Geological Sequestration of Anthropogenic Carbon Dioxide in the Western Canada Sedimentary Basin: Suitability Analysis
Authors: Bachu S. , Stewart S. 
Published: March 2010

Geological sequestration of anthropogenic carbon dioxide is a potential solution to the release into the atmosphere of CO2, a greenhouse gas thought of as significantly contributing to the global warming trend observed since the beginning of the industrial revolution. Basically, CO2 can be sequestered in geological media:through enhanced oil recovery (EOR),by storage in depleted oil and gas reservoirs,through replacement by CO2 of methane in deep coal beds (ECBMR),by injection into deep saline aquifers, and

by storage in salt caverns. Criteria in assessing the suitability of a sedimentary basin for CO2 sequestration are:tectonism and geology,the flow of formation waters and geothermal regime, andthe existence of storage media (hydrocarbon reservoirs, coal seams, deep aquifers and salt structures).

Generally, the Western Canada Sedimentary Basin is suitable for CO2 sequestration by all means because it is tectonically stable, it has regional-scale aquifers confined by aquitards or aquicludes, and it has oil and gas reservoirs in various stages of depletion, uneconomic coal seams, and extensive salt beds. However, various regions in the basin have different degrees of suitability, ranging from not suitable along the eastern edge of the basin, to extremely suitable in southwestern and central Alberta. Most major CO2 producers, such as power plants and refineries around Edmonton, are found in regions that are unsuitable for CO2 sequestration in geological media; however, some, such as the oil sands plants in the Athabasca area, are in regions that are not suitable. This analysis of the suitability of the Western Canada Sedimentary Basin for CO2 sequestration in geological media should provide industry and governments with essential information needed for developing plans and policies in response to climate change effects of anthropogenic greenhouse gas emissions into the atmosphere.

Introduction

Human activity since the industrial revolution had the effect of increasing atmospheric concentrations of gases with a greenhouse effect, such as carbon dioxide (CO2) and methane (CH4), leading to climate warming and weather changes(1, 2). Because of its relative abundance compared with the other greenhouse gases, CO2 is by far the most important, being responsible for about 64% of the enhanced "greenhouse effect"(1). On a sectoral basis, the energy sector contributes globally the most (45%) to anthropogenic (produced by human activity) effects on climate change(3). The high use of fossil fuels (85% of the world's energy needs), foreseen to continue well into the future(2, 4), is the major contributor to increased emissions of CO2 into the atmosphere. Thus, a major challenge in mitigating anthropogenic (man-made) effects on climate change is the reduction of these emissions.

Figure 1 shows Canada's profile in CO2 emissions by sector and by province. The profile of CO2 emissions in the Western Canada Sedimentary Basin is different from the national and other regions' profile because the basin is a major North American producer of fossil fuels.