深水气井测试水合物临界沉积粒径及敏感因素

针对水合物颗粒与管壁之间的浸入态与非浸入态两种情况,分析水合物颗粒形成后影响沉积的黏附力和拖曳力因素,建立水合物颗粒沉积过程中的力学模型,在此基础上提出以固固黏附力为主作用力、不发生滚动移除为基本准则的水合物颗粒临界沉积条件判别方法;结合深水气井测试实际工况,分析温度、压力、气相产量、液相产量、流通管径等参数对水合物颗粒移除力矩与黏附力矩的影响。结果表明:水合物颗粒在沉积过程中存在临界粒径,水合物颗粒粒径小于临界粒径时可进一步沉积,否则会在外力作用下被移除;随着温度、气相产量增加,水合物颗粒沉积粒径减小,而压力、液相产量、流通管径增加,水合物颗粒沉积粒径增大;气相产量对水合物临界沉积粒径影响占主导因素。
For the two kinds of immersion and non-immersion states between hydrate particles and pipe wall, the impacts of adhesion stress and drag stress on hydrate deposition were analyzed respectively. And the mechanical model of the hydrate particles deposition was established. Based on the solid adhesion force as dominate stress and the non-rolling removal as the basic criterion, a method for judging critical deposition of hydrate particle was proposed. In combination with the practical conditions of the deep water gas well test, the effects of production parameters on removal torque and adhesion torque of hydrate particles, including temperature, pressure, gas production rate, liquid production rate and circulation pipe diameter were investigated. The results indicate that hydrate particles have critical sizes in the deposition process. When the hydrate particle size is smaller than the critical particle size, it can be further deposited. Otherwise, the hydrate particles would be migrated under external forces without deposition. Temperature and gas production rate are negatively correlated with the critical deposition size of hydrate particle. While pressure, liquid flow rate and circulation pipe diameter are positively correlated with the critical deposition size of hydrate particle. Gas production rate plays a dominant role in the critical deposition diameter of hydrate particle