| In general, there are essentially two significant subcomponents in a reservoir simulator - the physical model (PM) and the discretization method (DM). PM characterizes the reservoir problem by the implementations of different governing equations. DM provides the computations of the flux terms which are determined exclusively by the selection of the discretization. If the two are modularized, decoupled and independently developed, it would be possible to create a number of different simulators by combining any two different PM and DM modules. The current state of the art does not allow this decoupling. In this research, an efficient modularization and decoupling approach for the independent development of different PM and DM modules has been created.;We developed a thermal PM that handles a variety of thermal recovery processes such as steam flooding, in-situ combustion and steam assisted gravity drainage. Solution of the equations in a robust and efficient manner required computation of the Jacobian, ordering of variables in the equations, treatments of phase equilibria and choice of linear and nonlinear solvers, etc. An analytical Jacobian calculation method and an equation alignment scheme were used in this research. In addition to finite-difference and control-volume finite-element discretization methods, a flexible connectivity based input method for multipoint flux calculation was developed. In dealing with the representation of fractures and faults in reservoirs, a discrete fracture network model was also implemented.;Thermal reservoir simulation is the most complex of all reservoir simulators and thus, the most computationally intensive. A general parallelization scheme was developed to handle domain decomposition of a system containing a network of fractures and complex wells. The parallelization scheme allowed individual fractures and wells (line sources) to be partitioned into multiple subdomains.;The simulator was verified and validated using a few physical problems. The capability of the simulator was demonstrated using steam flooding and in-situ combustion in domains containing discrete fractures. This research has resulted in the creation of an efficient, parallel, modularized thermal simulator that uses unstructured grids and discrete fractures, and is applicable to highly complex fractured, faulted geologic systems. |
