Controlling flood displacement fronts using a parallel analytical streamline simulator

The Analytical Element Method (AEM), originally developed for mathematical modeling of groundwater flow, is here applied in closed-loop waterflood simulations. The Parallel Analytical Streamline Simulator (PASS), based on AEM, enables fast time-of-flight (TOF) calculations and visualizations of sweep efficiency in homogeneous, heterogeneous and fractured reservoirs. Simulations with PASS can test the sweep efficiency for a wide range of well patterns even before field development. We assume a simple direct-line drive and various initial reservoir attributes: a homogenous base case and further explore the effects on the flood advance of zones with heterogeneous permeability and an impervious fault. For all cases, analytical streamline patterns and time-of-flight contours for the flood front (obtained with PASS) are compared to those generated via an independent method based on numerical discretization by a commercial reservoir simulator. The results are convergent and confirm that PASS can be used to determine in closed-loop simulations the well rates that will avoid the occurrence of premature water breakthrough in the production wells. Early breakthrough in the homogenous reservoir occurs for the central producers and occurs later for the peripheral producers. Real-time adjustments of the water injection rates based on closed-loop surveillance of the pressures in producer wells can redirect and control the reservoir flow such that the floodfront arrives simultaneously at all producers. For the heterogeneous reservoir, smart-field well-control for improved sweep efficiency is also visualized. However, when an impervious fault zone blocks the flow path between injector and producer wells the occurrence of premature arrival of injection water in some producers cannot be avoided.