Eugene Island block 330 oil field

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Eugene Island block 330 oil field
Country United States
Region Gulf of Mexico
Block Eugen Island 313, 314 south, 330, 331, 332, 337, 338
Offshore/onshore offshore
Operators Apache Corporation; Devon Energy[1]
Field history
Discovery 1971
Start of development 1971
Start of production 1972
Peak year 1977
Production
Peak of production (oil) 95,290 barrels per day (~4.748×10^6 t/a)
Peak of production (gas) 482,000 million cubic feet per day (13,600×10^6 m3/d)
Producing formations Pliocene-Pleistocene sands

Eugene Island block 330 oil field is an oil field in the United States Exclusive Economic Zone in the Gulf of Mexico. It is located 170 miles (270 km) southwest of New Orleans, 70–85 miles (113–137 km) off the Louisiana coast comprising six and a half leased blocks: Eugene Island 313, 314 south, 330, 331, 332, 337 and 338.[2]

History[edit]

In the outer continental shelf lease sale on December 15, 1970 240,361 hectares (593,940 acres) were offered for lease, including Eugene Island blocks. The Block 330 area was acquired by Pennzoil (now part of Royal Dutch Shell). As the Pliocene-Pleistocene sands were considered geochemically immature and wells drilled to the north of Block 330 discovered natural gas, Pennzoil expected to discover a natural gas not oil. The oil field was discovered in March 1971 while drilling the 1 OCS G-2115 well.[2] Approximately at the same time oil was discovered by Royal Dutch Shell in the adjoining block 331.[3]

By the end of 1971, two platforms had been installed in the field. The first development well was drilled on Block 330 by Pennzoil's "A" platform in November 1971. Production started in September 1972 in the block 331. During 1972 four more platforms were installed and later the number of platforms increased to nine.[3]

From 1975 to 1980, the field was the largest producing field in the Federal outer continental shelf. Production peaked in 1977 by 95,290 barrels (15,150 m3) of liquids (crude oil and gas liquids) and 482,000 million cubic feet (13,600×10^6 m3) per day.[2] Enhanced oil recovery operations started in August 1975. Water injection was used on blocks 331 and 314, and starting from December 1979 gas injection was used on block 330.[3]

Geology[edit]

The field is an anticlinal structure on the downthrown side of a major salt diapir associated growth fault and produces from 25 Pliocene-Pleistocene delta-front sandstone reservoirs at depths from 1290 to 3600 m.[4] The structure was located with reconnaissance reflection seismology 2D lines recorded from 1966 to 1970, coupled with well data defined lithofacies and isopach maps indicating large delta systems.[4] Relative amplitude seismic profiles reveal "prominent hydrocarbon indicators" such as bright spots and flat spots, and seismic facies analysis show shingled, oblique and sigmoid reflections typical for delta-front sandstones.[4]

Depletion rate[edit]

The oil field is best known for the controversy surrounding its depletion rate. According to a 1999 Wall Street Journal article:

Something mysterious is going on at Eugene Island 330. Production at the oil field, deep in the Gulf of Mexico off the coast of Louisiana, was supposed to have declined years ago. And for a while, it behaved like any normal field: Following its 1973 discovery, Eugene Island 330's output peaked at about 15,000 barrels per day (2,400 m3/d). By 1989, production had slowed to about 4,000 barrels per day (640 m3/d). Then suddenly -- some say almost inexplicably -- Eugene Island's fortunes reversed. The field, operated by PennzEnergy Co., is now producing 13,000 barrels per day (2,100 m3/d), and probable reserves have rocketed to more than 400 million barrels from 60 million.[5]

—Christopher Cooper, Wall Street Journal

However, Richard Heinberg provides his own figures:

Production from Eugene Island had achieved 20,000 barrels per day (3,200 m3/d) by 1989; by 1992 it had slipped to 15,000 bbl/d (2,400 m3/d), but recovered to reach a peak of 30,000 bbl/d (4,800 m3/d) in 1996. Production from the reservoir has dropped steadily since then.[6]

Richard HeinbergEnergy Bulletin

The source of additional oil was analyzed as migrating through faults from deeper and older formations below the probable Jurassic and Early Cretaceous age. The oil contains biomarkers closely related to other very old oils which were long trapped in deep formations.[7]

Eugene Island 330's fame comes from its status as an unusual anomaly. Most petroleum scientists believe that the depletion profile is adequately explained by replenishment from deeper reservoirs of normal biologically derived petroleum.

In regard to oil depletion concerns, while the rate went up again in the early 1990s along with the overall estimated recoverable petroleum, the rate has since declined.[clarification needed]

Production and ownership[edit]

As of 1987 June 30 the cumulative production of Eugene Island 330 was 481 million barrels (76.5×10^6 m3) of oil equivalent,[2] which is equivalent to an average of about 82,000 barrels per day (13,000 m3/d), taking 1971 as start of production. Oil and condensate production alone totaled 271 million barrels (43.1×10^6 m3) with a maximum daily production of 95,290 barrels per day (15,150 m3/d) in 1977.[2] Oil is exported through the Shell Pipeline Co LP operated Eugene Island Pipeline System.[8]

As of 1999 the owners of the block leases (numbers in parentheses) are Chevron Corporation (313), ExxonMobil (314 south half and 332), Royal Dutch Shell (331), Ecee, Inc (330), Palo Petroleum (337), and Tenneco Oil (338).[2]

References[edit]

  1. ^ "Central Shelf Operations". Energy XXI. Retrieved 2010-07-05. 
  2. ^ a b c d e f Holland, David S.; Leedy, John B.; Lammlein, David R. (1999). "Eugene Island Block 330 Field--U.S.A. Offshore Louisiana". AAPG Treatise of Petroleum Geology, Atlas of Oil and Gas Fields, Structural Traps III (American Association of Petroleum Geologists): 103–143. Retrieved 11 June 2010. "Fig. 2. Acquisition history and current lease ownership" 
  3. ^ a b c Lewis, Ronald L.; Dupuy Jr., Harvey J. (November 1983). "Eugene Island Block 330 Field — Development and Production History". Journal of Petroleum Technology (Society of Petroleum Engineers) 35 (11): 1956–1962. doi:10.2118/10003-PA. ISSN 0149-2136. Retrieved 2010-07-05. 
  4. ^ a b c Holland, D.S., Nunan, W.E., Lammlein, D.R., and Woodhams, R.L., 1980, Eugene Island Block 330 Field, Offshore Louisiana, in Giant Oil and Gas Fields of the Decade:1968-1978, AAPG Memoir 30, Halbouty, M.T., editor, Tulsa:American Association of Petroleum Geologists, ISBN 0891813063, pp. 253-280.
  5. ^ http://interactive.wsj.com/archive/retrieve.cgi?id=SB924151147795357823.djm Christopher Cooper, "Odd Reservoir Off Louisiana Prods Oil Experts to Seek a Deeper Meaning?", Wall Street Journal, April 16, 1999
  6. ^ http://www.energybulletin.net/2423.html The Abiotic Oil Controversy - Richard Heinberg, Oct 6 2004 by Alternative Press Review: Energy Bulletin
  7. ^ Robert Cooke, Oil Fields Are Refilling...Naturally - Sometimes Rapidly, Newsday 2002
  8. ^ "CEugene Island Pipeline System". Shell Pipeline Co LP. Retrieved 2010-07-05. 

External links[edit]