Peter Haile and Jim Munns UK DTI The UK Continental Shelf – petroleum geology and future opportunities “Breathing new life into a mature province” Peter Haile and Jim Munns UK DTI AAPG Salt Lake City 13th May 2003 Good evening and thank you for inviting me to talk here tonight. I work for the Oil and Gas division of the DTI within a small team with the specific task of promoting the UKCS abroad with an objective to attract New Entrants into the UK. For the last year or so we have been attending Trade Fairs. The title of my talk is “The Petroleum Geology of the UK Continental Shelf or “breathing new life into a mature province. British Geological Survey

UKCS Structural Elements Structural Elements of the UKCS.- Basinal areas in dark blue - Green – oilfields; North, Central NS and WOS - Red - gas fields; SNS and Irish Sea - 260 fields in production 2. Intraplate setting since the Permian -Passive Margin very similar to West Africa -Failed Rift system in the North Sea, crustal thinning but no emplacement of oceanic crust -Continent –Ocean boundary on the western seaboard

Stratigraphy Summary stratigraphy Very petroliferous basin Virtually all sandstones from the Devonian to the Eocene contain oil and gas fields Kimmeridge Clay (Ur. Jurassic) is a world class source rock, typically 5% plus TOC and often into the teens Westphalian gas prone source rock is important in the SNS

Structural Development Intraplate setting since Permian times: five main tectonic events control HC distribution Permo-Triassic rifting and thermal subsidence Middle Jurassic domal uplift Late Jurassic to Early Cretaceous crustal extension Post Rift thermal subsidence Rifting on the Atlantic Margin Intraplate setting since Permian times: five main tectonic events control HC distribution Permo-Triassic rifting and thermal subsidence Middle Jurassic domal uplift Late Jurassic to Early Cretaceous crustal extension Post Rift thermal subsidence Rifting on the Atlantic Margin

Projected UKCS production from discovered reserves (mmboe) This slide looks at future production on the UKCS Currently at plateau with significant decline projected particularly in the large oilfields Following the “oil price shock in 1998” the government and industry held a joint task force that looked at ways to stimulate the industry resulted in Vision for 2010 of which 3 mmboe/d production was the key target current projections have a ½ mmboe/d gap if you include all probable and possible new developments and brownfield investment. BUT this model has no new exploration success or development of the 250 plus undeveloped discoveries. These we areparticularly keen to promote to new entrants. ATP an example of the type of company to fill undeveloped discovery niche

Exploration wells vs. oil price Exploration wells by year from 1974 in blue Discoveries in green Brent yearly average price in red Peak of activity 1987-1993 Clear correlation between activity levels and discoveries 1989 27 discoveries from approx. 140 wells Last three years fall off in E&A wells but an increase in success rate, potentially eight discoveries from less than 30 wells in 2001including the giant Buzzard field

Some specific discoveries.... This graph now includes 10 large discoveries that have been made in the last 25 years. I have included liquid discoveries here only, gas would further improve the argument. Also there are the examples of wells that were considered as marginal originally such as Leadon that could be added. This further illustrates that lurking amongst the 250 plus undeveloped discoveries there might be another “Leadon” Several of these discoveries have opened up a new play such as Britannia, Captain and Foinaven and Scheiallion and have driven a burst in activity.

This slide reiterates that there are hydrocarbon occurrences throughout the stratigraphic column. The primary reservoirs in the Southern North Sea being Permian in age with the Post rift Paleocene and synrift Jurassic reservoirs of the Central and Northern North Sea.

Focus of future activity Syn-rift Upper Jurassic combination /stratigraphic play at basin margin Lower Cretaceous stratigraphic play Deep basin axis HPHT play Lower Permian Rotliegende pinchout play Atlantic Margin Play Palaeogeographic play We see six primary trends as the focus of future activity: Upper Jurassic syn rift combination/stratigraphic play at the basin margin Lower Cretaceous stratigraphic play Deep basin axis HPHTplay Lower Permian Rotliegend pinch-out play Atlantic Margin post rift play Tertiary palaeogeomorphic play I will now give an example of four of these in the interest of time.

