Study on TOF-SIMS of desmocollinite of C-P coals in Bohaiwan Basin

Abstract

The Time of Flying-Secondary ion Mass Spectrometry (TOF-SIMS) is a new technique that can be used to explore the chemistry component and composition of a great variety of macerals in source rocks. It has some characteristics of extensive application and high sensitivity, therefore it has been used in many research fields. The desmocollinite of same coal rank in Taiyuan Formation (C_2t) coals and Shanxi Formation (P_1s) coals of PermianCarboniferous in North China have difference in physics, chemistry and technical character. For example, the element (H, O and S) contents and felted index in Taiyuan Formation coals are larger than that in Shanxi Formation. The desmocollinites with same or different coal ranks distributed in the same place, have been compared by TOF-SIMS in this paper. It is revealed that there are some alkyl and alkene scrap ions in the desmocollinite, showing that it is rich in hydrogen, and the abundance of hydrogen in Taiyuan Formation coals is much larger than that in Shanxi Formation. The type of organic scrap ions in Taiyuan Formation coals is more abundant than that in Shanxi Formation in the same coal rank coals, and the intensity of organic scrap ions is similar to each other. In the desmocollinites with different coal ranks, the type of organic scrap ions with higher maturity is less than that in the lower one, and the intensity of organic scrap ions with higher maturity is lower. The difference of chemical component and composition in Taiyuan Formation coals and Shanxi Formation ones have been obviously revealed, therefore, the TOF-SIMS has distinctive superiority in research on the macerals chemical component and composition, and can be directly used to appraise the oil-gas resources. On the base of their hydrocarbon characters research, the quantitative parameters (T_o, T_g, T_a) for hydrocarbon generation potentials of different macerals have been proposed. The larger To and T_g are, the larger oil-gas generation potentials are; the larger T_a is, the less the hydrocarbon potential is. Therefore, the proposition of quantitative parameters would promote the application of TOF-SIMS on the evaluation of oil-gas resource.