钻井液添加剂对形成天然气水合物的影响

针对深水钻井中水基钻井液易形成天然气水合物从而导致钻井作业无法正常进行的问题,利用自行设计研制的气体水合物反应装置,模拟深水钻井温度压力条件,对水基钻井液添加剂进行了天然气水合物形成的实验研究。分析了各实验体系形成水合物的过冷度。以过冷度为评价指标,评价了各种钻井液添加剂在深水钻井水合物形成过程中的作用。结果表明,在钻井液使用的加量范围内,阳离子聚丙烯酰胺CPAM、两性离子聚合物FA367等对天然气水合物的形成有抑制作用,且随着加量的增加抑制作用增强;磺甲基丹宁SMT、木质素磺酸盐FCLS对天然气水合物的形成有微弱的促进作用,但影响不大。聚合物添加剂的离子类型对天然气水合物的形成影响不大。

Effect of chemical additives used in drilling fluid on hydrate formation

Natural gas hydrate can be easily formed from the water base drilling fluid during the deep water drilling, which will affect the normal progress of drilling operation. To solve the problem, a reaction equipment was designed and developed, which can simulate the temperature and pressure conditions of deep water drilling .The effects of additives used in water drilling fluids including CPAM, 80A51, HPAM, FA367, NW-1, MP-Ⅱ, HEC, MC, XY-27, SMT, FCLS, EG_(600), HCOONa, HCOOK and NaCl on natural gas hydrate formation were investigated. And the subcooling degree of drilling fluid system was obtained. The result shows that CPAM, 80A51,HPAM, FA367, NW-1, SMP-Ⅱ, HEC, CMC, XY-27, EG_600, HCOONa, HCOOK, NaCl and KCl can inhibit the formation of natural gas hydrate to some degree, but SMT and FCLS can help the formation of natural gas hydrate faintly in water base drilling fluids. The inhibition of the ion species of polymer additives on gas hydrate can be ignored.