The underground injection of oil field waste has been permitted through the California Division of Oil, Gas and Geothermal Resources’ Underground Injection Control Program since the early 1990’s. Oil field wastes approved for underground disposal must be integrally associated with oil exploration or production operations. Approved wastes include drilling mud and cuttings, produced sand, tank bottoms, crude oil saturated soil and produced water. Waste streams from refineries, agriculture and other industries are prohibited from these projects. The high cost of land in Southern California, urban development, increasing environmental regulations and long-term liability are factors driving the disposal of Class II wastes into depleted oil zones. Active disposal projects are located in the Wilmington, Inglewood, Oxnard, Ventura and South Elwood Offshore fields. All projects except Wilmington inject waste at pressures not exceeding the formation fracture pressure. One project in the Oxnard oil field is operated commercially and except waste from several oil operators. Since 1994, the Wilmington project has disposed of 2 million barrels of waste into one dedicated injection well. This is the only disposal project in California with approval to inject over the formation fracture gradient. The presentation will discuss the Division’s process for project approval and requirements for on-going monitoring.
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