Combination of Methyl from Methane Early Cracking: A Possible Mechanism for Carbon Isotopic Reversal of Overmature Natural Gas

Table 2

Components and carbon isotopes of gaseous products at different temperatures.

Temperature (°C)	Contents (%)									δ^13C (‰)
	CH4	C2H6 (×10^-1)	C2H4 (×10^-3)	C3H8 (×10^-2)	C3H6 (×10^-3)	iC4H10 (×10^-3)	nC4H10 (×10^-3)	H2 (×10^-1)	N2	CH4	C2H6
425	89.66	0.01	0	0.01	0	0	0	0	10.34	-26.01	/
450	89.65	0.01	0	0.02	0	0	0	0	10.35	-26.08	/
475	89.55	0.01	0	0.03	0	0	0	0	10.45	-25.94	/
500	89.53	0.01	0	0.04	0	0	0	0.01	10.47	-25.71	/
525	89.48	0.01	0	0.04	0	0	0	0.05	10.51	-25.71	-33.78
550	89.44	0.02	0	0.04	0	0	0	0.15	10.54	-25.84	-33.51
575	89.3	0.15	0	0.11	0	0	0	0.21	10.66	-25.74	-33.22
600	89.21	0.39	0	0.20	0	0	0	0.35	10.71	-26.01	-32.74
625	89.12	0.69	0.14	0.37	0.31	0	0.27	0.7	10.74	-25.69	-32.47
650	89.06	1.08	0.19	0.56	0.38	0.24	0.37	1.07	10.72	-25.97	-30.26
675	88.66	3.08	2.33	5.19	2.89	1.68	2.56	2.26	10.75	-25.81	-27.47
700	88.41	4.50	1.14	3.97	0.96	0.97	1.62	3.38	10.76	-25.83	-26.02
725	87.25	10.11	1.05	3.75	0.83	0.90	1.39	5.03	11.25	-25.66	-25.11
750	86.25	9.54	0.86	3.41	0.61	0.67	1.15	7.06	12.00	-25.28	-24.82
775	85.02	8.60	0.58	2.63	0.36	0.45	0.68	8.12	13.28	-25.04	-24.68
800	82.34	7.20	0.22	0.75	0.14	0.24	0.30	9.10	16.02	-24.60	-24.50

/: none detected.