Potential water resource impacts of hydraulic fracturing from unconventional oil production in the Bakken shale

Shrestha, Namita; Chilkoor, Govinda; Wilder, Joseph; Gadhamshetty, Venkataramana; Stone, Jeff

doi:10.1016/j.watres.2016.11.006

Cited by 129 publications

(43 citation statements)

References 58 publications

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“…For example, the Weyburn-Midale field design eliminated the need for 115 tank batteries (Scott 1966). In North Dakota, where non-pipelined oil and gas operations evolved rapidly, 56% of Bakken crude oil is transported by truck and 44% is transported by pipeline (Shrestha et al 2017). We could not find similar statistics for Saskatchewan.…”

Section: Interpretationsmentioning

confidence: 71%

“…Of the 93 emitting unconventional sites, 88% included wells, and 22 had >1 well (μ=1.18, σ=0.74). Multi-well sites are common in this region and also the North Dakota Bakken, where multiple horizontal wells on the same pad increase the economic potential of unconventional oil (Shrestha et al 2017). At the well, emissions may originate from fugitive or vented sources at the wellhead stuffing box, or via surface casing vent flow (Lackey et al 2017).…”

Section: Site Characteristicsmentioning

confidence: 99%

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Methane emissions from conventional and unconventional oil and gas production sites in southeastern Saskatchewan, Canada

Baillie

Risk

Atherton

et al. 2019

Environ. Res. Commun.

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Energy development in southeastern Saskatchewan, Canada, is unique because conventional and unconventional oil and gas production is co-located. Mobile surveys are ideal for understanding emissions in this area because the overlap of production makes it difficult for airborne or satellitebased methods to differentiate emissions from each type of infrastructure. In this study, we conducted truck-based mobile surveys in the unconventional Canadian Bakken and conventional Weyburn-Midale fields to enumerate and attribute individual methane plumes, estimate methane (CH 4 ) emission rates, and compare emission vectors. We sampled downwind of 645 conventional and 289 unconventional sites, covering over 4500 km of public roads. We found that 28% of surveyed conventional sites were emitting, compared to 32% of surveyed unconventional sites. Mean emissions intensities in each development were 20 m 3 CH 4 /day per conventional site and 59 m 3 CH 4 /day per unconventional site. Emissions intensities in southeastern Saskatchewan fall on the lower range of other emissions estimates from developments in the US and Canada.

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Section: Interpretationsmentioning

confidence: 71%

Section: Site Characteristicsmentioning

confidence: 99%

Methane emissions from conventional and unconventional oil and gas production sites in southeastern Saskatchewan, Canada

Baillie

Risk

Atherton

et al. 2019

Environ. Res. Commun.

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“…Hydraulic fracturing with subsequent production from horizontal wells is used both in shale gas and in shale oil fields (Caper, 2010; Daly et al, 2016; Shrestha et al, 2017). A key difference is that shale oil production can also require injection of water for continued oil recovery (Laurenzi et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…A key difference is that shale oil production can also require injection of water for continued oil recovery (Laurenzi et al, 2016). Flowback waters obtained from shale gas fields are highly saline (Daly et al, 2016; Khan et al, 2016; Shrestha et al, 2017), as are produced waters obtained from shale oil fields (Strong et al, 2013). However, in the case of shale oil fields the salinity of produced water may change depending on the salinity of the injection water used (Shrestha et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Control of Sulfide Production in High Salinity Bakken Shale Oil Reservoirs by Halophilic Bacteria Reducing Nitrate to Nitrite

An¹,

Shen²,

Voordouw³

2017

Front. Microbiol.

