Investments in rank wildcats pay off

Deep Waters Off Mozambique Yield Big Gas Finds

Bob Daniels
Bob Daniels

Offshore Area 1 of the deepwater Rovuma Basin off the coast of Mozambique in southeast Africa is proving to be a bonanza for Anadarko Petroleum Corp.

The area garnered considerable attention of the industry and others early on, particularly when the company announced the Tubarao prospect discovery well last February.

The well reached TD at approximately 13,900 feet in 2,950 feet of water about 18 miles off the Mozambique coast. It encountered more than 110 net feet of natural gas pay and no water in a high-quality Eocene-age reservoir.

The reservoir is separate and distinct from hydrocarbon accumulations in the company’s three earlier discoveries in this region.

“This (Tubarao) is our fourth significant discovery in the offshore Rovuma Basin and further strengthens our confidence in our geologic and geophysical models of the basin,” Anadarko senior vice president-worldwide exploration and AAPG member Bob Daniels said in a company press release.

Worth the Effort

When Anadarko signed the original license in December 2006 for deepwater acreage, the basin was very under-explored, according to an earlier report by AAPG member and former Anadarko staff member Carol Law. She noted there was only one well in all of northern Mozambique, and it was onshore.

Law added that this was rank wildcat area with little 2-D seismic data. The available seismic revealed the presence of a significant Tertiary basin with what was basically a well-developed fold and thrust belt structural setting.

This apparently was sufficient to convince Anadarko to invest some serious greenbacks and work-power.

It’s no doubt been worth it.

In early October the company stated that cumulative results of exploration and appraisal successes offshore Mozambique served to increase the resource potential in the Offshore Area 1. Anadarko has five junior partners in the project.

The appraisal section of the Camarao prospect exploration well, which was announced at that time, tapped into about 240 net feet of natural gas pay in what was referred to as “excellent quality reservoir,” and confirmed static pressure connectivity with the earlier announced Windjammer and Lagosta discoveries.

The Camarao well hit more than the expected pay dirt given that it discovered about 140 net feet of natural gas pay in shallower Miocene and Oligocene sand bodies not seen in prior wells.

“The results of our activity to date provide high confidence that the Windjammer, Barquentine, Lagosta and Camarao complex holds at least 10 Tcf of recoverable natural gas resources,” Daniels said.

“We are optimistic that our current resource estimates will increase,” he added, “as we still have significant exploration and appraisal work ahead of us.”

Full Speed Ahead

This was a prophetic statement.

On Nov. 28 the company announced that its successful Barquentine-3 appraisal well hit more than 662 net feet of natural gas pay in two high-quality Oligocene-age fan systems.

As a result, the estimated recoverable resource jumped from 10 Tcf to a range of 15 to 30-plus Tcf of natural gas, with an estimated 30 to 50-plus Tcf of natural gas in place.

Barquentine-3 marked the sixth successful penetration in the complex to the north-northeast of the Tubarao prospect. The complex includes the Windjammer, Lagosta, Barquentine and Camarao discoveries.

“The results of Barquentine-3 indicate that we continue to encounter very thick sands with high quality rock throughout these massive, connected reservoirs,” noted Anadarko president and chief operating officer Al Walker.

“Recoverable resources of this size and quality are perfectly suited for a large-scale LNG development, which is currently being designed to consist of at least two trains with the flexibility to expand to six trains.”

It’s full speed ahead for activity in the area.

New seismic data sets have been analyzed, and rig commitments are in place for continued appraisal work. In addition, the partnership will accelerate exploration activity, including the testing of an increasing number of high potential prospects in other segments of Offshore Area 1.

Eni is tasting success in the Rovuma Basin as well.

Also in the deep offshore Area 4 of Rovuma Basin of Mozambique, Eni announced in late October a gas discovery in the Mamba South area in 1,585 meters of water, estimating up to 22.5 trillion cubic feet of gas from both Oligocene and the deeper Eocene pays.

Anadarko operates the 2.6-million acre Offshore Area 1, with a 36.5 percent working interest. It said in mid-December a sale of a portion is being considered to raise cash for the LNG project and other cash obligations.

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