Investigation of Stimulation-Response Relationships for Complex Fracture Systems in Enhanced Geothermal Reservoirs

Abstract

Hydraulic fracturing is currently the primary method for stimulating low-permeability geothermal reservoirs and creating Enhanced (or Engineered) Geothermal Systems (EGS) with improved permeability and heat production efficiency. Complex natural fracture systems usually exist in the formations to be stimulated and it is therefore critical to understand the interactions between existing fractures and newly created fractures before optimal stimulation strategies can be developed. Our study aims to improve the understanding of EGS stimulation-response relationships by developing and applying computer-based models that can effectively reflect the key mechanisms governing interactions between complex existing fracture networks and newly created hydraulic fractures. In this paper, we first briefly describe the key modules of our methodology, namely a geomechanics solver, a discrete fracture flow solver, a rock joint response model, an adaptive remeshing module, and most importantly their effective coupling. After verifying the numerical model against classical closed-form solutions, we investigate responses of reservoirs with different preexisting natural fractures to a variety of stimulation strategies. The factors investigated include: the in situ stress states (orientation of the principal stresses and the degree of stress anisotropy), pumping pressure, and stimulation sequences of multiple wells.

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Additional Info

DOE Project Name: Stimulation of Complex Fracture Systems in Low Pressure Reservoirs for Development of Enhanced Geothermal Systems
DOE Project Number: AID 19979
DOE Project Lead: Eric Hass
DOI: 10.15121/1358113
Last Updated: over a year ago
Jan
2011
Data from January, 2011
Submitted Feb 7, 2013

Contact

Lawrence Livermore National Laboratory


Status

Publicly accessible License 

Authors

Pengcheng Fu
Lawrence Livermore National Laboratory
Scott M. Johnson
Lawrence Livermore National Laboratory
Charles R. Carrigan
Lawrence Livermore National Laboratory

Keywords

geothermal, enhanced geothermal system, egs, discrete fracture flow, modeling, reservoir stimulation, stimulation, hydraulic fracturing

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