Deep find offshore Brazil leads list

Important Discoveries Hit in’07

2007 was a good year for discoveries, according to Ken White, senior editor of The IHS Energy International Oil Letter, with the Tupi 1 discoveryby Petrobras being a world-class discovery that will be talked about for decades.

Additionally, Africa continued to contribute to the list of important discoveries this past year, with an offshore Angola wildcat addition to the country’s portfolio of big producers.

And in Nicaragua a new field wildcat on the Oklanicsa Block in the Pacific Coastal Basin is being seen as having enormous potential.

Below is a list, provided by IHS Energy, of significant discoveries of’07.

Australasia

Australia – Thebe 1, a deepwater BHP-Billiton discovery, ranked as one of the largest in Australia this year. It is located just to the north of the Scarborough gas field and could provide much needed reserves to finally get that LNG project off the ground.

Australia – Drilled by Apache, Julimar-1 is significant as it proved up an area of the North Carnarvon Basin where subsequent follow-up drilling has led to a further discovery at Brunello, with more drilling planned in the area. Two of the four gas-bearing fluvial channel sands encountered in the well flowed a combined 85 MMcfg/d.

The block is surrounded by large gas discoveries, with Tryal Rocks West and John Brookes to the south and Pluto, Xena, Wheatstone and Iago to the north.

Australia – Prelude 1A was drilled in Shell’s WA-371-P license and proved up the extension of Inpex’s Ichthys Field into the block.

Having identified this potential, Shell put in a then-record breaking bid of 13 wells and work commitments that come to nearly US$100 million over six years.

CIS

Azerbaijan – BP finally completed Shah Deniz SDX 4 at a cost of around US$120 million, one of the most expensive wells ever drilled in the Caspian Sea. It tested over 35 MMcfg/d, and more than 2,300 b/d of condensate and discovered a new gas reservoir in the Pereryva suite.

Turkmenistan – North Nayip 1, drilled by Turkmengeologiya, is an important new pool discovery. Located north of the Nayip field which has three Lower Cretaceous clastic reservoirs, this new find has been successful in its objective Upper Jurassic carbonate play.

Testing is thought to be incomplete but results to date have produced 0.3 MMcfg/d from the Oxfordian-Kimmeridgian between 2,255-2,317m.

Turkmenistan – Yagtylyk 1 is showing some promise as an important well. To date five open hole tests have been run, of which the Hauterivian between 2,773-2,815m flowed 230,000 cfg/d.

The well has yet to reach planned total depth of 3,800 meters, and the best potential is thought to be in Upper Jurassic carbonates, as evidenced in the recent finds at Yuloten Gunorta and Osman.

Far East

China – Xin 2 and 3 provided further evidence that in the Sichuan Basin there is huge gas potential in the deep Xujiahe Formation, the evaluation of which only began in 2000. Xin 2 penetrated a 150-meter gas column in the Xujiahe 2 formation and tested 18 MMcfg/d, while Xin 3 flowed 8.2 MMcfg/d. Such is the potential of the area, Sinopec –Sichuan plans to drill five exploratory wells and eight outpost wells to further explore gas in the Deyan area of the west Sichuan basin during 2008.

China – Dabei 3 is considered significant, as the structure is located 20 kilometers east of the Dabei 1 Field, adding some certainty to the huge gas potential in the Kuche area. The Dabei 3 is drilling ahead in the Cretaceous.

The Dabei 1 Field was discovered in 1998, but it was not until 2006 that the company drilled the first outpost around three kilometers to the southeast of Dabei 1; this well also struck gas and condensate.

The reservoirs of the Dabei Field are Tertiary and Cretaceous sandstones, buried at depths of 5,700-5,800 meters, with porosities ranging from 4 to 9 percent. It is estimated to hold 3.5 Tcf of proven in-place gas and 5.3 Tcf of probable reserves.

The field is undergoing further appraisal.

India – The CY-III-D5-A1 (Dhirubhai 35) well, drilled by Reliance Industries, is ranked as the most significant discovery in India – one of nine finds the company made during 2007. This well is singled out because it is the first deepwater discovery in the Cauvery Basin. It encountered a clastic reservoir with a gross hydrocarbon column of around 150 meters in the Cretaceous. It yielded 31 MMcfg/d and 1,200 bc/d from the main zone while a deeper second horizon tested around 550 bo/d and 1 MMcfg/d.

