Technical Report

The Integrated Assessment of Water Resources for Unconventional Oil and Gas Plays, West-Central Alberta Project

The Petroleum Technology Alliance of Canada

Executive Editor’s Note

We have all heard of the debate on hydraulic fracturing and the concerns about groundwater contamination. The availability to and consumption by the oil industry of water resources during the course of developing unconventional resource plays is another important issue for the industry, regulatory authorities, and the society in general. The joint industry project mentioned here starts to tackle this issue by identifying the shallow and deepwater sources in the deep basin study area. 

Gökhan Coskuner
Chairman, JCPT

The West-Central Alberta Water Project is a prime example of a Petroleum Technology Alliance of Canada (PTAC) project that demonstrates broad benefits by working together to identify and address current challenges related to water management. PTAC’s mission is to facilitate innovation, collaborative research and technology development, demonstration, and deployment for a responsible Canadian hydrocarbon energy industry. PTAC has facilitated the Alberta Upstream Petroleum Research Fund (AUPRF) for more than 10 years.

Soheil Asgarpour, PhD, P. Eng
PTAC President

Introduction and Context

The Integrated Assessment of Water Resources for Unconventional Oil and Gas Plays, West-Central Alberta Project (known as the West-Central Alberta Water Project) is cofunded by AUPRF and a partnership of 11 oil and gas companies.  The project is being conducted by integrated water resources (IWR), a team of three consulting companies. The 2-year project was initiated in June 2012, and Year 1 results are now available. The project will be completed by 30 June 2014.

With the development of horizontal drilling, multistage hydraulic fracturing, and multiwell pad technologies, industry is developing unconventional oil and natural gas resources (Alberta’s Montney and Duvernay plays are two prime examples in the heart of the project area). Significant volumes of water will be required to sustain these activities. The science-based information provided by this project is required for appropriate planning and associated resource management decisions.

The project aligns with other water-related initiatives, including Alberta’s Water for Life Strategy, and the Alberta Water Council recommendations for enhancement of baseline groundwater information and enhancement of analysis, interpretation, and reporting tools. It focuses on water sources and fluid disposal that are within the broader water and fluid-management cycle for unconventional activities. In addition, the project supports the Canadian Association of Petroleum Producers’ (CAPP) guiding principles for hydraulic fracturing and the hydraulic-fracturing Operating Practice 5: Water Sourcing, Measurement, and Reuse.

The West-Central Alberta Project

The key goal of the project is to assess and integrate information on all potential water sources, including: (1) surface waters; (2) shallow aquifers in unconsolidated materials and bedrock; and, (3) deep saline aquifers. The deep aquifers are also being assessed as potential deep disposal zones for flowback and produced fluids. The project is not evaluating fluid recycling or fluid treatments.

Project Area Description. The project includes an extensive area of oil and natural gas resources and activity. It covers more than 142 000 km2 of surface terrain and 91 000 km2 of subsurface area (Fig. 1). The surface project area includes parts of the Peace/Smoky, Athabasca, North Saskatchewan, and Red Deer River watersheds. 

Glacial sediments dominate the landscape, with vast expanses of morainal and glaciolacustrine material deposited in a relatively thin cover (<10 m) over the uppermost bedrock units. 

Precipitation is relatively evenly distributed throughout the year, with summer temperatures cooling with increasing elevation towards the Rocky Mountains. The quantity and timing of precipitation varies substantially across the project area and plays an important role in surface water resources.

Geological Setting. The subsurface portion of the project area lies on the western flank of the Western Canadian Sedimentary Basin, where the sedimentary succession measures more than 4000 m thick. Strata are relatively undeformed, and dip uniformly southwestward toward the Rocky Mountain foothills. This setting hosts an extensive basin-centred hydrocarbon regime (the Deep Basin), containing numerous unconventional oil and gas plays in shale, tight sandstone, and tight carbonate. 

The project encompasses the Montney and/or Duvernay plays (Fig. 1). However, other plays are now being accessed using horizontal, multistage hydraulic-fractured wellbores; including Swan Hills, Glauconite/Bluesky/Wilrich, Falher/Notikewin, Cardium, and other tight sandstones (e.g., the Rock Creek, basal Belly River, and Dunvegan).

