PREDICTION OF INTERWELL TRACER FLOW BEHAVIOR IN HETEROGENEOUS RESERVOIRS

A new numerical approach has been developed for predicting the interwe ll tracer flow behaviour in heterogeneous porous media typical of wate r and oil reservoirs. This approach uses a mixed finite-element method with triangular elements to predict pressure and velocity fields, and a novel random walk model to simulate the tracer transport through th e reservoir, and to perdict the concentration response at the producti on well. The mixed finite-element method solves the pressure and veloc ity simultaneously imposing suitable boundary conditions for both pres sure and velocity, which allows the solution of the tracer velocity to be more accurate and to conserve mass more precisely than a standard finite-element method. The random walk model can reflect the tracer fl ow behaviour directly by tracking the movement of particles representi ng the tracer input volume. The technique has been validated by compar ing the predicted results with analytical solutions of tracer concentr ation response for a homogeneous five-spot pattern, and with published experimentally observed tracer fronts at breakthrough for homogeneous and three heterogeneous cases of five spot pattern. Good agreement ha s been achieved for all cases. The model presented in this paper is ge neral, and can therefore be applied to drive patterns other than the f ive-spot pattern, and for different types of heterogeneities; it can a lso include effects such as longitudinal and transverse dispersion and adsorption.