Special Report: Remote, underexplored basins still objects of exploration

Aug. 24, 2009
Exploration has persisted in some of the world's remote and underexplored basins even in the face of weak oil prices at half or less than their level of a year ago.

Exploration has persisted in some of the world's remote and underexplored basins even in the face of weak oil prices at half or less than their level of a year ago.

Discoveries have also resulted as operators work to minimize the time elapsed between obtaining acreage and deriving revenue from hydrocarbons discovered, produced, and sold.

The Russian-owned Deep Venture drillship handled the drilling of the Kunene-1 exploratory well for the Sintezneftegaz group on Block 1711 in the Atlantic off Namibia. Photo by Jeff Greenblum, courtesy of EnerGulf Resources Inc.

This article describes exploration projects in the Namibe basin off Namibia, the Flamingo Trough between Australia and Timor-Leste, several basins off southwestern Greenland, the Pelagian basin in the Mediterranean off Tunisia and Italy, the Mediterranean off Libya, and a remote area of the Western Canada Sedimentary basin in east-central Saskatchewan.

Namibe basin, Namibia

At least 6 months of data integration lie ahead for a group that made what appears to be a giant gas-condensate discovery off northernmost Namibia (Fig. 1).

Reservoir quality appears to be poor at the Kunene-1 discovery, but with only a single wellbore the group hopes that formation characteristics improve beyond the local area.

More drilling will be required to answer the question, but the group released the Deep Venture drillship, formerly Valentin Shushan.

Namibia's Ministry of Mines and Energy released a statement saying that the Kunene-1 exploratory well in the Namibe basin "could contain a potential gas resource of up to 14 tcf."

Sintezneftegaz of Moscow operated the well, and a Moscow subsidiary of Schlumberger Ltd. that ran the tests and analyzed the results attributed the resource to an interval at 4,698-4,748 m, the ministry said. TD is 5,052 m.

EnerGulf Resources Inc., Vancouver, BC, the only public company in the well, elected not to participate in the tests. EnerGulf, with 10% interest in 960,000-acre Block 1711, said it did not receive a copy of the Schlumberger unit's report and has not verified the potential resource. EnerGulf said the resource "may not be compliant with NI 51-101."

EnerGulf said the joint operating agreement allows it to reinstate its pro-rata rights in a commercial discovery in the interval that was tested by paying twice its share of the test's costs. The company had previously said the well, the first on the block, demonstrated the presence of hydrocarbons but probably will not be a commercial producer (OGJ, Aug. 18, 2008, p. 46).

The 6 months of analysis will involve integrating information from cuttings, well logs, and core samples and calibrating it to 3D seismic data, said Jeff Greenblum, chairman and chief executive officer of Energulf.

Other interests in the block are Sintezneftegaz 70%, PetroSA 10%, and Namibia's state Namcor 7% carried.

Vanco Energy Co., Houston, originally shot 2,000 km of 2D seismic and 685 sq km of 3D seismic on the block before relinquishing its interests.

The ministry said, "Seismic reinterpretation and reprocessing over the Kunene and Hartmann prospects have demonstrated that both these structures can be correlated with the Apto-Albian sediments of the South West African margin.

"There were gas shows in the Albian and Aptian sediments, confirmed by wireline logging. It was not possible to fully evaluate the hydrocarbon potential of the penetrated section due to operational problems during testing. However, seismic interpretation suggests that alteration of the sediments by igneous activity may be localized to an area near the borehole, and therefore both the tested zones and some untested zones have great potential."

EnerGulf said it looks forward to continuing the exploration program on the remote block, 800 miles northwest of Kudu gas field and several hundred miles south of the nearest production off Angola.

Saskatchewan, Canada

Hunt Oil Co., private Dallas independent, and Nordic Oil & Gas Ltd., Winnipeg, Man., signed a strategic development agreement regarding gas exploration in east-central Saskatchewan.

Nordic didn't discuss specifics of the geology but has previously said that its lands, on the northeast flank of the Western Canada Sedimentary basin, have gas and oil potential in at least 10 formations from the Second White Specs to the Winnipegosis sand. The area has no oil or gas production.

