Title: Reactive Transport Modeling of Shale–Fluid Interactions after Imbibition of Fracturing Fluids

Abstract

Injection of hydraulic fracturing fluid (HFF) into shale formations for unconventional oil/gas production results in chemical reactions in the shale matrix. Our recent experimental study determined the depths to which different types of reactions between the shale matrix and the HFF extended. In the present study, we built continuum scale reactive transport models to understand the coupling of chemical reactions and the transport of aqueous species in theses shale-HFF systems. Calibration of the model with our previous experimental results reveals that it takes hours to months for the shale matrix to completely neutralize the imbibed acids, depending primarily on the carbonate content of the shale. Both the HFF pH and pore pH affect the location of barite precipitation, resulting in unique barite precipitation profiles extending millimeters into calcite-rich Eagle Ford shale but only tens of micrometers into low-carbonate Marcellus shale. In addition, dissolved oxygen and extracted bitumen are key to reproducing the experimental observation of Fe(III)-(oxyhydr)oxide formation in the shale matrix as a result of pyrite dissolution in the shales. Comparison between the modeling results of porosity in the present study with experimentally measured permeabilities in our previous study suggests that chemical reactions occurring at a greater depth than themore » observable reaction zone might have impacted permeability. Our model serves as a benchmark for efficiently modeling water-rock interactions in similar systems where bulk rock samples react with a solution in batch reactors. Important reactive transport processes were ascertained via modeling, which allows quantitative prediction of shale-HFF interactions in shale matrices given the shale and HFF compositions.« less

Authors:

Li, Qingyun  ^[1];

• Search DOE PAGES for author "Li, Qingyun"
• Search DOE PAGES for ORCID "0000-0003-2038-1050"

Jew, Adam D.  ^[2];

• Search DOE PAGES for author "Jew, Adam D."
• Search DOE PAGES for ORCID "0000-0002-6167-8769"

Brown, Gordon E. ^[1]; Bargar, John R.  ^[2];

• Search DOE PAGES for author "Bargar, John R."
• Search DOE PAGES for ORCID "0000-0001-9303-4901"

Maher, Katharine ^[3]

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+ Show Author Affiliations

1. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., CA (United States)
2. SLAC National Accelerator Lab., Menlo Park, CA (United States)
3. Stanford Univ., CA (United States)

Publication Date:

Mon Apr 20 00:00:00 EDT 2020

Research Org.:

SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., CA (United States)

Sponsoring Org.:

USDOE Office of Fossil Energy (FE)

OSTI Identifier:

1638144

Alternate Identifier(s):

OSTI ID: 1759992

Grant/Contract Number:  

AC02-765F00515; SC0019165

Resource Type:

Accepted Manuscript

Journal Name:

Energy and Fuels

Additional Journal Information:

Journal Volume: 34; Journal Issue: 5; Journal ID: ISSN 0887-0624

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Porosity; Dissolution; Fluids; Shale; Precipitation