THMC Modeling of EGS Reservoirs – Continuum through Discontinuum Representations: Capturing Reservoir Stimulation, Evolution and Induced Seismicity Geothermal Project

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Last modified on July 22, 2011.

Project Title THMC Modeling of EGS Reservoirs – Continuum through Discontinuum Representations: Capturing Reservoir Stimulation, Evolution and Induced Seismicity
Project Type / Topic 1 Recovery Act: Enhanced Geothermal Systems Component Research and Development/Analysis
Project Type / Topic 2 Integrated Chemical, Thermal, Mechanical and Hydrological Modeling

Project Description The ability to routinely develop a long-lived, high-volume, low-impedance and high-heat-transfer-area reservoirs at-will and at-depth is central to the viability of EGS as a low-carbon energy source. The evolution of porosity, permeability and heat transfer area in such pressure-sensitive fractured reservoirs is strongly controlled by the intense interaction of Thermal, Hydrological, Mechanical and Chemical (THMC) effects in these systems pushed far from equilibrium

This project addresses the critical issue of quantifying the impact of strong and innately coupled interactions of stress and chemistry on the evolution of fluid transport and thermal drawdown in EGS reservoirs. It accommodates (i) crucial modes of failure in reactivated relic fractures and intact material treated as aseismic through seismic rupture in a discontinuum; (ii) a full coupling for the interaction of concurrent THMC effects; and (iii) elucidation of the sequencing and severity of THMC effects on reservoir production and longevity.

State Pennsylvania
Objectives - Extend current Thermal, Hydrological, Mechanical and Chemical (THMC) models representing equivalent dual porosity deformable continua to accommodate new process laws and develop new models to follow the intense process interactions during stimulation and early production.


- Apply these models to understand reservoir-scale processes in concert with demonstration and production projects and apply them to explore methods of reservoir management and manipulation.

Awardees (Company / Institution) Pennsylvania State University

Awardee Website http://www.psu.edu/
Partner 1 Lawrence Berkeley National Lab










Funding Opportunity Announcement DE-FOA-0000075

DOE Funding Level (total award amount) $1,113,024.00
Awardee Cost Share $489,476.00
Total Project Cost $1,602,500.00



Principal Investigator(s) Derek Elsworth of PSU
Other Principal Investigators Joshua Taron, PSU; Eric Sonnenthal, LBNL

Targets / Milestones - Develop coupled THMC models capable of accommodating (i) rupture and failure in discontinuous fractured reservoirs (ii) where the full quadruplet of THMC interactions is rigorously accommodated.


- Develop models to accommodate multiple modes of porosity, permeability and strength evolution and the generation of reactive surface area. These include mechanical rupture, dilation and the generation of flow-occluding wear products and mechanically-mediated chemical effects of healing and sealing, sub-critical crack growth; etching dissolution and precipitation.
- Develop discontinuum models with relic fractures capable of accommodating multiple modes of extensional and shear failure and the creation of new fracture-surface area including dilation, block translations and rotations. Such models are key in adequately representing stimulation through long-term production including aseismic and seismic rupture. PSU will develop a model linking the mechanical discontinuum code PFC3D to TOUGHREACT.
- Improve continuum representations of these coupled THMC behaviors capable of more efficiently representing post-stimulation evolution of the reservoir through production. PSU will refine a model linking the mechanical continuum code FLAC3D to TOUGHREACT.
- Examine the relative strength, sequence and timing of the various mechanical, versus thermal, versus chemical effects in controlling the evolution of EGS reservoirs from stimulation through production to abandonment including the role of heterogeneities in either promoting or frustrating thermal sweeps and in stemming the propensity for short-circuiting.
- Demonstrate the effectiveness of these models against evolving datasets from EGS demonstration projects both currently and newly in progress (Geysers and Newberry Volcano).
- Educate the next generation of geothermal engineers and scientists through integration of undergraduate and graduate scholars in science and engineering through travel, data gathering and research via the GEYSER initiative.





Location of Project University Park, PA



Impacts Addresses insufficient modeling and validation capabilities to effectively couple fluid flow, geochemistry, and thermal-mechanical phenomena for stimulation prediction and reservoir simulation.
Funding Source American Recovery and Reinvestment Act of 2009

References EERE Geothermal Technologies Programs[1]

References

  1. EERE Geothermal Technologies Programs