The East Falklands Basin 2012 Drilling Programme

Transcription

1 The East Falklands Basin 2012 Drilling Programme

2 Location Map Sea Lion FI61/05 1 Toroa The FOGL acreage (in Yellow) lies to the south and east of the Falklands. The Falklands Plateau and surrounding basins are located at the eastern edge of the South American continent. The Falklands used to be part of southern Africa. The DSDP wells to the east of the FOGL acreage were drilled in the early 1980 s and form a key data point in the development of the petroleum story.

3 Basin Comparison (49,000sqkm) Gulf of Mexico Comparison North Sea Comparison FOGL has a very large acreage position as shown above by superimposing the FOGL licences onto maps of the North Sea and Gulf of Mexico - at the same scale.

4 Plate Tectonic Reconstructions of the South Atlantic Source: ODSN The Falkland Plateau basins formed as a result of the break-up of the Gondwana supercontinent in the Jurassic period. This continental mass comprised of, what are now, the continents of America, Africa, Antarctica, Australia and part of Asia. One of the earliest parts to fragment from the massive landmass was Antarctica. This created a small ocean basin, called the Weddell Sea, between the Falklands and Antarctica to the south. It was in this basin, that much of the petroleum system was deposited. In the Early Cretaceous (about 130 million years ago) the final phase of the break up of Gondwana was initiated as South America began to separate from West Africa. By 100 million years ago, the separation was complete and an open seaway existed between the Weddell Sea to the south of the Falklands and the South Atlantic to the north. The continued growth of the South Atlantic resulted in increased 4 separation of South America and West Africa until the present day configuration was achieved.

5 The Falkland Islands as a Source of Good Quality Reservoir Sands Source area for quartzitic sand B A B A NW B B A A SE The Falkland Islands and the plateau that extends to the east of the islands, is dominantly composed of hard, Silurian-Devonian ( million years old), quartz rich rocks. These have been eroded over millions of years to form beautiful sandy beaches, like those that fringe the Falklands today. The Falklands used to be much higher above relative sea level and the landmass was much more extensive (the North Falklands Basin was a fresh water lake, surrounded by land, for millions of years). The sand deposits around the islands were ultimately shed into the basin and then reworked to form the reservoir targets for the deepwater drilling campaign. The shoreline in the Jurassic and Cretaceous was much further to the south and the Toroa well (drilled 2010), drilled near that ancient shoreline, demonstrated 5 good sand development in the Springhill play and excellent, thick clean sands in the mid Cretaceous.

6 2012 Drilling Programme Northern Licences The Toroa well was drilled on the edge of the Fitzroy sub-basin near the ancient shoreline. The first target in the deepwater drilling programme will be the Loligo prospect which is located over 300km to northeast. It sits directly above a large, ancient high between the two major sub-basins. Hydrocarbons can be sourced from either basin and will tend to migrate into the younger shallower formations that form the Tertiary Channel Play. The play was not sampled at the Toroa location. Isopach map of Jurassic to early Cretaceous The DSDP wells (see page 1 and inset below) were drilled in a continuation of the volunteer sub-basin. Thick (200M) organic rich shales are present in these wells. These are excellent source rocks for oil, and if buried more deeply, gas. The youngest of the source rocks (Aptian -110 million years ago) in these wells is particularly rich and has been buried (heated) to oil generating depths immediately below the Scotia and Hero prospects. 6

7 Depositional Settings and Reservoir Development This diagram shows present day marine depositional environments that are similar to those being targeted in the plays in the East Falklands Basin. Toroa was drilled into sediments that were deposited in a near shore environment. Loligo and the Nimrod complex were deposited in a slope setting where deepwater channels scoured into the underlying sediments and dumped their load of sands, while finer materials were shed further into the basin. Sheets of sand were also deposited in a less confined setting by turbidite flows. The sandstones in the Scotia and Hero prospects (Mid Cretaceous play) were deposited far offshore (over 100km) during times of lowered sea level when the sands high up on the shelf were deeply gouged and canyon systems shed huge volumes of the sands out across the shelf and down slope into the basin.

8 Play Types North Mid Cretaceous Fan Play Analogue: Jubilee Field (Tullow, Ghana) Tertiary Channel Play Analogue: Marlim Complex (Campos Basin, Brazil) 1,500 5,000 ft South Loligo, Nimrod, Vinson x Toroa Hero, Scotia Springhill Play Analogue: Carina (Magallanes Basin, Argentina) Darwin Inflexible Stebbing Undine Schematic cross section through Licence area There are 3 main plays in the FOGL licences. 1) the Springhill Sandstone play proven at Toroa - traps most of the hydrocarbons in the Argentine Magallanes Basin. These tend to be shoreface sands developed along the basin margin. 2) The Mid Cretaceous Fan Play. Recent successes in Ghana and French Guiana have highlighted the potential of this play. 3) The Tertiary Channel play that is uniquely developed in the East Falklands Basin. Similar deepwater plays work on the Brazilian and West African Atlantic margins. Oil and gas is generated from source rocks organic rich shales. Once these have been heated (buried) to about 100 o C (3-4km) oil and gas forms, is expelled and may then migrate into sandstone reservoirs in one of the plays.

