DefinePK

Abstract

The paper presents methodology for determining penetration depth of water jet into gas hydrate deposit and investigation results on influence of water pressure on wall thickness of working column pump pressure, rotation and lifting speeds of working column, diameter of hydromonitor nozzles on penetration depth of high pressure seawater jet into gas hydrate deposit on bottom of the Black Sea. It has been determined that for safe water supply regime at a pressure of 50 MPa, the wall thickness of pipe of the boring column should be less than 0.0065 m. The dependencies for water jet penetration into gas hydrate disperse deposits within a working water supply pressure range of 10 MPa to75 MPa to hydromonitor nozzles. for nozzle diameter of 0.05, the rotation speed of 100 rpm and lifting speed of 1 m/min, have been established. The increase of pressure by about 8 times increases penetration depth of water gets into gas hydrate deposits by no less than two times. The established dependency shows that with an increase of hydromonitor nozzle diameter from 0.01 m to 0.2 m, the radius of penetration depths increases from 0.29 m to 23.85 m, i.e. by 82 times. The study on dependency penetration depth on hydromonitor rotation speed from 20 rpm to 100 rpm, at water supply pressure of 50 MPA, and lifting speed of 1 m/min and a nozzle diameter of 0.15 m have revealed, that expected value is constant and is equal to 15.4 m. The study on influence of lifting speed of hydromonitor in range of 0.5 m/min to 3 m/min, at water supply pressure of 50 MPa, rotation speed of 20 rpm and nozzle diameter of 0.15 m, have revealed that depth of water penetration into gas hydrate body, increases from 8.5 m to 21.3 m, with decreasing speed of monitor lifting. Thus the most rational parameters for jet technology for developing gas hydrate deposits on the bottom of the Black Sea are: Nozzle diameter 0.15 m, hydromonitor lifting speed 0.5 m/min, water supply pressure 50 MPa, rotation speed 20 rpm, the wall thickness of working column 0.065 m. At these parameters, the diameter of destroyed gas hydrate deposit reaches 42 m.