<font size="3"><font face="Times New Roman">Thermochemical sulfate reduction font>font-family: 宋体; mso-ascii-font-family: ’times new roman’; mso-hansi-font-family: ’times new roman’">(<font face="Times New Roman">TSRfont>font-family: 宋体; mso-ascii-font-family: ’times new roman’; mso-hansi-font-family: ’times new roman’">)<font face="Times New Roman"> might alter the stability of oils and the yield of cracked gas in reservoirs because its reaction pathway or mechanism differs from that of oil cracking. In order to ascertain the effect of TSR on the generation of cracked gas from oils, we performed a series of non-isothermal pyrolysis experiments involving different sulfates and an oil font>font-family: 宋体; mso-ascii-font-family: ’times new roman’; mso-hansi-font-family: ’times new roman’">(<font face="Times New Roman">QB3font>font-family: 宋体; mso-ascii-font-family: ’times new roman’; mso-hansi-font-family: ’times new roman’">)<font face="Times New Roman"> with a gold-tube system. The generation of considerable amounts of non-hydrocarbon gases font>font-family: 宋体; mso-ascii-font-family: ’times new roman’; mso-hansi-font-family: ’times new roman’">(<font face="Times New Roman">including H2 Sfont>font-family: 宋体; mso-ascii-font-family: ’times new roman’; mso-hansi-font-family: ’times new roman’">)<font face="Times New Roman"> indicates that TSR is in- itiated by the presence of gypsum and magnesium sulfate font>font-family: 宋体; mso-ascii-font-family: ’times new roman’; mso-hansi-font-family: ’times new roman’">(<font face="Times New Roman">MgSO4font>font-family: 宋体; mso-ascii-font-family: ’times new roman’; mso-hansi-font-family: ’times new roman’">)<font face="Times New Roman">. Comparatively, the yield and generation activation energy of gaseous hydrocarbons are not obviously affected by TSR involving gypsum. Whereas TSR involving MgSOg leads to about 13.1% decrease in the methane yield and also a remarkable decrease in the stability of C2font>font-family: 宋体; mso-ascii-font-family: ’times new roman’; mso-hansi-font-family: ’times new roman’">+<font face="Times New Roman"> , and the addition of MgC12 to the MgSO4 system results in a further increase in the H2S yield but a further decrease in the hydrocarbon gas yield. Moreover, the redox reaction be- tween C2font>font-family: 宋体; mso-ascii-font-family: ’times new roman’; mso-hansi-font-family: ’times new roman’">+<font face="Times New Roman"> and actively structured HNO4 - can take place in the MgSO4 pyroysis system, which is attributed to an important cause for decreasing the yield of gaseous hydrocarbons. Therefore, the effect of TSR on the generation of cracked gas is significantly domina- ted by sulfate types and the concentration of active species in formation water.font>font>