Effect of analcime on hydrocarbon generation for type I kerogen in organic-rich shale by semi-open pyrolysis

Analcime, a key mineral especially in organic matter-rich sediments, plays a critical role hydrocarbons generation from kerogen. However, its effect on hydrocarbon generation from type I kerogen remains unclear. In this study, semi-open thermal simulation experiments were conducted on lacustrine shale to investigate the relationship between analcime and hydrocarbon generation. Semi-open pyrolysis experiment was performed on type I kerogen in organic-rich shale containing of 15 %, 27 %, and 35 % analcime concentrations across a temperature range of 300 degrees C to 500 degrees C. The analcime collected from the study area is sedimentary and diagenetic, characterized as low-silica analcime formed by chemical reactions between clay minerals and sodium-rich alkaline water. Results demonstrate that increasing analcime contents significantly enhances hydrocarbon yields of oil and gas while reducing activation energy, indicating that analcime accelerates hydrocarbon generation from kerogen. However, the durations of hydrocarbon generation appear to decline with increasing analcime contents. Thus, analcime influences hydrocarbon generation by increasing the conversion rate and reducing the generation cycle primarily due to its catalytic effects. Specifically, analcime promotes organic matter decomposition through acidic catalysis and adsorption, establishing an efficient catalytic system.