Study On Pyrolysis Performance And Kinetics Of Crude Oil Components At High-temperature And High-pressure

In recent years, with the rapid development of oil exploration technology, the valuableoil resources in deeper geological formations were found. There is a growing recognition thatthe traditional oil and gas exploration theory "The Economic Deadline" is defective. Whetherfor the exploration and development of oil fields or for the evaluation of oil reservoirs, it isvery important to study oil cracking under geological conditions of high temperature and highpressure.In this thesis, the four subfractions (saturates, aromatics, resin and asphaltene) of crudeoil were used as the material for thermal cracking experiments, in order to eliminate theinfluence of complexity of crude oil on cracking. The effects of such factors as temperature,pressure, time, water and others on properties of thermal cracking of each subfraction wereinvestigated. By analyzing the cracking gas with the gas chromatographic, the yield ofpyrolysis gas is calculated, so we can derive pyrolysis gas production characteristics of thecrude oil four components. By analyzing the liquid pyrolysis products with gaschromatography-mass spectrometry, the composition of the liquid phase pyrolysis productswas determined, then we can demonstrate the mechanism of pyrolysis of crude oilcomponents. At30MPa/24h, within the investigated temperature range, the temperatureincreasing promotes the cracking of crude oil components, pyrolysis gas production rateincreases. In addition, gas production rate of saturates and aromatics have a peak in about470℃, and the maximum gas production rate of the resin and asphaltene also appears at the490℃. At450℃/24h,the pressure increasing promotes saturates pyrolysis, but restrains thepyrolysis of the other three components. Four-component pyrolysis gas rate is with reactiontime at30MPa/450℃, at the first increase, then level off, at last substantially increase. Hradicals provided by outside water can combine with alkyl radicals cleavage of thefour-component, it can also be self-bonding to form H2. So the water involved in the chemicalreaction of the pyrolysis of crude oil, and increase of the yield of hydrogen, the same time in acertain extent increase the yield of hydrocarbons, especially have a marked increase in theyield of methane.The GC-MS analysis results of the saturate thermal cracking residue shows that underdifferent conditions, the obviously different cracking degree and the cleavage product were found. Furthermore, this result is consistent with the gas analysis, demonstrated the importantrole of the temperature, pressure on the thermal cracking of saturates. The chemical kineticssimulations and the calibration to pyrolysis data of the crude oil components showed that thetheoretical value of the crude oil pyrolysis simulation coincides well with the experimentalvalue. In the activation energy of160-350kJ·mol-1range of the four components of crude oil,the pyrolysis reaction is divided into20kinds of first order parallel reactions, the excellentreliability of the model simulation is obtained.