Current Wastewater DisposalPractices in Western Canada

Conclusions and Recommendations

Introduction

Risks and Mitigations for Hydraulic Fracturing Wastewater Disposal Operations in Western Canada

Mauricio Reyes Canales(1), Rabia Ladha(2), Melissa MacDonald(3), Wayne Sunghyun Park(4)

The authors are scholarship recipients and graduates of the NSERC CREATE ReDeveLoP Program Grant number #386133824

The Hydraulic Fracturing Water Cycle Recycling Flowback Water

References

Sources of Risks and Current Mitigation Measures for Wastewater Disposal

In Western Canada, most hydraulic fracturing wastewater isdisposed of in deep injection wells. Risks associated withwastewater disposal include groundwater contamination in case ofleakage and generation of induced seismic events. The use of freshwater represents an important amount of the operational budgetand incentives in the water recycling can improve the economicalsustainability of this practice. The objectives of this study consistof: (1) identify the sources of risks associated to groundwatercontamination, (2) show the current mitigation strategies, and (3)study water recycling and alternative uses of water to reducedisposal activities. This study investigates how existing regulationsin Western Canada mitigate the known risks of watercontamination and how incentivizing water recycling practices canreduce fresh water consumption and wastewater disposal volume.

1. Based on the current regulations and mitigation strategies, the risks of groundwatercontamination associated with deep injection wells is relatively low.

2. Further improvements on water recycling technologies can reduce the consumption offresh water and reduce the associated costs. Furthermore, policies to incentivize waterrecycling are recommended.

3. Current regulations do not allow the reuse of wastewater once it is classified asindustrial waste water. If the wastewater is properly treated, it could be reused in otheroil and gas operations, as long as the geochemical conditions are favorable.

4. There are still some uncertainties associated with wastewater disposal practices. Theserisks are difficult to verify because of uncertainties such as physical and chemicalhydrogeological factors. Further research is recommended.

Flowback water can be treated and recycledto reduce the amount of both freshwaterused and wastewater disposed. Of the totalwater used in 2017 in Alberta, 4% of thewater came from recycling. Several factorsdetermine the amount of recycled waterused in hydraulic fracturing operations,including the volume of flowback water,chemistry of flowback and formation water,and costs (recycling, storage, transport). In2017, Hydraulic fracturing operators usedroughly 23% of their non-saline waterallocation, which is relatively low incomparison to other oil and gas activities.6

1. Alberta Energy Regulator (1994). Directive 051: Injection and Disposal Wells – Well Classifications, Completions, Logging, and Testing Requirements. 2. Alberta Energy Regulator (2001). Directive 055: Storage Requirements for the Upstream Petroleum Industry. 3. Alberta Energy Regulator (2011). Directive 077: Pipelines- requirements and reference tools. 4. Alberta Energy Regulator (2017). Directive 071: Emergency Preparedness and Response Requirements for the Petroleum Industry. 5. Alberta Energy Regulator (2018). Directive 013: Suspension Requirements for wells. 6. Alberta Energy Regulator. (2017). Alberta Energy Industry Water Use Report(Rep.). Alberta, Canada: AER. 7. Alberta Energy Regulator. (2017). Alberta Energy Industry Water Use Report- Hydraulic Fracturing (Rep.). Alberta, Canada: AER. 8. Alessi, D. , Zolfaghari, A., Kletke, S., Gehman, J., Allen D., Goss, G. (2017) Comparative analysis of hydraulic fracturing wastewater practices in unconventional shale development: Water sourcing, treatment and disposal practices, Canadian Water Resources Journal.105-121. 9. BC oil and Gas commission (2015). 2015 Annual Report on Water management for oil and gas activity. British Columbia, Canada. BCOC. 10. Horton, S. (2012). Disposal of Hydrofracking Waste Fluid by Injection into Subsurface Aquifers Triggers Earthquake Swarm in Central Arkansas with Potential for Damaging Earthquake. Seismological Research Letters, 83(2).11. Kniewasser, Maximilian and Riehl. Risks to Water and Public Health from Unconventional Gas in B.C. The Pembina Institute, 2018. 12. Maliva, R. G., Guo, W., & Missimer, T. (2007). Vertical migration of municipal wastewater in deep injection well systems, South Florida, USA. Hydrogeology Journal, 15(7), 1387-1396.13. Pierce, D. 2010. Water recycling helps with sustainability. SPE Asia Pacific Oil and Gas Conference, Brisbane, 2010. SPE 13413714. Petrinex: Canada’s petroleum information network. Alberta Public data. Retrieve from: https://www.petrinex.ca/PD/Pages/APD.aspx15. Schultz R. A., Uno, M., & Bere A. (2016). Critical Issues in Subsurface Integrity. ARMA, American Rock Mechanics Association, ARMA 16-037.16. Vengosh, A., Jackson, R. B., Warner, N., Darrah, T. H., & Kondash, A. (2014). A Critical Review of the Risks to Water Resources from Unconventional Shale Gas Development and Hydraulic Fracturing in the United States. Environmental Science & Technology,48(15), 8334-8348.

