MONITORING GEOLOGICAL STORAGE THE IN SALAH GAS CO_2 STORAGE PROJECT

摘要

In Salah Gas (ISG) is a Joint Venture (JV) Project between BP (33%), Sonatrach (35%) and Statoil (32%). The project comprises a phased development of eight gas fields located in the Ahnet-Timimoun Basin in the Algeria Central Sahara. The initial development focuses on the exploitation of the gas reserves within the 3 northern fields of Krechba, Teguentour and Reg to deliver the contracted sales gas stream of 9 bcm/yr. These gas fields contain CO_2 concentrations ranging between 1 to 9% which is above the export gas specification of 0.3% and therefore require CO_2 removal facilities. In addition to the CO_2 removal facilities, and instead of employing atmospheric disposal of the CO_2 ISG has made a further discretionary investment to enable compression and re-injection of the produced CO_2 stream (up to 70mmscf/d or 1.2 million tonnes per year) for geological storage. The CO_2 stream is re-injected back into the aquifer zone of one of the shallow gas producing reservoirs. This will be the world's first CO_2 storage operation in an actively produced gas reservoir. Production operations and CO_2 re-injection are planned to start during the middle of 2004. Tools used in the design of the project have been presented at earlier conferences, including GHGT-6 in Kyoto. This paper provides an update on the In Salah Gas Project and the accompanying CO_2 Storage Assurance Project, which it is proposed will be managed under the umbrella of a Joint Industry Project. This CO_2 project differs significantly in geological character and storage process from the existing Sleipner and Weyburn monitoring projects and offers an ideal opportunity to gain important additional information on the permanence and safety of CO_2 geologic storage. The ISG Project provides an important opportunity to study a gas field development project where geological storage at a field scale is employed to mitigate the environmental impact of the produced CO_2 stream, which represents ～60% of the projects emissions footprint.