Zong Cheng  
1 College of Construction Engineering, Jilin University, Changchun 130026, China; [EMAIL_ADDRESS] (C.C. ); [EMAIL_ADDRESS] (D.P. ); [EMAIL_ADDRESS] (H.Z. ); [EMAIL_ADDRESS] (B.L. ); [EMAIL_ADDRESS] (C.J. ); [EMAIL_ADDRESS] (C.J. ); [EMAIL_ADDRESS] (Y.C. ); [EMAIL_ADDRESS] (X.Z.) Zong Cheng  
1 College of Construction Engineering, Jilin University, Changchun 130026, China; [EMAIL_ADDRESS] (C.C. ); [EMAIL_ADDRESS] (D.P. ); [EMAIL_ADDRESS] (H.Z. ); [EMAIL_ADDRESS] (B.L. ); [EMAIL_ADDRESS] (C.J. ); [EMAIL_ADDRESS] (C.J. ); [EMAIL_ADDRESS] (Y.C. ); [EMAIL_ADDRESS] (X.Z.) [PERSON]  
1 College of Construction Engineering, Jilin University, Changchun 130026, China; [EMAIL_ADDRESS] (C.C. ); [EMAIL_ADDRESS] (D.P. ); [EMAIL_ADDRESS] (H.Z. ); [EMAIL_ADDRESS] (B.L. ); [EMAIL_ADDRESS] (C.J. ); lixt15@mails.jlu. these NGH exploitation methods have some limitations for NGH reservoirs in the South China Sea, which are characterized by shallow burial depth, non-trap structure, low consolidation strength, non-diagenesis, and low permeability [13; 14]. Hydrate secondary formation and ice formation are easily caused by depressurization [15; 16], which may block the permeability path of the non-diagnetic NGH reservoirs and be unfavorable for long-term exploitation. The main disadvantage of the thermal stimulation method is that the heat utilization efficiency is not high [10; 17]. For the inhibitor injection method, injection of the chemical reagents for NGH recovery is not feasible and economical [4; 18], and the low permeability of the NGH reservoirs will lead to the slow action of chemical reagents on NGH formation. In addition, owing to the weak cementation of the hydrate reservoirs, the above three exploitation methods are based on the principle of direct decomposition of NGH, which easily causes instability of the formation. With respect to the CO\({}_{2}\) replacement method, the production period is long [12; 19], and similarly, the low permeability of the NGH reservoirs has a great impact on mining efficiency. Therefore, the above common methods cannot meet the requirements for safe, long-term, and efficient exploitation of NGH reservoirs in the South China Sea. On the basis of this, an innovative exploitation method, namely, the solid fluidization mining method, which is suitable for exploiting non-diagenesis and weakly cemented marine NGH reservoirs, was proposed by [PERSON] [13; 20]. Figure 2 illustrates the schematic diagram of this method [20]. The hydrate-bearing sediment (HBS) is crushed into fine solid particles by a high-pressure water jet at the bottom of the well, and then the fine particles are transported upward along the drilling fluid to the offshore platform. Finally, methane gas is obtained by decomposition, separation, and other postprocessing operations. Furthermore, the solid fluidization method was successfully applied to the trial production of NGH in the Shenhu sea area of the South China Sea [13; 14]. The successful application of the solid-fluidization method shows that it is feasible to exploit NGH with a high-pressure water jet. Figure 1: Location of natural gas hydrates (NGH) production test in the Shenhu area of the South China Sea. The water jet erosion of HBS is one of the core technologies of the solid fluidization method [13; 14]. However, there are few studies dealing with the water jet erosion of HBS, described as follows. [PERSON] [13] carried out experiments to research the solid fluidization exploitation mechanism of hydrates. In the experiments, the pipeline transport efficiency and the water jet erosion efficiency of HBS were obtained, but they were not discussed in detail. [PERSON] [14] designed nozzle tools for HBS jet erosion and the relationship between the borehole diameter and the breaking rate of NGH were investigated, however, the water jet erosion efficiency of HBS under different operation parameters was not researched.