oa Effects of Heating Rate, Hydrogen and Pressure on Kerogen Pyrolysis: Implications for Hydrocarbon Generation During Magma Intrusion

The thermal evolution of source rocks was influenced by multiple factors in geological conditions. However, studies on their synergistic effects remained limited. In this work, the yields and distributions of kerogen pyrolysates at two heating rates (Fast (F) and Slow (S)) and two gas types (He and H2) at different pressures (10∼400 psi) were contrasted. The results indicated that slow heating rate increased aliphatic yields and saturation index of aliphatics (SIA). Using H2 to replace He increased the pyrolysate yields. Increasing helium pressure (PHe) or hydrogen pressure (PH2) at fast heating rate significantly promoted the formation of aromatics. Increasing PHe or PH2 in F-He, F-H2 and S-He modes decreased aliphatic yields. Increasing PH2 in S-H2 mode promoted n-alkanes with low carbon numbers, but inhibited n-alkanes with high carbon numbers. Increasing PHe or PH2 in any mode always increase SIA and isomerization index (ISO) values. Additionally, the enrichment of polycyclic aromatic hydrocarbons in igneous-influenced crude oil was not only affected by abnormal heat but also high geofluid pressure. The absence of n-alk-1-enes in crude oils may be related to slow geological sedimentation, hydrogen and high geofluid pressure.