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Offshore Hydrocarbon Seeps in Southern California: A U.S. Geological Survey—Minerals Management Service Cooperative Project

Overview

Sources, Transportation, and Fate of Natural Oil and Gas Seepages: Tar and oil residues are common on California beaches, especially in southern California where natural oil seeps are present. Baseline information on tar and oil accumulations from natural seepage and spills is sought in order to manage the offshore production of oil and gas. The Minerals Management Service and the County of Santa Barbara have funded the USGS organic geochemistry team in Menlo Park, California to provide geochemical information that can be used to distinguish between sources of tar from natural seeps of from man-made spill. Baseline tar accumulation on beaches is an important management tool to assess the environmental impact of natural oil seepage in contrast to possible oil spills or illegal dumping at sea. Tar accumulation on specific beaches is monitored on a periodic basis providing details of tar composition, amount, and possible transport pathways as they vary with time.

Related Projects

Submarine Oil Seep Study: Southern Santa Maria Basin and Western Santa Barbara Channel
http://www.mms.gov/omm/pacific/enviro/submarine-oil-seep-study/submarine-seeps.htm

Santa Barbara County Natural Seep Inventory Project (2002-2004)
http://www.countyofsb.org/energy/information/naturalSeepProjectSummary.asp, project report

University of California Santa Barbara "Bubbleology" Coal Oil Point interactive explorer
http://www.bubbleology.com/seeps/SeepMapFrame.html
http://www.bubbleology.com/BubbleologyFrame.html

USGS seeps page
http://seeps.wr.usgs.gov/

Start/End Dates:

7/1/2001 - 12/1/2009

Location

Offshore southern California within the area between Point Arguello and Ventura.

Investigators

Lorenson, Tom, Geologist
Rosenbauer, Bob, Geologist

Tar-lined blowhole at Carrington Point, north side of Santa Rosa Island in the Santa Barbara Channel off southern California.

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Objectives

The major goal of this project is to establish the geologic setting, source(s), and ultimate dispersal of natural oil and gas seeps in the offshore southern California within the area between Point Arguello and Ventura. The surveys will focus on likely areas of hydrocarbon seepage which are known to occur over the Pt. Arguello oil field, and the area near Santa Barbara where huge amounts of offshore oil seepage occur. Objectives in reaching this goal are to:

document the locations and geochemically fingerprint natural seeps within the offshore southern Santa Maria and Ventura Basins;
geochemically fingerprint coastal tar residues and potential sources, both onshore and offshore, in this region and compare these data with the existing database from this and other coastal regions of California;
establish chemical correlations between offshore active seeps and coastal residues thus linking seep sources to oil residues;
measure the rate of natural seepage of individual seeps and attempt to assess regional natural oil and gas seepage rates;
attempt to predict transport pathways of oil from seep sources to the coastline;
interpret the petroleum system history for the natural seeps; and
extend coastal tar residue study to include beaches of Santa Barbara County.

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Approach

The Minerals Management Service has awarded the USGS funds over a 5 year period to conduct this program with the understanding that the USGS and our partners, will provide salary for our respective personnel. Below is a detailed workplan for years one to five.

