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28 th International Meeting on Organic Geochemistry 17 – 22 September 2017, Florence, Italy HYDROCARBON GENERATION KINETICS OF OIL CRACKING IN DIFFERENT IONS CATALYSIS REACTION SYSTEM WANG Tongshan 1* , HU Suyun 1 , LI Xia 1 , ZHENG Hongju 1 , LI Qiufen 1 1.PetroChina Research Institute of Petroleum Exploration & Development, China *presenting author: [email protected] Introduction Pyrolysis experiment of crude oil with three reaction systems (MgSO 4 +H 2 O+crude oil, CaSO 4 +H 2 O+crude oil, crude oil) are carried out to simulate the gas generation characteristic when H 2 O and ions such as SO 4 2+ , Mg 2+ , Ca 2+ participate in the oil cracking, and discuss the generating mechanism of natural gas containing H 2 S, and quantitatively calculate the deplete of hydrocarbons and their carbon isotope by TSR. The experiment results show that the TSR reaction did not occur under the system of “CaSO 4 +H 2 O+crude oil”, oppositely, TSR obviously occurred under the system of “MgSO 4 +H 2 O+crude oil”. It could indicate that participation of Mg 2+ make an important influence on the hydrocarbon generation in oil cracking reaction. Sample and experimental A normal marine crude oil sample was selected for pyrolysis experiment from Ordovician interior reservoirs in the depth of 5940-5983m in Well YM2 in Tarim Basin. The oil sample contains 77.3% saturates, 14.9% aromatics, 6.62% non-hydrocarbons and 1.1% asphaltenes. Pyrolysis experiment was carried out in anhydrous closed system (gold tubes) under a constant pressure of 50 MPa at heating rate of 20℃/h and 2℃/h. The analysis of gaseous hydrocarbons was performed by an Agilent 6890N gas chromatography. The isotopes of gas components were determined by Delta plus XL GC-IRMS. Results and discussions The experiment results show that the TSR reaction did not occur under the system of “CaSO 4 +H 2 O+crude oil”, oppositely, TSR obviously occurred under the system of “MgSO 4 +H 2 O+crude oil” and the yield rate of H 2 S reach up to 60~80ml/g. Hydrocarbon yield rates under the reaction system with TSR occurred are significantly lower than that in the reaction system without TSR occurred (Fig 1), indicating the deplete of gaseous hydrocarbons by TSR [1]. In addition, TSR also had a significant effect on the carbon isotope fractionation of hydrocarbons, so that methane, ethane, propane carbon isotope weight gain with a range of 3~6‰ (Table 1). The activation energy distribution show that, the activation energy of gas generation under the system of “MgSO 4 +H 2 O+crude oil” lower than that in the system of “CaSO 4 +H 2 O+crude oil”, the former is 48~60KJ/mol, while the latter is 62~74KJ/mol. It could indicate that participation of Mg 2+ make a low activation energy of hydrocarbon generation and oil cracking reaction easier. Conclusion TSR reaction did not occur under the system of “CaSO 4 +H 2 O+crude oil”, oppositely, but obviously occurred under the system of “MgSO 4 +H 2 O+crude oil”. The participation of Mg 2+ make an important influence on the hydrocarbon generation in oil cracking reaction.
