Influence And Mechanism Analysis Of Air Catalytic Oxidation On Heavy Oil Properties

With the rapid consumption of conventional oil and gas resources in the world,the proportion of heavy oil resources in the overall oil and gas resources is getting higher and higher,and the efficient development of heavy oil has received more and more attention.According to the sensitivity of heavy oil to temperature,most of the heavy oil development uses thermal recovery methods,such as steam injection thermal recovery,In-Situ Combustion and its derivative thermal recovery technology.However,conventional thermal recovery technology resources are consumed in a large amount,and the degree of use of the reservoir is low.In response to these problems,the idea of in-situ upgrading of heavy oil has been continuously proposed.It is hoped that heavy oil can be upgraded in the process of oil layer flow,achieving the goal of irreversible viscosity reduction.Aiming at this idea,this paper is based on the air oxidation synergistic catalysis of catalyst and viscosity reduction thermal recovery technology.The static and dynamic experimental schemes are used to simulate the different reservoir conditions that may be encountered during the development process,and the reaction principle is briefly analyzed.As a widely distributed resource,air does not need to consider the geographical environment and transportation condition of the mine if air is used as a gas source during the development process;static experiments simulate cracks and caves in carbonate reservoirs or that storage spaces are anisotropic,heterogeneous,and poorly permeable reservoirs in sandstone reservoirs;dynamic experiments simulate uniform reservoirs,good permeability,and smooth advancement of displacement fronts during production.During the experiment,the effects of catalyst type,catalyst dosage,reaction temperature,time,pressure and hydrogen honor were screened,and the viscosity,composition,acid value and recovery of heavy oil before and after the reaction were collected and analyzed.In order to facilitate the analysis and comparison,the experimental conditions of the static and dynamic experiments are controlled at the same level except for the different equipment.Through the analysis of different experimental schemes and test results,it is concluded that the oxidation of heavy oil under static experiment leads to the increase of viscosity of heavy oil,but the dynamic experiment under the same conditions can achieve the purpose of viscosity reduction.Because of the filtration and adsorption of heavy components by quartz sand under dynamic experimental conditions and the uniform distribution of heavy oil in the reaction tube,the comparison results of the catalytic effects in the seven catalysts provided are:oil-soluble catalyst>dispersed catalyst>water-soluble catalyst,wherein the four oil-soluble catalysts have the best effect when the amount of manganese naphthenate catalyst is 0.2%by mass;under the condition of indoor dynamic simulation and the condition of air pressure of 2MPa,temperature is higher than 350? and addition of decalin as a hydrogen donor,the sample recovery can reach more than 85%,and the sample viscosity reduction rate is above 98%.The key to the catalytic oxidation of heavy oil is the synergy between the catalyst and the hydrogen donor.The catalyst can promote the cleavage of heavy oil macromolecules to generate a large number of small molecule radicals.The hydrogen donor provides a large number of hydrogen atoms that are easily trapped by free radicals to quench the free radicals to prevent the polymerization between free radicals and active macromolecules.The active molecule is simultaneously diluted to reduce the probability of occurrence of a chain reaction between the active molecules.Eventually the asphaltene component is reduced and the viscosity of the crude oil is greatly reduced.