requires to be done by a unit volume of hydrocarbon fluid in its internal migration to the effective source rock center. In the study of the effect of fluid potential on the control of petroleum, attention should be paid to the fact that different types of fluid potential are produced by different dynamic forces, to which the relative strength consideration must be given respectively. The migration, accumulation and pooling of petroleum may be realized by the joint control of multiple dynamic forces, and the characteristics of such movements remain unchanged in zones with low potential. A successful practical application of the fluid potential concept to petroleum exploration is exemplified using an example from the Dongying Depression, the Bohai Bay Basin, east China, where over 90% of the commercial discoveries in the reservoirs within the Shahejie Formation are distributed in areas with both favourable lithofacies and a low potential.