Mechanical Properties of Hydrate Reservoir Overburden Layer Regulated by Biopolymers

The stability control of caprock in shallow deep water gas reservoirs is crucial for ensuring the safe development of natural gas hydrates and the efficient utilization of shallow gas resources. This study proposes the use of low-concentration biopolymers to regulate the mechanical behavior of soil, and a series of rheological, consolidation, and shear tests were conducted. The key findings are as follows: (1)The biopolymer solution exhibits a nonlinear increase in both viscosity and shear stress with increasing mass concentration. (2) The biopolymer specimen demonstrates a 28% reduction in compression index and a 53% enhancement in swelling index. (3) During the shear test, the specimen displays strain-hardening behavior, with nonlinear increases in strength and stiffness, achieving a maximum improvement in breaking strength of approximately 10%. (4) Based on the scanning electron microscopy (SEM) analysis, it is evident that xanthan gum forms a cohesive matrix by covering and connecting soil particles, consequently enhancing the mechanical strength. Since hydrate overburden layers are particularly failure-prone, biopolymer reinforcement demonstrates critical significance for commercial mining by substantially improving caprock stability. The results confirm biopolymers’ superior performance in maintaining hydrate reservoir integrity, offering a feasible solution to mitigate overburden damage risks during gas production