تاثیر نانوذرات و درجه حرارت بر ویسکوزیته روغن سنگین Effects of nanoparticles and temperature on heavy oil viscosity

1. Introduction  Heavy oil, extra heavy oil, and bitumen constitute about 70% of worlds’ total oil reserves (Schlumberger,  2006); yet, most of it has remained untapped. The primary reason is high viscosity reduces their mobility4 and results in commercially unfavorable low-productivity wells. Thermal recovery techniques often used to recoup these reserves involve introducing heat into reservoirs to reduce oil viscosity. However, the  methods have limited commercial application because of high costs, low efficiency, technical complexity,  and operational challenges. Non-thermal means such as pump assisted production, cold production with  sand, horizontal and multilateral wells, or water flooding have primarily been neglected due to low  recovery. With emerging of nanotechnology, many research efforts are being directed toward employing nanoparticles in improving heavy oil recovery. The use of nanoparticles with heavy oil is not new. The earlier applications of nanoparticles were primarily as catalysts to improve the efficiency of ex-situ 13 upgrading of heavy oil and bitumen. The first comprehensive efforts to employ nanoparticles for enhancing heavy oil recovery were made by Clark et al. (1990). They used metallic nanoparticles to improve production in steam stimulation process. To date, several researchers (Farooqui et al. 2015; Hascakir et al., 2008, 2010; Li et al. 2007; Shokrlu and Babadagli, 2010, 2011, 2014) have confirmed the benefits of using metallic nanoparticles to improve thermally assisted heavy oil recovery techniques. At high temperatures (typically >100-150°C), metallic (Ni, Cu and Fe) nanoparticles, initiate aquathermolysis process, which transfers hydrogen from steam to oil via water gas shift reactions (WGSR). The process results in hydrolysis of C-S bonds and eventually reduction of oil viscosity (Fan et al., 2004, 2002; Muraza and Galadima, 2015). In addition to upgrading heavy oil by cleavage and removal of Oxygen, Sulfur, and Nitrogen derivatives, nanoparticles have also been identified to increase thermal conductivity. Almost all the research work so far has been focused on the high-temperature (>120°C) effects of nanoparticles in which catalytic properties of nanoparticles play the more dominant role than their iscosity reducing the behavior. Surprisingly, very limited research has been undertaken to examine the application of nanoparticles in non-thermal recovery. Few recent studies have indicated that nanoparticle can alter heavy oil viscosity even at ambient temperature (Hascakir et al., 2010; Shokrlu and Babadagli, 2014; Srinivasan and Shah, 2014).