In salah gas, a fully integrated project

Abstract

In the mid-Nineties, a joint venture between SONATRACH and BP successfully demonstrated the commercial potential of gas in Southern Algeria, sanctioning the development of the integrated, complex multi-field "In Salah Gas Project", which will bring 9 billion cubic meters of dry gas per year to the markets of Southern Europe. Key challenges faced by the jointly staffed In Salah Gas project team were to insure the sustainability of 9 billion cubic meters for 13 years minimum in one of the most hostile environments, to put in place the infrastructures to transfer dry gas to the "Centre National de Dispatching de Gaz" (CNDG), 500 km north of the contractual perimeter and finally to meet the high environmental commitments that had been outlined by the Algerian Ministry of Mines & Energy and the SONATRACH and BP management. The requirement is that the CO2 concentration in the gas stream should be less than 0.3%, significantly below the concentrations present in the In Salah Gas fields, which range between 1% and 9%. The most important aspect of the project is the commitment to non-atmospheric disposal of the 0.66 billion cubic meters per year of extracted CO2 stream that results from the fields production to meet the contracted sales gas volumes. This means that an alternative solution to simply venting would be required. Storage and sequestration of the extracted CO2 stream is planned within the aquifer region of the hydrocarbon bearing Carboniferous formation adjacent to the Krechba field, the most northerly of the gas fields currently in production since July 2004. Three CO2 injection wells have been drilled with results as prognosed from seismic, providing access into the east and north aquifer reservoir region for storage and sequestration of CO2. The project is now operating one of the largest sequestration and storage schemes in the world. Another important aspect of the project is the environmental certification ISO 14001, the first one in the world to get this distinction during the construction phase. Another challenge is to sustain this certification for the whole life of the project. This document provides a case study of one of the first major gas developments where an integrated mitigation plan was constructed in the initial stages of project design, ahead of project sanction. The paper will describe the project and outline the key elements of the development, and the complexity faced by the project team to resolve the environmental, geographical and logistic issues. It will also focus on the options and the solutions that have been identified for managing the key environmental issues of CO2 management and ISO 14001 certification.