scholarly journals Thermal drawdown and late-stage seismic-slip fault reactivation in enhanced geothermal reservoirs

2014 ◽  
Vol 119 (12) ◽  
pp. 8936-8949 ◽  
Author(s):  
Quan Gan ◽  
Derek Elsworth
Keyword(s):  
Late Stage ◽  
Fault Reactivation ◽  
Geothermal Reservoirs ◽  
Seismic Slip ◽  
Enhanced Geothermal Reservoirs

scholarly journals Fault slip in hydraulic stimulation of geothermal reservoirs: Governing mechanisms and process-structure interaction

2020 ◽  
Vol 39 (12) ◽  
pp. 893-900
Author(s):  
Inga Berre ◽  
Ivar Stefansson ◽  
Eirik Keilegavlen
Keyword(s):  
Fault Reactivation ◽  
Fluid Injection ◽  
Hydraulic Stimulation ◽  
Structure Interaction ◽  
Geothermal Reservoirs ◽  
Biot Coefficient ◽  
Matrix Permeability ◽  
Stress Changes ◽  
Process Structure ◽  
Stimulation Of

Hydraulic stimulation of geothermal reservoirs in low-permeability basement and crystalline igneous rock can enhance permeability by reactivation and shear dilation of existing fractures. The process is characterized by interaction between fluid flow, deformation, and the fractured structure of the formation. The flow is highly affected by the fracture network, which in turn is deformed because of hydromechanical stress changes caused by the fluid injection. This process-structure interaction is decisive for the outcome of hydraulic stimulation, and, in analysis of governing mechanisms, physics-based modeling has potential to complement field and experimental data. Here, we show how recently developed simulation technology is a valuable tool to understand governing mechanisms of hydromechanical coupled processes and the reactivation and deformation of faults. The methodology fully couples flow in faults and matrix with poroelastic matrix deformation and a contact mechanics model for the faults, including dilation because of slip. Key elements are high aspect ratios of faults and strong nonlinearities in highly coupled governing equations. Example simulations using our open-source software illustrate direct and indirect hydraulic fault reactivation and corresponding permeability enhancement. We investigate the effect of the fault and matrix permeability and the Biot coefficient. A higher matrix permeability leads to more leakage from a permeable fault and thus suppresses reactivation and slip of the fault compared to the case with a lower matrix permeability. If a fault is a barrier to flow, increase of pressure because of the fluid injection results in stabilization of the fault; the situation is opposite if the fault is highly permeable compared to the matrix. For the given setup, lowering the Biot coefficient results in more slip than the base case. While conceptually simple, the examples illustrate the strong hydromechanical couplings and the prospects of physics-based numerical models in investigating the dynamics.

A novel fully-coupled flow and geomechanics model in enhanced geothermal reservoirs

2013 ◽  
Vol 107 ◽  
pp. 1-11 ◽  
Author(s):  
Litang Hu ◽  
Philip H. Winterfeld ◽  
Perapon Fakcharoenphol ◽  
Yu-Shu Wu
Keyword(s):  
Coupled Flow ◽  
Geothermal Reservoirs ◽  
Enhanced Geothermal Reservoirs ◽  
Fully Coupled
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