Converting the Pecorade Oil Field Into an Underground Gas Storage
- Philippe Coffin (Total) | Genevieve Lebas (Total)
- Document ID
- Society of Petroleum Engineers
- SPE Projects, Facilities & Construction
- Publication Date
- March 2008
- Document Type
- Journal Paper
- 1 - 6
- 2008. Society of Petroleum Engineers
- 4.1.2 Separation and Treating, 5.8.3 Coal Seam Gas, 5.4.2 Gas Injection Methods, 4.3.4 Scale, 4.2.3 Materials and Corrosion, 4.2 Pipelines, Flowlines and Risers, 1.6 Drilling Operations, 4.6 Natural Gas, 3 Production and Well Operations, 5.1.2 Faults and Fracture Characterisation, 5.5 Reservoir Simulation, 4.1.5 Processing Equipment, 4.1.4 Gas Processing
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The need for additional underground gas storage (UGS) in Europe and in France is increasing. TOTAL has therefore undertaken feasibility studies to convert the depleted Pécorade oil field, situated in South West France, into an UGS.
The Pécorade field offers a number of positive characteristics which make it a good candidate for UGS, but it is also deep at 2500 m and contains hydrogen sulphide.
This paper describes some of the challenges faced by the project, including:
- The sizing of the working volume (volume of gas which can be stored and cycled each year), which required the acquisition and processing of a new 3D seismic program, and the construction of specific geological and reservoir models.
- The safety and environmental issues related to caprock integrity and sour-gas production.
- The conversion of existing oil and gas wells into gas injection and production wells.
- The processing of cycled gas (including sour-gas treatment).
- The cost of the project compared to more conventional UGSs.
The main benefits expected from the project are:
- The development of a sizeable working volume, in the order of one billion cubic meters, in an ideal location to serve the French and possibly Spanish market.
- An improved oil recovery, as the annual cycling of the gas would induce production of an additional 20 to 30% over current projections.
These studies also confirmed that the development of a sizeable UGS is a lengthy, difficult, and complex project.
The decision to launch the project is mainly dependent on the results of the future preproject studies, regulations, and market conditions.
While Europe's gas consumption is increasing, domestic gas production is declining, and gas imports are on the rise. Therefore Europe is eager to secure additional gas imports, cater for seasonal gas demand, and prevent supply shortages. One of the means to achieve these targets is the development of new underground gas storage (UGS), and it is estimated that Europe UGS capacity must at least double in the next 25 years (Plan Indicatif 2006).
France has not been endowed with a proliferation of oil- and gas-bearing reservoirs, and as a result the vast majority of existing UGS are of the aquifer type. However, the development of this type of UGS is now facing more stringent environmental regulations, and therefore TOTAL has undertaken studies to convert the depleted Pécorade oil field into a UGS.
The Pécorade field is situated in South West France, 150 km from Bordeaux, and has produced oil since 1978 (Fig. 1). The field was selected as a possible UGS after a screening study of the oil and gas fields situated in the area. Pécorade presents the following advantages:
- It is situated near an existing gas pipeline network.
- It has a proven gas capacity, as it contained an initial gas cap.
- It is depleted, with reservoir pressure having declined from an initial pressure of 26.5 MPa to today's 10 MPa.
- It has proven caprock integrity.
However, the reservoir is deep by UGS standards at 2500 m and contains hydrogen sulphide. These are major disadvantages and drive the development cost of UGS up. Therefore, a feasibility study was launched and completed to assess the possibility of economically converting this oil field into a UGS. This paper describes the feasibility studies performed and the particular challenges overcome during the project evaluation.
|File Size||2 MB||Number of Pages||6|
European Union Second Gas Directive. 2003. 26 June 26. Official Journalof the European Union: 15 July 2003
Favret, F. 2003. Up-To-Date Researches and Future Trends in Underground GasStorage Facilities: A State Of the Art Review. NATO Advanced Research Workshop,Security of Natural Gas Supply Through Transit Countries, Tbilisi, Georgia,22-24 May.
Plan Indicatif Pluriannuel des Investissements dans le secteur dugaz-Période 2006-2015. 2006. Paris: Ministère de l'Economie et desFinances.