Title: Comparative geochemistry of flowback chemistry from the Utica/Point Pleasant and Marcellus formations

Abstract

Flowback/Produced fluid samples were collected from several wells from two Utica/Point Pleasant (UPP) sites (UPPW and UPPS) in Ohio, and one Marcellus (Marcellus Shale Energy and Environment Laboratory (MSEEL)) site in West Virginia over a period of approximately two years. Although these formations have different ages, depositional environments, diagenetic histories, and geochemical and mineralogical compositions (i.e. the UPP is significantly more carbonate rich than the Marcellus which is more siliceous), analysis of trends in fluid species over time shows that, overall, the TDS and major solubilized elements (Na, Ca, Cl) in the UPP and Marcellus brines are remarkably similar. Total dissolved solutes (TDS) in these brines ranged from approximately 40 to 250 g/L salt, and in general, concentrations increased with time elapsed since natural gas well completion and stimulation. The behavior of Na, Br, and Cl suggests that the produced water signatures from these formations are largely derived from the native formational brines which display evidence of originating from evaporated seawater. There is a strong correlation between Cl and Br, indicating that both species behave conservatively, and the similarity among each of these brines suggests no appreciable contribution of salt from halite dissolution because Br is excluded from the halitemore » structure. Cl/Br ratios in the brines range from ~80 to 120 (mg/L/mg/L). Other elements, such as K, which readily reacts between fluids and ion exchange sites on clays, generally exhibit conservative behavior for an individual site, but show significant variations among each of the different well pads. The concentrations of Sr and Ba vary dramatically among well sites, and increase with respect to Cl- over time, suggesting increasing solubilization, presumably from desorption from clay minerals or dissolution of carbonates or sulfates from the source formation(s). The UPPW well site has very low Ba due to high-sulfate input fluid, which resulted in precipitation of barite/celestite in the brines. In contrast the UPPS well site had elevated Sr (~ 3500 mg/L), presumably due to the use of Sr-rich recycled brine used in hydraulic fracturing. The Marcellus site had the highest Ba concentrations (up to 10 g/L) and highest Ba/Sr ratios in the fluids, due to the high concentration of barium in the Marcellus target (~ 1000 ppm, as compared to ~200 ppm in the UPP). These observations suggest that solutes in the FP fluids are derived from native brines, water-rock interactions that have occurred over geologic time scales, as well as some contribution from contemporaneous reactions in the subsurface. The results also show that the composition of the injected fluid can influence flowback fluid chemistry and possibly production efficiency.« less

Authors:

Welch, Susan A. ^[1]; Sheets, Julia M. ^[1]; Daly, Rebecca A. ^[2]; Hanson, Andrea ^[3]; Sharma, Shikha ^[4]; Darrah, Thomas ^[5]; Olesik, John ^[1]; Lutton, Anthony ^[1]; Mouser, Paula J. ^[6]; Wrighton, Kelly C. ^[1]; Wilkins, Michael J. ^[1]; Carr, Tim ^[4]; Cole, David R. ^[1]

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+ Show Author Affiliations

1. The Ohio State Univ., Columbus, OH (United States). School of Earth Sciences
2. Colorado State Univ., Fort Collins, CO (United States). Dept. of Soil and Crop Sciences
3. Colorado State Univ., Fort Collins, CO (United States). Dept. of Civil and Environmental Engineering
4. West Virginia Univ., Morgantown, WV (United States). Dept. of Geology and Geography
5. The Ohio State Univ., Columbus, OH (United States). School of Earth Sciences; The Ohio State Univ., Columbus, OH (United States). Global Water Inst.
6. Univ. of New Hampshire, Durham, NH (United States). Civil and Environmental Engineering

Publication Date:

Sat Jan 16 00:00:00 EST 2021

Research Org.:

West Virginia Univ., Morgantown, WV (United States); The Ohio State Univ., Columbus, OH (United States)

Sponsoring Org.:

USDOE Office of Fossil Energy (FE); USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; National Science Foundation (NSF)

OSTI Identifier:

1849147

Alternate Identifier(s):

OSTI ID: 1775631

Grant/Contract Number:  

FE0024297; SC0006878; 1342701; 1830742; EAR-1847684

Resource Type:

Accepted Manuscript

Journal Name:

Chemical Geology

Additional Journal Information:

Journal Volume: 564; Journal Issue: C; Journal ID: ISSN 0009-2541

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Geochemistry & Geophysics; Fracking; Flowback; Brine; Utica/Point Pleasant; Marcellus