A Scalable Thermal Reservoir Simulator for Giant Models on Parallel Computers

Abstract

This paper introduces the model, numerical methods, algorithms and parallel implementation of a thermal reservoir simulator that designed for numerical simulations of thermal reservoir with multiple components in three dimensional domain using distributed-memory parallel computers. Its full mathematical model is introduced with correlations for important properties and well modeling. Various well constraints, such as fixed bottom hole pressure, fixed oil, water, gas and liquid rates at surface condition and reservoir condition, constant heat transfer model, convective heat transfer model, heater model (temperature control, rate control, dual rate/temperature control), and subcool (steam trap), are introduced in details, including their mathematical models and methods. Efficient numerical methods (discretization scheme, matrix decoupling methods, and preconditioners), parallel computing technologies and implementation details are presented, including option parsing, keyword parsing, parallel IO (input and output), data management and visualization. The simulator is designed for giant models with billions or even trillions of grid blocks using hundreds of thousands of CPUs. Numerical experiments show that our results match commercial simulators, which confirms the correctness of our methods and implementations. SAGD simulation with 15106 well pairs is also presented to study the effectiveness of our numerical methods. Scalability testings demonstrate that our simulator can handle giant models with 216 billion grid blocks using 100,800 CPU cores and the simulator has good scalability.