Geographical frontiers

Petrobras is planning to invest $174bn (£105bn) between 2009 and 2013, of which $105bn will be spent on exploration and production. Much of this will be applied to the pre-salt basins, which though vast are highly challenging: complex reservoirs buried beneath deep water and a thick, seismic-blurring salt layer.

This year has proved quiet and saw some dry holes drilled, but next year promises to refocus attention on Brazil. A new licensing round and new legislation are expected to be accompanied by drilling taking off in the Campos basin, which could yield yet more large pre-salt discoveries.

Leading pioneers: Petrobras and BG.

West Africa

The scale of the Brazilian Santos basin discoveries led geologists to search for pre-salt analogues on the opposite side of the Atlantic. The theory is that South America and Africa were once joined as part of a super-continent, and a geological feature such as oil found on the east coast of Brazil has a high chance of being replicated on the west coast of Africa. Explorers are evaluating the pre-salt potential of Angola, which has a thinner salt layer compared with Brazil but hasn't yet demonstrated the scale of the Brazilian basins.

Further north, the Jubilee field offshore Ghana, in which Tullow Oil and Anadarko have interests, could hold up to 1.8bn barrels of oil. The two partners recently discovered more oil in a comparable structure offshore Sierra Leone, which hints at a new oil province that could stretch across 1,100km from Ghana to Sierra Leone (also encompassing Ivory Coast and Liberia), and which could hold multiple Jubilee-scale discoveries.

Leading pioneers: Anadarko and Tullow Oil.

Deepwater Gulf of Mexico

BP has enjoyed considerable success in the US Gulf of Mexico, where it is the largest oil and gas producer and has demonstrated an ability to develop large, deep discoveries. The Thunder Horse field it operates is expected to become the largest field in the region and is one of the key discoveries upon which the group is pinning its production growth ambitions. Producing from some of the deepest wells in the region, Thunder Horse's success also bodes well for BP's prospects of commercialising its even deeper Tiber discovery.

Leading pioneers: BP, ExxonMobil and ConocoPhillips.

Kurdistan

Iraq's production has seldom matched the potential of its vast reserves (estimated to be the world's second largest). Even restoring production to pre-Gulf War levels is proving a challenge and Iraq's first licensing attempt in June failed as all but one bidder rejected the oil ministry's tough terms.

In contrast, while Baghdad has struggled to grow southern production, the Kurdistan Regional Government (KRG) in the north of Iraq has licensed operators to discover, produce and sell oil. With IOCs not wanting to be blacklisted by Baghdad for doing business with the KRG, the field has been opened to smaller players such as Gulf Keystone. This Aim-traded minnow's Shaikan-1 well is one of the most successful exploration wells drilled this year, having found a mean 2.8bn barrels of oil without having yet reached its ultimate target depth.

Leading pioneers: Heritage Oil and Gulf Keystone.

Arctic Circle

The US Geological Survey (USGS) describes the Arctic continental shelves as potentially constituting the "geographically largest unexplored prospective area for petroleum remaining on Earth". It estimates that the undiscovered oil and gas lying within the Arctic Circle may exceed 90bn barrels of oil, 1,669 trillion cubic feet of natural gas and 44bn barrels of natural gas liquids.

Exploration of several onshore areas in Canada, Russia and Alaska has already discovered over 400 oil and gas fields north of the Arctic Circle. USGS highlights the most prospective regions as including Greenland and the Barents Sea, where recent licensing rounds have attracted substantial interest.

Cairn Energy is a leading acreage holder in Greenland, with interests in eight licences. A recent farm-out deal with Petronas gives Cairn additional cash and a partner, and it plans to drill its first well in 2011. Faroe Petroleum, which has recently enjoyed exploration success in the West of Shetland Atlantic Margin, holds a prospective block in the Barents Sea that it plans to drill in 2012.

Leading pioneers: Cairn Energy and ExxonMobil.

Falkland Islands

Explorers are expected to drill in the Falkland Islands in early 2010 – the first attempts in a decade to exploit the huge oil and gas reservoirs believed to lie beneath the frontier waters of this remote and very lightly explored region.

The North Falkland basin and South Falkland basin are distinct areas with very different characteristics. In the North basin (where Desire Petroleum and Rockhopper Exploration are active), targets of 150m-500m barrels of oil lie beneath water depths of 100m-600m. In the South basin (where Falkland Oil & Gas and Borders & Southern are active), targets of 1,000m-3,000m barrels of oil compensate for more challenging conditions lying beneath 500m-1,200m of water.

Rockhopper etched the Falklands firmly in investors’ minds this summer when it re-interpreted a former Shell well as a gas discovery, but it was not until Desire Petroleum announced in September that it had secured a drilling rig that Falklands’ exploration finally started to look a reality.

The rig should arrive in the Falklands next February, with a commitment to drill at least four wells with options for a further six. Desire raised £42m to let it take up drilling options and Rockhopper raised £50m to finance the drilling of two prospects with combined best estimate resources of 326m barrels.

Given their remoteness, any Falklands discoveries will need to be very large to prove this a valuable new hydrocarbons province. However, this distant drilling in early 2010 could herald a hugely exciting year for the oil explorers.

Leading pioneers: Desire Petroleum, Rockhopper Exploration.

Undiscovered oil and gas resources

Exploration wells to watch