深水气井测试返排阶段水合物生成及防治研究

Study on the formation and prevention of hydrate in the backflow stage of deep water gas well test

清井返排是深水气井测试流程的重要阶段,该阶段管柱内水合物的生成及堵塞问题一直是安全测试研究的重点。从水合物生成、生长、沉积、堵塞的微观机理分析出发,结合清井返排的具体阶段,首次将水合物形成与管柱气液流型结合研究不同流型下水合物形成流动障碍的风险大小。研究结果表明,泡状流、段塞流、搅拌流下水合物形成流动障碍的风险较小,环状流下仍然具有形成测试管柱堵塞的风险,须进行合理的测试参数设计,并在不同阶段实施防控措施,从而有效避免水合物堵塞事故。本文研究成果可为现场测试施工提供理论支撑。

Well cleaning and backflow is one of the important stages of deep water gas well testing.The forming and clogging of hydrate in the string has been the focus of safety test research in the long term.Based on the microscopic mechanism analysis of hydrate formation,growth,deposition and clogging,combined with the specific phases of well cleaning and backflow,this paper innovatively proposed to integrate the formation of hydrate with the gas-liquid flow patterns of the string to study the risk of flow barrier caused by hydrate formation under different flow patterns.The results show that the risk of forming flow barrier under bubble flow,slug flow and agitation flow is reduced.However,there is still a risk of test string blockage under annular flow.Therefore,proper test parameter design must be carried out and the preventive measures shall be implemented at different phases to effectively avoid hydrate blockage accidents.The research results in this paper can provide theoretical support for on-site test operation.