A Study On The Effect Of Chlorizated Salts On Hydrocarbon Generation Process

In order to investigate the effect of chloride salts on the process and mechanism of hydrocarbon generation,this paper selected source rock samples of upper Ganchaigou Formation from Well Nan-9 in western Qaidam Basin to do pyrolysis experiments with different salinity of sodium chloride,magnesium chloride and calcium chloride respectively,and calculated the kinetic parameters of hydrocarbon generation.The result shows this three kinds of chloride decreased the amount of pyrolysis hydrocarbon and hydrocarbon generation rate under the open system.In addition,selected the kerogen samples in Well Liang-5 of western Qaidam Basin to carry out the simulation experiments of hydrocarbon generation with distilled water and NaCl solution in gold tube confining system,to simulate the hydrocarbon generating characteristics of source rocks in freshwater and saltwater environments.Then analyze the influence on the hydrocarbon productivity and hydrocarbon generation kinetic parameters in detail.According to the hydrocarbon generation simulation experiment,sodium chloride plays a significant role in promoting,which cause the hydrocarbon generation stage in advance and promote the generation of oil and gas in the early stage of kerogen evolution.After the peak period of hydrocarbon generation,sodium chloride has a certain inhibition action on organic matter evolution.Through the calculation of hydrocarbon generation kinetic parameters,the activation energy range of methane and gaseous hydrocarbon was narrowed,and the activation energy was concentrated to the high value,while the activation energy range of C6-14 became wider and more dispersed.In the saline lake of the Paleogene and Neogene in western Qaidam Basin,the maturities of the most of hydrocarbon source rocks are within the oil window,the hydrocarbon source rock evolution is presents a distribution patter of two-stage hydrocarbon generation,which has a well corresponding relationship with two distinct sedimentary cycles of salty.Especially the hydrocarbon generating rate of low-mature oil in shallow layers is higher than the general freshwater lacustrine source rocks,indicating that salt reducing environment have particular transformation effects on the source rock organic matter,thereby reducing the reaction activation energy and promoting the formation of oil and gas.Finally build up a model of organic matter evolution and oil and gas generation in salt water environment.