Modelling geothermal brines in complex geological settings with the ComPASS flow simulator
Simon Lopez will present a seminar to give us an update on new developments at BRGM & INRIA.
Abstract
Faults and fractures play a crucial role in controlling fluid flow and heat transfer in deep geothermal reservoir. They also serve as major feed zones for production wells. As a consequence, to appraise geothermal resources or to accurately simulate geothermal field operations, it’s essential to consider these features at different spatial scales and their coupling with the whole reservoir. Yet, in modelling multiphysics subsurface phenomena, there is often a tension between the need for a realistic, detailed geological model and practical considerations that lead to its simplification, or even degradation, in order to obtain results within an acceptable computation time.
Our main objective in developing the ComPASS geothermal flow simulator, was to take into account all of these geometric constraints in a flow and heat transfer numerical model using generic unstructured polytopal meshes. To achieve this objective we relied on coupling variants of the Vertex Average Gradient numerical scheme which was considered to be a versatile finite volume scheme and is particularly well-suited to tetrahedral meshes.
In its current state, the ComPASS provides an open-source parallel implementation of a spatio-temporal discretization of the non-linear equations driving compositional multi-phase non-isothermal flows in porous fractured media.
It allows an explicit discretization of faults and fractures as 2D hybrid objects, embedded in a 3D matrix. The resulting approach is particularly flexible and robust in terms of modeling. The physical model description uses a classical Coats-type formulation and its implementation is separated from the simulation engine so that different equation of states can be implemented by the user. Extension to other field of application (CO2, mechnanics…) are currentlty considered.
We will focus on the main components of the code, its specificities including some constraints concerning mesh generation from geological models and illustrate its application and current limitations to model high energy brines.