InterPore2021

Modeling the evolution of fractured media using a multiscale approach

4 Jun 2021, 15:15

15m

Oral Presentation (MS8) Mixing, dispersion and reaction processes across scales in heterogeneous and fractured media MS8

Speaker

Sergi Molins (Lawrence Berkeley National Laboratory)

Description

Understanding the evolution of fractured media is essential in many subsurface energy applications, including subsurface storage, shale gas production, fracking, CO2 sequestration, nuclear waste storage, and geothermal energy extraction. This evolution is the result of coupled flow, transport, reaction and geomechanical processes and is affected by both the physical and mineralogical heterogeneity of fractured media.

Here we focus on the geochemically driven evolution of fractured media and the role of transport processes. In the fracture opening, the transport of solutes is determined by the dynamics of flow in the complex geometry of the fracture. In the matrix bordering the fracture, reactions with the solid phase and solute transport through the porous medium are affected by the heterogeneity in the mineralogical composition of the matrix and in the porous medium properties. The evolution brought on by the dissolution-precipitation reactions may result in further enhancement of this heterogeneity. This includes the development of an altered layer in the matrix bordering the fracture, with heterogeneous porosity, tortuosity and permeability, and widening/narrowing of the fracture opening.

In this work, we develop a model of fracture evolution that conceptualizes the fractured medium as a multiscale medium composed of a fracture (or fractures) and a porous matrix. Fracture processes are described with a pore-scale model, while matrix processes are described with a porous medium model. The model is implemented in the Chombo-Crunch reactive transport code (Molins et al. 2012; Trebotich et al. 2014; Molins et al. 2014, 2017, 2019, 2020). We use this model to simulate CO2 attack on fractured cementitious media. The geochemical problem follows from experimental and modeling work by (Li, Steefel, and Jun 2017). Flow of a CO2-rich solution in the fracture is followed by the alteration of the cementitious matrix as the invading solution diffuses into the matrix. Both precipitation and dissolution reactions take place resulting in increases and decreases in porosity locally. In contrast to previous work, consideration of flow and transport processes in the fracture (both over its width and along its length) makes it possible to capture the heterogeneous evolution of the matrix not only in the direction perpendicular to the fracture but also parallel to the fracture.

References

Li, Qingyun, Carl I. Steefel, and Young-Shin Jun. 2017. “Incorporating Nanoscale Effects into a Continuum-Scale Reactive Transport Model for CO 2 -Deteriorated Cement.” https://doi.org/10.1021/acs.est.7b00594.

Molins, Sergi, Cyprien Soulaine, Nikolaos I. Prasianakis, Aida Abbasi, Philippe Poncet, Anthony J. C. Ladd, Vitalii Starchenko, et al. 2020. “Simulation of Mineral Dissolution at the Pore Scale with Evolving Fluid-Solid Interfaces: Review of Approaches and Benchmark Problem Set.” Computational Geosciences, January. https://doi.org/10.1007/s10596-019-09903-x.

Molins, Sergi, David Trebotich, Bhavna Arora, Carl I. Steefel, and Hang Deng. 2019. “Multi-Scale Model of Reactive Transport in Fractured Media: Diffusion Limitations on Rates.” Transport in Porous Media 128 (2): 701–21.

Molins, Sergi, David Trebotich, Gregory H. Miller, and Carl I. Steefel. 2017. “Mineralogical and Transport Controls on the Evolution of Porous Media Texture Using Direct Numerical Simulation.” Water Resources Research 53 (5): 3645–61.

Molins, Sergi, David Trebotich, Carl I. Steefel, and Chaopeng Shen. 2012. “An Investigation of the Effect of Pore Scale Flow on Average Geochemical Reaction Rates Using Direct Numerical Simulation.” Water Resources Research 48 (3). https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2011WR011404.

Molins, Sergi, David Trebotich, Li Yang, Jonathan B. Ajo-Franklin, Terry J. Ligocki, Chaopeng Shen, and Carl I. Steefel. 2014. “Pore-Scale Controls on Calcite Dissolution Rates from Flow-through Laboratory and Numerical Experiments.” Environmental Science & Technology 48 (13): 7453–60.

Trebotich, D., M. F. Adams, S. Molins, C. I. Steefel, and C. Shen. 2014. “High-Resolution Simulation of Pore-Scale Reactive Transport Processes Associated with Carbon Sequestration.” Computing in Science Engineering 16 (6): 22–31.