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The technology of TCP combined well testing is widely used in deepwater perforation and can cause string damage accidents. In order to improve the safety of the perforating string ANSYS/LS-DYNA software was used to analyze the influence of different parameters such as number of ammunition, tubing length, and the choice of perforation technology, on the tubing strength and deformation. Numerical simulation results show that the most vulnerable segment of the tubing is located at the bottom of the tube. The tubing length parameter can be effectively used to reduce the risk of tubing damage. The simulation model was verified by a field application case study. [ABSTRACT FROM AUTHOR]

The successful offshore hydrate production tests in the South China Sea proved the high productivity of clayey-silty hydrate reservoirs. However, the mechanical characteristics of these clayey-silty sediments have not been comprehensively investigated since the concerns about the productivity of such low-permeability reservoirs. In this study, based on the sediment matrix from the South China Sea, specimens were remolded with a porosity of 41% and hydrate saturation of 30% to perform a comprehensive mechanical investigation from micro to macro. Microcosmically, the hydrate in the clayey-silty sediment presents patchy distribution, being particle-displacive and particle-wrapped segregated hydrate morphology. Macroscopically, the compression and swelling indices of hydrate-bearing sediments in the South China Sea are obtained for the first time, which are larger than that of the hydrate reservoir in Krishna-Godavari Basin. The increasing effective confining pressure can slightly reduce the strain-softening and dilation characteristics of the hydrate-bearing sediments in the South China Sea. What's more, the failure strength and stiffness increase with an increasing effective confining pressure, while the failure volumetric strain firstly increases and subsequently decreases with an increasing effective confining pressure. These results are essential input parameters to establish a constitutive model and numerical simulations. • Hydrate presents particle-displacive and particle-wrapped in the clayey silt. • The compression and swelling indexes of hydrate reservoir in the South China Sea are obtained for the first time. • Increasing burial depth can reduce the strain-softening and dilation of the hydrate reservoir in the South China Sea. [ABSTRACT FROM AUTHOR]