PMMA纳米胶乳在钻井液中的性能评价

The Performance of PMMA Nano-latex in Drilling Fluids

在油气勘探钻井过程中,如在钻井液中添加纳米胶乳,利用纳米粒子的"球轴承"作用,可以降低摩阻,防止卡钻;同时利用纳米胶粒在一定温度下的可变形特性,可以更好地封堵地层微孔隙,形成致密泥饼,降低钻井液滤失量。利用种子乳液聚合法合成了一种钻井液用纳米胶乳(PMMA),其平均粒径为73nm。透射电镜分析结果表明,PMMA纳米乳胶颗粒大致呈球状,分散均匀。性能评价结果表明,1%PMMA纳米胶乳溶液的页岩回收率为68%,且与KCl复配使用后效果更好;在4%膨润土浆中加入1%PMMA后,黏度略有降低,滤失量降低了约40%,润滑系数降低了80%左右,泥饼黏附系数降低了约40%;加有2%PMMA的聚磺钻井液的砂床封堵滤失量和膜结构密封度滤失量分别为10mL和2mL,在180℃下仍具有良好的沉降稳定性。以上结果表明,PMMA纳米胶乳具有一定的降黏、降滤失性能,较强的封堵能力,良好的抑制性、润滑性能和高温稳定性能。

A nano-latex PMMA Used in Drilling Fluids,with an average size of 73 nm,is synthesized using emulsion polymerization for use in drilling fluids as a lubricant to prevent pipe sticking based on the'ball bearing'function of the nano-latex particles,and as a filtration reducer based on the deformability of the nano-latex particles under certain temperatures,forming a tough filter cake and sealing off the micro fissures in the formations drilled.Laboratory study shows that the nano-latex particles are roughly in spherical shape,and are uniformly distributed in solution.Percent recovery of shale samples in hot rolling test is 68%using a drilling fluid treated with 1%of the latex,and better result can be obtained with the latex compounded with KCl.Treatment of 4%bentonite mud with 1%PMMA results in a slight decrease in mud viscosity,a 40%reduction in filtration rate,an 80%reduction in friction coefficient and a 40%reduction in mud cake adhesion coefficient.Filtration tests are conducted on a sand pack and a filming-form device,and the filtration rates of the polymer drilling fluid containing 2%PMMA are 10 mL and 2 mL,respectively.Hot rolling at 180℃for 16 h,the drilling fluid still has good suspending performance.All these results showed that PMMA nano-latex has the capacity of viscosity reduction,filtration control,strong sealing,good inhibition,lubrication and high temperature stability.