Clarifying the creep behaviors of hydrate-bearing sediment (HBS) under long-term loading is crucial for evaluating reservoir stability during hydrate exploitation. Figuring out a way of characterizing deformation behaviors and their geophysical responses to HBS is the basis for modeling creep behaviors. In this study, we propose a novel device to test time-dependent deformation and the ultrasonic response of HBS under high-pressure and low-temperature. The experimental device consists of a high-pressure chamber, an axial-load control system, a confining pressure system, a pore pressure system, a back-pressure system, and a data collection system. This testing assembly allows temperature regulation and independent control of four pressures, e.g., confining pressure, pore pressure, back pressure, and axial loading. Columned artificial HBS samples, with a diameter of 39 mm and a height of 120 mm, can be synthesized in this device. Afterward, in situ creep experiments can be achieved by applying stable confining pressure and axial load, together with geophysical signals acquisition. During loading, the stress–strain relationships and ultrasonic data can be obtained simultaneously. Through analyzing the stress–strain relationship and ultrasonic data, the macroscopical failure and microcosmical creep deformation law of the samples can be figured out. Preliminary experiments verified the applicability of the device. The method provides some significance for field observation of reservoir failure via geophysical techniques during hydrate exploitation.

The process of extracting natural gas from gas hydrate‐bearing sediments (GHBS) may yield significant sand influx due to the metastable nature of GHBS. Selecting appropriate sand control media is vital to addressing the challenges caused by excessive sand production. This study proposes a protocol called holding coarse expelling fine particles (HCEFP) for sand control design. The protocol aims to provide a new optimization method for screen mesh size selection for clayey silt hydrate reservoirs. Detailed optimizing procedures of proper candidate screen mesh sizes in hydrate exploitation well in clayey silt hydrate reservoirs are depicted based on the HCEFP. Then, the site W18, which is located in the Shenhu area of the northern South China Sea, is taken as an example to illustrate the optimization procedure for screen mesh size selection. The results reveal that complete solid retention via a standalone screen is rarely beneficial as high clay contents can adversely affect wellbore productivity due to excessive plugging. Screen aperture size selection for clayey silt hydrate wells should strike a balance between retaining coarser particles and avoiding screen blockage by the relatively fine particles. Furthermore, longitudinal heterogeneity of the PSDs also increases the difficulties associated with sand control design. Multistage sand control optimization is necessary in hydrate production wells. For Site W18, we recommend that the entire production interval can be divided into two subintervals for multistage sand control operations.