Jamal H. Abou-Kassem

Appraisal of Steamflood Models

Eleven numerical steamflood models, developed by various investigators over 1969-1982, are analyzed for this evaluation. These models are sometimes similar in certain aspects and different in others. A comparative evaluation of existing numerical steamflood models contributes greatly to the state of the art, and helps in developing new ideals and detecting missing links that may not be realized otherwise. This paper presents a general steamflood model. The assumptions and derivation of equations of various steamflood models are presented. Similarities and differences between models in the areas of mathematical models, treatment of nonlinearities, formulation methods, and methods of solution used are presented and discussed in detail.

Recent developments in numerical simulation techniques of thermal recovery processes

Numerical simulation of thermal processes (steam flooding, steam stimulation, SAGD, in-situ combustion, electrical heating, etc.) is an integral part of a thermal project design. The general tendency in the last 10 years has been to use commercial simulators. During the last decade, only a few new models have been reported in the literature. More work has been done to modify and refine solutions to existing problems to improve the efficiency of simulators. The paper discusses some of the recent developments in simulation techniques of thermal processes such as grid refinement, grid orientation, effect of temperature on relative permeability, mathematical models, and solution methods. The various aspects of simulation discussed here promote better understanding of the problems encountered in the simulation of thermal processes and will be of value to both simulator users and developers.

Heat loss calculation in thermal simulation

An appraisal is presented for four different methods that are usually incorporated in thermal simulators to estimate the rate of heat loss to surroundings. The methods are the analytical solution using a superposition theorem, the analytical solution using a numerical approximation to the convolution integral, the semi-analytical solution, and the numerical solution. This appraisal includes expressing the equations in a form that can be incorporated into a fully implicit simulator, computer programming complexity, and the computer CPU time and memory storage requirements. A steam flood problem is used for the comparison, and the gas recovery, oil recovery, and heat loss performances for a reservoir in one and two dimensions are presented.It is found that the numerical solution is sensitive to grid size in the overburden, the semi-analytical solution is the simplest to program but its prediction is the least accurate, the analytical solution is the most expensive, whereas the analytical-numerical solution combines both accuracy and acceptable storage requirements, and therefore, it is recommended for use in thermal simulation.