Analysis On Seepage Law Of Oil In Open Hole Oil Well In Coal Rock Mass

CoalThere are a large number of overlapping areas of coal and petroleum resources in the central and western regions of China.In the process of coal resources exploitation,early abandoned oil wells have a significant impact on the safe and efficient mining of mines,increasing potential safety risks and exploitation risks.Among them,a variety of toxic and harmful gases are generated in abandoned oil wells with a long history,and a large amount of enrichment is formed in coal and rock mass through seepage,which poses a great threat to the life safety of workers in the wells.Therefore,it is of great significance to study the percolation range and shape,percolation speed and pressure variation of oil in coal and rock mass in open-hole abandoned oil wells,and to determine the diffusion law of toxic and harmful oil-type gas produced by abandoned oil wells,so as to control the disasters of abandoned oil wells.Based on the engineering background of the 10104105 working face of Shuangma C.oal Mine and the abandoned petroleum well of Matan 31,this paper combines the mechanical characteristics analysis of coal and rock mass in the laboratory,the similarity experiment in the laboratory and the numerical analysis.Secondly,through the analysis of field monitoring results.Finally,according to the combination of laboratory and field,the seepage law of oil in abandoned oil wells in coal and rock mass is studied.Research shows:1 The diffusion range of oil-type gas produced by waste petroleum is larger than the percolation range of waste petroleum in coal and rock mass.Waste petroleum is the source of toxic and harmful gases,so the diffusion range of oil-type gases through physical and hemical reactions is larger than the percolation range of waste petroleum.2 Oil seepage from abandoned oil wells in coal and rock mass forms an ellipsoid centered on oil wells.The seepage radius of the ellipsoid is 240-260m,and the diffusion radius of oil-type gas is more than 260.Combined with field monitoring results and numerical analysis,it can be concluded that the seepage radius of the ellipsoid is less than 300m.3 The seepage velocity of petroleum in abandoned oil wells in coal and rock mass is relatively small,and the seepage velocity in rock mass is less than that in coal mass.When the pressure is 10 MPa,the average seepage velocity of waste petroleum in coal is 8 m/a.The pressure change in abandoned oil wells increases first and then tends to be stable.Finally,a dynamic equilibrium system is formed with coal and rock mass.Laboratory tests and field monitoring analysis show that the pressure in abandoned oil wells of Matan 31 is about 10 MPa.