Source Rock Distribution ? Jurassic mudstones Jurassic mudstones – uncertain distribution Carboniferous coal measures This slide shows the distribution of source rock quality mudstones and coal measures and demonstrates the large variety of basins around the UK and hence the mix of frontier and mature plays. The source rock distribution in the AM is poorly understood because the main plays are Tertiary in age, but the Kimmeridge Clay is present both onshore and offshore and the age of the onset of rifting is important Three cross sections are highlighted that I will refer to later in the talk to highlight remaining prospectivity on the UK shelf Carboniferous basinal mudstones Regional cross-section

Central North Sea Now we shall look at a couple of examples in the prolific Central Graben with large reserves in the Paleocene and the Jurassic Halokinesis very important in trap formation due to both active and passive salt movement HPHT and TRIASSIC RAFT play underexplored Ur. Jurassic basin floor fans/contourites in the deep axial part of the basin INDIVIDUAL BASIN IN THE NORTH SEA WITH MOST POTENTIAL TO PRODUCE A NEW PLAY TYPE

Upper Jurassic stratigraphic play Seismic amplitude play within the Upper Jurassic syn-rift “brightening” below the Intra Kimmeridgian unconformity reservoir encased within mature source rock reservoir is the Burns sandstone member Monte Carlo reserves between 165 and 700 mmbo with a deterministic case at 330 mmbo.

Upper Jurassic stratigraphic play The prospect is best demonstrated with this Instantaneous amplitude section provided by Fugro-Geoteam which resolves the intra Jurassic reflectivity Note: Base Cretaceous Unconformity Intra Kimmeridgian event that forms the updip topseal Note the brightening within the the hanging wall section of the basin bounding fault and the dimming updip Basin floor sands are proven in the basin Instantaneous amplitude section: prospect 12/23. Updip pinchout of Ur Jurassic basin-floor sandstones Seismic line courtesy of Fugro-Geoteam AS

Deep basin (HPHT) play This is an example of a six kilometre offset seismic line on the HP/HT play kindly provided by Veritas. The increased offset gives significantly improved imaging at depth. The line clearly shows the structuration in the pre-rift with rotated tilted fault blocks dipping to the right. The pre-rift play is under-explored although we have an example of a pre-rift Rotliegend play on our CD. The syn-rift sequence clearly shows detachment from the pre-rift with basinward gliding into the footwall. The rotation of this syn-rift sequence sets up plays in the hanging wall of the fault to the west with highly prospective Upper Jurassic reservoirs likely to be present. 6km offset 2D Seismic Data data Acquired Q4 2000 'Seismic data sample supplied courtesy of Veritas DGC Limited'

Atlantic Margin The northernmost section is on the Atlantic Margin. Classic rift basin the Faroe/Shetland basin. As you can see there is more than 10 Km. of section. The western limit is masked by Paleocene basalts, which causes real imaging problems in the sub basalt. Main plays are Paleogenebasin floor fans stratigraphically trapped updip. Vertical migration is important. Very large Clair field trapped in fractured Devonian basement. Note: Eocene trap geometry THIS PLAY IS RELATIVELY UNDEREXPLORED DESPITE THE DISCOVERY OF TWO GIANT FIELDS IN THE EARLY NINETIES

Atlantic Margin Play Atlantic Margin Play 213/10 prospect on the Atlantic Margin Structure map to Caledonia Fan which is within the Eocene Proven play concept in the basin Basin floor fan In this example structural closure at the top of the fan package Large reserve potential up to almost 3 Tcf sourced by vertical migration from the Kimmeridge Clay

Promote Licence – tap into new thinking Split 4 year Initial Term First 2 years to enable work up of prospects and attract resource/commitment Second 2 years to fulfil ‘significant activity’ – normally a well Low cost 10% of normal licence fee (first 2 years)

21st Round best since the 1970’s 4 7 2 30 Traditional 40 Promote 140 blocks bid 75 companies 36 new companies 5 3 6 2 8

Fiscal Position Corporation Tax 40% Decreases Removal of Royalty Improved First Year Allowance Tax reduction on new tariff business Treasury consultation on stimulating exploration

Summary – why the UKCS? 10 BBOE plus Yet to Find 2001 BUZZARD largest UKCS discovery since 1993 Deep water Atlantic Margin under-explored Subtle traps and non-conventional plays in the North Sea 35% E&A well success rate A reiteration of why the UKCS is a “good place to explore” 27 BBOE Y to F Major world class discoveries such as the Pan Canadian Buzzard this year. Largest since 1993 Deepwater AM play- Faroes Amerada discovery that was press released?? Many UKCS fields are structural traps (240), opportunities for subtle and non-conventional traps to be explored E&A success rate 35%

Conclusions Full spectrum of opportunities remain Trying to make the UK a better place to do business – stable, responsive, transparent, competitive Want to get licenses in hands of those who are ‘hungry and innovative’ – Brian Wilson (UK Energy Minister)