Salt Lake Oil Field

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Location of the Salt Lake Oil Field in the Los Angeles Basin and Southern California. Other oil fields are shown in gray.

The Salt Lake Oil Field ( English Salt Lake Oil Field ) is an oil field under the city of Los Angeles in California in the United States . Discovered in 1902, the deposit was rapidly developed in the following years and was once the most productive oil field in the state ; more than 50 million barrels of crude oil were extracted here, especially in the first half of the 20th century. On a smaller scale, oil has been pumped out of the ground in a small area within the urban area since 1962. In 2009, Plains Exploration and Production (PXP) was the only company producing in the oil field. The oil reserve is also notable as the source of long-term crude oil spills along the 6th Street Fault known as the La Brea Tar Pits .

The neighboring and geologically related South Salt Lake oil field was only discovered in 1970. This is still productive, also from an inner-city drilling site it shares with the nearby Beverly Hills oil field , and is also being exploited by Plains Exploration and Production.

location

Detail of the Salt Lake oil field with the South Salt Lake oil field, their position within Los Angeles and neighboring cities as well as the location of the active "drilling rigs"

The oil field is one of many in the Los Angeles Basin . Directly to the west is the San Vicente oil field and to the southwest the large Beverly Hills oil field . To the east are the Los Angeles City Oil Field and the Los Angeles Downtown Oil Field , which are among the oldest in the basin and, along with the Salt Lake Oil Field, contributed to the boom at the beginning of the 20th century. Neighboring to the southwest is the South Salt Lake oil field, which was developed later and is still active. The land in this area is approximately 60  m high and slopes gently to the south-southwest, from the Santa Monica Mountains to the Santa Monica Bay of the Pacific Ocean , and is drained by Ballona Creek .

The productive area of ​​the oil field is about five kilometers long and about one and a half kilometers wide, with the long axis running from west to east and thus parallel to Beverly Boulevard , roughly between its intersections with La Cienega Boulevard and Highland Avenue . The entire area is within the City of Los Angeles and is heavily populated; the Salt Lake oil field is therefore one of the few active oil fields in the United States that is entirely in an urban setting. The entire oil field has abandoned drilling sites. These are now completely built over with residential and commercial areas, while active exploitation via drilling in a screened, noise-insulated drilling facility at Beverly Center east of San Vicente Boulevard between Beverly Blvd. and 3rd Street takes place. Because the usual vertical drilling in a densely populated, urban environment is impractical - active drilling sites are noisy and generate dirt - the individual boreholes in this drilling device are directed at an angle into different parts of the oil field, similar to the technology used on oil drilling platforms. Only eleven wells, all of which are in this self-contained facility, are active today, up from the more than 450 wells that were once scattered across the area that is now Midtown Los Angeles. Several wells are producing from the neighboring San Vicente and Beverly Hills oil fields.

The neighboring South Salt Lake oil field is much smaller than the neighboring oil field to the north. It was discovered in 1970 and is only about 1,600 meters long and about three hundred meters wide. It is being exploited from an inner city well at the intersection of Genesee Avenue and Pico Boulevard within the Beverly Hills Oil Field. The only active operator here is Plains Exploration and Production; In 2009 there were 16 active wells in the South Salt Lake oil field.

geology

The oil field is on the northern edge of the Los Angeles Basin , about two miles south of the Hollywood Hills , the closest part of the Santa Monica Mountains. The Santa Monica Fault, which is not considered active, forms the boundary between the basin and the mountains. Several other faults intersect the oil field including the 3rd Street Fault and the 6th Street Fault; the latter is believed to provide the passage for the crude oil that comes to the surface at the La Brea tar pits . These are located at Hancock Park on the southern edge of the oil field, near Wilshire Boulevard . A Quaternary sediment layer with both alluvial and shallow marine deposits forms an approximately 65 m thick cover layer over several oil-bearing layers. The first is the non-oil-bearing Upper Pliocene Pico Formation. These include the Repetto Formation from the late Miocene and the Puente Formation. This formation is a mixture of sandstone and conglomerate that was likely formed in an abyssal alluvial fan and forms one of the most important oil deposits in the Los Angeles Basin. Below the Repetto Formation lies the Puente Formation from the late Miocene. All of these rock layers are folded and warped, forming structural inclusions in which the petroleum is anticlinal and trapped by faults.

Six producing horizons have been identified in the Salt Lake oil field, labeled A above to F below. Only the production horizon A lies within the Repetto formation and lies on average about 300 meters below the surface. Horizons B and C were found in 1904 and the deeper oil reserves D, E and F, which lie between 870 meters and 1000 meters below the surface, were found in 1960 when drilling from the Gilmore rig resumed. The oil extracted here is heavy and sulphurous and has an API grade between 9 and 22, but mostly 14-18; the sulfur content is high at 2.73%.

