EGU2020-21236
https://doi.org/10.5194/egusphere-egu2020-21236
EGU General Assembly 2020
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Modeling and experimental investigation of the evolution of altered zones at the shale-fluid interface

Hang Deng1, Sergi Molins1, Carl Steefel1, John Bargar2, Adam Jew2, Alexandra Hakala3, Christina Lopano3, and Wei Xiong3
Hang Deng et al.
  • 1Lawrence Berkeley National Laboratory, United States of America
  • 2Stanford Synchrotron Radiation Lightsource National Accelerator Laboratory, United States of America
  • 3National Energy Technology Laboratory, United States of America

Unconventional oil and gas production involves the use of acidic hydraulic fracturing fluids that interact with the rock matrix bordering the fractures. As a result, fracture permeability and mass transfer between the matrix and the fracture can be altered, affecting production performance. The evolution of the altered zones are controlled by the gradients of pH and concentrations of various species perpendicular to the fracture-matrix interface, mineral reactions in the matrix as the reactive fluid diffuse into the matrix, and potential mineral coating on the fracture surface where the matrix fluid and fracture fluid mix. In this study, we use reactive transport model to investigate the evolution of the altered zones bordering the fractures. The simulations are based on batch and fracture flow experiments of shales and syntheized hydraulic fracturing fluids. Through the simulations, we quantify the reaction front of different mineral phases and the change of local porosity, and examine their dependence on mineral composition and fluid chemistry. We also discuss the impacts of the altered zones on matrix diffusivity and fracture permeability.

How to cite: Deng, H., Molins, S., Steefel, C., Bargar, J., Jew, A., Hakala, A., Lopano, C., and Xiong, W.: Modeling and experimental investigation of the evolution of altered zones at the shale-fluid interface, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21236, https://doi.org/10.5194/egusphere-egu2020-21236, 2020.