| Organic-inorganic interaction exists in the process of mineralization of oil,gas,coal and uranium.In the case of coexistence of multiple energy sources in the same basin,petroleum,natural gas and coal provide reduction environment for uranium enrichment and mineralization.Revious studies have shown that uranium has different effects on hydrocarbon generation and evolution of hydrocarbon source rocks of type ?,type ? and type ?,and uranium may also have some effects on hydrocarbon generation and evolution process and products of coal.Coal-bearing basins are abundant in China,and coal-bearing hydrocarbon source rocks are widely distributed.Coal-derived gas plays an important role in China's natural gas industry.Therefore,it is of great practical value and theoretical significance to study the influence of uranium on coal-derived hydrocarbon evolution.In this thesis,uranyl carbonate solution is added to lignite to carry out hydrocarbon generation simulation experiment at 200?,250?,300?,350?,400?and 450?.The possible role of inorganic uranium in coal hydrocarbon generation process is discussed by comparing the parameters of hydrocarbon generation simulation experiment products of lignite samples with and without uranium.The experimental results show that uranium can change the generation rate and yield of liquid hydrocarbon and gaseous hydrocarbon,change the evolution process of coal hydrocarbon generation,and play the role of reformer to the hydrocarbon generation of lignite.The existence of uranium improves the yield of liquid hydrocarbon in the simulating experiment of lignite hydrocarbon generation.Except for individual temperature,the existence of uranium makes the high temperature of condensate oil formation in the simulating experiment of lignite hydrocarbon generation reach earlier,reduces the threshold of oil generation,increases the output of discharged oil and light oil at the peak temperature of hydrocarbon generation,and increases the output of residual oil as a whole in the liquid hydrocarbon generating stage.During the gaseous hydrocarbon generating stage of hydrocarbon pyrolysis,it may accelerate the cracking of liquid hydrocarbons.The presence of uranium is beneficial to increase the proportion of hydrocarbon gas in gaseous products,promote the conversion of long-chain hydrocarbons to short-chain hydrocarbons and unsaturated hydrocarbons to saturated hydrocarbons,increase the proportion of methane in gaseous hydrocarbons,promote H to enter the structure of hydrocarbons,and ultimately increase the degree of dry gasification of gaseous products.At the same time,the existence of uranium is due to the varying degrees of changes in various components of natural gas in the experimental products of coal hydrocarbon generation,resulting in a significant increase in the proportion of H2 in natural gas components,and an increase in the proportion of CO in natural gas products.Uranium promotes the abscission of oxygen-containing functional groups in lignite in the early stage of hydrocarbon generation.The presence of uranium changes the parameters of biomarkers of saturated hydrocarbons,and changes the gas chromatographic and mass spectrometric characteristics of saturated hydrocarbons at different simulated temperatures.Uranium has changed the evolution process of coal hydrocarbon generation.It can not only change the evolution speed of lignite hydrocarbon generation,but also change the functional group structure of lignite hydrocarbon generation.In the low temperature stage,uranium promotes the evolution of lignite hydrocarbon generation,while in the high temperature stage,uranium may play a role in reducing the excessive maturity of organic matter.Therefore,the study of the role of uranium in the evolution of lignite hydrocarbon generation may give some hints to the exploration of coal-formed gas,and may increase the resources and reserves of coal-formed gas.It is helpful to promote the study of coal-formed hydrocarbon mechanism,and it will be helpful to the study of the genetic mechanism of coexistence of multi-energy minerals and the comprehensive exploration of multi-minerals.The development provides experimental materials and theoretical support,which may give new inspiration and thinking to the important issue of the scale and prospect evaluation of oil and gas resources in China... |
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