Over the past several decades the oil and gas industry has developed full-system approaches for safe and cost-effective injection of methane, carbon dioxide and acid gas. Projects have been executed successfully in formations spanning a full range of depths, reservoir quality, pressures and temperatures. Injection has been into both aquifers and hydrocarbon bearing intervals. Lessons learned about site selection, storage design and site monitoring are directly applicable to current and future CO2 geo-sequestration projects. The standard for performance for geo-sequestration projects, as defined by the USA National Energy Technology Laboratory, is for 99+% permanence of storage and 30+% efficiency of pore space utilization. The focus of this paper will be on project design and well completion options to manage plume growth and promote safe, efficient and reliable storage in different geologic settings. Safe and reliable long term storage of carbon dioxide within a defined permit area will require knowledge and observance of limits on cap rock fracture pressures, formation stratigraphy and properties, knowledge of formation spill points and calculation of maximum rates of injection. Optimum design will achieve both permanence of storage and efficient use of pore space to mitigate adverse sweep related to gravity override of injected gas. To manage these issues in deep saline formations, with or without closed anticline structures, may require inclusion of brine withdrawal as part of the project design. Options for achieving the above will be discussed in the context of a staged development process.
By use of specific examples across a range of possible storage scenarios this paper will illustrate that site specific data, combined with detailed dynamic modeling, is very important to a complete assessment of storage site capacity and to design well completions that will achieve project objectives.
