Development and Assisted Injection of Sub- And Supercritical Water by the Oil-Soluble Catalysts for the Intensification of Upgrading Process of the Bazhenov Oil Shale and Production of Synthetic Oil

Abstract

Abstract In this paper, an EOR technology was proposed, including a development of oil soluble catalytic compositions and their injection with sub- and supercritical water (sub- and SCW) for in-situ hydrothermal upgrading of oil shale and intensifies the generation of synthetic oil. The experiments were carried with the oil shale sample from the Bazhenov formation (Russia) with 9.13% of the total organic carbon (TOC) which 83% composed of kerogen, at the sub- and SCW conditions of 300-400°C taking into account of the reservoir pressure ≥ 250 bars and with time (6-24h) in the presence and absence of catalysts. Combined methods have been used to characterize the catalysts, oil shale and assess the composition of the reaction products, are illustrated in the experimental section. Additionally, simulation software (Hysys v.12) was also used to calculate the heat load. In this study, the designation of the Kat-1 and Kat-2 refers to Nickel (Ni2+) based catalysts with the «vegetable oil» and «tall oil» as organic ligands, and the Kat-3 and Kat-4 refers to Iron (Fe3+) based catalysts with similar above organic ligands, respectively. The results of injection of sub- and SCW without catalyst showed that the maximum oil shale conversion reaches 52.46% at 350°C and 24h. Consequently, the higher synthetic oil yields of 29.22%, 43.59% and 9.75 % have been obtained after the non-catalytic upgrading process at temperatures of 300°C, 350°C, 400°C and time 24h, 6h and 6h, respectively. It has been established that an increase in reservoir pressure can lead to a proportional increase in yield of gas up to 2.74% at 400°C. Injection of sub- and SCW with oil soluble catalysts at temperatures of 300°C - 400 °C improves the oil shale upgrading and it reveals that the maximum organic maters conversion of 76.67% at 350°C was obtained using the Kat-1. Particularly, it has been found that due to high activity of nickel and considerable amount of π bonds in the ligand the catalyst, the Kat-2 exhibits good performance for upgrading reactions and generate the synthetic oil. Consequently, at an identical temperature of 350°C the yield of synthetic oil increased from 29.22% for the absence of a catalyst to 39.1% using the Kat-2. That means that the Kat-2 can increase more additionally 9.88% of synthetic oil also reducing 4 times the necessary time for the non-catalytic upgrading process. Moreover, at conditions of 350°C and 24h, around 214.06 kg additional of synthetic oil can be produced from a ton organic using Kat-1. Overall, it found that the catalysts (Kat-2 and Kat-4) show appropriate ability for synthetic oil production, while the catalysts (Kat-1 and Kat-3) selectively improve the quality of synthetic oil and the gas yields. Thus, the reasons for good selectivity of Kat-2 and Kat-4 for the synthetic oil production is not only attributed to the metals (Ni2+ and Fe3+) activities, but more to the types of the used ligand. The greater the number of pi bonds in the organic ligands of catalysts, the faster the catalyst is activated. We also observed that at a high temperature of 400°C, a significant decrease in the synthetic oil yield is possible, due to fast decomposition of kerogen into gas and polymerization of intermediate products to coke. According to the results of GC the obtained synthetic oil at the optimal conditions of (350°C, 6h, 24h and the Kat-3) most composed of gasoline - 6.95%, kerosene - 16.88%. It is revealed that the required amount of catalyst to upgrade a ton of Bazhenov organic potential is 13.42 kg, and the amount of sub- and SCW for injection is (8-10:1). After calculation, optimal energy load to reach optimal conversions (46.5% - 50.7%) is 2833 - 4250 kW/h. Thus, use of oil soluble catalysts for the synthetic oil production from the Bazhenov formation is potentially recommended, due to its ecological and has perspective for the exploitation of oil shale in Russia.