Effect of non-condensable gases (NCG) on Effective Thermal Conductivity of oil sands

Abstract

Effective thermal conductivity (ETC) of oil sands is a key parameter affecting the distribution of heat in the thermal enahnced oil recovery, especially in Steam-Assisted Gravity Drainage (SAGD) operations. ETC depends on the the size and distribution of sand grains and also fluids filling the pore space. The co-injection of non-condensable gases (NCG) with steam, as a technique to improve the oil sand production, also significantly affects ETC. There is very limited experimental data for thermal conductivity of oil sands when it is saturated with bitumen, steam condensate and NCG. The objective of this research is to measure the thermal conductivity of oil sands at varying saturations of NCG and operating conditions using a rapid unsteady state technique. A needle probe emitting heat as a line source is used to determine the effect of NCG saturation on ETC of oil sands at different temperatures and pressures. The experimental data is later fitted into existing ETC models to develop modified correlations of ETC of oil sands incorporating gas saturation, temperature, and pressure. The intricacy of this work thus lies in determining ETC of a porous medium containing three-phase saturations. A part of the study also includes the estimation of ETC of oil sands in the presence of a surfactant in conjunction with NCG. The experimental correlations developed from this study can be used for simulating SAGD process involving NCG co-injection.