9 The Springhill Fault Block Play Areas of Development in the East Falklands Basin Hersilia Fan Area

10 Inflexible Prospect Springhill Play Inflexible is a large well defined tilted fault block along strike from the B&S Darwin prospect Inflexible has mean prospective resources of 253 million bbls A site survey was completed in 2011 Reservoir potential upgraded by Toroa well (mid Cretaceous possible plus Springhill) DARWIN Other fault blocks have been mapped locally Larger tilted fault blocks are present in the northern Licences - Endeavour Darwin Structure (well projected) Inflexible Along Strike from Darwin Loligo Squid

11 Mid Cretaceous Basin Floor Fans Areas of Development in the East Falklands Basin Hersilia Fan Area

12 Jubilee Analogue: Ghana Scotia/Jubilee Shelf By passed slope Basin Floor Fan Jubilee is a mid Cretaceous fan formed at the base of slope like Scotia Jubilee source and reservoir Cretaceous like Scotia are mid Close proximity lowers play risk Scotia sits below the regional seal Jubilee has a Class II AVO response Like Scotia Updip Pinchout Jubilee/Scotia There are numerous follow on prospects along the West African margin in the play just as there are several mapped similar targets to Scotia (Hero, Challenger, Quest)

13 Tertiary Channel Play Areas of Development in the East Falkland Basin The Tertiary Channel Play is widespread in the basin but is not present at the Toroa well location. The best prospects within the play lie in the northern Licences (Loligo Complex, Nimrod, Vinson West).

14 Loligo Location Above Old Basin High The map illustrates the thickness of sediment in the two sub-basins at about 140 millions years ago (the Valanginian). Two sub basins clearly exist separated by a large intra basin high. This is called the Berkeley Arch. Later, about 80 million years ago, deposition of the Tertiary Channel sequence commenced. Sands within the Loligo complex were deposited directly above the old high.

15 Loligo This seismic section through the massive Loligo prospect shows the oil migration pathway from the adjacent basins, the probable vertical migration and the large seismic amplitude (bright) that is associated with feature. The inset maps illustrates brightness of the seismic event when compared to the surrounding area.

16 Loligo AVO Class III Amplitude Brightens with Offset Near Amplitudes Far Amplitudes AVO Response Summary Moderate Bright Loligo AVO Dim Moderate Loligo at T1 Dim V Bright Loligo at T1 Simple Gulf of Mexico style Class III moderately bright on near offset, very bright on far offset Map shows seismic amplitudes from the upper part of the target zone- near and far offset response Near Stack Far Stack Seismic shows near and far offset in the upper target zone

17 Loligo NW 2635m The Loligo Complex (see inset map) is formed by the vertical stacking of several different prospects. The sands that form the stacked targets were shed from different parts of the basin at different times. Towards the south east end of Loligo a single, carefully located well may penetrate more than one prospect. The benefits of a single deep well on Loligo versus a more optimally placed shallower well are under consideration.

18 Play Openers Loligo Prospect Hopper FOGL Prospects Play Licence Area Pmean Prospective Resources Loligo Tertiary Channel Northern 4700 Nimrod Tertiary Channel Northern 1500 Scotia? Vinson Tertiary Channel Northern 733 Scotia Mid Cretaceous Northern 1062 Hero Mid Cretaceous Northern 1071 Darwin (B&S) Quest Mid Cretaceous Northern 1400 Inflexible Springhill Southern 253 Lutra Springhill Southern 900 Stebbing B&S) Endeavour Springhill Northern 400 Undine Fold Belt Southern 300 Four wells are scheduled to be drilled in 2012 in the East Falklands Basin. The first 2 wells will be drilled by Borders and Southern Petroleum. These wells will target the Darwin and Stebbing prospects. FOGL has decided not to drill a look alike prospect (Inflexible) at this stage of exploration but will monitor the drilling closely. The same applies to Stebbing which will be drilled in the fold belt. FOGL have not focussed on this play but it is present in the south of the FOGL licences. FOGL will be targeting the Tertiary Channel Play at Loligo. If this is successful more wells on Loligo like targets may follow. In the event of failure, the mid Cretaceous would be the main focus of exploration. FOGL has mapped several large prospects, which havebeensitesurveyedand could be drilled in 2012 in the Tertiary, Mid Cretaceous and Springhill plays. FOGL is well prepared for the 2012 exploration programme.