Mathematical and Numerical Modelling of Process-Structure Interaction in Fractured Geothermal Systems

Projektinformationen

MaPSI

ID Finanzhilfevereinbarung: 101002507

DOI

10.3030/101002507

EK-Unterschriftsdatum 12 Januar 2021

Startdatum 1 August 2021

Enddatum 31 Juli 2027

Finanziert unter

• EXCELLENT SCIENCE - European Research Council (ERC)

Gesamtkosten

€ 2 000 000,00

EU-Beitrag

€ 2 000 000,00

Koordiniert durch

UNIVERSITETET I BERGEN
Norway

Periodic Reporting for period 3 - MaPSI (Mathematical and Numerical Modelling of Process-Structure Interaction in Fractured Geothermal Systems)

Berichtszeitraum: 2024-08-01 bis 2026-01-31

Zusammenfassung vom Kontext und den Gesamtzielen des Projekts

In the development and production of high-temperature geothermal resources, large induced gradients in pressure and temperature during injection operations result in complex, coupled dynamics. This includes boiling of geothermal fluids and deformation of the fractured rock. The interaction of coupled processes with changes in formation structure related to deformation and propagation of fractures is currently not well understood. This provides a core motivation as well as challenging test cases for the mathematical and numerical developments in the MaPSI project. The MaPSI project has been funded by the ERC to establish mathematical models and simulation technology that assess subsurface process-structure interaction in geothermal systems during hydraulic and thermal stimulation.

The project aims to develop pioneering mathematical and numerical models that simulate multiphase flow and phase-change in thermo-poroelastic media with deforming and propagating fractures. Through this approach, MaPSI seeks to advance expertise in development and production of high-temperature geothermal systems, knowledge is crucial to promote sustainable resource exploitation.

MaPSI has as its main objective to provide mathematical models and simulation technology required to assess subsurface process-structure interaction in the context of hydraulic and thermal stimulation in development and production of high-temperature geothermal resources.

This will be achieved by a highly novel and timely research programme which will:
- Combine new techniques with recently developed methodology to develop unprecedented mathematical and numerical approaches to enable modelling of multiphase flow and phase-change in thermo-poroelastic media with fractures that may slip, deform and propagate;
- Advance competences in the main scientific fields involved; and
- Improve understanding of coupled processes in development and production of high-temperature geothermal systems towards sustainable exploitation of the resource.

The project will provide new mathematical and numerical models along with open-source software that have capabilities in modelling of coupled process-structure interaction in fractured porous media that greatly exceed those of existing platforms. Specific case-studies will assess process-structure interactions for development and production operations in high-temperature geothermal systems, providing timely contributions to further developments of these resources.

Arbeit, die ab Beginn des Projekts bis zum Ende des durch den Bericht erfassten Berichtszeitraums geleistet wurde, und die wichtigsten bis dahin erzielten Ergebnisse

In geothermal systems, networks of fractures provide main fluid pathways. Hydraulic stimulation of fractured geothermal reservoirs can increase the possibility of geothermal fluid to flow through the formation by causing sliding and dilation of preexisting fractures as well as fracture propagation. This represents a complex coupled process-structure interaction, where the fractured structure of the formation both dominates coupled fluid flow and rock deformation and conversely is altered because of these processes. A main result achieved in the project so far is a novel coupled thermo-hydro-mechanical simulation model for hydraulic stimulation of fractured porous rock, where slip, dilation and propagation of fractures result as a consequence of fluid injection.

Fundamental progress has also been made in the simulation of reactive thermal multi-phase flow in high-temperature geothermal systems. For the phase equilibrium problem, we have developed formulations that enables simultaneous determination of phase stability and splits for a wide range of subsurface conditions. The developed methodology provides a modular way to include and couple the local fluid phase equilibrium within compositional multi-phase flow simulations. This enables simulating injection into and production in high-enthalpy, including superhot geothermal systems. The combination of high salt content, boiling and condensation, and temperature‑ and pressure‑dependent mineral precipitation/dissolution requires specialised equations of state. These have been combined with mathematical models for reactive compositional multiphase flow with phase change.

Substantial work has also been performed on novel mathematical models for deformable fractured media, numerical solution strategies, and necessary software improvements in the open-source framework PorePy, much of which is central to prepare for the next phase of the project.

Fortschritte, die über den aktuellen Stand der Technik hinausgehen und voraussichtliche potenzielle Auswirkungen (einschließlich der bis dato erzielten sozioökonomischen Auswirkungen und weiter gefassten gesellschaftlichen Auswirkungen des Projekts)

The project has made significant progress towards its main objective. Novel results have been published on computational models of process-structure interaction in the context of hydraulic stimulation of geothermal reservoirs, and, in parallel, the project has developed new mathematical models and simulation technology required to simulate multi-phase flow in high-temperature geothermal reservoirs. With the project's ongoing effort of combining these developments, the ambitious goal of assessing process-structure interaction in the context of high-enthalpy geothermal resources should be within reach.

Example simulation of injection-induced fault reactivation based on fracture geometry and injection