Predicting Stimulation-Response Relationships for Engineered Geothermal Reservoirs Geothermal Lab Call Project

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Last modified on July 22, 2011.

Project Title Predicting Stimulation-Response Relationships for Engineered Geothermal Reservoirs
Project Type / Topic 1 Laboratory Call for Submission of Applications for Research, Development and Analysis of Geothermal Technologies
Project Type / Topic 2 Stimulation Prediction Modeling

Project Description Future engineered geothermal reservoirs will be created mainly by stimulation of a lower permeability target formation through hydraulic fracturing to create the subsurface heat exchanger component for an enhanced geothermal system (EGS). However, the ability to create an adequate level of formation fracture permeability and interconnectivity between injection and producing wells has yet to be demonstrated according to a recent DOE GTP evaluation panel report. As a preliminary to the successful propagation of fracture permeability between the injectors and producers, both the MIT study and DOE GTP panel express the need for guidance provided by credible hydraulic-fracturing stimulation models capable of addressing the propagation of clusters of shear fractures in hard rock.

The models developed through this project will be used to explore not only the local effects of stimulation near a single well bore, but also how the stimulation of multiple wells, spaced across the reservoir, will influence heat transfer on a reservoir scale by enhancing formation connectivity and permeability subject to realistic thermal and regional stress conditions. It is our intent that these models will provide insight into selecting the best choices for producing long-term permeability enhancement on a site-by-site basis.

State California
Objectives Develop realistic computer-based models of EGS stimulation-response scenarios involving hydraulic and explosive propagation of shear fracture systems in hard rock formations where a pre-existing fracture network may be present along with regional stress and temperature distributions.
Awardees (Company / Institution) Lawrence Livermore National Laboratory

Funding Opportunity Announcement DE-PS36-09GO99017

DOE Funding Level (total award amount) $925,000.00

Total Project Cost $925,000.00

Principal Investigator(s) Charles R. Carrigan

Targets / Milestones - Acquire data is needed and available for existing and prospective EGS sites that can be used in the project's modeling efforts.

- Evaluate the modeling aspects along with novel techniques for explosive fracture propagation using ALE3D.
- Implement the FAST fracture-propagation model into the ALE3D program which is required for performing hydrofracture propagation simulations.
- Use NUFT code to evaluate how using a fracture network as a heat exchanger leads to formation cooling and a potential increase in fracture permeability due to temperature induced volume changes.
- Use capabilities developed in task 3 with data from task 1, to perform some preliminary ALE3D/FAST-based simulations of hydraulic fracturing in EGS scenarios.
- Couple model permeability fields between NUFT and ALE3D/FAST.
- Evaluate non-equilibrium, thermo-chemical effects resulting in fracture permeability changes.
- Address the influence of the local/regional stress field on fracture propagation in the ALE3D/FAST models.
- Incorporate the site data, the full capability of ALE3D/FAST, the stochastic fracture-permeability generator, and the heat and reactive transport simulation capability of NUFT to simulate EGS-relevant stimulation models that are then evaluated for their heat transfer characteristics in both short- and long-term operation periods.
- Catalog the results of the tasks that are intended to provide insight into both the stimulation of an EGS site as well as its evolution during heat exchange operations.

Location of Project Livermore, CA

Funding Source American Recovery and Reinvestment Act of 2009

References EERE Geothermal Technologies Programs[1]


  1. EERE Geothermal Technologies Programs