Steam chamber evolution during SAGD and ES-SAGD in thin layer oil sand reservoirs using a 2-D scaled model

Abstract

Bitumen recovery from thin oil sand reservoirs was modeled on a 150:1 scale, two-dimensional apparatus based on the theory of steam assisted gravity drainage. Injections of only steam and of steam and organic solvent were compared at high temperature (180°C) and high pressure (686–882kPa). Oil sand was simulated using homogeneously mixed extra heavy oil (<10mPas at 200°C) and glass beads (diameter 1.5mm) to achieve a porosity of 0.3. Steam temperatures, pressures, flow rates, and the evolution of steam chambers were monitored during the extractions. Recovery factor and steam chamber growth rate were compared. Extraction using steam with 3.0–7.4vol% hexane improved the bitumen recovery factor by at least 30%. The added solvent resulted in the steam chamber reaching its greatest area 1200s sooner than when using steam alone, equivalent to 0.9 year in the field. The extra heavy oil was analyzed by HPLC before and after extraction and the relative compositions of SARA were compared. The oil's asphaltene content was reduced from 17.6wt% to 10.8wt% and to 9.7wt% by extraction without and with the added solvent, respectively. Amounts of aromatics and resin were increased by both extraction methods.