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Team gains in understanding deposition

Red Sea an Intriguing Frontier

By DAVID BROWN, EXPLORER Correspondent

Does the north Red Sea area hold more energy resources than we ever realized?

That might seem like a strange question, because both Saudi Arabia and Egypt border the north Red Sea – and, yes, those countries are known to have some hydrocarbon resources.

What’s surprising is the possible extent of additional resources in the area:

• Hess Corp. has evaluated Red Sea geology for a drilling program on its exploration block there. The studies found “all the key elements of the Gulf of Suez petroleum system exist in the north Red Sea.”
• Recent years have brought a flurry of gas discoveries in the Nile Delta. In November, BP Egypt reported an Oligocene deepwater discovery on its Hodoa prospect in the West Nile Delta area.
• Apache Corp. continues an active program in northern Egypt, stretching as far east as Beni Suef in the Nile Valley. Somewhat under the radar, Apache completed 177 wells in Egyptian Middle-to-Late Cretaceous targets during 2010 and planned to complete another 171 this year.

Most of Apache's attention in Egypt has shifted to its western concessions, including the Faghur Basin, where it recently reported results of a discovery that flowed 7,150 barrels of oil and 11.4 million cubic feet of gas per day.

• Israel, with a small patch of shoreline on the Gulf of Aqaba, could have 250 billion barrels of oil in oil-shale deposits. The country is starting an initiative aimed at commercial production.
• China-based seismic company BGP recently completed an acquisition project for Saudi Aramco. It also began conducting a large-scale, complex 2-D survey around the Red Sea, including both onshore and offshore areas.
• And some of the most intriguing frontier exploration possibilities lie in the Red Sea itself.

Hess is evaluating chances on its North Red Sea Block 1 concession, where a well drilled in 1,700 meters of water on the Cherry prospect earlier this year failed to find commercial production. Hess had an 80 percent interest in the well and Premier Oil 20 percent.

“This has been a block where four wells had been drilled, and they found shows but no large hydrocarbon accumulations,” said AAPG member Jennifer Scott, a geologist for Hess in London.

“What Hess has been looking at is whether the Gulf of Suez play can be extended south,” she said.

Scott’s credentials to speak to the subject are strong; she presented an overview of the petroleum systems of the north Red Sea and evaluation work done by Hess scientists at the 2010 AAPG International Conference and Exhibition in Calgary.

The paper was so well received that it won last year’s Gabriel Dengo Memorial Award, presented to honor the best oral presentation at the conference.

Her co-authors were AAPG members Benn Hansen, Niall McCormack and Laura Lawton, all with Hess in London, and AAPG members John Guthrie, Steve Crews, Andy Pepper and Caroline Burke, all with Hess in Houston.

Other co-authors were Graeme Gordon, Dean Griffin, Rod Graham and Tim Grow.

Two Were Better Than One

Scott said a key to their analysis was evaluating the potential presence of two source rocks – and first and most important was a marine, pre-rift source rock found in other parts of the region.

“We were looking to see if that prolific source rock could be extended to the north Red Sea,” she said.

The other was a secondary source rock intermittently present. She described it as “not as dependable, but it is thought source some fields in Saudi Arabia.”

“One thing that was a game-changer was the onshore bore holes that Hess was involved in,” Scott said. “The holes went through these pre-rift rocks, and we were hoping we’d find the source rock there.”

Although some samples and data were available from older drilling in the 1970s, Hess went to Cairo for permission to get more samples for study, she said.

Testing of shallow boreholes showed a thick, oil-prone section within 50 kilometers of where Hess wanted to drill.

The secondary source rock also appeared to be present.

“I went back and looked at the geochemistry of the oil from the wells that had been drilled before. When we plotted out the oil shows, it was actually a mixture of the sources,” she noted.

Scott primarily used two biomarkers to evaluate the oil shows – one a marker based on carbonate content, the other an anoxia indicator.

“You could separate out the oil families based on these facies indicators,” she said. “The overall trend of the biostratigraphy matched what we were seeing in these oil families.”

A New Framework

A multi-disciplinary team at Hess developed a new framework for the region. Onshore fieldwork and mapping of sediments and faults led to a better understanding of sandstone and carbonate deposition offshore.

A special difficulty in identifying prospects on the offshore Hess block is the need for subsalt imaging.

“Imaging subsalt is quite a challenge, but at Hess we have an internal expertise,” Scott said.

According to Scott and the Hess team, reprocessing and new seismic data acquisition have “produced a step-change improvement in imaging of the prospective pre-rift section.”

Hess scientists have used several approaches in evaluating the north Red Sea’s prospectivity, “trying to think of new ways to solve the problem,” Scott said.

In her work, “I had a load of meetings by teleconference with our global experts in Houston who were sort of mentoring me on the process,” she noted.

“In doing the geochemistry, I actually used a piece of software used by our planners. It was a novel use that allowed me to analyze a large amount of data in a short time,” Scott said.

The Red Sea exploration block held by Hess covers a 100-kilometer by 250-kilometer area, Scott said. She called it a “completely frontier exploration area.”

“The size of the block is really large – it’s humongous,” she said. “And there are only five wells there now.”