  It is the purpose of this work to develop new approach for chemical
compositional reservoir simulation, which may be regarded as a sequential
method. The development process can be roughly divided into the following two
stages: (1) development of a new mathematical formulation for the sequential
chemical compositional reservoir simulation, (2) implementation of a sequential
solution approach for chemical compositional reservoir simulation based on the
formulation described in this paper. This paper addresses the first stage of
the development process by presenting a new mathematical formulation of the
chemical compositional reservoir flow equations for the sequential simulation.
The newly developed mathematical formulation is extended from the model
formulation used in existing chemical compositional simulators. During the
model development process, it was discovered that the currently used chemical
compositional model estimates the adsorption effect on the transport of a
component reasonably well but it violates the principle of mass conservation.
The energy conservation equation in the currently used chemical compositional
model does not consider any change in the effective pore size caused by
adsorption, which leads to inconsistency between the overall compositional
balance equations and the energy conservation equation by violating
conservation of energy. With these partial differential equations as governing
equations, several simulators have been developed. In this article, we propose
a formulation to model the change in pore volume due to adsorption that
satisfies the conservation laws for mass and energy, and allows applying a
sequential solution approach.
