Characterization And Potential Treatment of the Lindbergh Produced Sand
Authors: Jamaluddin A.K.M. , Kim J.Y. , Gair J.D. 
Published: March 2010

Experiments were carried out using a conventional flotation unit to study the feasibility of cleaning the sand produced from unconsolidated heavy oil formations. This study was undertaken to evaluate whether flotation treatment would produce a sand product that could be disposed of as clean fill.

Results of the flotation tests indicate that more than 99% reduction in hydrocarbon and salt content could be achieved by treating the sand in a flotation unit. The addition of a surface active chemical (surfactant) enhanced the disengagement of hydrocarbon from the sand surfaces. The cleaning of the produced sand was achieved by using a sand-to-water ratio of 1:2 and a surfactant concentration of around 1,000 mg/kg of solid.

Introduction

Heavy oil production operation in Alberta generate large volumes of oil-waste material. Much of this waste is formation sand produced in conjunction with the heavy oil. The sand is lifted to the surface along with the produced fluids and collected in above ground tanks. In most operations, the oil and oil/water emulsion are subsequently hauled to a cleaning plant for separation, the sand is transferred to a central storage pad, and the free water is taken for disposal.

Noreen Energy Resources Limited produces heavy oil in the Lindbergh field of northeastern Alberta from shallow and unconsolidated sandstone formations (e.g., Basal Mannville and Rex). Norcen's Lindbergh operations produce three oily-waste streams (clean sand, oily sand, and slop oil), characterized by their different levels of primary contaminants (e.g., oil and chloride). The three waste streams are characterized in Table 1. Despite the lower levels of contamination in the clean sand, the large volumes of this stream make it the most difficult of the three to dispose.

The low level of contaminants in the clean sand stream is a result of the process used by Norcen to remove the sand from the production tank at individual wellsites. The production tank at each well is first drained of produced fluids (i.e., oil and water) and filled with hot fresh water. The fresh water and sand are agitated and removed from the tank using a stinger and vacuum truck. The use of heated fresh water reduces the chloride content of the sand to below 2,000 mg/kg and the oil content to approximately 1% (w/w). This clean sand is then hauled and stored on a centralized asphalt pad to await final disposal.

The method currently employed to dispose of the clean-sand stream is by road-bed construction in the Lindbergh area. The government agencies responsible for waste disposal in the oil industry have recently indicated that this method will not be permitted over the long term because of the hydrocarbon, chloride, and possibly the BTEX (benzene, toluene, ethylbenzene, and xylene) content and that alternate solutions should be sought. Recently, Norcen has completed an in-depth study of the treatment and disposal alternatives that may be applicable to the clean sand waste stream. Consideration of numerous criteria including cost and long-term liability indicated that an on-site soil washing process may be an attractive method of reducing the contamination to a level that would make the sand suitable for use as clean fill.