St Griede Licence, onshore Aquitaine Basin: Gas2Grid Limited - 100%
(Updated 26 May 2015)
The St. Griede licence was awarded by the French Government to Gas2Grid Limited (50%) and its joint venture partner Gippsland Offshore Petroleum Limited (50%) on the 31st May, 2008 after a two year application process. The licence originally covered 1,238 square kilometres within the onshore part of the Aquitaine Basin, north and east of the city of Pau in the south of France.
Gas2Grid Limited now owns 100% of the St. Griede licence after purchasing the joint venture partner’s 50% interest in August 2011. Gas2Grid Limited regards the oil and gas exploration potential within the St. Griede licence as being exceptional and the 100% ownership provides a great opportunity to create significant value for shareholders.
A licence renewal application was submitted in January, 2013 for a second 5 year period from May 2013 accompanied by a 50% relinquishment of the original licence area. The total work commitment for the second 5 year period totals €1.177 million. The renewal application has been processed and approved by the Department of Exploration and Production of Hydrocarbons (BEPH) and is now awaiting a decree on the renewal by the Minister. Following confirmation of the licence renewal the Company plans to carry out a seismic survey that has already been approved by the BEPH in July 2014 – under a work program that was submitted in 2013.
There has been no exploration activity within the licence for over 30 years with the last seismic acquisition and drilling programs being conducted in the early 1980s. The lack of activity provides excellent exploration opportunities as the licence is regarded by the Company as being under-explored for hydrocarbons. Three oil fields are located a few kilometres west of the licence boundary – they have each produced approximately between 21-32 million barrels of oil and 38-40 petajoules gas.
Existing technical data has been acquired from the French Government and activities to date include integration of existing petroleum well information and seismic reprocessing. The Company has also acquired a Full Tensor Gravity (FTG) airborne survey, totalling nearly 5,000 line kilometres. These data have been integrated with the recently reprocessed vintage seismic, available within the licence and immediately surrounding areas.
The immediate exploration plans include the acquisition of a new seismic survey when the licence has been renewed, hopefully in the first half of 2015. Subject to the results of the seismic interpretation, the drilling of one exploration well is planned in the twelve months following the seismic acquisition.
The Aquitaine Basin is a prolific hydrocarbon province with a long history of discovery and production. Over 13,000 petajoules (approximately 13 trillion cubic feet) of gas and 450 million barrels of liquid hydrocarbons have been discovered within the basin, mainly by the large French Government owned corporations. There has been a hiatus in exploration activity since the 1980s but a resurgence of licensing activity and operations has occurred over a year ago, coincident with the then increase in both oil and natural gas prices. There has been neither seismic acquisition nor any drilling activity within the area covered by the St. Griede licence for more over 30 years. Until 2014, when three wells were drilled, there had been no exploration drilling activity within the whole Aquitaine Basin for more than 10 years.
Geology: The Aquitaine basin is a depression located in front of Pyrenees Mountains, to the south of the Massif Central, the basin merges to the east with basins of the Provence region and to the west, the basin is continuous with the Bay of Biscay. The Aquitaine basin developed since the Triassic on a heterogeneous Paleozoic basement, which is generally interpreted as a segment of the southern branch of the Variscan orogeny of Paleozoic age. Late Carboniferous and Permian troughs up to a few thousand metres thick have developed locally as a result of post-Variscan stress releases.
In Mesozoic times, a major hinge line (the "Celtaquitaine flexure") running from Arcachon in the NW, to Toulouse in the SE, separated a stable and relatively less subsiding platform to the northeast from more rapidly subsiding basins and intervening highs to the southwest. The latter area can be subdivided into two distinct domains:
In the south, the northern edge of the Pyrenees thrust belt and its moderately folded foreland developed as a foreland basin from late Cretaceous to late Eocene. This area is generally termed the Ardour Basin and contains the Arzacq, Tarbes and Commings sub-basins.
To the west is the Parentis Basin, which has been interpreted as a rapidly subsiding trough related to the opening of the Bay of Biscay in late Jurassic and early Cretaceous times. Total Mesozoic sediment thickness is in the order of 5 km.
To the north-east is the Mirande sub-basin, which has seen relatively little drilling and exploration. Thrust faults and Triassic salt features are recognisable.
The Mesozoic stratigraphy of the thrust belt and the foreland deep basins is shown in the stratigraphy of the Arzacq Basin. Total sedimentary thickness is up to 12 km and hydrocarbons occur in Jurassic-Cretaceous age carbonate sequences and Eocene age clastics.
The Parentis Basin is characterised by a more condensed sequence, but nevertheless it has a total sedimentary thickness in its western, onshore portion of about 6 - 7 kilometres. Hydrocarbons occur in late Jurassic and Cretaceous carbonates including bioherms and also in Cretaceous-Eocene clastics.
