Model of hydrocarbon gases generation from typical brown coal with transitional organic matter type of Ⅱ 2-Ⅲ

Abstract：By using self-developed DK-Ⅱ hydrocarbon generation and expulsion simulation experimental instrument,the hydrocarbon gases generation from typical brown coal with transitional organic matter type of Ⅱ 2-Ⅲ was studied under a confined spatial system of different temperature and pressure with episodic close and open.Three stages of hydrocarbon gases generation for typical brown coal with transitional organic matter type of Ⅱ 2-Ⅲ were revealed.The results show that the early period of oil window(Ro≤0.82％) is a stage of oil generation associated with hydrocarbon gases.The yield of hydrocarbon gases is obviously lower than that of oil,which is 23.69 kg/tc in total.The hydrocarbon gases consists of only CH4,C2H6 when Ro is 0.50 ％,and CH4,C2 H6,Ca H8,iC4 H10,nC4 H10,iC5 H12 and nC5 Hi2 when Ro is in the range of 0.60％-0.82％.The middle-late period of oil window (0.82 ％＜Ro≤1.30％) belongs to a stage of hydrocarbon gases generation associated with oil.The yield of hydrocarbon gases is obviously higher than the yield of oil,which is totally 35.19 kg/tc.The compositions of hydrocarbon gases are CH4,C2 H6,C3 H8,iC4 H10,nC4 H10,iC5 H12 and nC5 H12 during this stage.The period of high-post maturity is the main hydrocarbon gases generation stage,and the total yield of hydrocarbon gases is higher than 142.73 kg/tc.The hydrocarbon gases in this stage is composed of not only CH4,C22 H6,C3 H8,iC4 H10,nC4 H10,iC5 H12 and nC5 H12,but also a little C3H6.The results provide evidence for reasonable evaluation of coal-formed gas resource with transitional organic matter type ofⅡ 2-Ⅲ at different evolution stages.