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Microbial communities in shale oil fields are still poorly known. We obtained samples of injection, produced and facility waters from a Bakken shale oil field in Saskatchewan, Canada with a resident temperature of 60°C. The injection water had a lower salinity (0.7 Meq of NaCl) than produced or facility waters (0.6–3.6 Meq of NaCl). Salinities of the latter decreased with time, likely due to injection of low salinity water, which had 15–30 mM sulfate. Batch cultures of field samples showed sulfate-reducing and nitrate-reducing bacteria activities at different salinities (0, 0.5, 0.75, 1.0, 1.5, and 2.5 M NaCl). Notably, at high salinity nitrite accumulated, which was not observed at low salinity, indicating potential for nitrate-mediated souring control at high salinity. Continuous culture chemostats were established in media with volatile fatty acids (a mixture of acetate, propionate and butyrate) or lactate as electron donor and nitrate or sulfate as electron acceptor at 0.5 to 2.5 M NaCl. Microbial community analyses of these cultures indicated high proportions of Halanaerobium, Desulfovermiculus, Halomonas, and Marinobacter in cultures at 2.5 M NaCl, whereas Desulfovibrio, Geoalkalibacter, and Dethiosulfatibacter were dominant at 0.5 M NaCl. Use of bioreactors to study the effect of nitrate injection on sulfate reduction showed that accumulation of nitrite inhibited SRB activity at 2.5 M but not at 0.5 M NaCl. High proportions of Halanaerobium and Desulfovermiculus were found at 2.5 M NaCl in the absence of nitrate, whereas high proportions of Halomonas and no SRB were found in the presence of nitrate. A diverse microbial community dominated by the SRB Desulfovibrio was observed at 0.5 M NaCl both in the presence and absence of nitrate. Our results suggest that nitrate injection can prevent souring provided that the salinity is maintained at a high level. Thus, reinjection of high salinity produced water amended with nitrate maybe be a cost effective method for souring control.

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“…Hazards and risks associated with owback and produced water include hazards associated with accidental spills, leaks, and other emissions. [8][9][10][11] Concerns also arise from the potential contamination of surface water and aquifers due to poor well construction or maintenance, disposal of spent uids, and disposal of uids generated during oil and gas production. 7, 12,13 Previous studies have investigated the phenomenon of owback in produced water from stimulated wells and found that water quality of the return-ow changed over time, typically with an initial composition (as indicated by total dissolved solids (TDS) or other chemical indicators) similar to the injected uid, with a gradual transition to more saline connate water.…”

Section: Introductionmentioning

confidence: 99%

Flowback verses first-flush: new information on the geochemistry of produced water from mandatory reporting

Stringfellow

Camarillo

2019

Environ. Sci.: Processes Impacts

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Unconventional oil and gas development uses the subsurface injection of large amounts of a variety of industrial chemicals, and there are concerns about the return of these chemical to the surface with water produced with oil and gas from stimulated wells. Produced water, including any flowback of injected fluids, must be managed so as to protect human health and the environment, and understanding the chemistry of produced water from stimulated wells is necessary to ensure the safe management of produced water. In 2014, California instituted mandatory reporting for all well stimulations, including sampling produced water two times and comprehensive chemical characterization of fluids injected and fluids recovered from stimulated wells. In this study, we analyzed data from mandatory reporting with the objective of closing previously identified data gaps concerning oil-field chemical practices and the nature of flowback and produced water from stimulated wells. It was found that the plug-flow conceptual model of flowback developed in shale formations, where salinity increases over time as produced water is extracted, was not appropriate for characterizing produced water from unconventional wells in these oil reservoirs, which are predominately diatomite and sandstones. In these formations stimulation caused a "first-flush" phenomena, where salts and metals were initially high and then decreased in concentration over time, as more produced water was extracted. Although widely applied to meet regulatory requirements, total carbohydrate measurement was not found to be a good chemical indicator of hydraulic fracturing flowback. Mandatory reporting closed data-gaps concerning chemical use, provided new information on acid treatments, and allowed more detailed analysis of hydraulic fracturing practices, including comparison of water use by geological formation. Environmental signicanceMandatory reporting by industry allowed detailed analysis of hydraulic fracturing practices, including comparison of chemical use and produced water quality by geological formation. The pseudo-plug-ow conceptual model of owback developed in shale formations, where salinity increases over time as produced water is extracted, was not applicable to unconventional wells in these oil reservoirs, which are predominately diatomite and sandstones. In these formations stimulation caused a "rst-ush" phenomena, where salts and metals were initially high and then decreased in concentration over time, as more produced water was extracted. New information on acid treatments and the use of chemical indicators of owback indicate that acid fracturing treatments are infrequently applied and the use of chemical indicators needs to be further validated.

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Potential water resource impacts of hydraulic fracturing from unconventional oil production in the Bakken shale

Cited by 129 publications

References 58 publications

Methane emissions from conventional and unconventional oil and gas production sites in southeastern Saskatchewan, Canada

Methane emissions from conventional and unconventional oil and gas production sites in southeastern Saskatchewan, Canada

Control of Sulfide Production in High Salinity Bakken Shale Oil Reservoirs by Halophilic Bacteria Reducing Nitrate to Nitrite

Flowback verses first-flush: new information on the geochemistry of produced water from mandatory reporting

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