P105 Block 49/29b Tristan NW Relinquishment Report

Transcription

1 P105 Block 49/29b Tristan NW Relinquishment Report Date: January 2011 Document No: BEL-TNW-REP-004- Rev1 Page 1 of 7

2 Document Approval, Distribution & Revision Prepared by: Signature Alasdair MacMillan. Reviewed by: Trevor Malloch. Approved for Issue: Ernie Edwards.. Report Distribution Copy Number Recipients 1 DECC 2 Bridge Energy - Aberdeen 3 MCX Document Revision Revision Number Description Date Prepared by 1 Relinquishment Report 20/01/11 Alasdair MacMillan 2 3 Date: January 2011 Page 2 of 7

3 Contents 1.0 Header Synopsis Exploration Activities Prospectivity Analysis Maps and Figures...6 List of Figures Figure 1: Location of Licence P105 Figure 2: Tristan NW Top Rotliegendes Depth Map Figure 3: Tristan NW Field E-W Geoseismic Section Date: January 2011 Page 3 of 7

4 1.0 Header Licence Number: P105 Licence Round: 3 rd Round Licence Type: Traditional Block Number: 49/29b Operator: Bridge Energy ASA % (Formerly Granby oil and gas followed by Silverstone Energy) Partners: MCX % 2.0 Synopsis Licence P105 is located in 49/29b within the main Rotliegend Leman fairway of the Southern North Sea adjacent to the Welland NW and Tristan Fields. The licence contains the abandoned Tristan NW Field (Figure 1). Silverstone Energy acquired Granby Enterprises in 2008 and assumed operatorship of licence P105. A large area of the licence was relinquished in November 2009 by a combination of Silverstone and Perenco containing the abandoned Welland NW and Tristan Fields and the 49/29b rest of block area, leaving only the Tristan NW Field remaining. Silverstone subsequently combined with Bridge Energy AS to form Bridge Energy ASA in 2010 and are the current operators of the licence. Following the decommissioning of the Tristan NW Field, the partnership now wishes to relinquish the remainder of the licence with immediate effect. Date: January 2011 Page 4 of 7

5 3.0 Exploration Activities The Tristan NW field was discovered by Mobil s exploration well 49/29b-5 drilled in The discovery well tested gas at a rate of 16.7 mmscf/d from an 85ft gas column in the Rotliegendes Leman sandstone. The field GWC was interpreted at 7960ft TVDss. A consortium led by Granby oil and gas then drilled the 49/29b-11 development well in The well was completed as a gas producer and brought onstream, though significantly lower than expected reservoir pressure led to economic rates not being achieved. It was noted that between the discovery of the accumulation (49/29b-5) and the production testing of 49/29b-11, Tristan NW reservoir pressures fell substantially. Additionally during this interval larger than expected volumes (38 bscf) of gas were produced from the nearby Tristan Main field and it was concluded that the Tristan NW Field has been de-pressurised as a result. Significantly less gas therefore remained in the trap at the time of development. Following modest gas production, 49/29b-11 well was shut-in and subsequently decommissioned in October The reservoir within the Tristan NW Fields is the sandstones of the Lower Permian Rotliegendes Group and comprises a sequence of stacked aeolian dunes with minor thin dry and wet interdune intervals. The aeolian dune facies display very good reservoir characteristics while the interdune facies are of much poorer quality. Typically, trapping structures in the region tend to be NW-SE trending anticlines (commonly faulted) that have been formed by Late Permian to Late Jurassic extension and subsequent Tertiary inversion. The trapping mechanism for NW Tristan conforms to this regional picture. As with most fields in the region, NW Tristan is sealed by the Zechstein evaporites. The source rock for all hydrocarbon accumulations in the area is believed to be the regionally extensive Westphalian Coal Measures. Gas expulsion from this source likely began in the Mid-Jurassic with migration continuing into the early Tertiary. 4.0 Prospectivity Analysis No further prospectivity is recognised on the licence Date: January 2011 Page 5 of 7

6 5.0 Maps and Figures Gawain 49/29c 49/29d P105 49/29g 49/29e Tristan NW Welland NW Tristan Figure 1 Location of Licence P105 Outlined in red Date: January 2011 Page 6 of 7

7 Figure 2 Tristan NW Top Rotliegendes (Leman Sand) Depth Map Figure 3 Tristan NW Field E-W Geoseismic Section (plane of section displayed on Figure 2) Date: January 2011 Page 7 of 7