Deep Aquifer Fluid Disposal Project

- Petrel Robertson Consulting Ltd. and Canadian Discovery Ltd.

Natural gas exploration and development in northeast B.C. require large volumes of water. This water is needed to access the natural gas locked within tight shale rock reservoirs during a process called hydraulic fracturing, or "fracking." This process releases the gas and/or oil by creating spaces in the otherwise tight reservoir that allow the gas to flow.

In utilizing large volumes of water to access shale gas, large volumes of "produced" water are created and have to be disposed of and stored in a safe and sustainable manner. To ensure no contamination of drinking water, these produced waters must be injected into deep aquifers known as disposal zones. In the ongoing effort to foster responsible development of B.C.'s natural gas resource, Geoscience BC collaborated with the BC Oil and Gas Commission, and the BC Oil and Gas Research and Innovation Society (BC OGRIS) in 2014, to develop a program that would address the challenges of water disposal.

Called the Deep Aquifer Fluid Disposal, or DAFD project, the objective was to characterize the capacity of deep disposal zones within the Montney unconventional play fairway in northeast B.C. Petrel Roberston Consulting Ltd. (PCRL) was contracted to perform the first step of the DAFD project: map and characterize three different deep saline aquifers identified as high-priority disposal zone targets.

A regional map suite was created by PCRL using the region's pre-existing well information in combination with rock samples to examine the ability of the zones to accommodate large volumes of produced water. The maps also give a high/medium/low favourability ranking for each potential aquifer or zone, where high favourability indicates areas with good aquifer characteristics and capacity with little or no risks arising from development of potential nearby shale gas reservoirs. On the other hand, a low favourability ranking for a target aquifer indicates poor aquifer characteristics and/or significant risks of impacts from existing or potential shale gas development.

In early 2015, Geoscience BC engaged Canadian Discovery Ltd. to perform step two of the DAFD project. This will involve a focused assessment of aquifer hydrogeology, including projections of the capacity of the aquifers to accept produced fluids.

Technical Articles
2015: "Characterization of Belloy, Kiskatinaw and Debolt water disposal zones in the Montney play area, northeastern British Columbia"
- Summary of Activities 2014, Report 2015-1 p. 85-88 (pdf, 2.4 MB)

Final Deliverables
Geoscience BC Report 2015-03
Characterization of Belloy and Debolt Water Disposal Zones in the Montney Play Fairway, Northeast B.C. - Petrel Robertson Consulting Ltd.

Intensive development of the Montney tight siltstone and shale play in northeastern B.C. presents new challenges to both operators and to the BC Oil & Gas Commission. One of the key challenges is in accessing appropriate water source and disposal zones to support horizontal drilling and multifrac completions. Source water can be obtained from surface water bodies, shallow non-saline aquifers, or deep saline aquifers. However, spent completion fluids and produced waters must be injected into deep saline aquifers to ensure complete isolation from surface waters and non-saline groundwater.

The Montney unconventional play fairway spans both Plains and Foothills areas in the Peace River region and northwestward. Potential disposal zones in deep saline aquifers exist across the fairway, but their distribution and injectivity characteristics are highly variable. Geoscience BC's Montney Water Project provides a comprehensive regional inventory of water resources and potential for deep geological disposal sites in the Montney (http://www.geosciencebc.com/s/Montney.asp), and is an excellent starting point for detailed local work on specific water disposal issues.

Recent injection activity has shown that more work is required, as performance of some existing injection wells has not been satisfactory. Geoscience BC and the BC Oil & Gas Commission have collaborated to develop a scope of study that addresses many of the water disposal challenges. The Belloy, Kiskatinaw and Debolt formations have been identified as high-priority disposal zone targets requiring detailed assessment.

Petrel Robertson Consulting Ltd. (PRCL) was engaged by Geoscience BC to undertake regional reservoir characterization of the Belloy, Kiskatinaw, and Debolt formations, with emphasis on identifying their capacity to act as secure disposal zones. This report summarizes PRCL's findings, and is designed to support future focused reservoir engineering assessments.

Geoscience BC Report 2015-14
Characterization of Belloy and Debolt Water Disposal Zones in the Montney Play Fairway, Northeast B.C. - Canadian Discovery Ltd.

The study examines the hydrogeological and geomechanical aspects of two subsurface rock formations in northeast B.C.- the Belloy and Debolt formations - and assesses the potential for injected fluids to fracture the rock and suggests limits for injection pressures. These limits are significantly higher than the limits prescribed and monitored by the BC OGC. The geomechanical and hydrogeological study components also address concerns related to potential drinking water contamination. In March 2015, initial work performed by Petrel Robertson Consulting Ltd. was released on reservoir characterization and geologic favourability mapping, which helped define the two focus areas for this analysis.

Both publicly-available data and a small amount of project stakeholder data were used to constrain geomechanical properties in the Belloy and Debolt formations in the defined study areas. Results are limited by both data availability and the limited evaluation of geomechanical risk. This study is, however, useful for a regional perspective on potential fluid injection sites, though specific injection programs should not be planned without site-specific data gathering and geomechanical modeling.

Canadian Discovery Ltd. was engaged by Geoscience BC to complete this study. The results are summarized in this report.

 


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