深水钻井液高效水合物抑制剂研究

Study on high performance gas hydrate inhibitor in deepwater drilling fluid

关键词:  深水  钻井液  天然气水合物  动力学抑制剂  作用机制  抑制剂组合

Key words:  deepwater  drilling fluid  gas hydrate  kinetic hydrate inhibitor  inhibition mechanism  combination of inhibitors

摘要:

通过分子结构优化,研制出海洋深水钻井新型水合物动力学抑制剂SDH。利用自行研制的天然气水合物抑制性能评价实验装置模拟超深水海底低温/高压环境,进行水合物抑制性评价实验。结合压力-温度曲线和温度、压力随时间的变化情况,分析SDH作用下水合物生成的动力学过程,探讨其作用机制。考察低剂量的SDH与热力学抑制剂NaCl的复配使用效果。研究表明:在SDH作用下,可将水合物生成过程划分为水合物成核、水合物缓慢生长和大量生成3个阶段; SDH可吸附在水合物表面,通过空间位阻作用有效抑制水合物的生长,其最优加量为1.0％;低剂量的SDH与热力学抑制剂NaCl的复配具有很好的协同作用,在模拟3km水深条件下(2℃,30MPa),1.0％SDH与10％NaCl复配使用可保证钻井液搅拌12h无水合物生成,满足超深水钻井需要,同时可降低成本。

Abstract:

An innovative kinetic hydrate inhibitor SDH was prepared based on the optimization of molecular structure. The inhibition characteristics of SDH were experimentally investigated in ultra high pressure and low temperature condition of ultra deepwater by utilization of a simulating device for the inhibition assessment of gas hydrate. The kinetics of hydrate formation in the presence of SDH was investigated based on the pressure-temperature curve and the variations of pressure and temperature with time. The results indicate that the kinetic process of hydrate formation in the presence of SDH can be divided into three periods:hydrate nucleation, slow growth and significant formation. SDH is effective in controlling hydrate growth by steric hindrance effect due to the adsorption on the surface of hydrate crystals under the optimum dosage of 1.0%. The inhibition property of SDH and NaCl mixed system was also tested, and the mixed system could strongly hinder hydrate formation. In a simulation environment (2℃, 30MPa) at 3.0km water depth, the combination of 1.0% SDH and 10% NaCl can prevent the hydrate formation at least 12hours under stirring, which can not only meet the demand of hydrate control in ultra deepwater drilling, but also reduce the cost.