新型超高温页岩抑制剂特性实验研究

Experimental Study on a New Ultrahigh Temperature Shale Inhibitor

为满足超高温深井钻井工程的需要,提升抗高温水基钻井液的抑制页岩水化能力,研选了一种新型超高温页岩抑制剂HT-HIB该抑制剂分子结构与聚醚二胺类似,端部含有2个胺基,但分子链为刚性的环烷基。通过抑制膨润土造浆实验、页岩滚动分散实验、页岩膨胀实验、压力传递测试、X射线衍射分析黏土层间距、Zeta电位测试和热重分析等,综合评价了该页岩抑制剂的抑制性能,并揭示其作用机理。结果表明,HT-HIB能抑制泥页岩水化膨胀和分散,并可在一定程度上阻止压力传递,作用优于目前高性能水基钻井液中使用的聚胺抑制剂;同时HT-HIB可在220℃下保持性能稳定。HT-HIB通过端部的胺基单层吸附插入黏土层中,破坏黏土表面水化层结构并排出层间水分子;黏土表面吸附HT-HIB后亲水性显著降低,从而阻止了水分子的吸附;此外,HT-HIB的溶解度随pH值变化,可使HT-HIB从溶液中析出并堵塞页岩微孔隙,也有利于阻止液相侵入。总之,HT-HIB借助化学抑制、润湿反转以及物理封堵协同作用,因而表现出突出的抑制性能,为开发新一代抗高温高性能水基钻井液打下了基础。

Study on high temperature shale inhibitors is of great importance in satisfying the needs of high temperature deep well drilling and in improving the inhibitive capacity of high temperature water base drilling fluids. A new ultrahigh temperature shale inhibitor, HT-HIB, was studied for its high temperature performance and working mechanism through laboratory experiments, such as test of bentonite to yield, hot rolling test, shale core swelling test, pressure transmission measurement, x-ray diffraction to measure the c-spacing of clay, Zeta potential test and thermogravimetric analysis etc. The study has shown that HT-HIB was able to inhibit the hydration, swelling and dispersion of shales, and to contain pressure transmission to some extent, and was superior to the potyamine shale inhibitors presently used in high performance water base drilling fluids. In the experiment, HT-HIB remained stable at 220℃. HT-HIB worked by inserting its amine group at the end of its molecular chain, in a way of monolayer adsorption, in between the crystal layers, thereby destructing the surface hydration structure of the clay particles and squeezing the adsorbed water out of the crystal layers. After adsorbing HT-HIB molecules, the hydrophilicity of clay particles was greatly reduced, and adsorption of water molecules was thus stopped. Furthermore, the solubility of HT-HIB changed with pH of the system, and was thus able to separate out from the system to plug the micro fractures in shales, beneficial to hinder the invasion of water molecules into shales. To summarize, HT-HIB showed excellent inhibitive capacity through synergy of chemical inhibition, wettahility reversal and physical plugging. It paves the way to developing the new generation high temperature high performance water base drilling fluids.