Kinetics Of Carbon Isotope Fractionation In The Process Of Organic Thermally Cracking Into Natural Gas And Its Application

Qijia-Gulong area, located in north Songliao basin and west Changgeng, constructed by Qijia and Gulong sunken areas, and have developed many mature hydrocarbon source rocks (HSR). In this work, the HSRs were investigated from aspects of abundance of organic matter, type and maturity, and we found that the these HSRs are capable of generating hydrocarbon.Using chemical kinetics theory (CKT) and generation potential of hydrocarbon (GPH) method, we have systematically investigated the rock areas quantitatively. The productivity of generating hydrocarbon of the HSR areas was calculated in various terranes and time. Based on the CKT, the results was obtained as follows: the total amount of oil generated in the area is 717.13×10⁸t, the total amount of oil expulsion is 505.34×10⁸t, the total amount of gas generation is 59.99×10¹¹m³, and the total amount of gas expulsion is4.26×10¹¹m³. From the GPH calculation, the total amount of oil generation in the area is 672.13×10⁸t, and the total amount of oil expulsion is 485.75×10⁸t.Through the investigation of the history of oil generation and expulsion, and the threshold of generating and expulsing oil, we found that the threshold depth of oil generation for the main HSR is 1500m, which is about 300m deeper than other's previous work. This result should be beneficial to the oil mining industry of this area.Based on the analysis of effects of the rupturing strip, singular high pressure, and the ancient construction on the accumulation of oil and gas, we obtained that Qijia-Gulong sunken areas belong to the oil source rupturing model. By the comparison of oil and gas source, the Fuyang oil layer mainly has the model of up-layer generation and down-layer accumulation. The Putaohua oil layer developed a mode of up-layer generation and up-layer accumulation. However, in the high areas of construction like Longhupo, a self-generation and accumulation mode was developed. These results should be helpful for the further understanding of the oil and gas generation in the HSR areas.