A reduction in natural seeps is occurring off the coast of Coal Oil Point, and this is directly related to oil and natural gas production from Platform Holly.
Seep reduction has been occurring steadily over the last 30 years, to the point that in late 2013 output from one of the most prolific seeps was reduced to an almost non-detectable level. Natural seeps in the Santa Barbara Channel are one of the largest sources of air pollution in Santa Barbara County. Offshore oil production in areas in which there are active seeps has proven benefits to the Santa Barbara community in terms of reduced air pollution and less tar on local beaches.
The seeps are part of Santa Barbara history and are well documented in early accounts from the Chumash Indians and early explorers along the coast. More than 1,200 natural seeps have been charted in the Santa Barbara Channel, according to the California State Lands Commission. The majority of these seeps occur within a three-mile radius of Coal Oil Point.
Natural seeps leak oil and natural gas into the Santa Barbara Channel. The oil slick from the seeps eventually evaporates and degrades into tar balls, which are common along the water’s edge at many local beaches. It has been estimated that approximately 6,000 gallons of oil seeps naturally into the Santa Barbara Channel every day. In addition to the oil, an estimated 5 million cubic feet of natural gas is released into the air each day. The Santa Barbara County Air Pollution Control District classifies natural seeps as one of the largest sources of air pollution in Santa Barbara County.
The reduction of seeps related to oil and natural gas production is well documented in numerous academic and peer reviewed publications, including research work from UCSB and CSU Long Beach. Platform Holly, installed in 1967 and currently owned and operated by Venoco Inc., has produced more than 75 million barrels of oil and 78 billion cubic feet of gas to date. This production has resulted in a significant decrease in the oil and gas bearing reservoir pressure, the main driving force behind seep activity.
In 1982, two seep tents were installed by ARCO to reduce local air emissions related to a particularly large concentration of naturally seeping gas. These tents have captured 7.6 billion cubic feet of natural gas to date, and the relationship between seep reduction and oil production has been clearly demonstrated. The natural pollutants in this volume of captured gas that would otherwise have been released to the atmosphere are equivalent to the amount of air pollution associated with 59 million round trips between Los Angeles and Santa Barbara in a Honda Civic or 30 million round trips in a Ford F-150 truck. A thorough inspection of the tents and associated equipment verifies that the reduction in seep tent output is not due to mechanical failure. Several visual surveys of the ocean surface in the vicinity of Platform Holly and seep tents also validate that one of the most active seep areas in the Santa Barbara Channel is no longer visible.
“We are not seeing the elimination of all seeps,” said Ian Livett, vice president of Southern California operations. “Due to production from Platform Holly, we are experiencing a measurable reduction in one area offshore within a vast field of natural seeps.”
In the past, Venoco provided Seep Tours to give the public an opportunity to view the seeps from the Condor Express while learning the history of oil development in the Santa Barbara Channel. Hundreds of residents and tourists saw this natural phenomenon up close.
Venoco is no longer offering the boat tours because the most prolific seep area near Coal Oil Point is no longer visible. Continued production from Platform Holly will result in further lowering of reservoir pressure and continued reduction of seep activity in the area.
— Steve Greig is the government relations manager for Venoco Inc.