Petroleum History: The western half of the French Pyrenees and their immediate foreland is the most prolific gas-bearing province in France. The two major gas fields, Lacq (deep pool) and Meillon produce from deep and structurally complex traps. The producing intervals are late Jurassic and Cretaceous (Neocomian) dolostones and the petroleum source-rocks are Kimmeridgian marl and limestone. Porosities are generally low, but dolomitisation and highly fractured zones greatly enhance reservoir productivity. In the same area, six other fields are also currently producing from the same stratigraphic intervals and also from younger (Senonian) or older levels (Liassic).
The Aquitaine basin has a number of distinctive sub-basins which have been explored with varying degrees of intensity and which are, from north east to southwest as follows:
The Ardour Basin in SW France is the principal area of French oil and gas production and hence will likely be an interesting place to explore for further hydrocarbon accumulations. A long history of structural deformation and sedimentary deposition has resulted in prolific oil and gas generation in the basin. The St. Griede licence is located beside the Pecorade (31 million narrels oil & 38 PJ gas), Vic-Bilh (32 million barrels oil & 40 PJ gas), Castera-Lou (3.3 million barrels oil), Lagrave (24 million barrels oil), and Lameac oil fields.
The southern part of the St. Griede licence is located in the northern part of the Tarbes Basin which has been a focus of oil generation and migration from the late Albian (early Cretaceous) into the Tertiary. No significant exploration has been undertaken in this area for the last 20 years and the early focus of the exploration effort involved the acquisition of an aero-gravity survey (full tensor), seismic reprocessing and reinterpretation to investigate petroleum traps along the flank of the Tarbes Basin.
Hydrocarbon Traps: There are 2 principal trap types- compressional anticlines modified by salt movement and unconformity traps on the flanks of salt structures. The structures in the Ardour Basins have been deformed by extensional block faulting followed by Pyrenean compression with most structures influenced by salt tectonism. The basin morphology has been produced by the combined effects of the complex extension-compression-salt intrusion tectonic history of the Pyrenean region.
The northern part of the St. Griede licence is located in the Mirande Basin immediately to the northeast of the Audignon salt ridge, north of the Pecorade oil field, and the composite Garlin- Maubourguet-Antin salt ridge, north of the Lagrave, Castera-Lou and Lameac oil fields. The breaks between the salt ridges are likely to have acted as a hydrocarbon migration pathways from the prolific southern basins into the Mirande Basin. This whole area that encompasses the St. Griede licence has seen almost no exploration activity in the last 20 years - only 3 wells have been drilled in the last 19 years. Seismic data coverage in some areas is sparse and future work will include the acquisition of additional seismic data in order to define prospects for drilling in the later years of the license.
The complex structural history of the area has resulted in the development of many highly prospective structural traps. The compressional events at the end of the Jurassic (Neocomian), the end of the Aptian and Albian and in the Late Cretaceous-Tertiary have produced structural traps attractive to exploration.
Reservoirs: The main reservoir sections are Jurassic dolomites and Barremian limestones, and their distribution is defined by the Jurassic and early Cretaceous palaeogeography. The stratigraphic chart highlights the main reservoir targets which are located in the Jurassic and Early Cretaceous.
Gas Markets: Markets and infrastructure are well developed and the commercialisation of even small discoveries is feasible.
Work Completed: Data processing and interpretation of the 5,000 line kilometre aero-gravity survey has been completed. In addition, the Company has reprocessed and interpreted 740 kilometres of pre-existing seismic data. Seismic reprocessing attempted to enhance vintage data that was acquired over the period 1960-1980. These seismic data showed excellent improvements due to the reprocessing. Interpretation of these data was integrated with the newly acquired aero-gravity data set indicating excellent exploration potential for structural hydrocarbon traps.
Based on the successful results achieved with the initial seismic reprocessing, the Company made a decision in 2011 to reprocess all the other, available vintage seismic data within the St. Griede licence and a few additional vintage seismic lines that tied nearby producing fields and wells to provide additional geological control.
A total of 1,232.6 kilometres of vintage field seismic data was purchased from the BRGM. These data were supplied to the Company by BRGM in two batches. The first data batch (898.6 kms) was received on the 28 June 2011 and processing commenced on the 30 June 2011. Processing was completed for this batch of data on 26 December, 2011 with some delays being experienced due to bad location data and unknown geometry. Reprocessed data quality is generally excellent.
The second data batch (334 kms) was received on 20 December 2011. These data are still being processed. It is anticipated that processing of these data will be completed in February 2012. Interpretation of all reprocessed seismic data has also been completed with the delineation of several drilling prospects that require additional seismic coverage prior to drilling.
2015 Planned Activities: The Company plans on the following work activities for 2015:
Complete the acquisition of a minimum 150 kms of new seismic data.
If a petroleum exploration prospect and drilling location has been delineated by the new seismic data then a petroleum exploration well will be drilled in 2015-6.