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A hydro-geomechanical porous-media model to study effects of engineered carbonate precipitation in faults

Yue Wang, Holger Class

TL;DR

This work develops a hydro-geomechanical model that explicitly couples flow, deformation, and precipitation-induced cementation within porous media, implemented in the open-source DuMuX framework. The authors introduce a cementation-based link between porosity loss from biomineralization and increases in rock stiffness and strength, combined with a two-phase flow description and a fixed-stress decoupling strategy for computational efficiency. Verified against standard HM benchmarks and compared with EICP-treated sand-column data, the model is then applied to a reservoir-scale CO$_2$ injection scenario with fault zones to assess leakage sealing, stress evolution, and induced seismicity. Key findings show that carbonate precipitation can increase stiffness and alter the rupture location and timing of seismic events, potentially reducing seismic magnitude while advancing failure onset, with results strongly dependent on geometry and treatment extent, highlighting the need for site-specific validation and further model refinement.

Abstract

Hydro-geomechanical models are required to predict or understand the impact of subsurface engineering applications as, for example, in gas storage in geological formations. This study puts a focus on engineered carbonate precipitation through biomineralization in a fault zone of a cap-rock to reduce gas leakage from a reservoir. Besides hydraulic properties like porosity and permeability, precipitated carbonates also change the mechanical properties of the rock. We present a conceptual modeling approach implemented into the open-source simulator Dumux and, after verification examples, at hand of a CO2-storage scenario, we discuss impacts of biomineralization on the stress distribution in the rock and potentially altered risks of fault reactivations and induced seismic events. The generic study shows the tendency towards increased stiffness due to precipitated carbonate, which may cause shear failure events to occur earlier than in an untreated setup, while the magnitude of the seismicity is smaller.

A hydro-geomechanical porous-media model to study effects of engineered carbonate precipitation in faults

TL;DR

This work develops a hydro-geomechanical model that explicitly couples flow, deformation, and precipitation-induced cementation within porous media, implemented in the open-source DuMuX framework. The authors introduce a cementation-based link between porosity loss from biomineralization and increases in rock stiffness and strength, combined with a two-phase flow description and a fixed-stress decoupling strategy for computational efficiency. Verified against standard HM benchmarks and compared with EICP-treated sand-column data, the model is then applied to a reservoir-scale CO injection scenario with fault zones to assess leakage sealing, stress evolution, and induced seismicity. Key findings show that carbonate precipitation can increase stiffness and alter the rupture location and timing of seismic events, potentially reducing seismic magnitude while advancing failure onset, with results strongly dependent on geometry and treatment extent, highlighting the need for site-specific validation and further model refinement.

Abstract

Hydro-geomechanical models are required to predict or understand the impact of subsurface engineering applications as, for example, in gas storage in geological formations. This study puts a focus on engineered carbonate precipitation through biomineralization in a fault zone of a cap-rock to reduce gas leakage from a reservoir. Besides hydraulic properties like porosity and permeability, precipitated carbonates also change the mechanical properties of the rock. We present a conceptual modeling approach implemented into the open-source simulator Dumux and, after verification examples, at hand of a CO2-storage scenario, we discuss impacts of biomineralization on the stress distribution in the rock and potentially altered risks of fault reactivations and induced seismic events. The generic study shows the tendency towards increased stiffness due to precipitated carbonate, which may cause shear failure events to occur earlier than in an untreated setup, while the magnitude of the seismicity is smaller.

Paper Structure

This paper contains 28 sections, 44 equations, 16 figures, 3 tables, 2 algorithms.

Table of Contents

  1. Introduction
  2. Model concepts
  3. Governing equations
  4. Mass balance equation of the fluid
  5. Momentum balance of matrix
  6. Effective porosity
  7. Fixed-stress splitting as decoupling method
  8. Effects of engineered carbonate precipitation on porous media
  9. Mechanical effects
  10. Hydraulic effects
  11. Rock failure and induced seismic events
  12. Residual tensile stress
  13. Shear-stress failure / fault reactivation
  14. Estimating seismic events
  15. Simulation workflow of geomechanical problems
  16. ...and 13 more sections

Figures (16)

  • Figure 1: Simplified process (follow subfigures counter clockwise) of rock cementation.
  • Figure 2: Estimation of rock mechanical properties in response to the cementation
  • Figure 3: Illustration of the boundary conditions of the domain for the injection problem, i.e., the first verification case.
  • Figure 4: Comparison between the analytical and numerical solutions for the injection problem. $\hat{p}_{Water}$ is equivalent to $p_d$ in DeSimone2017_benchmark.
  • Figure 5: Verification of Mandel's problem
  • ...and 11 more figures