Latin America

Brazil – The Tupi 1 well drilled by Petrobras is ranked as the biggest find of the year (see page 14), establishing a new carbonate facies previously unknown in Brazil. The 3-RJS-646 (3-BRSA-496-RJS) well in the Santos Basin found 28-degree API oil, with gas-oil-ratio estimated at 15-20 percent in a structure believed to hold five to eight billion barrels of oil equivalent.

Based on the 15 wells drilled to date in the subsalt trend, eight of which have been tested, Petrobras believes the productive trend extends from the Espirito Santo Basin to the southern end of the Campos Basin.

Speculation is the entire pre-salt trend could hold up to 56 Bboe reserves of light oil.

Chile – Palenque 1 is gaining in importance now that the first appraisal has been successful. It is the first discovery in the country for 15 years and is potentially opening up a shallow gas play trend in the Magallanes Basin.

Located in the Dorado Riquelme Block, the well tested gas at a rate of 2.8 MMcfg/d from three different reservoirs in the interval 800 to 1,000 meters in the El Salto Formation. It is located 8.5 kilometers northwest of Puerto Sara 1 – a 1984 one-well gas discovery that was never developed by ENAP.

Nicaragua – Norwood Resources completed the San Bartolo Rodriguez Cano 1 new field wildcat on the Oklanicsa Block in the Pacific Coastal Basin as a potential oil producer. Drillstem tests were run on 11 intervals totaling a net 179 meters, of which seven recovered oil; all but one of these is considered productive.

The six intervals have an estimated production ranging from 10 to 100 bo/d with a total combined production estimated at 205 b/d of 34- to 43-degree API crude.

The well is considered as having the potential to open a new play in the Pacific.

Peru – With pre-drill reserves estimated at 120 MMbo, Petro-Tech’s San Pedro Este 1-X well located in the southern part of offshore Block Z-2B in the Sechura Basin is now looking to be more significant than originally thought. Sited in just 30 meters of water, the well reached a total depth of 2,152 meters seeking a Paleozoic primary objective.

It flowed at a maximum rate of 4.9 MMcfg/d with a psi of 2,300 on a 20/64-inch choke.

Middle East

Iran – The Minister of Petroleum claims the NIOC Sefid Zakhur 1 wildcat in southern Iran is a giant discovery. Reserves of 11.4 Tcf were mentioned, with around 8.5 Tcf recoverable.

Saharan Africa

Egypt – The Ramadan North 1 wildcat in the Egyptian Gulf of Suez, in which ONGC has equity, is a significant oil and gas discovery.

The well established 40 meters of net pay in the Asl formation and tested 2,979 b/d of 36.50 API oil and 1.5 MMcfg/d.

Sub-Saharan Africa

Angola – Chevron’s Malange 1 well in Block 14 offshore Angola is a significant find, with a 65-meter net oil column in the Cretaceous Pinda formation.

The first Pinda discovery on the acreage, it tested 7,669 bo/d.

Equatorial Guinea – Wildcat I-1, the first well to be drilled on Block I (in which Noble is the technical operator), was an instant success in that it confirmed the potential of the Douala Basin.

Two successful appraisals followed, the last of which (I-3) tested 36 MMcfg/d and 371 bc/d and may have been drilled on the same structure as Yoyo 1 in Cameroon.

Ghana – Kosmos/Anadarko claim a significant find in the deep waters off Ghana. The Mahogany 1 well encountered a 270-meter hydrocarbon column.

To be tested at a later date, reserves are estimated as high as 600 MMb.

Tanzania – Completed in January 2007, Mkuranga 1 (operated by Mayrel and Prom) was the first well to establish potentially commercial gas flows of 19.2 MMcfg/d from the Upper Cretaceous. It is located just five kilometers from the gas pipeline to Dar es Salaam and is to be appraised in 2008.

Uganda – Kingfisher 1 flowed 4,120 bo/d (30-degree API) from Lower Pliocene sands in the last quarter of 2006. However, the discovery of the main 44-meter net reservoir in the Upper Miocene was made by the Kingfisher 1A sidetracks in the first quarter of 2007 (aggregate of three tests: 9,773 bo/d).

Ken White
Ken White

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