钻井液用多功能阳离子聚合物乳液研制及其作用机制

Preparation and mechanism of cationic polymer latex as multi-functional additive in water based drilling fluid

以苯乙烯、甲基丙烯酸甲酯、丙烯酰胺、甲基丙烯酰氧乙基三甲基氯化铵为单体,合成一种阳离子聚合物乳液ZD-1;通过页岩线性膨胀实验、泥页岩热滚回收实验和粒度分析评价ZD-1的抑制性能,分析其抑制机制;使用污染前后低渗人造岩心气测渗透率变化评价其封堵性能;利用极压润滑性能实验评价其润滑性能。结果表明:与常用页岩抑制剂聚醚胺和氯化钾相比,ZD-1具有较好的抑制页岩水化膨胀和分散的能力,膨润土岩心试样16 h的膨胀率相对于氯化钾有大幅度降低,当质量分数为2.0%时,易水化泥页岩岩屑的热滚回收率超过80%;纳米级别的ZD-1颗粒表面具有阳离子基团,能够中和膨润土表面的负电荷、提高泥页岩表面的疏水性,并可通过吸附作用在泥页岩表面形成疏水层来降低水对泥页岩的侵入,从而达到抑制泥页岩水化膨胀和分散的作用;ZD-1可有效封堵低渗岩心,2%加量下封堵率大于90%,性能优于磺化沥青;ZD-1作为球形纳米级颗粒,有利于提高钻井液的润滑性,摩阻系数降低率高于固体润滑剂石墨。

A cationic polymer latex ZD-1 was synthesized by reaction of styrene, methyl methacrylate, acrylamide and methacryloxyethyltrimethylammonium chloride. The inhibition performance of ZD-1 was evaluated by shale linear swelling experiments, shale recovery experiments and particle size analysisthrough which the inhibition mechanism was then investigated. The gas permeability of the low-permeability artificial core before and after pollution was tested to evaluate its plugging performance. The extreme pressure lubrication experiment was used to evaluate the lubricating performance. The results indicate that ZD-1 has a better capability to inhibit the swelling and dispersion of shale in comparison with the commonly used shale inhibitors polyether-amine and potassium chloride. The swelling ratio of the bentonite core samples treated by ZD-1 for 16 h is significantly lower than that treated by potassium chloride. When the dosage of ZD-1 is 2.0%, the shale recovery ratio of the easily-hydratable muddy shale cuttings is more than 80%. The nano-scale ZD-1 particles having cationic groups on their surface inhibit the hydration swelling and dispersion of shale by neutralizing the electronegativity of the clay surfaces, improving the hydrophobicity of the shale surface and forming a hydrophobic film on the shale surface by adsorption to reduce the invasion of drilling fluid to shale. ZD-1 can effectively plug the low-permeability core. The plugging rate is greater than 90% with an addition of 2%, which is better than that of sulfonation asphalt. In addition, ZD-1, as spherical nano-sized particles, is conducive to improving the lubricity of drilling fluids, and the friction coefficient reduction rate is higher than that of solid lubricant graphite.