ABSTRACT: A Case Study: Recovering Liquid Hydrocarbon from an Unconfined Sandy Aquifer

J. M. Inglis, R. E. Zinner

The development of a plan for recovery of liquid hydrocarbon is a multiphased program: subsurface assessment, determination of the feasibility of a variety of remedial options, and the actual implementation of the most effective options. This case study is an effective recovery system in a nonpotable, unconfined sandy aquifer under a petroleum facility in southern California. The recovery system was designed after attaining a fundamental understanding of the multiaquifer hydrogeologic system present beneath the facility and delineating the true spatial extent of the liquid hydrocarbon pool. A three-dimensional finite element groundwater flow model was used to evaluate viable recovery and recharge scenarios with the intention of establishing target production rates and wel spacing to best achieve the objectives of the recovery program and to plan for the future phases of hydrocarbon recovery.

Major factors considered in the recovery system design included protecting the property's borders by maintaining the direction of groundwater flow within the site boundary, injecting groundwater in areas of high hydraulic conductivity and thick vadose zones, and operating the dual-pump recovery wells at relatively low pumping rates to optimize hydrocarbon/water separation in the wells. In addition, the potentiometric surface change associated with liquid hydrocarbon recovery could not negatively impact a publicly operated water injection project on the east border of the property; this reinjection provides protection of interior-basin potable aquifers from saltwater intrusion.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990