Exploration discoveries

	Vol. 228 No. 7
ARTHUR BERMAN, CONTRIBUTING EDITOR, bermanae@gmail.com

In addition to the Bohai Bay discovery discussed on the previous page, a major gas field was discovered in Sichuan province, southwest China. According to officials in Dazhou, a cumulative 134 Tcf (3.8 Tcm) of gas has been found in the western part of the Sichuan basin, of which 49.4 Tcf (1.4 Tcm) were found in 2007. (The exact timeframe this amount was discovered is unclear.) Included in the above amount is 8.6 Tcf (244 Bcm) of newly-discovered, proven exploitable reserves, plus an already-announced 12.6 Tcf (356 Bcm) in Puguang gas field.

Fig. 1. Four China basins produced discoveries.

There were two other recent discoveries in China. One is a 1.1 Tcf (30 Bcm) gas field discovered in Karamay, the Junggar basin, Xingiang Uygur Autonomous Region; the other discovery is in the Tarim basin, where Sinopec discovered oil in Block 12, at Tahe, with original oil-in-place geological reserves of up to 1.58 Bboe (200 million t of oil equivalent). Tahe field is the third major oil and gas discovery China has announced this year.

BP made an oil and gas discovery with its Gulf of Mexico Isabela-1 exploration well. It was drilled in 6,500 ft of water, 150 mi southeast of New Orleans in Mississippi Canyon Block 562. The well reached a 19,100-ft TD in Miocene sands. BP operates with 67% interest, while partner Noble Energy has a 33% interest, Fig. 2.

Fig. 2. Two discoveries were announced in the Gulf of Mexico’s deepwater trend.

Marathon Oil Corp. completed the appraisal well on the previously announced Droshky discovery in Gulf of Mexico Green Canyon Block 244. Droshky is in 2,900 ft of water, 137 mi south-southwest of Venice, Louisiana. Marathon estimates the field holds 80–90 million boe of mean recoverable resource.

Statoil discovered oil in the Ermintrude prospect in the North Sea. The well was drilled in 114 m of water to a 3,850-m TD in Block 15/6-9 S, some 10 km north of Sleipner. The discovery is estimated to hold 50 million bbl of recoverable light oil reserves. The well reached TD in Triassic age rocks and produced from Jurassic age sandstones. Gas was also produced from Tertiary sandstones. Statoil is operator with 100% interest.

Korea National Oil Corp. announced an oilfield discovery off Russia’s Kamchatka Peninsula. A KNOC spokesman said the reserves could be more than 10 Bbbl of oil. The South Korean consortium led by KNOC has a 40% interest, while Rosneft has 60% interest.

BP Exploration Angola discovered oil offshore Angola in Block 31. The Cordelia project is in 7,573 ft of water, 99 mi from shore. The well was drilled to a 13,337-ft TD and was flow tested at an operationally restricted rate of 2,063 bopd through a 20/64-in. choke. BP Exploration Angola operates Block 31 with partners Sonangol, Esso Exploration and Production Angola and Marathon International Petroleum.

Marathon participated with operator Total in two discoveries back in May on Angola Block 32. The Louro Well-1 discovery is in 6,178 ft of water, 103 mi off the Angolan coast. It was drilled to a 16,136-ft TD and found Miocene and Oligocene reservoirs. The nearby Cominhos Well-1 discovery is in 5,227 ft of water. It was drilled to a 14,751-ft TD into Oligocene reservoirs. The well flowed 6,258 bopd of 32° API gravity.

Pioneer Natural Resources Co. made a discovery in the Shaheen-1 well on Jenein Nord Block in Tunisia. PNR operates the well with 50% interest; ETAP participation is also 50% interest. Daily gross production was about 8,000 boe from multiple zones. The company has drilled four wells for four discoveries in the block. The four wells have been tested at about 30,000 boe per day, a combined multi-zone rate yielding 85% oil and 15% gas, Fig. 3.

Fig. 1. Pioneer made a significant discovery in Tunisia.

Petrolifera Petroleum discovered oil in Well RN.RR.x-1001, a 1,000-m field confirmation test in Rinconada Block. This block is part of the Puesto Morales/Rinconada onshore concession in the Neuquen basin, Argentina. The well flowed 690 bpd of light oil through a 16-mm choke from the Sierras Blancas Formation.

Petrohawk Energy Corp., Houston, set production casing at 16,001 ft the 1-Clark 4-4 well in 4-8n-6w, Wayne County, Mississippi, in a Jurassic Smackover oil and gas play in the Mississippi Salt basin. Petrohawk cased to the first three wells drilled on trend in the last half of 2006, went online in February. Board of Education 16-11, Board of Education 16-14, and  Clark 4-5 flowed an initial, cumulative 2,166 bopd and 3.0 MMcfgd.    

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.