Nordic will have the opportunity to earn an interest in 153,600 acres of Hunt-owned land at Preeceville, 130 miles northeast of Regina, Sask. The ensuing exploration work on the lands will result in Hunt having the option to participate on a 50-50 go-forward basis with Nordic, or allow Nordic to retain a 100% interest in the land with Hunt earning a gross overriding royalty.

Hunt's acreage lies a few miles southeast of lands held by Nordic, where survey work has begun for a five-well program. Drilling is to start in September 2009. Nordic has an 80% interest in 137,780 acres.

Flamingo Trough, Timor Sea

A two-well exploration program could start as soon as late 2009 subject to rig availability on Block JPDA 06-103 in the Timor Sea between northwestern Australia and Timor-Leste.

Japan Energy Corp. took a farmout from Oilex Ltd., Perth, to earn an interest in the large Block JPDA 06-103 production sharing contract. Oilex will remain operator of the PSC.

The block is replete with large structures off the northeast flank of oil fields in the Flamingo Trough (see map, OGJ, Apr. 27, 2009, p. 39).

Interpretation of 2,140 sq km of 3D seismic over the central two-thirds Block 06-103 identified more than 20 prospects and leads. Four of the prospects are in less than 470 m of water.

The first two targets and their mean prospective resources are Lore at 195 million bbl and Lolotoe at 90 million bbl.

Oilex noted that the area's prospectivity is implied by the discovery of Kitan oil field by Eni SPA, for which a development plan has been submitted, and the Kuda Tasi and Jahal discoveries north of Kitan, Laminaria and Corallina fields to the west, and Bayu-Undan field to the south.

Kitan-1 flowed 6,100 b/d of oil on test. TD is 3,568 m. It is on Block 06-105 held by Eni 40%, Inpex of Japan 35%, and Talisman Resources Pty. Ltd. 25% (OGJ, Mar. 17, 2008, Newsletter). Kitan-2, 1.6 km east, went to TD 3,540 m. Early estimates are that 30-40 million bbl of oil are recoverable from Kitan.

Eni's proposed development area encompasses Kitan field and a satellite closure, Kitan South, 1.5 to 2 km south. A development plan calls for producing three wells through an FPSO and possibly tieing in the 1996 Jahal and 2001 Kuda Tasi marginal discoveries (OGJ Online, July 23, 2008). Jahal and Kuda Tasi hold a combined 10 million bbl recoverable.

Oilex's agreement with Japan Energy is conditioned on the JPDA Designated Authority extending the contract which ends in January 2010 and approval by the authority and other participants who have preemption rights of the transfer of interest to Japan Energy.

After the conditions are satisfied, interests will be Oilex (JPDA 06-103) Ltd., operator, 10%, Global Energy Inc., GSPC (JPDA) Ltd., and Bharat PetroResources JPDA Ltd. 25% each, and Japan Energy E&P JPDA Pty. Ltd. 15%.

West Greenland basins

With only seven wells drilled, most of them in the 1970s, underexplored western Greenland has begun to attract exploration companies as deepwater drilling technology has emerged.

Cairn Energy PLC, Edinburgh, said, "The results of these wells, together with more recent onshore geological mapping over the past 15 years, have confirmed the presence of all the essential elements required for the generation and trapping of hydrocarbons."

The Bureau of Mineral Resources points out that two breakthroughs in the late 1980s and early 1990s changed industry's appreciation of the area's hydrocarbon prospectivity.

One was the realization that prospective sedimentary basins are much larger than was believed through the 1970s. The other was the discovery of extensive oil seeps in the onshore Nuussuaq basin, whereas the area had been interpreted previously as being gas prone.

"Modern understanding suggests that the sedimentary basins offshore southern and central West Greenland cover an area of more than 200,000 sq km, which is larger than the combined Viking Central graben system of the North Sea," BMR said.

As of mid-2009, Greenland had granted 13 oil and gas licenses that cover a combined 130,000 sq km, and a record of more than 30,000 line-km of 2D seismic was shot in the summer of 2008. Controlled source electromagnetic surveys have also been run on several blocks.

Each of the 13 licensed blocks covers 10,000 to 13,000 sq km (Fig. 2). The seven northernmost blocks lie above the Arctic Circle.

