Idea: Extended Drilling
Reach Out and Touch Some Oil
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Graphics, data courtesy of Tom Bjorklund, Search and Discovery
Oh, the irony of it all.
Groups both pro and con battle passionately over offshore drilling in many regions of the United States -- and they battle so intensely that perhaps everyone is overlooking an obvious solution.
While the mere suggestion of installing drilling platforms in environmentally sensitive offshore areas such as California, Florida, etc., triggers a major freak-out among many elected officials -- and others -- a technology exists to tap some of the close-in offshore resources by drilling from an onshore location.
Is it possible that everyone can be happy?
The technology is called extended reach drilling (ERD), and it enables long horizontal offsets to be drilled to sites that might otherwise be inaccessible.
Perhaps the best known ERD success story can be found in southern England’s BP-operated Wytch Farm field, which reportedly is the largest onshore oil field in western Europe. The field actually lies underneath Poole Harbor stretching out to sea beneath Poole Bay in the Dorset Coast region, which is one of the most environmentally sensitive areas in the United Kingdom.
At the Wytch Farm field, long-reach deviated wells are drilled in a radial pattern from a camouflaged central well pad onshore to locations several miles out into scenic Poole Bay. In fact, a well reached within less than 2,000 feet of a seven-mile departure, according to Tom Bjorklund, research scientist in the geosciences department at the University of Houston.
During the recent AAPG Annual Convention in Long Beach, Calif., Bjorklund’s poster presentation on using ERD to develop California OCS reserves left no doubt he’s on a mission to get the word out about the potential for this technology.
“I wanted to get information out to the public more,” Bjorklund said, “because (in) all of the discussions in Congress last year about offshore drilling, they kept talking about 200, 100, 50 miles offshore.
“The discussion was missing the possibility of a large potential from zero to seven miles offshore that could be developed without offshore rigs or platforms,” he noted. “This was not included in all the talking.
“My point is to get this particular subject out as part of the dialog in offshore drilling,” he added. “The use of ERD to develop the offshore resources of the United States should be considered in the formulation of a rational, knowledge-based energy policy.”
By the Numbers
The volumes of oil and gas awaiting recovery offshore California are huge.
“Discovered and undiscovered conventionally recoverable oil and gas resources of the Pacific OCS region are estimated to range from 14 to 19 billion BOE, according to the MMS,” Bjorklund noted.
Fractures in the Monterey Formation exposed on a wavecut platform along the California coast near Santa Barbara. The industry and local residents historically have had a delicate relationship, but an AAPG member believes use of extended reach drilling technology could make safe development of the area’s rich potential possible.
Photo courtesy of Coast Geological Society
“In the Santa Maria and Santa Barbara-Ventura basins in the California OCS, 24 offshore fields have been discovered with reserves of 1.3 billion BOE, but remain undeveloped because of federal and state offshore drilling restrictions,” he said.
“The highside potential -- including prospects in state waters -- may reach 3.4 billion BOE.”
Bjorklund said the potential exists to develop between 500 and 1,000 MMBOE from onshore sites, assuming ERD wells can develop reserves within seven miles of the California coast.
The numbers from a completed ExxonMobil project at Sacate Field are telling.
Since 1999, the company has drilled 15 ERD wells at Sacate, using Platform Heritage at the adjacent Pescado Field. The platform is located in 1,075 feet of water in the Santa Barbara channel, eight miles off the coast.
The 15th well drilled reaches more than five and one-half miles from the platform and is the longest ERD well in North America, according to Bjorklund.
(Recent reports show that ExxonMobil has gone beyond the seven-mile mark at its Sakhalin 1 project.)
He noted the field has produced over 18 MMBO and 15 BCFG. Estimated ultimate recovery is pegged at 106 MMBOE.
The list of environmental benefits using ERD technology to develop Sacate is noteworthy:
- Fewer wells required.
- No additional platform needed.
- Reduced noise and visual impact.
- Reduced air emissions.
- Reduced impact on marine biology and habitats.
So Close, and Yet So Far
Companies are on the move to try to navigate the tedious process of acquiring leases and permits to develop other areas offshore California using ERD.
For example, Plains E&P reportedly has applied to the State Lands Commission for a lease to implement development of the T-Ridge prospect in state waters.
Sunset Exploration also has proposed a competing project to develop the T-Ridge structure via ERD from an onshore site at Vandenberg Air Force Base and has signed a letter of intent to participate in the project with ExxonMobil, according to Bjorklund.
He noted the horizontal departures of a well to develop fractured Monterey formation on the T-Ridge structure from either onshore or Plains’ Platform Irene would be about four miles -- and the payoff likely would be impressive.
“Based on 3,000 acres of closure,” Bjorklund said, “the potential of the T-Ridge prospect may range from 40-100 MMBOE.”
A list of only a few possible onshore drill sites to tap into unproven OCS reserves within seven miles of the California coastline, along with possible reserves in state waters, reveals some impressive reserve potential numbers:
- North Vandenberg Air Force Base: 230-470 MMBOE.
- South Vandenberg Air Force Base: 110-220 MMBOE.
- Pt. Conception: 110-210 MMBOE.
- Capitan: 30-60 MMBOE.
- West Montalvo: 40-90 MMBOE.
There’s far more to ERD than simply having an existing site to use as a well kickoff point to reach an otherwise inaccessible area. In fact, considerable upfront evaluation is a must-do.
“Each site has to be investigated in detail,” Bjorklund said, “to know if it’s economic, practical, whether the resource can be exploited from onshore.
“That’s a story in itself.”
Tom Bjorklund’s complete poster, “The Case for Using Extended Reach Drilling to Develop California OCS Reserves From Onshore Locations,” is available online at Search and Discovery, AAPG’s online journal at http://www.searchanddiscovery.com/documents/2007/07027bjorklund/index.htm