Lost Hills Oil Field

. In 1998, one of the field's gas wells was the site of a spectacular blowout, producing a pillar of fire which burned for 14 days and was visible more than convert|40|mi|km away. [ [http://www.geocities.com/mudsmeller/gushers.html The Bellevue Gusher, at the San Joaquin Geological Society] ]

etting

The Lost Hills Field underlies a long, low range of southeast-to-northwest trending hills of the same name adjacent to the San Joaquin Valley. The hills rise scarcely more than convert|200|ft|m above the San Joaquin Valley to the east, and only convert|100|ft|m or less above the Antelope Plain to the west; in places they are almost flat. The hills and associated oil field are between Interstate 5 to the east and State Route 33 to the west, both of which parallel the field; Interstate 5 runs about four miles (6 km) away and Route 33 about seven. The California Aqueduct runs adjacent to the field boundary on the northeast.

The climate in the Lost Hills area is arid to semi-arid, with an average rainfall of five to six inches (152 mm) a year, almost all in the winter months. Vegetation in the vicinity of the field is mostly grassland and sparse scrub, with some adjacent orchards, although in the oil field itself most vegetation has been removed from the areas of active operations.

Geology

The Lost Hills Field is one of a series of oil fields along anticlines between the Coalinga Oil Field on the north and the Midway-Sunset Field on the south, along the western edge of the San Joaquin Valley. These anticlines run closely parallel to the San Andreas Fault to the west, and formed as a result of compression from tectonic movement. The Lost Hills Field occupies a portion of a doubly-plunging anticline. There are six oil pools in the five producing units, which are, from the top, the Tulare Formation, of Pleistocene age; the Etchegoin Formation, of Pliocene age; the Reef Ridge Formation, of Miocene age; the enormous Monterey Formation, also of Miocene age, which can be found in much of coastal California; and the Temblor formation, underneath the others, of Oligocene and Miocene age. A well drilled to convert|11553|ft|m by Mobil Oil Corp. in the Williamson Lease identified further rock units as old as the Upper Cretaceous below the Temblor, but none of these lowest units have had oil pools. [Land, p. 3-9]

The Belridge Diatomite portion of the Monterey Formation defines the productive limits of the field. Characteristic of this rock unit is that it is full of oil – almost 50% of the unit is saturated, and the unit has high porosity, in the 45% to 70% range – but very little of the oil has been recoverable from the unit (only three to four percent so far). According to Chevron's estimate, there are approximately convert|2.2|Goilbbl|m3 of oil in place in the Lost Hills Field, only five percent of which has been extracted. This estimate is about twenty times greater than the California Department of Oil and Gas estimate (109 million barrels of oil in reserve). [ [http://www.osti.gov/energycitations/purl.cover.jsp?purl=/753983-xVDoLJ/webviewable/ Pasqual R. Perri, et al. "Advanced Reservoir Characterization in the Antelope Shale to Establish the Viability of CO2 Enhanced Oil Recovery in California's Monterey Formation Siliceous Shales".] Chevron USA Production Company, prepared for US Department of Energy, April 2000.]

Well spacing on Lost Hills varies based on the geologic characteristics in the unit being drilled, with one well per five acres in siliceous shale to one well per convert|1.25|acre|m2 in diatomite. [Chevron, 2000]

A peculiarity of the Lost Hills operations is the pronounced subsidence of the ground surface as it collapses into the area vacated by the petroleum after being pumped out. Portions of the hills overlying the oil field have subsided up to eight feet in the central region of operations, and subsidence occurs field-wide at a rate of about nine inches per year. The dropping land surface causes operational problems, including fractures of well casings, and sometimes complete well failures. Waterflooding – the practice of filling the reservoir with water to push petroleum to recovery wells, and thereby also reoccupying the space vacated by oil and gas – has partially mitigated the problem. [ [http://petroleum.berkeley.edu/papers/patzek/spe77646.pdf Lost Hills Field Trial: Incorporating New Technology for Reservoir Management, p. 4] ] [ [http://www.swrcb.ca.gov/centralvalley/board_decisions/tentative_orders/0509/chevronusa_inc/chevronusa-wdr.pdf California State Regional Water Quality Control Board: Discharge Conditions for Lost Hills] ] Some wells have actually disappeared into craters: in 1976, a Getty Oil well blew out, and quickly collapsed into a crater over convert|15|ft|m deep and 30 across, taking with it the concrete pad, casing, and pumping unit. Yet another Getty well suffered the same fate in 1978. [Land, p. 12]

