Isothermal gravitational segregation: algorithms and specifications

New algorithms for calculating the isothermal equilibrium state of reservoi r fluids under the influence of gravity are presented. Two types of specifi cations are considered: the specification of pressure and composition at a reference depth; and the specification of the total overall content of the reservoir, along with the reservoir geometry. It is shown how both types of calculations can be performed in an efficient and robust manner using volu me-based thermodynamics. The new method makes it possible to evaluate the i nfluence of reservoir geometry and gravity segregation on the hydrocarbon r eserves. (C) 2000 Elsevier Science B.V. All rights reserved.