Project Components

There are three separate components for the project: (a) surface water; (b) shallow aquifers; and (c) deep saline aquifers and disposal zones.

Component 1 Surface Water. Information on surface water resources was collected from a significant body of pre-existing research. This included “State of the Watershed” reports prepared by Watershed Planning and Advisory Councils, as well as numerous government and academic publications describing water resources. A large amount of spatial data on various components of the water cycle was collected and used to identify the characteristics of each component across the project area. Hydrologic analysis has been performed to characterize regional and seasonal patterns of water availability at the watershed scale.

Analysis. Using more than 30 subbasins identified by the Prairie Farm Rehabilitation Administration and the Water Survey of Canada, unique characteristics of the individual basins were assessed using spatial analysis. 

Results

Results of the subbasin analyses are included in the Year 1 surface water report. Surface water is more abundant locally at higher elevations in the study area, both toward the Rocky Mountain foothills and the drainage divide between the Athabasca and Smoky River watersheds. Data compiled during the first year and results of the subbasin analyses will form the basis of the Year 2 surface hydrologic modelling. Ultimate availability in surface water bodies will be strongly influenced by the upstream area of the contributing watershed and other pre-existing water users.

Component 2 Shallow Aquifers in Unconsolidated Sediments and Shallow Bedrock. For the purposes of this project, shallow aquifers occur from just below surface to the depth designated by Alberta Energy Regulator as the base of groundwater protection (BGWP). These include unconsolidated sediments and shallow bedrock formations. The following data sources have been compiled to assess the shallow aquifers: (1) quaternary geology maps, (2) sand and gravel (aggregate potential) maps, (3) drift thickness and bedrock topography maps and data, (4) thalweg maps and data, (5) hydrogeology reports and maps, and (6) Paskapoo isopach and sandiness.  Most of these materials were obtained from the Alberta Geological Survey, Alberta Research Council (ARC), and the Prairie Farm Rehabilitation Administration (PFRA).

Shallow Bedrock Aquifers. Continental sandstone, siltstone, and mudstone of the tertiary Paskapoo formation make up the shallow bedrock over much of the southern portion of the subsurface project area.  To the north, upper cretaceous units subcrop beneath the unconsolidated quaternary cover.  There is a substantial body of literature addressing these units, which has been compiled and summarized in Year 1. 

Component 3 Deep Bedrock Aquifers and Disposal Zones. Characterization of deep bedrock aquifers as potential water sources and deep disposal zones is an important component of the project. Waters contained in deep aquifers range from brackish to hyper-saline, and by definition lie below the BGWP depth. In petroleum boreholes, most deep aquifers occur below the base of surface casing, and thus can be analyzed using wellbore geophysical logs, drill cuttings, cores, and test data collected in the course of petroleum exploration and development.

A review of the entire stratigraphic column identified six deep saline aquifer units with broad regional extent: (1) Cardium formation, (2) Cadotte member, (3) Bluesky formation, (4) Cadomin formation, (5) Montney formation, and (6) Pekisko formation (Fig. 2).

Conclusion

The West-Central Alberta Project is designed to provide independent, third party water inventory information across a large portion of Alberta, where unconventional oil and gas exploration and development is occurring. Year 1 concentrated on the compilation and initial synthesis of broad and diverse data sources. The project will provide a regional framework upon which planning, assessments, and operational decisions can be made. It will assist companies in their efforts to achieve desired outcomes that the Alberta Government is developing under its new Unconventional Regulatory Framework. The project outputs also have broader application in water-related decision making and discussions.

Full details of the project summarized here are provided in an overview paper and three technical reports available at http://www.ptac.org/projects/371 and at the Integrated Water Management Website http://www.integratedwaterresources.ca/projects/#s0

Fig. 1—The project area showing delineation of surface and subsurface
project areas in west-central Alberta.


Fig. 2—Summary image depicting deep saline aquifer distribution across the project area.