水基钻井液用锂皂石增黏剂的合成及性能研究

Synthesis and Study on Hectorite Viscosifier Used in Water Base Drilling Fluid

针对天然锂皂石矿物稀缺和钻井领域亟需抗高温水基钻井液增黏剂的现状,优选了微波辅助法合成锂皂石,利用粉末X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、粒径分析对合成锂皂石进行了表征,并研究了其作为水基钻井液增黏剂的效果。结果表明,利用微波辅助法合成了纯度较高的纳米级锂皂石,其粒径尺寸主要分布在18.17～58.77 nm,平均粒径仅为29.72 nm;随着锂皂石浓度从0.3%增加到1.5%,4%膨润土基浆的黏度、切力以及动塑比均显著增大,滤失量也逐渐降低,说明锂皂石还具有一定的降滤失效果,加入1.2%锂皂石,基浆黏度可提高2.64倍,且切力和动塑比保持适中;1.5%的锂皂石能抵抗至少2.5%的钙侵和15%的盐侵;随着老化温度从80℃增加到220℃,4%基浆＋1.5%锂皂石的表观黏度先减小后增大,维持在20 m Pa s以上,动切力和动塑比同样先减小后增加,但是下降幅度较为明显;在200℃,常规的有机聚合物增黏剂均失效,而锂皂石增黏剂却仍能保持很好的增黏效果。因此,合成锂皂石是一种理想的抗高温型水基钻井液增黏剂,且具有良好的配伍性。

Hectorite can be used as a high temperature viscosifier in water base drilling fluids, and it is a rare mineral found in nature. A hectorite has been successfully synthesized in laboratory using microwave irradiation method and characterized with XRD, FTIR and particle size distribution analysis. The performance of the synthesized hectorite in water base drilling fluid has been evaluated. The particle sizes of the synthesized hectorite falls in the range between 18.17 nm and 58.77 nm, averaged at 29,72 nm. 4% bentonite slurry treated with 0.3% - 1.5% synthesized hectorite, has viscosity, gel strength and YP/PV ratio remarkably increased, and filter loss reduced. When the concentration ofhectorite is 1.2%, the viscosity of the slurry is increased by 2.64 times, while the gel strength and YP/PV ratio still remains moderate. The bentonite slurry treated with 1.5% hectorite can resist the contamination of calcium （2.5%） and salt （15%）. With temperatures increased from 80 ℃ to 220 ℃, the apparent viscosity of the 4% bentonite slurry ＋ 1.5% hectorite decreases followed by an increase, and finally remains at above 20 mPa · s. The gel strength and YP/PVratio changes at a same pattern as that of apparent viscosity, but with remarkable decreases at first. At 200℃, almost all conventional polymers lose their efficiency as viscosifiers in water base drilling fluid, while hectorite is still functioning. Thus the synthesized hectorite is an ideal viscosifier for use in high temperature water base drilling fluid, and is well compatible with other additives.