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North Sea

Oonagh Werngren, but with a lot of prospectivity for areas and improve exploration well is also operations director at Oil & Gas

Petroleum Exploration the future. The Hebrides and Forth performance. UK and is responsible for running ? ve

Society for Great

Approaches basins are both under

In addition to the ETF’s work, the different PILOT workstreams dedicated

Britain president and

Department of Energy and Climate to maximizing recovery from the UKCS, explored.

operations director

Change (DECC), the Natural Environment including the ETF. “The northern North Sea and at industry body Oil

Research Council (NERC), and industry “Although the central North Sea has southern North Sea are two of the & Gas UK. Photo from Oil body Oil & Gas UK also sponsored a been developed, there are still signi? cant oldest basins and were explored & Gas UK.

very quickly and major ? elds cross-industry scoping study by SLR resources to be developed, including put online. The upside might

Consulting. The study’s aim was to high-pressure, high-temperature (HPHT), st be more limited, but that isn’t to say assess how to produce an online, 21 and the western margin of the platform. UK’s subsurface manager Andy Spencer. century exploration road map to the That area offers the greatest potential there are not plays to be developed going Typically, reservoirs have been exploited

UKCS to aid in providing a better under- for the next tranche of developments, deeper.” at 8-11,000ft in the Southern Gas basin. standing of its resources. because there is a lot of ullage available Some areas are already opening, such GDF SUEZ is now looking at the poten-

The impetus to improve exploration in the existing infrastructure and a lot of as the Carboniferous. It has lower calo- tial for going deeper.

performance is strong—if new discover- interest in drilling in that area. ri? c-value gas than the already produced The reasons why some of these areas ies are not made soon, current infra- “West of Shetland is the least mature Permian gas, and earlier drill stem tests have not been fully explored vary. For area, with limited existing infrastructure, structure will be removed, limiting the on it did not ? ow. “Now we have a better the northern part of the gas basin, it was economic chances of future discoveries, understanding of the geology, the lower calori? c-value gas, challeng-

Oil & Gas UK and Petroleum Exploration the zones that have permeability, ing reservoir quality and higher costs

Society for Great Britain president and where it offers the greatest associated with drilling hazards in the

Oonagh Werngren warned. production,” Werngren says. As Zechstein salt. Spencer says improved “We have been exploring here for 50 a result, a whole new play in the seismic imaging from modern 3D surveys years, but there are vast differences in northern margin of the southern will play a key role in identifying new understanding between the different North Sea has been opened up. opportunities which were not seen on the basins,” says Oonagh Werngren, who GDF SUEZ E&P UK has existing 20 year old datasets.

explored the Southern basin In the fractured basement, the issue is

Carboniferous with success and is about technology, around well comple- now developing Cygnus, a signi? - tions, and also the depth of such reser- cant four-platform development, voirs, Werngren says. “The basement as a result. “Our view is that the rock itself has very low permeability,

Carboniferous has got a lot more so it is also around our understanding to give,” says GDF SUEZ E&P of the additional permeability you can get through fractures. In some areas, it

The Alpha wellhead platform in is about the hardness of the rock and place in the Cygnus ? eld. Photo from GDF Suez E&P.

our ability to see through it, such as

New/underexplored plays on the UK Continental Shelf, outlined by Oil & Gas UK

One of the main challenges is to establish

West of Hebrides

Within the west of Hebrides area there are whether there is a viable petroleum system a number of known geologic provinces for other frontier areas including the Hatton that include the North and South Rockall basin and Hatton Continental Margin far- basins, Hatton basin, Rockall Plateau and ther to the west. Initial limited exploration of the Hatton Continental Margin. these basins has led to the identi? cation of potentially attractive tilted fault-block plays.

The Rockall basin is a major component

The presence and maturity of signi? cant of the rift system, which formed as a precur- source rocks remain to be proved.

sor to the present Atlantic Ocean. To date there is no conclusive proof of a pre-Creta- ceous extensional phase within the Rockall

Carboniferous beneath

Trough, which would provide the source rock

Central North Sea, East Irish Sea which is required for a working petroleum and Southern North Sea system to be in place. A viable but rather

Carboniferous reservoirs are usually laid local petroleum system has been proved down in deltaic (river delta) or ? uvial (river) for the Rockall basin: in the UK sector, the environments, formed from the precipita-

Benbecula well tested positive for gas while tion of calcium carbonate. To date, most in the Irish sector, tests of the Dooish well

Carboniferous traps rely on a closure, either established the presence of gas condensate. dip or fault bounded, at Top Carboniferous

However, there are vast areas with no wells but there is potential for exploration of and very sparse, low quality 2D seismic deeper traps. coverage that remain unexplored.

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