An integrated experimental and modeling investigation of the impacts of micro-reactions on unconventional gas production
Abstract
Unconventional oil and gas production involves the use of acidic and chemically complex hydraulic fracturing fluids that interact with the shale matrix. As a result, chemical reactions, including redox reactions and mineral dissolution and precipitation, happen in the fractured shale and alter its transport and hydraulic properties. The location and the extent of these reactions are both critical in determining how much the transport and hydraulic properties are changed, and they are controlled by local gradients of pH and concentrations of various species, which are in turn largely influenced by diffusion. A small amount of precipitation that coat the fracture surface or clog the pore throats can significantly reduce flow and transport pathways important for unconventional gas production. In order to capture the feedback between chemical reactions and flow and transport, understanding at the micro-scale is required. In this study, we use an integrated experimental and modeling approach to investigate the impacts of micro-reactions. Specifically, we focus on pyrite oxidation and dissolution, iron-bearing secondary mineral phases, and scaling of barite, as well as their impacts on fracture permeability and shale matrix diffusivity. Combining reactive transport models and batch and fracture flow experiments, we quantify the reaction front of different mineral phases, the change of local porosity, and examine their dependence on mineral composition and fluid chemistry. This integrated framework also provides information for upscaling the impacts of micro-scale reactions to reservoir-scale modeling.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMMR013..07D
- Keywords:
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- 1858 Rocks: chemical properties;
- HYDROLOGY;
- 1859 Rocks: physical properties;
- HYDROLOGY;
- 3653 Fluid flow;
- MINERALOGY AND PETROLOGY;
- 8045 Role of fluids;
- STRUCTURAL GEOLOGY