The hydraulic fracturing water cycle can be summarized in four main stages: (1) Water sourcing, (2) Hydraulicfracturing and well completion, (3) Treatment of flowback water, and (4) Recycling or disposal of water.8

Decision Parameters are driven by technical, environmental and economical factors. Water transportationoccurs throughout the water cycle and that may posed some risk of groundwater contamination. Water istransported by railcar, truck or pipeline in Alberta.

Figure 3. The hydraulic fracturing water life cycle and decision flowchart.

Figure 2. Location of active wastewater disposal wells in Alberta during 2018. From Petrinex database. 14

Figure 1. Water disposal volume per year in Alberta. From 2015 to 2018.From Petrinex database. The current trend of the increasing productionof natural gas suggests that the wastewater volume will continue toincrease in the foreseeable future.14

Figure 5. Total water used and hydrocarbonproduction associated to hydraulic fracturingactivities in Alberta for the year 2013-2017. 7

7

Definitions of Water in Hydraulic Fracturing Operations6,7

WastewaterA mixture of flowback fluids and produced waters that are not recycled. It has a high Total dissolved solids (TDS) and may also contain hazardous compounds, including methane, synthetic organic compounds, and radioactive materials.

Make up waterWater that is added to an energy process to replenish water lost. It can be obtained from either non-saline or saline water.

Recycled waterWater that was previously used in an energy activity and is then reused by operators in that same process.

Non-saline water Water having a TDS content of 4000 mg/L or less, sometimes is referred to as fresh water.

Alternative waterWater other than surface water and non-saline groundwater, including saline groundwater, produced water, etc.

Produced vs. Flowback WaterFlowback refers to the return of injected fluids plus produced water, while produced water is formation water that is high in gas and oil.

(1)Dept. of Physics, University of Alberta, (2) School of Public Policy, University of Calgary, (3) Dept. of Geoscience, University of Calgary, (4) Dept. of Civil and Environmental Engineering, University of Waterloo

No. Risks of Injection of Wastewater via Disposal Wells

1Leakage from cracks developed on wastewater pipelines because of corrosion and metallurgical defects15

2 Leakage occurs because of poorly sealed or failed injection well casing15

3Infiltration from storage ponds to shallow aquifer caused by improper lining and management11,16

4 Spills from surface storage tanks and trucks to shallow aquifer11,16

5A joint cross-cutting multiple subsurface layers providing potential flow paths for injected wastewater to the shallow aquifer11,12,16

6 Vertical migration of wastewater along along the wellbore wall12

7Potential casing shear failure/rupture caused by injection-induced fault movement10

8Formation of leakage path on caprock/top-seal caused by over-pressurizing the reservoir relative to the rock tensile strength12,16

9A fault cross-cutting multiple subsurface layers providing potential flow paths for injected wastewater to the shallow aquifer10

10Migration of injected wastewater to the shallow aquifer and to the nearby wells11,12,16

11Reactivation of existing faults inducing earthquakes because of injection activity causing changes in pore fluid pressure, temperature and volume of rocks in the reservoir10

The Alberta Energy Regulator (AER) addresses appropriate mitigation measures, reducing the above risks of contamination:

(1): Companies are required to identify, manage, monitor, and address any potential hazards associated with individual pipelinesand develop comprehensive integrity management programs, safety and loss management systems [Pipeline act, Pipeline rules,Directive 077]3

(2) & (6): Any well integrity failures (E.g. casing failures) should be reported and immediately repaired [Directives 013 and 051] 5,1

(3) & (4): Leak detection and mitigation is achieve by incorporating layers of porous materials, monthly visual inspection of thestorage tanks, and leakage detection devices (E.g. weeping tile system) [Directive 055].2

(5), (8), (9) & (10): Disposal injection occurs kilometers away from the potable groundwater resources.(7) & (11): In the rare case scenario of a reactivated fault that could compromise the well integrity, the companies are requiredto take appropriate action to report and repair the failures [Directive 013].5

Figure 4. Risks Associated with Injection of Wastewater.