Basin Resource Management and Carbon Storage

1. Basin Resource Management and Carbon Storage S. Varmaa,b, K. Michaela,E. Bekelea, B. Ciftcia, J. Hodgkinsona, L. Langhia, B. Harrisc, C. Trefrya, K. Woutersa CSIRO EARTH SCIENCE AND RESOURCE ENGINEERING Sunil Varma e sunil.varma@dmp.wa.gov.au t08 9222 3267 aCSIRO Earth Science and Resource Engineering, bWestern Australian Department of Mines and Petroleum, cCurtin University The potential for interactions between various resources and CO2 storage in a sedimentary basin needs to be assessed for both positive development synergies and risk of adverse impact. A generalised workflow for the evaluation of resource interactions with carbon storage has been developed. Introduction A risk based approach to CO2 geological storage assessment will focus on the potential for resource contamination and increased development costs as in the case of conventional oil and gas or groundwater. CO2 storage may compete with coal seam gas produced water disposal for the use of deeper pore space or it could pose resource competition risk to coal mining. Alternatively, CO2 may provide benefits to enhanced oil or gas recovery, enhanced coal seam gas operations, or as a working fluid in geothermal applications. Beyond the CO2 itself, an increase in formation pressure could provide pressure support for producing oil or gas fields and limit the decline of groundwater levels in stressed aquifer systems. Other risks to be assessed include the potential that increased pressure may displace brine into usable groundwater aquifers, induce seismicity and compromise seal integrity. Various aspects of basin resource management and carbon storage are assessed for groundwater, petroleum, conventional, coal seam gas, shale and tight gas, coal and geothermal resources. The monitoring and remediation strategies for effectiveness in assessing the identified resource interaction risk have also been reviewed. The final outcome is a document providing a generalised workflow for the evaluation of resource interactions which is described here. Generalised workflow The Part I of the workflow document provides background information on the classification and assessment methods of the main basin subsurface resources that are known to exist in the Australian sedimentary basins (Figure 1). As a first step, each of the resources including groundwater, oil and gas (including shale and tight gas), coal and coal seam gas, and geothermal must be identified and characterised. Part II of the document sets forth a process to qualitatively determine the potential impacts of site-scale CO2 geological storage on other basin resources (e.g. groundwater, hydrocarbon, coal and coal seam gas developments, and geothermal). It follows the US Energy Protection Agency’s framework for the Vulnerability Evaluation Framework (VEF) for Geological Sequestration (USEPA, 2008). Assessment of potential interactions The first steps in the assessment of potential impacts from CO2 injection are the delineation of the extent of suitable areas for CO2 geological storage and the identification and mapping of areas with present or future resource developments. If the location of a CO2 injection operation is known, its Area of Impact (AoI) can be used to further focus the assessment of potential resource interactions to a specific area. In this case, a more detailed characterisation of each resource is required. Depending on the level of interaction potential (or degree of vulnerability), different site characterisation requirements, M&V and mitigation strategies would be recommended. Many of the decision points in the example workflow may require substantial data collection, interpretation and expert risk assessment (Table 1). An example of the process for evaluating a CO2 storage project is shown in Figure 2. Table 1:Summary of data requirements for characterisation of various basin resources. Parameters marked as deep blue are essential, those in light blue are desirable and grey indicates that parameter is not required for a particular resource. Figure 2:Example for evaluating the suitability of a CO2 storage site with respect to potential resource interactions within its Area of Influence (AOI) (from Michael et al., 2012). Summary The final outcome is a generalised workflow for the evaluation of resource interactions following the methodology proposed by the USEPA (2008) for assessing potential resource interactions. Its primary purpose lies in the identification of areas that have the potential for adverse or beneficial interactions between CO2 geological storage and other resources. More detailed characterisation will be required for project specific assessments within the Area of Impact (AoI) of a CO2 storage project. Figure 1: High-level workflow for the assessment of potential interaction of CO2 geological storage with other basin resources, depicting how the different Parts and Sections (Sec.) of the document address specific aspects of the workflow. References Michael, K., Hortle, A. and Bunch, M., 2012, A Classification System for the Assessment of CO2 Storage in Saline Aquifers: Cooperative Research Centre for Greenhouse Gas Technologies, Canberra, Australia, CO2CRC Publication Number RPT12-3623. USEPA, 2008, Vulnerability evaluation framework for geologic sequestration of carbon dioxide, Volume EPA430-R-08-009, U.S. Environmental Protection Agency, 85 pp. Acknowledgements The authors wish to acknowledge financial assistance provided through Australian National Low Emissions Coal Research and Development (ANLEC R&D) and WA Department of Mines and Petroleum. ANLEC R&D is supported by Australian Coal Association Low Emissions Technology Limited and the Australian Government through the Clean Energy Initiative.