CSEGR
Feasibility Study on the Potential of CO2 Storage for Enhanced Gas Recovery in Mature German Gas Reservoirs
According to a qualitative ranking (including criteria like storage capacity, safety, geotechnical suitability, economics and energy balance), gas fields should be the prime choice for CO2 storage in Germany. More than 50% of the German gas reservoirs are already in a mature status and operators consider options for future use of the reservoirs. Mature fields offer the opportunity to enhance residual gas production through CO2 injection, to extend the production lifetime, and to increase their ultimate gas recovery (CSEGR = carbon storage and enhanced gas recovery, or CO2-EGR). Finally, after CO2 breakthrough, production wells could be shut-in and the reservoir could be further used for CO2 storage. Depleted or mature gas reservoirs have proven their capability for long-term storage of natural gas. The capacity of gas storages in Germany has already reached a strategic 20% share of the annual consumption and a major further increase is not expected at present. Therefore the option of CO2 storage is gaining interest by the oil and gas industry. CO2-EGR is a theoretical concept still that has not been practiced yet. It could help to increase the national energy resources and security of supply and to reduce the costs of CO2 storage in comparison to other options intending underground storage alone. Energy and emission balances could benefit from the production of additional natural gas that could substitute other fossil energy carriers with higher specific CO2 emissions. Key factors, to optimise gas recovery and efficient storage of CO2 simultaneously, are the injection control and the retardation of CO2 break-through by either separating the fluids in the carrier rock due to the differences in gravity between dense CO2 and the lighter hydrocarbons, or by reducing the mobility of the CO2 in layered reservoirs. The tectonic architecture of a gas reservoir and the facies type of reservoir rocks strongly influence CO2-EGR performance. The feasibility of CSEGR will be studied under different geological conditions of German gas reservoirs. Two prototypes of reservoirs are in principle suited for this task: Heterogeneous, fine-scale structured, and anisotropic layered gas carrier rocks, in Rotliegend reservoirs, like those in the Altmark. Homogeneous, large-scale-structured, isotropic Bunter sandstone reservoirs. This study shall investigate likely storage systems including producing gas reservoirs, regional CO2 sources, and linking corridors of existing pipelines. The geological, technical and economical key parameters that could influence the optimisation of CSEGR will be investigated. Their sensitivity for the planning of future field tests in Germany will be defined.
Project co-ordination:
Prof. Pusch
TU-Clausthal Zellerfeld
Partners:
TU-Clausthal Zellerfeld
BGR Hannover
Vattenfall Europe
EEG - Erdgas Erdöl GmbH
E.ON-Ruhrgas
Wintershall Kassel
