某深水油田集输管线水合物生成预测及防治*

Prediction and Prevention of Hydrate Formation in Gathering and Transportation Pipeline for a Deepwater Oilfield

张在孝 张 雪 陈立涛 江 鑫 师浩林 薛迦文

ZHANG Zaixiao ZHANG Xue CHEN Litao JIANG Xin SHI Haolin XUE Jiawen

深水油气钻井和开发过程中极易生成天然气水合物，对深水钻井和油气集输造成严重影响。某深水油田 的伴生气组分复杂，现有水合物生成预测模型计算误差较大。为准确预测该油田伴生气的水合物生成风险，本 文利用天然气水合物微观实验装置，模拟油田多组分气体，进行了水合物生成条件测定，并探索了乙二醇对多组 分气体水合物生成的影响。研究表明，在温度低于15 ℃时，某深水油田的伴生气的相平衡条件低于甲烷和二氧 化碳，高于乙烷和丙烷；在温度高于15 ℃时，其相平衡条件低于甲烷、乙烷和二氧化碳。这表明，与甲烷气体相 比，该多组分气体由于乙烷、丙烷等的存在，更容易生成水合物，且水合物晶体呈针状生长，其针状结构会迅速发 展成体型结构，极易造成管线堵塞。在集输管线流体平均压力为5 MPa时，40%的乙二醇溶液可使模拟气体的水 合物相平衡温度降低5.3 ℃，为该油田水下油气集输过程中的水合物防治工作提供了理论依据。图10参19

Natural gas hydrates were easily generated in the drilling and development of deepwater oil and gas reservoirs，which will have a serious impact on deepwater drilling and oil and gas gathering and transportation. The components of associated gas in a deepwater oilfield were complex，and the existing hydrate formation prediction models had large calculation errors. In order to accurately measure the hydrate formation risk of the associated gas in the oil field，a natural gas hydrate micro-observation experimental device was used to determine the hydrate generation conditions of the multi-component gas in the oil field. The influence of ethylene glycol on the formation conditions of multi-component gas hydrate was explored. The results showed that when the temperature was below 15 ℃，the phase equilibrium condition of the multi-component gas was lower than that of methane and carbon dioxide，and higher than that of ethane and propane. When the temperature was higher than 15 ℃ ，the phase equilibrium condition of the multi-component gas was lower than that of methane，ethane and carbon dioxide，which showed that compared with methane gas，the multi-component gas was easier to form hydrate due to the presence of ethane and propane. In addition，hydrate crystals growed in acicular form，and the acicular structure would rapidly develop into body structure，which would easily cause pipeline clog. When the average pressure of the fluid in the gathering and transportation pipeline was 5 MPa， 40% ethylene glycol solution could reduce the equilibrium temperature of the simulated gas hydrate phase by 5.3 ℃，providing a theoretical basis for hydrate prevention and treatment in the process of underwater oil and gas gathering and transportation in this oilfield.

10.19346/j.cnki.1000-4092.2021.03.026