The blocks off western Greenland lie 900-1,600 miles north of nearest oil production on the Grand Banks off Newfoundland, although an estimated 2.3 tcf of gas-condensate was discovered in Paleocene sands as close as 300 miles west at the Hekja O-71 well in 1979-80 in Canadian waters off the south end of Baffin Island (OGJ, July 12, 1982, p. 145). Hekja has not been developed.

The Atammik and Lady Franklin blocks are EnCana Corp.'s only exploration interests outside North America.

Cairn Energy PLC said its Capricorn Energy Ltd. subsidiary plans its first operated exploratory drilling off southwestern Greenland in 2011. The eight blocks in which Capricorn's interests total 72,000 sq km in 50-2,200 m of water.

Cairn shot 7,130 line-km of 2D seismic in 2008 on the Sigguk and Eqqua blocks, which cover 23,024 sq km in the Baffin Bay basin in 260 m to more than 1,000 m of water, and planned in 2009 to survey a conceptual pipeline route from Sigguk to a peninsula just north of Disko Island.

About 3,000 line-km of 2D seismic were to be shot on the four blocks in the Cape Farewell region off southernmost western Greenland in 2009 following the 2,000 line-km taken in 2008. An aerogravity and magnetic survey that began in 2008 was to be finished in mid-2009.

A planned government licensing round in 2010 is to cover eastern Baffin Bay from north of the Sigguk block as far north as 75° N. Lat., near Kap York and Thule Air Base in Greenland east of Ellesmere in the Arctic Islands of Nunavut off Canada. A planned round in 2012 extends along the East Greenland coast at similar latitudes.

Tunisia-Italy offshore

AuDAX Resources Ltd., Perth, invited 15 drilling contractors to bid to drill the Sambuca prospect in the Sicily Channel off Tunisia in the first half of 2010 using a semisubmersible rig.

Sambuca is in the contiguous G.R15.PU exploration permit northwest of Pantelleria Island off Italy and the Kerkouane permit off Tunisia. It appears to be one of the largest undrilled structures in the Mediterranean Sea with a mean unrisked potential of 270 million boe recoverable.

The prospect covers 60 sq km in 400 m of water in the Pelagian basin north of Tazerka oil and gas field. Main objective is the Miocene Birsa sandstone at 1,440 m, and other targets are Miocene Ain Grab and Cretaceous Abiod as deep as 2,500 m.

Libya offshore

Operators have drilled two wells on Gulf of Sirte blocks acquired in Libyan licensing rounds.

A group led by the Braspetro BV international unit of Brazil's Petroleo Brasileiro SA spudded the A1-18/01 well in Area 18 about 75 miles east-northeast of Tripoli in late May 2009 using the Songa Saturn drillship (Fig. 3).

The wildcat was designed to test the Caliph 3D seismic prospect that has several geological objectives to its planned total depth of 4,700 m. The license, which was awarded in 2005 and expires in 2010, is in 300-700 m of water.

In early August, partner Oil Search Ltd., Sydney, said drillers were running in the hole to drill ahead in sidetrack No. 2 from a depth of 2,603 m after having encountered hole problems in a first sidetrack.

Besides proven oil plays in Eocene and Cretaceous carbonates, the well targets new gas plays in Jurassic and Triassic clastics.

A second large lead is being worked up on reprocessed seismic and could form the basis for a second well, Oil Search said.

Block interests are Braspetro 70% and Oil Search (Libya) Ltd. 30%.

Meanwhile, ExxonMobil Exploration Co.'s Libyan affiliate spud a deepwater exploration well off Libya in late July.

The A1-20/3 well is being drilled in Contract Area 20 in the Sirte basin in the Mediterranean northeast of Misrata, Libya.

ExxonMobil Libya Ltd. didn't give the water depth or projected depth of the well. It is using Noble Africa Ltd.'s Noble Homer Ferrington semisubmersible capable of drilling to 30,000 ft in as much as 7,200 ft of water.

Elsewhere in Libya, the subsidiary has completed two 3D seismic surveys in offshore Contract Areas 20 and 21 and three 2D seismic surveys in offshore Contract Areas 44, 20, and 21.

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