基于颗粒堆积理论的管壁水合物沉积层力学特性研究

管壁水合物沉积层的稳定性与管壁水合物沉积层的力学特性密切相关，研究管壁水合物沉积层的力学特性对深水流动安全保障具有重要意义。为研究管壁水合物沉积层的力学特性，假设沉积层内所有水合物均为大小相同的球形颗粒，且沉积层是由多层水合物颗粒相互堆积而成。根据水合物颗粒堆积方式的不同，将管壁水合物沉积层分为简单立方堆积型、六方堆积型、复六方堆积型、四面体堆积型、角锥堆积型和随意堆积型6类。不同类型的水合物沉积层对应有不同的空隙率和层间受力特性，以此为基础，分别计算分析了各类水合物沉积层的压缩波速、剪切波速、泊松比、弹性模量、抗拉强度，并依据摩尔--库仑强度准则给出了各类管壁水合物沉积层的抗剪强度。同时，计算分析了退火作用对管壁水合物沉积层抗拉强度和抗剪强度的影响。本文研究成果可为油气管道水合物防治技术的发展提供理论支持。

Investigation on the mechanical properties of pipe wall hydrate deposits based on particle packing theory

The stability of pipe wall hydrate deposits is closely related to its mechanical properties. Investigation on the mechanical properties of pipe wall hydrate deposits is of great importance to deep water flow assurance. In order to study the mechanical properties of pipe wall hydrate deposits, it is assumed that the deposits consist of several layers of hydrate particles with a same particle diameter. According to the ways in which hydrate particles are acclimated, the pipe wall hydrate deposits can be divided into the following types, simple cubic packing deposit, orthorhombic packing deposit, rhombohedral packing deposit, tetrahedral packing deposit, pyramid packing deposit and random packing deposit. Different deposit types correspond to different porosities and interlayer mechanical behaviors. Based on this, compressional wave velocity, shear wave velocity, Poissons ratio, modulus of elasticity and tensile strength of different pipe wall hydrate deposits are calculated. In addition, the shear strength of pipe wall hydrate deposits is given according to Mohr-Coulumb failure criterion. The effect of annealing on tensile strength and shear strength is also analyzed. The results and conclusions in this paper can provide theoretical supports for the development of hydrate management strategies in oil and gas pipelines.