注空气管内原油蒸气爆炸过程数值分析

 在注空气采油生产过程中,必须高度重视可燃油蒸气的爆炸问题。本文借助AutoReaGas气体爆炸模拟软件对注空气管内原油蒸气在高压状态(30MPa)不同初始温度下发生爆炸的过程进行了数值模拟。结果表明,爆炸产生的超压可达450MPa,温度可达2400K,会对油管和井口采气树等设施造成严重破坏;管内爆炸超压值与初始温度关系密切,在爆炸冲击波与反射波未叠加前,初始温度升高会导致爆炸超压的下降,在叠加区域内爆炸初始温度升高会导致爆炸超压的明显升高,750m远处压力基本不再变化;初始温度对爆炸温度影响甚微,初始压力为30MPa时,无论初始温度多大管内温度在距井口600m以后都恢复到初始温度。分析可知,爆炸只会造成充气区域及其附近管段内压力和温度急剧升高,对远场作用不明显。

Numerical Simulation of Crude Oil Vapor Explosion in Air Injection Pipe

The air injection is an issue much studied and with a large amount of field practice experience, as it is an efficient way for oil recovery from the oil-gas reservoirs with low permeability. The flammable gas explosion should be considered during the process. In order to study the explosion scope and the explosion intensity, numerical simulations on the crude oil vapor explosion in the air injection pipeline under 30 MPa with different initial temperatures were conducted with the help of software AutoReaGas. The model is established according to an air injection pipe in an oilfield. The initial conditions are the typical parameters in the production process, such as the pressure 30MPa, the temperatures 20 ℃,45 ℃ and 90 ℃. The explosion temperature and the overpressure are analyzed as the two important parameters. It is found that after the explosion, the overpressure will reach 450 MPa and the temperature will reach 2400 K, which will do a great harm to the oil pipe and the Christmas Tree. The overpressure in the pipe is closely related to the initial temperature. The overpressure decreases when the initial temperature increases before the superposition of the explosive wave and the reflected wave, while the overpressure increases evidently when the initial temperature increases after the superposition area. However, the overpressure in the area more than 750m away will almost be zero. The initial temperature has little effect on the explosive temperature. When the initial pressure is 30 MPa, the temperature in the pipe will be back to the initial temperature in the area more than 600m away no matter how high the initial temperature is. It is concluded that only in the area filled with gas and the nearby area, the pressure and the temperature will rise after the explosion, the far away areas are little influenced.