Development And Testing Of At Synthetic Cold Lake Oil Sand

Abstract

Abstract A displacement process was used to produce a synthetic Cold Lake oil sand by saturating outcrop formation sand with synthetic Cold Lake formation water followed by Cold Lake bitumen. A new packing technique, which was developed for packing high fines content sands, is described. The synthetic oil sand was evaluated by using the crumble test, the hot water extraction test, the core evaluation test and microscopy. The packing of the clays in the sand tended to flatten their delicate structures and profoundly affect their intricate relationship to the sand grains. Despite this effect, the bitumen recovery tests indicated that the synthetic oil sand was a reasonable substitute for real Cold Lake oil sand. Introduction The Alberta Research Council has recently focused attention on the effects of steam injection processes pertaining to the extraction of bitumen from Cold Lake formations. No readily available source of Cold Lake oil sand exists. Only barren sands of similar nature outcrop on the surface. Consequently, it was necessary to make synthetic oil sand in order to obtain the large quantities required for our steam injection experiments. The project could be considered to be a step toward the ultimate goal of duplicating the complex structure of real oil sand. This paper was designed to show the development and testing techniques used in the project so as to assist future researchers in this area. Suggested improvements to the techniques are also discussed. Two methods of manufacturing oil sand were considered. The "mixing method " involved:soaking of barren sand in water to ensure the sand was water wet;removal of excess water in a centrifuge; andmixing of the wet sand and bitumen. The main problem with this method is that the oil sand must subsequently be packed into a pressure vessel for the steam injection tests. As a result, the oil sand may have entrained air channels through which injected fluids can more easily penetrate than they would in an actual reservoir. Consequently, it was decided to use a method which was based on the displacement process. This method minimizes the formation of air channels and mare closely simulates the natural formation of oil sand deposits. Sand was packed in a coreholder and flooded successively with a synthetic formation water followed by hot bitumen (80 °Cto 90 °C). The packing of barren sand which contains clay is difficult because clay particles tend to aggregate and form low-permeability flow regions. The method developed in this project reduces this phenomenon. Other packing methods described in the literature(1,2,3) were considered inappropriate for the high clay content sand which was used. Two different sand pack geometries were required for our experimental program. The first pack was cylindrical. Segments from this pack were used as test material for Core Evaluation Facility (CEF) tests. The second sand pack was a larger-scale 2-D slab which was prepared for steam-gas additive injection experiments described by Frauenfeld(4).