Synthesize acoustic evidence of gas and oil seepage based on reviews of existing seismic-reflection and sidescan-sonar data. Goal: to define most favorable areas for detailed offshore fieldwork during year 2.
1. Review MBARI EM-3000 multibeam bathemetry and acoustic backscatter imagery previously collected in the southern Santa Maria Basin.
2. Review USGS seismic-reflection and related data lines in areas of interest for:
  1. echo-sounding data at either 10 kHz or 12 kHz,
  2. high-resolution seismic-reflection data using both 3.5 kHz and boomer sound sources,
  3. side-looking sonar images,
  4. single-channel seismic-reflection data, and
  5. limited amounts of 24-channel seismic-reflection data.
3. Review of industry geophysical data archived by MMS.
Synthetic Aperture Radar (SAR) evidence for oil seepage to determine if SAR is useful in this area for identifying and locating seep-rich areas.
Review oceanographic conditions to determine if transport pathways for oil originating at offshore seeps can be predicted.
1. Review existing records of near-bottom transport taken by USGS personnel at sites north of Pt Conception.
2. Review surface current information (observations, analysis, and numerical models) from the SBC-SMC circulation study. Current data at various depths along the central California coast, available through Mr. Sig Larson at MMS, will also be reviewed.
Develop a chemical-fingerprint library for oil, gas and source rock signatures. Goal: Establish a library of oil chemistry fingerprints with the utility to identify oil samples and their likely sources in contrast to oil residues resulting from spillage, especially those of non-California sourced oils. Tar residues and oil or tar found in seeps, sediments, in the water column and the surf area from California coastline locations within the study area will be collected mainly during year one. These samples are expected to include:
1. a representative number of about 150, some collected seasonally, of tar residue samples from the coastline between Point Arguello and Point Conception,
2. oil and gas samples from offshore wells in the study area,
3. oil and gas samples from selected onshore wells or seeps in the study area, and
4. organic matter in selected oil source rocks.

In order to address the temporal variations in oil deposits, a sample set will be collected bi-yearly during years one and two at established stations located next to intertidal biological monitoring stations previously established by MMS. We hope to coordinate oil residue collections with MMS and the County of Santa Barbara. In addition we intend to work with, and have previously worked with Bill Castle of the California Department of Fish and Game who has developed a chemical fingerprint library in the vicinity of our proposed study area. We will also integrate the new geochemical information from southern California with our current database which contains data on tar residues from a broader extent of the California coast.

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Tasks and SubTasks

Submarine Oil and Gas Seeps of the Southern Offshore Santa Maria Basin, California: Source Markers, Semiquantitation of Seepage Rates, Transport Pathways, and Relation to Oil Residues on the Coastline
Natural Seep Inventory and Identification for the County of Santa Barbara, California
Synthesis of geochemical data related to California coastal tar contamination
Submarine Oil and Gas Seeps in the Santa Barbara Channel—Source Markers, and Relation to Oil Residues on the Coastline

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USGS Field Sampling and Cruises

2007 Jun-Jul: Z-1-07-SC seafloor mapping Gaviota, west COP
2007 Feb-Mar: G-1-07-SC COP seep monitoring
2006 Jul: Z-2-06-SC Coal Oil Point (COP) mapping
2006 Mar: Platform A, Loon Point
2005 Oct: Sacate, COP
2005 Sep: COP
2005 Jun: Monterey Canyon
2005 Apr: COP
2005 Feb: platform, Summerland OF
2005 Jan: platform
2004 Dec: Loon Point
2004 Nov: COP
2004 Oct: P-2-04-SC ROV aided seep sampling, Point Conception
2004 Sep: platform, Mussel Shoals
2004 Feb: Vallecitos OF
2004 Jan: COP
2003 Aug: Arroyo Burro, Casmalia, Point Conception, COP, Tajiguas
2003 Jul: Jalama, Tajiguas, Gaviota, Loon Point, Sacate, Arroyo Burro, COP
2003 Jun: COP, Sacate, Tajiguas, Surf, Jalama, Loon Point, Gaviota, Boathouse, COP, Casmalia
2003 May: Boathouse, Surf, Casmalia, Jalama
2003, Apr: Loon Point, Sacate, Boathouse, Casmalia, Surf, Jalama, Arroyo Burro, COP, Gaviota
2003 Mar: Arroyo Burro, COP, Surf, Boathouse, Sacate, Tajiguas, Casmalia, Jalama
2003 Feb: central California
2003 Feb: Arroyo Burro, COP, Casmalia, Tajiguas, Sacate, Surf, Jalama, Boathouse
2003 Jan: Boathouse, Surf, Jalama, Sacate, Arroyo Burro
2002 Dec: COP, Boathouse, Surf, Casmalia, Jalama
2002 Nov: Sacate, Tajiguas, Boathouse, Jalama, Surf, Casmalia, Loon Point, Arroyo Burro, COP
2002 Oct: Boathouse, Jalama, Casmalia Surf, Loon Point, Arroyo Burro, Gaviota, Sacate, Tajiguas
2002 Sep: Surf, Casmalia, Loon Point, Jalama, Tajiguas, Arroyo Burro, COP
2002 Aug: Casmalia, Jalama, Surf, Boathouse, Gaviota, Sacate, Tajiguas, Arroyo Burro, COP
2002 June 20-30: Tajiguas, Surf, Loon Point, Jalama, Boathouse, Arroyo Burro, COP
2002 Jun: A-1-02-SC sidescan mapping
2002 May 31/June: Surf, Casmalia, Jalama, Boathouse, Gaviota, Loon Point, Tajiguas, COP
2002 May 18:COP, dives
2002 Apr: Boathouse, Jalama, Casmalia
2002 Mar: P-1-02-SC seep detection, Point Conception
2002 Mar: COP, Channel Islands
2002 Feb: Platform A, Casmailia, Surf, Coal Oil Point (COP)
2002 Jan: Jalama, Surf, Casmalia, Boathouse
2001 Oct: Boathouse, Lompoc, Surf, Jalama, Casmalia
2001 Jul: Boathouse, Jalama, platforms, Casmalia

