--> Abstract: Impact of Hydrogeology on Contaminant Migration and Abandonment of Production Impoundments: Case Histories in Kern County, California, by L. M. Bazeley and J. M. Waldron; #90987 (1993).

Datapages, Inc.Print this page

BAZELEY, LAURA M., WZI, Inc., Bakersfield, CA; and * JAMES M. WALDRON, Chevron USA, Inc., Bakersfield, CA

ABSTRACT: Impact of Hydrogeology on Contaminant Migration and Abandonment of Production Impoundments: Case Histories in Kern County, California

Production impoundments are used by the oil and gas industry for storage, separation, and disposal of production fluids. The majority of impoundments will require closure to prevent groundwater degradation from constituents associated with crude oil production. These include organics, heavy metals, and salt water. At elevated levels, some of these constituents may be considered hazardous and the impoundment will require closure as a toxic pit. The guidelines for abandonment/closure are established in part by State regulations; however, negotiation of the closure requirements is still a critical element, and can make a significant impact on the economic bottom line. Site specific knowledge of the geology and hydrogeology play key roles in the negotiation process.

Two impoundments located in Cymric oil field required closure as toxic pits due to the presence of naturally occurring mercury in the produced fluids. Existing electric logs and sidewall sample information were used in agency negotiations to eliminate the requirement to drill a 700 foot, completely cored monitoring well to the first fluid. Delineation of the vertical and lateral extent of mercury and hydrocarbon contamination was required. The impoundments contained the same types of fluids, (condensate and produced water), and were located within the same formation at the surface but within different nonmarine depositional environments. The vertical extent of mercury and hydrocarbon contamination was similar in both impoundments, approximately 10 feet and 110 feet respectively. The d fferent depositional environments of alluvial fan and fluvial at each location controlled the lateral extent of hydrocarbon contamination at each site. Knowledge of the depositional environment can assist in contaminant delineation planning and closure.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.