Element | Natural gas/weight% | Crude oil/weight% | Bitumen/weight% |
---|---|---|---|
carbon | 65.0-80.0 | 85.0 | 80.2 |
hydrogen | 20.0-25.0 | 12.0 | 7.5 |
oxygen | trace | >2.0 | 7.6 |
nitrogen | 1.0-15.0 | >1.5 | 1.7 |
sulphur | >0.2 | >3.0 | 3.0 |
What kind of sediments are likely to form under such quiet conditions?
Kerogen type | H:C ratio | O:C ratio | Origin of organic material | Petroleum products |
---|---|---|---|---|
Type I | 1.7-0.3 | 0.1-0.02 | Algae in lacustrine and/or lagoonal environments | Light, high-quality oil and some natural gas |
Type II | 1.4-0.3 | 0.2-0.02 | Mixture of plant debris and marine microorganisms | Main source of crude oil and some natural gas |
Type III | 1.0-0.3 | 0.4-0.02 | Land plants in coaly sediments | Mainly natural gas with very little oil |
Type IV | 0.45-0.3 | 0.3-0.02 | Oxidised and charred wood | No petroleum potential |
Using the information in Table 2 , can you suggest what kerogen type characterises the Kimmeridge Clay?
Look at Figure 1 and estimate the subsurface temperature and depth at which peak oil generation is achieved.
Which sedimentary rock type is most likely to be a potential reservoir rock?
Field | Age/Formation | Reservoir | Net to gross/% | Porosity/% | Permeability/mD | Fluid |
---|---|---|---|---|---|---|
Alwyn North | Jurassic/Brent | sandstone | 87 | 17 | 500-800 | oil |
Alwyn North | Jurassic/Statfjord | sandstone | 65 | 14 | 330 | oil |
Auk | Permian/Zechstein | fractured dolomite | 100 | 13 | 53 | oil |
Auk | Permian/Rotliegend | sandstone | 85 | 19 | 5 | oil |
Brae South | Jurassic/Brae | sandstone | 75 | 12 | 130 | oil |
Britannia | Cretaceous/Britannia | sandstone | 30 | 15 | 60 | gas in liquid form under high pressures |
Buchan | Devonian/Old Red | fractured sandstone | 82 | 9 | 38 | oil |
Cleeton | Permian/Rotliegend | sandstone | 95 | 18 | 95 | gas |
Cyrus | Palaeocene/Andrew | sandstone | 90 | 20 | 200 | oil |
Ekofisk | Cretaceous/Chalk | limestone(fractured Chalk) | 64 | 32 | >150 | oil |
Ekofisk | Cretaceous/Chalk | limestone (Chalk) | 62 | 30 | 2 | oil and gas |
Forties | Palaeocene/Forties | sandstone | 65 | 27 | 30-4000 | oil |
Fulmar | Jurassic/Fulmar | sandstone | 94 | 23 | 500 | oil |
Frigg | Eocene/Frigg | sandstone | 95 | 29 | 1500 | Gas |
Heather | Jurassic/Brent | sandstone | 54 | 10 | 20 | Oil |
Leman | Permian/Rotliegend | sandstone | 100 | 13 | 0.5-15 | gas |
Piper | Jurassic/Piper | sandstone | 80 | 24 | 4000 | oil |
Ravenspurn South | Permian/Rotliegend | sandstone | 39-77 | 13 | 55 | gas |
South Morecambe | Triassic/Ormskirk | sandstone | 79 | 14 | 150 | gas |
Scapa | Cretaceous/Valhall | sandstone | — | 18 | 111 | oil |
Staffa | Jurassic/Brent | sandstone | 76 | 10 | 10-100 | oil |
West Sole | Permian/Rotliegend | sandstone | 75 | 12 | — | gas |
Suggest another type of trap on Figure 4 that might experience such leakage.
What would happen to seismic waves if there was a strongly reflective layer, such as an igneous sill or salt body, in the shallow subsurface?
Look at the 2-D seismic section in Figure 8. Even though it was produced to explore for coal seams it contains lots of information that might help the petroleum explorationist. What kinds of trap shown in Figure 4 might be present in that section?
What type of rig would be used to drill in the Amazonian rainforest and what preparation would be required before drilling commenced?
Imagine that you are the Managing Director of Spoof Oil, a small, entrepreneurial company that owns a 100 million barrel oil field with a primary recovery of 25%. Studies indicate that an alternating water and gas injection scheme would cost $80 million to install, but would increase recovery to 45%. Would you make the investment if forecasts of future oil prices are likely to remain above $30 per barrel?
Deep-sea disposal | On-shore dismantling |
---|---|
Tow the Brent Spar to the North Atlantic. | Tow the Brent Spar into a deep harbour. |
Use explosives to sink the platform in deep water. | Decontaminate the structure. |
Allow the structure to settle on the sea bed. | Dismantle and reuse the materials. |
Recognise that there will be local pollution for 12-14 months. | Dispose contaminants safely onshore. |
Technically the easiest option. | Technically complex and with a greater hazard to the workforce. |
Cost estimate about £10 million. | Cost estimate about £40 million. |
In recent years a virgin basin to the north of the Falkland Islands in the southern Atlantic has begun to be evaluated, and several exploration wells have been drilled. Media reports (and some oil companies) claim that more than 5 billion barrels of oil will be discovered here in due course. How would you assess the validity of their claim?
'We usually find oil in new places with old ideas. Sometimes, also, we find oil in an old place with a new idea, but we seldom find oil in an old place with an old idea. Several times in the past we thought we were running out of oil whereas we were only running out of ideas.' (Parke A. Dickey)
The estimated quantities of petroleum which geological and engineering data demonstrate with reasonable certainty to be recoverable in future years from known reservoirs under current economic and operating conditions.
Region | Reserves/109 toe | Share/% | R/P ratio/years |
---|---|---|---|
Middle East | 99.8 | 61.7 | 82 |
Europe and Eurasia | 18.9 | 11.7 | 22 |
Africa | 15.3 | 9.4 | 33 |
South and Central America | 13.8 | 8.5 | 41 |
North America | 8.3 | 5.1 | 12 |
South Asia and Pacific | 5.6 | 3.5 | 14 |
Global total | 161.6 | 100.0 | 40 |
Region | Reserves/1012 m3 | Share/% | R/P ratio/years |
---|---|---|---|
Middle East | 72.83 | 40.6 | >100 |
Europe and Eurasia | 64.02 | 35.7 | 61 |
South Asia and Pacific | 14.21 | 7.9 | 44 |
Africa | 14.06 | 7.8 | 97 |
North America | 7.32 | 4.1 | 10 |
South and Central America | 7.10 | 4.0 | 55 |
Global total | 179.53 | 100.0 | 67 |
What difference would a decade of consistently high oil prices make to the North Sea fields?