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News

Tar Balls Washed Onto Central California Beaches by Storms http://soundwaves.usgs.gov/2007/05/research2.html

Mapping the Sea Floor Off Santa Barbara, California http://soundwaves.usgs.gov/2006/09/fieldwork2.html

Mapping Benthic Habitat Around Oil Platforms in the Santa Barbara Channel, California http://soundwaves.usgs.gov/2004/11/fieldwork3.html

Report on Hazards Offshore California's Ventura County Coast Compiled in Response to Congressional Request http://soundwaves.usgs.gov/2004/11/pubs.html

Natural Tar Seeps in the Santa Maria Basin and Western Santa Barbara Channel Workshop, November 2004 http://www.mms.gov/omm/pacific/offshore/ROTAC/041102-ROTAC.htm

Survey of Offshore Hazards in Southern California http://soundwaves.usgs.gov/2002/08/index.html

Beginning the Search for Offshore Oil Seeps Near Point Conception, California http://soundwaves.usgs.gov/2001/09/fieldwork2.html

Ecology of Oil Seeps in Central California http://soundwaves.usgs.gov/2001/05/

Ubiquitous Coastal-Tar Residues on Santa Rosa Island, Offshore Southern California http://soundwaves.usgs.gov/2001/01/fieldwork.html

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Selected References

Committee on Oil in the Sea: Inputs, Fates, and Effects (including Kvenvolden, K.A.), 2003, Oil in the Sea III-Input, Fates, and Effects: The National Academies Press, Washington, D.C., 265 pp.

Dartnell, P., Cochrane, G., and Dunaway, M.E., 2005, Multibeam Bathymetry and Backscatter Data: Northeastern Channel Islands Region, Southern California: USGS Open-File Report 2005-1153
[http://pubs.usgs.gov/of/2005/1153/]

Dougherty, Jennifer A., Lorenson, Thomas D., Hostettler, Frances D., Rosenbauer, Robert J., 2003, Preliminary Assessment of Beach Tar Sources Along the Santa Barbara County Coastline; Geological Society of America Abstracts with Programs, Vol. 35, No. 6, September 2003, p. 243.
[http://gsa.confex.com/gsa/2003AM/finalprogram/abstract_65595.htm]

Hostettler, F.D., Rosenbauer, R.J., Lorenson, T.D., and Dougherty, J.A., 2004, Geochemical characterization of tarballs on beaches along the California coast. Part I - Shallow seepage impacting the Santa Barbara Channel Islands, Santa Cruz, Santa Rosa and San Miguel: Organic Geochemistry v. 35 p. 725-746. [PDF (0.5 MB)]

Hostettler, F.D., and Kvenvolden, K.A., 2002, Alkylcyclohexanes in environmental geochemistry: Proceedings, Proceedings of the 25th Arctic and Marine Oilspill Program (AMOP) Technical Seminar, Environment Canada, v. 1, p. 489-502.