Only two oil basins have been found in the South Salt Lake oil field to date, both in 1970. At a depth of 300 meters within the Clifton Sands and at a depth of 760 meters in the Dunsmuir Sands. The crude oil is found in several steeply upright sand layers, which are bounded by impermeable rock. These sand layers rise up towards the surface and the petroleum collects in the upper sections. The oil in this field is slightly less heavy than that in the Salt Lake oil field; the API level ranges from 22 to 26.

History of oil production

In the 1890s, dairy farmer Arthur F. Gilmore found petroleum on his land, probably around the La Brea Tar Pits. The oil field was named after the Salt Lake Oil Company, the first company to drill in the area. The drilling to discover the deposit began in 1902. Details of this borehole such as depth, exact location and production rate are no longer known.

The development of the oil field was rapid, drilling rigs were springing up in the landscape, and drilling companies were hoping for a boom similar to that which had occurred just a few miles east in the Los Angeles City oil field. The year with the highest output was already 1908. In 1912 there were 326 conveyor systems, of which 47 had already been abandoned; In 1917 their number had risen to 450. By then, more than 50 million barrels of crude oil had been produced. After this peak, the output decreased rapidly. However, land prices rose as the city of Los Angeles grew rapidly and drilling in the oil field stalled in favor of housing and commercial use. The early drilling sites were abandoned and many of their exact positions can no longer be determined, but are now obscured by roads and structures.

In the 1960s, new developments in oil drilling technology made the development of previously unexploitable oil possible, and Los Angeles inner-city oil fields, such as the Salt Lake Oil Field, caught the attention of oil companies. In 1961, work began from a well near the Farmers Market on the corner of 3rd Street and Fairfax Avenues and the Standard Oil Company of California resumed oil production after removing the three productive strata of sand (horizons D, E, and F ) had discovered. The promotion of these newly discovered horizons was only possible for a short time without further measures, after only one to two years it was necessary to pump. From 1973 onwards, highly saline wastewater, which was originally discharged into the city's storm sewers, was pumped into the drilling field, on the one hand as a convenient disposal method, on the other hand to increase the pressure in the reservoir and thus facilitate oil production. Similarly, the gas produced by the oil field was pumped back into the reservoir between 1961 and 1971 because, in contrast to oil fields that are active today with natural gas production nearby, there were no facilities for collecting, storing and transporting the gas. Operation at this facility, known as MacFarland Drilling Island or Gilmore Drilling Island , continued into the 1990s. This “drilling platform” comprises around 40 springs and was dismantled from 2001 onwards. The previous one- acre facility was on Grove Drive, across from and west of Pan-Pacific Park . According to Texaco, the last oil company to operate the facility, the facility has become uneconomical; In the end, the extraction of the exploited oil field at this point only resulted in around 30 barrels a day.

With the closure of the Gilmore facility, the payment of royalties to the landowners directly above the oil field also ceased. Some of them had received monthly payments of up to $ 2,500  , much like the Beverly Hills oil field.

Los Angeles originally planned to build a subway route along Fairfax Avenue, but decided to use a different route because of the high levels of methane gas below the surface, as this combustible gas is a safety hazard. It was only later discovered that the oil field was the source of the methane gas when, on the night of March 24, 1985, a clothing store filled with the gas and exploded, injuring 23 people.

A clothing store exploded in 1985

The escape of methane gas up faults and old wells led to the explosion of a Ross Dress for Less store on 3rd Street in the Fairfax District . The store still stands today (2010) on the 6200 block of 3rd Street, on the southeast corner of the intersection of Fairfax Ave. and 3rd Street. On the night of March 24, 1985, methane gas filled a side room of the store and ignited, causing an explosion that shattered all the windows and tore the roof off the building. As a result, 23 people were injured and the shop interior was completely destroyed. In addition, parts of the adjacent parking lot and sidewalks were damaged by the explosion, and burning gas escaped over a wide area and illuminated the night sky. Four blocks of the street were cordoned off by emergency services while the authorities puzzled what had happened.

