【摘要】 油基钻井液已广泛应用在非常规井钻井施工中，如何有效清除钻井液及泥饼，为水泥浆提供适合的胶结环境，是使用油基钻井液钻井后固井面临的关键难题。纳米乳液界面张力低、液滴粒径小、增溶能力强，是一项油基钻井液冲洗新技术。以冲洗效率及乳液粒径为评价标准，优选了冲洗油基钻井液的纳米乳液，通过稳定性、电位、粒径测试，分析了纳米乳液同隔离液处理剂的配伍性，最终构建了一套纳米乳液型冲洗隔离液体系。研究表明，随着烷基糖苷和聚氧乙烯醚2种表面活性剂复配比从2∶8到9∶1，纳米乳液冲洗效率先增加后降低，粒径先减小后增大。纳米乳液高冲洗效率与小粒径的一致性，为优选兼具高冲洗效率及动力学稳定性的乳液提供了理论基础。少量聚合物类外加剂会增加乳液黏度和油水界面张力，但对纳米乳液的稳定性影响并不显著；带相反电荷的表面活性剂会降低纳米乳液液滴的Zeta电位，导致纳米乳液稳定性下降。常规处理剂可直接用于调控纳米乳液性能，制备纳米乳液型冲洗隔离液。构建的隔离液体系在100℃内流变性恒定、沉降稳定性高，与水泥浆相容性好，120℃下3 min冲洗效率达99%以上，能显著提高使用油基钻井液后固井的胶结强度。更多还原

【Abstract】 Oil based drilling fluids have been widely used in drilling unconventional wells, and one of the key problems with the use of oil based drilling fluids is how to effectively clean off the residue mud and the mud cakes on the borehole wall to provide a good bonding surface for cement slurries. Nanometer emulsion has low surface tension, small droplets and strong solubilization capacity,making it a good flushing fluid for cleaning residue oil based drilling fluids. Take the flushing efficiency and the sizes of the emulsion droplets as the evaluation criteria, a nanometer emulsion was selected as a flushing fluid for residue oil based mud cleaning.By testing the stability, electric potential and sizes of the droplets, the compatibility of the emulsion and spacer additives was analyzed, and a nanometer emulsion flushing spacer was formulated as a result of the study. Laboratory studies show that by changing the ratio of two surfactants, which are alkyl glycoside and polyoxyethylene ether, from 2∶8 to 9∶1, the flushing efficiency of the nanometer emulsion first increased and then decreased, the sizes of the droplets first decreased and then increased. The consistency between the flushing efficiency and small droplet size of the nanometer emulsion provides a theoretical basis for selecting an emulsion with both high flushing efficiency and dynamic stability. Some polymer additives will increase the viscosity of the nanometer emulsion and the oil-water interfacial tension, but do not significantly affect the stability of the nanometer emulsion.Surfactants with opposite charges will decrease the Zeta potential of a nanometer emulsion droplet, leading to a decrease of the stability of the nanometer emulsion. Commonly additives can be directly used to control of properties of a nanometer emulsion and to make nanometer emulsion flushing spacers. The spacer formulated in this study has stable rheology, high settling stability and good compatibility with cement slurries at temperatures up to 100 ℃. At 120 ℃, the spacer has flushing efficiency in 3 min of more than99% and is able to remarkably enhance the bonding strength of the cement sheaths on the walls of the borehole drilled with an oil based drilling fluid.更多还原