Robust Semi-Implicit Three-Dimensional Upwind Techniques for Reducing Grid Orientation Effect in Thermal Simulations

摘要

In field-scale thermal reservoir simulation, grid orientation is one important factor affecting the accuracy of numerical results. Traditionally thermal reservoir simulators adopt the nine-point method to handle this issue. However, the nine-point method introduces extra bandwidth of the Jacobian Matrix which significantly increases the storage and CPU requirements. Also, that method has limitations which make it difficult to integrate with advanced gridding techniques. A new three-dimensional upwind technique was developed to reduce grid orientation effect without the disadvantages mentioned above. This new technique adopts a semi-implicit strategy such that no extra matrix bandwidth is added. Numerical results show that the new technique successfully reduces grid orientation effect while using much less CPU than the nine-point method.