Research on Mining Method of Submarine Natural Gas Hydrates Based on a Double-Channel Lift Pump

Abstract

Based on the geological characteristics of the submarine natural gas hydrates storage and the requirement of the mining environment, combined with the deep sea mining technology and the main characteristics of the double-channel lift pump, a new mining method called the mining method of submarine natural gas hydrates based on a double-channel lift pump is proposed in this paper , whose operating principle is that the hydrates are firstly cut into particles and extracted by a spiral reamer of a mining vehicle, next hoisted by a double-channel lift pump to the decomposing pool on the surface, and then decomposed and collected. After the mining method has been introduced, the hydraulic hoisting system parameters such as the pump head of the double-channel lift pump and the hoisting system parameters are analyzed. From calculation and analysis, it is obtained that the gas hydrate particles at the depth of 4000m pumped up to the sea surface require the pump head only 145 m and the working power only 236kw,which can be easily implemented by the existing technology, and the hydrates at the depth of 1000 pumped up to the sea surface just require the pump head about 50 and the working power about 80 kw, which the existing double-channel slurry pump can meet the requirements. Because the density of the mixture flow of the gas hydrates, the seafloor surface sediments and the seawater is similar to the seawater, the transportation mode that the hydrates are transported as ore slurries directly can ensure that the hoisting system keep working steadily and reliably for a long time. It is proved theoretically that the mining method is suited to exploit the submarine natural gas hydrates.