Modelling Leakage Risk Along a Fault Using Modified Discrete Elements

12 Pages Posted: 4 Apr 2019 Last revised: 27 Oct 2020

See all articles by Mats Rongved

Mats Rongved

Norwegian University of Science and Technology (NTNU)

Anthony Delbar

University of Paris-Saclay - Ecole Polytechnique

Pierre Cerasi

SINTEF Industry

Andreas Bauer

SINTEF Industry

Abstract

Capacity estimates for chosen CO2 storage reservoirs are limited by the prognosed maximum pore pressure, itself predicted to cause slippage of mapped faults and thus increase the risk of leakage from the site. In most simulation tools, shear failure criteria are checked for predicted pore pressure increased on inclined lines or surfaces representing faults; if the chosen criterion is met, the simulation stops and the pressure and stress distributions in the entire domain are recorded and assigned as critical values not to exceed. Here, we try a different approach, where instead of a line in 2D, a surface is delimited on both sides of a single fault, representing a fault process zone. An in-house model is used, Modified Discrete Element tool, capable of explicitly creating and propagating fractures. The model is coupled to the commercial flow simulator TOUGH2, thus enabling flow through the created fractures to be evaluated. A simple case is simulated, where a sandstone storage reservoir is bounded by a fault, continuing up through the caprock to the next sandstone layer. In the chosen case, the storage site undergoes depletion through gas production, before CO2 is stored in the reservoir, taking the pore pressure back to its initial level. Results show that during depletion, shear stresses may develop such that fractures run alongside the fault all the way up to the upper aquifer. By assigning a permeability value to the open fractured elements, a leakage rate along the fault can be computed. Thus, geological knowledge about the process zone of faults is translated in our tool into quantitative estimates of leakage rates as a function of stress path, historic and future, corresponding to injection plans.

Keywords: Leakage modelling, GHGT-14

Suggested Citation

Rongved, Mats and Delbar, Anthony and Cerasi, Pierre and Bauer, Andreas, Modelling Leakage Risk Along a Fault Using Modified Discrete Elements. 14th Greenhouse Gas Control Technologies Conference Melbourne 21-26 October 2018 (GHGT-14) , Available at SSRN: https://ssrn.com/abstract=3366124 or http://dx.doi.org/10.2139/ssrn.3366124

Mats Rongved

Norwegian University of Science and Technology (NTNU)

Høgskoleringen
Trondheim NO-7491, 7491
Norway

Anthony Delbar

University of Paris-Saclay - Ecole Polytechnique

55 Avenue de Paris
Versailles, 78000
France

Pierre Cerasi (Contact Author)

SINTEF Industry ( email )

Post box 4760 Torgarden
Trondheim, NO-7465
Norway

Andreas Bauer

SINTEF Industry

Post box 4760 Torgarden
Trondheim, NO-7465
Norway

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