Because naturally occurring methane gas is odorless, nobody noticed the methane that was forming, so that it could accumulate unhindered over a long period of time. The origin of methane gas was controversial; initial theories were based on the accumulation of gases produced by composting an old swamp. In this scenario, the gas was pushed through the porous cover layers to the surface by a rising groundwater level. A later developed theory, now accepted, assumed that the origin of the gas was to be found in the oil field itself and through the combination of the 3rd Street fault and several improperly abandoned wells between the hundreds of early 20th century holes made reaches the surface. Injecting sewage into the oil field to increase oil pressure to facilitate production also pushed the methane gas up through newer crevices in the fault, as well as through these old wellbores, until it reached the surface. Isotopic analyzes of methane near the surface supported this theory because the specific isotope distribution did not match what one would have expected from recent biogenic mechanisms; rather, these values ​​corresponded to the isotopic analyzes of methane gas directly from the oil field. This knowledge had far-reaching effects on urban development above no longer productive oil fields and led to the construction of monitoring facilities and ventilation holes in several places in Los Angeles. Due to the explosion in 1985 and subsequent investigations, the Los Angeles city council identified around 400 blocks of streets above the old oil field as a high risk zone due to methane gas formation. It was later ordered that all structures must be equipped with methane gas detectors so that residents would be warned before the gas content reached an explosive level.

Incident of February 7, 1989

In 1989, a similar methane bubble formed under 3rd Street and adjacent buildings, presumably because a valve installed after the Ross incident was clogged by mistake. As the gas vent became clogged with a build-up of debris, methane slowly began to build up again under the street and adjacent impervious surfaces. This erupted on the morning of February 7, 1989 in a fountain of water, mud and methane gas. Because there was no spark to ignite, there was no explosion and the city's civil protection forces were quickly on the spot and cordoned off the area. As a result of this incident, the city administration tightened the building regulations. New buildings must now have adequate ventilation systems. An impermeable membrane must be installed underneath them to prevent methane gas from building up under the foundation.

literature

  • 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). 1472 pages. Salt Lake Oil Field on pp. 442-447.
  • California Department of Conservation, Oil and Gas Statistics, Annual Report, December 31, 2006.
  • California Department of Conservation, Oil and Gas Statistics, Annual Report, December 31, 2007.

Individual evidence

  1. ↑ a b c d RL Meehan, Hamilton, DA; ed. by Bernard W. Pipkin and Richard J. Proctor: "Cause of the 1985 Ross Store Explosion and Other Gas Ventings, Fairfax District, Los Angeles," Engineering geology practice in southern California . Association of Engineering Geologists. Southern California Section, 1992, ISBN 0898631718 , pp. 145-147, p. 769.
  2. ^ A b Salt Lake Field query, California Department of Oil, Gas, and Geothermal Resources
  3. ^ A b South Salt Lake Field query, California Department of Oil, Gas, and Geothermal Resources
  4. ↑ a b c Hamilton / Meehan, p. 152
  5. ↑ a b Repetto Formation, Bureau of Economic Geology, University of Texas, Austin ( Memento of the original from July 19, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.beg.utexas.edu
  6. ↑ Hamilton / Meehan, p. 151
  7. ^ 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). 1472 pages. Salt Lake Oil Field on pp. 442–447.
  8. ↑ a b DOGGR, p. 443
  9. ↑ a b DOGGR, p. 444
  10. ↑ DOGGR, p. 446
  11. ↑ DOGGR, p. 447
  12. ^ A b c d Mitchell Landsberg: Decades-Old Oil Field Dies as Fairfax Area Mall Takes Shape (English) , Los Angeles Times. August 6, 2001. Retrieved November 15, 2010. 
  13. ↑ Paul W. Prutzman: Petroleum in Southern California . California State Mining Bureau, Sacramento 1913, p. 227.
  14. ↑ Hamilton / Meehan, pp. 146-147
  15. ↑ a b Hamilton / Meehan, p. 147
  16. ↑ a b c Dave Perera: Fresh Produce and Streets of Fire: Making Sense of the Methane Explosion in the Fairfax (English) , LA Weekly. May 10, 2001. Accessed on December 4, 2009.  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. @1@ 2Template: Dead Link / www.laweekly.com  
  17. ↑ a b c Jay H. Lehr, Marve Hyman, Tyler Gass, William J. Seevers: Handbook of complex environmental remediation problems . McGraw-Hill Professional, 2002, ISBN 0070276897 , pp. 8.45-8.47, p. 800.
  18. ↑ Hamilton / Meehan, p. 154
  19. ↑ Leonid F. Khilyuk, Chilingar, George V .: Gas migration: events preceding- earthquakes . Gulf Professional Publishing, 2000, ISBN 0884154300 , pp. 280-286, p. 389.
  20. ↑ George Ramos, Stephen Braun: Major Methane Gas Leak Closes Shopping Strip . Los Angeles Times. February 8, 1989. Retrieved November 17, 2010.