NUMERICAL SIMULATION OF A NATURALLY FRACTURED RESERVOIR

This research is concerned with the development of a numerical model for stratified normally fractured reservoirs. Three dimensional three phase flow black oil simulation model is adopted. The dual porosity-dual permeability model is used. The IMPES (Implicit Pressure Explicit Saturation) method is used to solve the difference equations. The Tertiary trap in K oil field (an Iraqi oil field) was simulated by the numerical model. The trap consists of six layers having different properties. Equally spaced Cartesian grids were used to divide each layer into 1600 cells in the x-y plane with the thickness as the dimension of each grid block in z direction. Applying the two IMPES pressure equations to each grid of the simulated domain resulting in a block seven diagonal coefficient matrix. Gauss-Seidel iterative method was used to solve the system of equations. The time steps are controlled through a maximum saturation difference and a material balance error limits. The actual production histories of the 15 wells in K oil field are used to get the past performance of the field for the production period. The calculated and measured average reservoir pressures, produced gas/oil ratio through the production periods had acceptable match.