Hostettler, F.D., and Kvenvolden, K.A., 2002, Alkylcyclohexanes in environmental geochemistry: Environmental Forensics, v. 3, p. 293-301.

Hostettler, F.D., and Kvenvolden, K.A., 2002, Forensic implications of spilled oil biodegradation in anaerobic environments: Abstracts with Programs, Geological Society of America Annual Meeting, v. 34. n. 6, p. 289.
[http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_41765.htm]

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Kvenvolden, K.A., and Cooper, C.K., 2003, Estimates of the rates at which crude oil seeps naturally into the oceans: American Association of Petroleum Geologists, Annual Convention, Official Program, v. 12, p. A97.
[http://www.searchanddiscovery.com/documents/ abstracts/annual2003/short/78134.PDF]

Kvenvolden, K.A., and Cooper, C.K., 2003, Natural seepage of crude oil into the marine environment: GeoMarine Letters, v. 23, p. 140-146 [PDF (0.3 MB)]

Kvenvolden, K.A., and Hostettler, F.D., 2003, Geochemistry of coastal tarballs in southern California-A tribute to I.R. Kaplan: Kaplan Volume, The Geochemical Society, Director's approval 05/03, 27 p.

Kvenvolden, K.A., and Cooper, C.K., 2002, Revised assessment of the rate at which crude oil seeps naturally into the ocean: AAPG Hedberg Research Conference, Near-Surface Hydrocarbon Migration: Mechanisms and Seepage Rates, April 7-9, 2002, American Association of Petroleum Geologists, Addendum to Abstract Book, 2 p.
[http://www.searchanddiscovery.com/documents/abstracts/hedberg2002/kvenvolden01/kvenvolden01.htm]

Kvenvolden, K.A., Hostettler, F.D., Lorenson, T.D., and Rosenbauer, R.J., 2002, Natural oil seeps and coastal tar in California-An extension of the Kaplan Legacy: Abstracts with Programs, Geological Society of America Annual Meeting, v. 34. n. 6, p. 219.
[http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_39120.htm]

Kvenvolden, K.A., Hostettler, F.D., Rosenbauer, R.J., and Lorenson, T.D., 2002, Geochemistry of coastal tar residues as tracers of their natural or human origin: Abstract Book, 7th International Conference on Gas in Marine Sediments, Baku, Azerbaijan, Nafta Press, p. 98.

Kvenvolden, K.A., Lorenson, T.D., Rosenbauer, R.J., and Hostettler, F.D., 2002, Hydrocarbon residues on the California coastline: Monterey Bay National Marine Sanctuary Symposium, Sanctuary Currents 2002, New Technologies: Revealing the Secrets of the Sea. March 9, 2002, California State University, Monterey Bay, California, p. 19.

Kvenvolden, K.A., Rosenbauer, R.J., Hostettler, F.D., and Lorenson, T.D., 2002, Application of organic geochemistry to coastal tar residues from Central California: In Ernst, W.G. (ed.), Frontiers in Geochemistry: Organic, Solution, and Ore Deposit Geochemistry, Konrad Krauskopf V. 2, International Book Series, V. 6, Bellwether Publishing, Ltd. For the Geological Society of America, p. 5-18.

Kvenvolden, K.A., Kolak, J.J., Hostettler, F.D., Rosenbauer, R.J., and Lorenson, T.D., 2001, Coastal tar residues of the state of California, USA: 20th International Meeting on Organic Geochemistry, Abstracts Volume 2, p. 270-271.

Kvenvolden, K.A., Rosenbauer, R.J., Hostettler, F.D., and Lorenson, T.D., 2000, Application of organic geochemistry to coastal tar residues from Central California: International Geology Review, v. 12, p. 1-14.

Kvenvolden, K.A., Rosenbauer, R.J., Hostettler, F.D., and Lorenson, T.D., 2000, Coastal tar residues on the shoreline of the Monterey Bay National Marine Sanctuary: Monterey Bay National Marine Sanctuary Symposium, Sanctuary Currents 2000, Causes of Ecosystem Change: Natural or Human?, p. 25.

