Study on the Pyrolysis Characteristics and Kinetics of Shale Under Water Medium Conditions

At present, there are many shale pyrolysis experiments based on thermogravimetric analyzers at home and abroad, which control the heating rate of pyrolysis experiments by programmed heating, but they cannot simulate the high temperature and high pressure environment of subsurface in situ transformation, so they cannot reflect the real situation of subsurface in situ pyrolysis, and there are few studies on the reaction kinetics of shale pyrolysis under water medium condition at home and abroad. In this paper, shale pyrolysis experiments under water medium condition were carried out by using a self-designed high-temperature and high-pressure reactor, comparing shale pyrolysis experiments under thermogravimetric analysis drying conditions, analyzing the characteristics and laws of shale pyrolysis under different conditions, calculating the kinetic parameters of shale pyrolysis in Longkou area by using Friedman, FWO and KAS methods, and analyzing the efficiency of shale pyrolysis under water medium condition. The activation energies of shale pyrolysis under water medium conditions were obtained by the Friedman, FWO and KAS methods with small differences of 95.68 kJ·min−1, 90.83 kJ·min−1 and 84.00 kJ·min−1, respectively; the activation energy under thermogravimetric conditions obtained by the Friedman method was 189.67 kJ·min−1, and the frequency factor was 4.54 × 1012 s−1, and the shale pyrolysis time was solved by the pyrolysis rate equation at different constant temperatures under aqueous medium conditions. The study shows that the presence of water can significantly reduce the activation energy and frequency factor of shale pyrolysis, shorten the shale pyrolysis time, effectively promote shale pyrolysis, and provide an important theoretical basis for the subsurface in situ transformation of shale.