Organic Matter Evolution And Hydrocarbon Generation Characteristics Of Oil Shale During Rapid Heating At Atmospheric Pressure

In recent years,in-situ conversion technology has gradually enabled oil shale resources to be exploited on a large scale with broad prospects.In this paper,the oil shale and coal in Minhe,Junggar,Huangxian,and Meihe Basins are selected under the background of rapid heating at atmospheric pressure to study the thermal evolution and production products of different types of organic matter.The effects of organic matter evolution and hydrocarbon generation products provide theoretical guidance for the in-situ production of different types of oil shale.Through two sets of tests to analyze the characteristics of oil water,gas production,and semi-coke in different heating stages,the products of pyrolysis of organic matter in different heating stages are obtained.The first stage produces water and a small amount of gas.The second stage mainly produces oil and gas.Only a small amount of gas is discharged in the third stage,and the optimal heating time is 30 minutes.The heating products of samples based on different types of organic matter and different heating times show that the main products in the initial heating stage I-II(room temperature-300 ?)are water and a small amount of gas;the intermediate heating stage III-VI(300 ?-475 ?)The products are oil and gas;in the late heating stage VII-VIII(475 ° C-520 °C),only a small amount of gas is discharged,but a large amount of carbon remains in the sample after the final heating,and the oil and gas conversion rate of organic matter is about50%.During the heating process,the organic geochemical parameters of different types of oil shale and coal show a certain pattern,and the organic matter abundance of different types of oil shale gradually decreases during heating,while coal is the opposite,and The change is greatest during the heating stage II;as the heating temperature increases,the fluorescence of organic micro-components such as algae gradually disappears,the organic hydrocarbon generation potential gradually decreases,and the greatest reduction occurs during the main oil and gas generation stage Under the background of rapid temperature increase in the open system,the initial heating causes the organic matter to be basically in the immature-low maturity stage,the organic matter in the middle heating stage is in the maturity stage,and the organic matter is in the high maturity-over-mature stage in the later stage of heating.The samples with different heating time showed a similar trend in general,which basically shows that the temperature is the key factor affecting the hydrocarbon expulsion during the rapid heating process.By drawing organic matter type,organic matter hydrocarbon generation and expulsion and other discriminant maps,it is shown that Minhe oil shale contains type I kerogen,Huangxian,Junggar and Meihe oil shale contains type II kerogen,and Meihe coal sample contains type III cheese,raw The oil capacity gradually weakens.The heating temperature of 300 ? promotes the organic matter to enter the oil generation window,and reaches the maximum hydrocarbon expulsion stage at about 440-475 ?.The proportion of oil and gas discharged by different organic matter types is different.The increase of heating time leads to the peak of hydrocarbon generation Migrating to low temperature areas,but the reduction is not large.Taking the thermal evolution of products and organic matter in the warming process of oil shale and Meihe coal in Minhe as an example,a hydrocarbon generation pattern map of oil shale and coal under the background of rapid heating in an open system was established,thus enriching the theory of hydrocarbon generation in source rocks It will provide some theoretical guidance for the in-situ conversion technology of oil shale.