水性丙烯酸树脂在油包水钻井液中的作用

Application of Aqueous Acrylic Resin in Invert Emulsion Drilling Fluids

现阶段广泛使用的油基钻井液降滤失剂沥青类和腐植酸类产品存在增黏严重、加量大、降滤失效果有限或抗温性能不理想等缺点。利用乳液聚合的方法,以苯乙烯、丙烯酸丁酯和丙烯酸作为单体,合成了一种水性丙烯酸树脂材料WAR,并使用红外光谱对其结构进行表征。热重分析表明单剂抗温可达237℃(失重2%)以上。分别在常规油基钻井液和无土相油基钻井液体系中,从乳液稳定性、流变性、降滤失性、封堵性和抗温性5个方面来综合评价WAR。实验结果表明:水性丙烯酸树脂对稳定乳液有非常积极的作用,放置24 h后基浆乳化率依然可达100%;WAR对油基钻井液流变性影响较小,具有突出的降滤失、封堵和抗温性能:180℃高温高压滤失量可以降至5 mL之内,且滤饼致密;180℃老化16 h后正向封堵率可达75%以上,反向封堵率可达70%以上;与氧化沥青进行对比实验表明,水性丙烯酸树脂综合性能优于氧化沥青。此外,文中分析了水性丙烯酸树脂在油包水钻井液中的作用机理。

Asphaltene and humic acid products widely used in oil base muds(OBMs)have deficiencies such as seriously viscosifying the OBMs,high concentration requirement,limited filtration control performance and poor high temperature stability.An aqueous acrylic resin,WAR,was developed for use in OBMs to solve these deficiencies.WAR was synthesized with monomers such as styrene,butyl acrylate,and acrylic acid through emulsion polymerization,and was characterized with IR spectrometry.WAR remained stable at237℃(weight loss by2%),as proved by thermogravimetric analysis.WAR was evaluated in laboratory for its emulsion stability,rheology,filtration control performance,plugging capacity and high temperature stability both in conventional OBMs and clay-free OBMs.It was shown that WAR performed positively in stabilizing the properties of emulsions.Emulsions treated with WAR remained their whole emulsibility after24h of standing.WAR had very slight effect on the rheology of OBMs,and appreciable filtration control ability,plugging capacity and high temperature stability.HTHP filter loss tested at180℃was less than5mL,with the mud cake being dense.After aging at180°C for16h,the percentage of forward plugging was more than75%,and that of backward plugging was moer than70%.Compared with oxidized asphalt,the aqueous acrylic resin had better overall performance as an OBM additive.The working mechanism of the aqueous acrylic resin in invert emulsion drilling fluids is also analyzed in this paper.