History and operations

Drillers Martin and Dudley discovered the Lost Hills Oil Field in July 1910 – accidentally. They were drilling a water well for livestock grazing; instead of finding groundwater, however, they struck oil, specifically the Etchegoin Pool at a depth of convert|530|ft|m. Other drillers, encouraged by the find, including the mighty Standard Oil of California, which had recently been subject to antitrust litigation and broken up by the Supreme Court, began drilling for more nearby; they soon found the Cahn and Reef Ridge pools, in 1913, and then the Tulare pool in 1915. [DOGGR, California Oil and Gas Fields, p. 257] There were relatively few wells on the field for the first several decades; indeed, by 1979, there were only 39 wells producing from the Monterey Formation, and each of these wells only produced an average of eight barrels per day. It took the development of advanced recovery technology to turn the Lost Hills into a high-producing oil field.

Unusually for a California oil field, the years of maximum recovery were not early in the 20th century, but recently: peak oil production from the Etchegoin Pool did not occur until the early 21st century, assisted by several enhanced recovery technologies, including water flooding and cyclic steam flooding. The early peak in production took place in 1917, during which four million barrels of oil were pumped; then production steadily declined, with a few spikes, until the enhanced recovery techniques which began to be employed in the 1960s began to pay off. In 1981 the field produced almost convert|6|Moilbbl|m3, and has remained a high producer, reaching close to convert|12|Moilbbl|m3 in 2006. During that year it had the fourth-largest production increase in the state, and preliminary estimates for 2007 show that production has increased yet again, to convert|12.2|Moilbbl|m3 [Land, p. 13-14] [ [ftp://ftp.consrv.ca.gov/pub/oil/annual_reports/2006/0102stats_06.pdf California Department of Conservation, Oil and Gas Statistics, Annual Report, December 31, 2006] , p. 67] [ [ftp://ftp.consrv.ca.gov/pub/oil/annual_reports/2007/PR03_2007.pdf California Department of Conservation, Oil and Gas Statistics, Preliminary 2007 Annual Report] , p. 1] As of 1997, four pools – the Tulare, Etchegoin, Cahn, and Reef Ridge – continued to have active recovery operations using waterflooding, steam flooding, and fire flooding. [DOGGR, California Oil and Gas Fields, p. 257] As of 2008, the principal operators on the Lost Hills Field were Chevron Corp. and Aera Energy LLC.

Bellevue blowout

In 1998, the Lost Hills Field was the site of one of the largest and most spectacular well blowouts in modern U.S. history. The Bellevue blowout – also called the "Bellevue gusher" – involved six months of uncontrolled natural gas expulsion, and a gigantic gas fire that lasted two weeks.

On the evening of November 23, a wildcat well being drilled into a promising anticlinal fold underneath the Monterey Formation, northeast of the main Lost Hills field, reached the depth of convert|17000|ft|m and hit a previously untapped reservoir of gas under intense pressure. Natural gas and petroleum condensate burst from the well, immediately exploding into flame, knocking over the massive drilling rig, destroying the trailer, and melting the nearby drilling equipment. This enormous pillar of fire, which rose more than convert|300|ft|m into the sky, could be seen more than convert|40|mi|km away, and the quantity of gas bursting from the well has been estimated at between 40 to convert|100|Mcuft|m3 per day. It burned for fourteen days, and continued spewing even after the fire was out; only a secondary well bore, drilled at a slant to intercept the main well, was able to plug the opening and snuff the blowout at last. [ [http://www.sjgs.com/gushers.html#losthills San Joaquin Geological Society: Bellevue Blowout] ]

References

* "California Oil and Gas Fields, Volumes I, II and III". Vol. I (1998), Vol. II (1992), Vol. III (1982). California Department of Conservation, Division of Oil, Gas, and Geothermal Resources (DOGGR). 1,472 pp. Lost Hills Field information pp. 256-259. PDF file available on CD from www.consrv.ca.gov.
* "California Department of Conservation, Oil and Gas Statistics, Annual Report, December 31, 2006."
* Paul E. Land, "Lost Hills Oil Field". California Division of Oil and Gas. Sacramento, 1984 and 1990. Available on the web at [ftp://ftp.consrv.ca.gov/pub/oil/publications/tr32.pdf their FTP site] .

Notes

External links

* [http://www.geocities.com/mudsmeller/history.html San Joaquin Geological Society: Oil history in Kern County]
* [http://www.netxn.com/~rossart/sidetrack/gallery.html Pictures and description of the 1998 Bellevue Blowout]