水基钻井液用无铬降粘剂腐植酸接枝聚丙烯腈的制备及其降粘特性

Preparation and Properties of Humic Acid Grafted Polyacrylonitrile Copolymer as A New Chromium-Free Thinner for Water-Based Drilling Fluid

随着世界能源需求的增加和钻探技术的发展,国内外深井、超深井数目日益增多。在钻井过程中,井眼越深,井筒内的温度越高,水基钻井液的稠化问题就越突出。特别是当淡水钻井液遇到盐或盐膏层入侵,就会发生严重的稠化,甚至失去流动性。降粘剂是钻井过程中不可缺少的钻井液处理剂之一,它对调节钻井液流变性起着非常重要的作用。常用的钻井液降粘剂主要以铁铬木质素磺酸盐(FCLS)为主,其抗温、抗盐性都比较优越。但由于其中含有污染环境的铬离子,国家已经明令禁止使用。因此,开发新型环境友好型降粘剂势在必行。本文以腐植酸和聚丙烯腈为主要原料,以乙酸锌和尿素为复合交联剂,接枝共聚合制备出了一种抗温、抗盐性与铁铬木质素磺酸盐性能相当的新型腐植酸接枝聚合物降粘剂。探讨了腐植酸原料选择、聚丙烯腈水解-降解条件优化、合成产物沉降稳定性,评价了新型降粘剂在不同钻井液基浆中的降粘性能对比,建立了科学评价降粘剂的实验方法。这种新型降粘剂合成工艺既解决了铬污染环境的问题,又降低了降粘剂的生产成本,大大提高了新型降粘剂的性价比和市场竞争力。

With the increase of the world＆#39;s energy needs and the advanced drilling techniques, more and more deep even more ultra deep wells were developed. In drilling, the hole deeper, the higher the temperature within the wellbore, and the water based drilling fluids tend to thickening. Thinner （viscosity reducer） is the indispensable of drilling fluid additive in the drilling process. It plays a very important role in adjusting the rheological characteristics of drilling fluid. The most used commercial drilling fluid thinner is the ferric chomium lignin sulfonate （FCLS）, it is a superior to resistance temperature and resistance to salt, but it contains environmentally hazardous chromium ions, so it has banned to use for so many years. Therefore, to develop a new non-toxic and harmless thinner is imperative. 〈br〉 A new chromium-free thinner for water based drilling fluid was produced through the grafted copolymerization used the humic acid and polyacrylonitrile as the main raw materials. By using a composite cross-linking agent composed by zinc acetate and urea greatly improved the temperature tolerance and salt resistance of the produced product. The paper investigated the effect of the compositions of humic acid, optimized hydrolysis and degradation conditions of polyacrylonitrile, analyzed the mechanism of the composite cross-linking agent, improved the sedimentation stability of the produced product slurry before spray drying, evaluated the performances of the new thinner in different based drilling fluid, and established an experimental method to evaluate a thinner＆#39;s comprehensive properties. The new thinner would not only solve the chromium pollution compared with FCLS, but also reduce the thinner＆#39;s production cost. The new thinner product has a higher market competition in future.