Experimental Study On The Genetic Mechanism Of Dibenzofuran Compounds In Source Rocks

Dibenzofuran（DBF）,as a very common and important compound of organic matter during oil and gas exploration,has been widely used in the identification of deposition environments of organic matter.At present,there is a preliminary study on the forming environment and chemical mechanism of DBF,it is believed that a relatively large amount of DBF can indicate a more oxidized depositional environment,but the research on its formation mechanism needs to be further studied.In this thesis,the formation mechanism of DBF in source rocks will be experimentally studied through the high temperature and high pressure tests using gold tubes.The thermal simulation test is a series of organic-inorganic reactions about biphenyl（BP）and various metal oxides（Fe₂O₃,Fe₃O₄,Mn O₂,Mn₃O₄）.The reaction results show that the metal oxide as an oxidizing agent can oxidize the organic matter BP as a reducing agent to form DBF whether with water or not.It is believed that in the diagenesis stage of organic matter,if these metal oxides of iron and manganese are present,BP in the organic matter can be oxidized and converted into DBF.According to the products of a series of oxidation reactions,in the process of BP to form DBF,it is possible to produce a series of hydroxybiphenyl compounds.As the oxidation progresses,2-hydroxybiphenyl will be further oxidized to form DBF.However,hydroxybiphenyl may not be the necessary intermediate for the formation of DBF from BP,and some,or even most,of the DBF will be produced by BP through other oxidative pathways.For the reaction system,the factors affecting the formation of DBF are mainly the strength of the oxidizing environment,the water content and the reaction temperature.The amount of DBF produced in the manganese oxide,especially the most electronegative one,Mn O₂ as the reactant,the amount of DBF is significantly larger than the experimental system of iron oxide as a reactant,which proves that DBF has a higher oxidation state,which can indicate a relatively strong oxidizing environment.Before the DBF reached its generating peak,the factor that has the greatest impact on its production is water.The presence of water promotes the rate of BP to generate DBF.At low temperatures,the formation of DBF is not obvious changed with temperature.It can be considered that the formation of DBF is not affected by the deepening of organic matter evolution stage during the diagenesis stage until it reaches the early stage of catagenesis.9-fluorenone as an oxygen-containing organic compound with a large output of the reaction products can also react to the extent of the oxidation reaction.In a normal situation,some organic matter oxidized in the air can form 9-fluorenone.In the high temperature,the organic matter BP under the action of metal oxide can be oxidized to form 9-fluorenone.The presence of water will inhibit the formation of 9-fluorenone and reduce the yield of 9-fluorenone.