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Lorenson, Thomas D., Jennifer A. Dougherty, William Ussler III, Charles K. Paull, 2003, Cruise Summary for P-1-02-SC: Acoustic Imaging of Natural Oil and Gas Seeps in Measurement of Dissolved Methane Concentration in Coastal Waters Near Pt. Conception, California USGS Open-File Report 03-122, 86pp.
[http://geopubs.wr.usgs.gov/open-file/of03-122/]

Lorenson, Thomas, William Ussler III, Jennifer Dougherty, Charles Paull, Siddhartha Mitra, Rendy Keaten, Keith Kvenvolden, Ira Leifer, and John Harris, 2003 Dissolved Methane Concentrations Adjacent to Natural Oil and Gas Seeps off Point Conception, California, American Society of Limnology and Oceanography, 2003 Aquatic Sciences Meeting, Salt Lake City, UT, Abstract book, p.88.

Lorenson, T.D., Hostettler, F.D., Peters, K.E., Dougherty, J.A., Rosenbauer, R.J., and Helix, M., 2007, Natural oil seepage in southern California: Occurrence, sources, and ecology: in Petrotech 2007 Proceedings CD-ROM. 6p.
[http://www.petrotech2007.com/TechnicalProceedings.asp, PDF (5 MB)]

Lorenson,T.D., Hostettler, F.D., Dougherty, J.A., Rosenbauer, R.J., Peters, K.E., and Dunaway, M., 2006 Overview of Natural Oil Seepage in the Santa Barbara Channel and Southern Santa Maria Basin, Southern California. California and the World Ocean 2006, Book of Abstracts, p. 153-154.
[http://resources.ca.gov/ocean/cwo06/PDF/abstracts.pdf, abstract PDF, poster PDF (file size: 5 MB; dimensions: 72in x 36in)]

Normark, W. R., C. E. Gutmacher, and R. Sliter, 2005, Natural hydrocarbon seeps on the inner shelf off Pt. Conception and western Santa Barbara Channel, California Geol. Soc. Amer. Cordilleran Section/Pacific Section American Association of Petroleum Geologists Meeting, San Jose, Official Program, p. 96-97.
[http://gsa.confex.com/gsa/2005CD/finalprogram/abstract_85048.htm]

Normark, William R.; Fisher, Michael A.; Gutmacher, Christina E.; Sliter, Ray; Hibbeler, Lori; Feingold, Beth; Reid, Jane A., 2003, Cruise Report for A1-02-SC: Southern California CABRILLO project, Earthquake Hazards Task: U.S. Geological Survey Open-File Report 03-110
[http://geopubs.wr.usgs.gov/open-file/of03-110/]

Peters, K.E., Hostettler, F.D., Lorenson, T.D. and Rosenbauer, R.J., 2007, Chemometrics Identifies Families of Crude Oils, Seep Oils and Stranded Tarballs in Coastal California. AAPG Annual Meeting, Long Beach, California. v. 91 (digital). 1p.
[http://aapg.confex.com/aapg/2007am/techprogram/A108751.htm]

Santa Barbara County, Planning and Development Department, Energy Division, and U.S. Geological Survey, Western Coastal and Marine Geology Team [Lorenson, T.D., Dougherty, J.A., Hostettler, F.D., and Rosenbauer, R.J.], Menlo Park, CA, 2004, Natural seep inventory final report
[http://www.countyofsb.org/energy/information/NaturalSeepInventoryFinalReport.htm]

Santa Barbara County, Planning and Development Department, Energy Division, and U.S. Geological Survey, Western Coastal and Marine Geology Team [Lorenson, T.D., Dougherty, J.A., Hostettler, F.D., and Rosenbauer, R.J.], Menlo Park, CA, 2004, Natural seep project summary
[http://www.countyofsb.org/energy/information/naturalSeepProjectSummary.asp]

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