The Effect Of Uranium On The Hydrocarbon Generation In A Closed System

In the Oil and Gas basins,the formation of organic oil and gas through long geological evolution is a very complicated process.In this process,it's accompanied by variety of roles,such as geological and geochemical effects,organic-inorganic interaction,and by a variety of geological environment and physical and chemical constraints,such as hydrocarbon system closed or not,the temperature,pressure,source rock mineral,fluid media et al.The distribution of radioactive uranium elements in the Ordos basin,which is typical of multiple energy and mineral enrichment areas in China,has a good correlation with the distribution of high quality source rocks.In understanding the organic matter has a strong adsorption of uranium,complexation and enrichment of uranium deposits,mineralization to form a good reduction environment at the same time,the presence of uranium elements also act on the hydrocarbon source rock evolution process.In order to clarify how the inorganic matter interacts with organic matters in their interaction,this paper has carried on the related simulation experiment by using different types of immature source rocks in Biyang Sag and Ningnan Basin.As the uranium nitrate solution has a great influence on the experimental results,we chose the uranium carbonate solution to react with different types of source rocks in thermal simulation experiments,after experiments we compared and analyzed the results.By investigating the distribution of uranium content in typical oil and gas basins in China,it is found that they generally contain higher uranium anomalies,so we decided using a higher concentration of uranium in the common formation.The experimental instrument uses stratified pore autoclave hydrocarbon generation simulation device.Experimental results show that the addition of UO2CO3 solution can effectively promote the final yield of oil and gas in hydrocarbon source rock;it can make the exogenous hydrogen more easily into the hydrocarbon generation process,made the product has the characteristics of saturated hydrocarbon;it could promoting the breaking of long-chain hydrocarbons,made the higher carbon numbers are broken into short chain hydrocarbons;the dry gasification of the products can be increased,the hydrocarbon yield in the simulation experiment can be improved;and the total gas production is increased after the addition of UO2CO3.The uranium can promote the formation of liquid hydrocarbons in source rocks,and improve the yield of liquid hydrocarbons during the low temperature stage.The addition of UO2CO3 solution can significantly promote the hydrogenation of olefins and reduce the content of olefins in the final product.The addition of UO2CO3 solution could increase the content of aromatic hydrocarbons in the products,reduce the ratio of saturated hydrocarbons to aromatic hydrocarbons in the products,promote the maturation of organic matter,made the molecular characteristics of the thermal simulation products of the source rocks are more close to the characteristics of low-mature oil in China,indicating that the presence of uranium is favorable for organic matter to form low mature oil and gas.The addition of UO2CO3 solution can significantly change the gas chromatographic characteristics of the hydrocarbon products,indicating that the presence of uranium can reduce the hydrocarbon generation threshold of hydrocarbon species in advance.It can reduce the number of carbon atoms,maintaining the organic matter at arelatively low level of maturity.The results show that with the increase of the concentration of UO2CO3 solution,the catalytic ability of the organic matter is also increasing.However,when the concentration of UO2CO3 solution reaches 200ppm,it's no longer have the ability to catalyze.