Exploration discoveries

	Vol. 228 No.8
ARTHUR BERMAN, CONTRIBUTING EDITOR, bermanae@gmail.com

Africa. Five major discoveries were made in Africa during June 2007, four offshore West Africa and one onshore Uganda, Fig. 1. Andadarko Petroleum announced the Mahogany-1 discovery in the Gulf of Guinea, offshore Ghana. The well was drilled in 4,330 ft of water on the deepwater West Cape Three Points Block in the Tano basin. Mahogany found an 885-ft oil column with about 312 ft of net pay in several stacked Cretaceous sandstone reservoirs. The well will be suspended at a TD of 13,780 ft for further evaluation and appraisal drilling. Anadarko and Kosmos Energy each have a 30.875% interest in the discovery. Tullow Oil has a 22.896% interest and Ghana National Petroleum will have a 10% working interest in the field development phase.

Noble Energy discovered gas with its Benita I-1 well on Block I, offshore Equatorial Guinea in the Gulf of Guinea, southeast of the Mahogany discovery. The well found 135 ft of net pay in high-quality Miocene reservoir sandstones. Noble tested 1,038 bcpd and 34.3 MMcfd from the I-1 discovery, which is located in 2,880 ft of water about 13 mi east of Bioko Island.

The Benita discovery is 13 mi south of the company’s Belinda discovery, located in Block O, announced in late 2005. Noble said that the Miocene reservoir section was considerably thicker at Benita than was encountered at Belinda, and that appraisal drilling will be necessary to determine the areal extent of the new field.

In the Douala basin offshore Cameroon, BowLeven tested commercial volumes of both gas and condensate in its D-1 well on Block MLHP5 in the Etinde Permit area. The well is located near Noble Energy’s Belinda discovery. D-1 tested 25 MMcfd of gas and 1,400 bcpd from 75 ft of Miocene turbidite sandstone reservoir pay. D-1 is the second successful well drilled by BowLeven offshore Cameroon.

Offshore Senegal, Hunt Oil, First Australian Resources and Societe; Petroliere du Senegal (Petrosen) have discovered heavy oil on the Sangomar-Rufisque Block. Few details were given, but a Senegal Ministry of Energy spokesman said that the discovery may have 1 billion bbl of oil, although it was not clear if this represents an in-place or recoverable volume.

Onshore Uganda, Tullow Oil discovered oil in its Nzizi-2 well in Block 2 of the Albertine basin on Lake Albert. The well was drilled to a TD of 3,281 ft. Tullow estimates recoverable reserves of 100-250 million bbl of oil. The company anticipates production of about 4,000 bopd by 2009. Tullow has 100% interest in the block.

South America. Enap announced a major natural gas discovery in the Magallanes area of Tierra del Fuego, southern offshore Chile, Fig. 2. The Palenque-1 exploration well tested 28.3 MMcfd of gas from three reservoirs at depths between 2,625 and 3,281 ft, about 87 mi north of Punta Arenas. The Palenque well is 5.6 mi from the company’s Baqueano-1 well, drilled last year, which Enap claims is capable of flowing 176 MMcfd of gas. Enap plans to drill about 50 wells in coming years to fully evaluate the resource potential of this remote area of Chile.

Elsewhere in South America, Petrobras discovered light oil in the Espiritu Santo basin offshore Brazil. The 4-ESS-175-ES exploratory well discovered deeper pays in the Pirambu field, after a drillstem test flowed rates of 1,250 bpd of oil in water depth of 4,167 ft.

Asia. Thailand’s national oil company, PTT Exploration & Production Public Co. Ltd. (PTTEP), discovered gas in June in the Zawtika-5 exploration well in Block M9, Gulf of Mataban region offshore Myanmar, Fig. 3. The well was drilled to an 8,291-ft TD and found net pay of 344 ft over seven zones and tested two zones at a combined flowrate of 71.5 MMcfd of gas. An appraisal, Kakonna-2, tested two zones for a combined flowrate of 53.8 MMcfd of gas. Six additional pay intervals were encountered for a total net pay of 154 ft. Proved reserves are projected to range 1.5-2.5 Tcf.

In Vietnam, the Lam Son Joint Operating Co. (PetroVietnam and Petronas Carigali) found oil offshore southern Vietnam on Block 02/97. The well reportedly flowed 4,700 bopd.

Elsewhere in Asia, in a rare find, Japan Petroleum Exploration (Japex) tested 4.4 MMcfd of gas and 286 bpd of oil offshore northwestern Japan.

Norway. Norske Shell announced estimated gas reserves for its Onyx Southwest field between 353 Bcf and 1.76 Tcf from Jurassic reservoirs. The field, discovered in 2005 in the Norwegian Sea, is located on Block 6406/9, 25 mi northwest of Draugen field in 981 ft of water.   

Arthur Berman is a geological consultant specializing in petroleum geology, seismic interpretation and database design and management. He has over 20 years working for major oil companies and was editor of the Houston Geological Society’s Bulletin. He earned an MS in geology from the Colorado School of Mines.