Fei Liu,Chengxiang Zhang,Xiaqing Li,Zhaoxiang Zhang,Xuewu Wang,Xiaodong Dai,Mengyue Zhou,Qingxue Liu
Wellbore instability caused by shale hydration and swelling is the critical issue in the drilling process of oil and gas wells . In this study, the nano-silica/cationic polymer composite (NS-DD) was synthesized and evaluated as novel shale inhibitor in water-based drilling fluids (WDFs). The inhibition performance of NS-DD was carried out and compared with the conventional inhibitor potassium chloride (KCl) and the extensively utilized inhibitor polyether diamine (PDA), where the inhibition performance tests consisted of bentonite inhibition tests, linear swelling tests, and shale cuttings rolling recovery tests. The results revealed that NS-DD exhibited outstanding inhibition performance compared to KCl and PDA even in high temperature environment. Specifically, in the presence of KCl and PDA, the third roll recoveries of shale cuttings after hot rolling at 150 °C for 16 h were 28.62% and 42.15%, respectively, however, the recovery of shale cuttings was as high as 70.06% when NS-DD was attended. Additionally, we proposed that the excellent inhibition ability of NS-DD may be attributed to its strong adsorption with clay through hydrogen and ionic bonding and plugging of nano-pores in WDFs filter cake and shale, preventing water penetration into the reservoir causing shale hydration and swelling based on the results of scanning electron microscopy, zeta potential , thermogravimetric and X-ray diffraction analysis. This study revealed the potential application of NS-DD as the shale inhibitor in WDFs.
Carbon nanotubes (CNTs) are promising candidates for numerous cutting-edge fields because of their excellent properties. However, the inherent black color of CNTs cannot satisfy the aesthetic/fashion requirement, and the flammability of CNTs severely restricts their application in high-temperature environments with oxygen. Here, we realized a structural coloration of CNTs by coating them with amorphous TiO 2 layers. By tuning the TiO 2 coating thickness, both CNT fibers and membranes exhibited controllable and brilliant colors, which exhibited remarkable superdurability that could endure 2000 cycles of laundering tests and more than 10 months of high-intensity ultraviolet irradiation. The TiO 2 -coated CNTs exhibited a notable fire-retardant performance and could endure 8 hours of fire burning. The structural coloration of CNTs with excellent fire retardance substantially improves their performance and broadens their applications.
Yixi Kuai,Feifei Wang,Jun Yang,Zhixin Xu,Hongping Li,Xiaochuan Xu,Yanna Nuli,Jiulin Wang
The high-voltage Ni-rich LiNixCoyMnzO2 cathode materials attract attention due to their high capacity and relatively low cost. However, the undesired instability originating from side reactions with liquid electrolytes at elevated temperatures still hinders their practical application. This research aims to build a stable interface between cathode and electrolyte. We use the coupling agent KH570 to induce vinyl ethylene carbonate (VEC) monomers to in situ polymerize on the surface of LiNi0.6Co0.2Mn0.2O2 (NCM622) to form a uniform, ultrathin (∼12 nm), and highly ion-conductive poly(vinyl ethylene carbonate) (PVEC) solid polymer electrolyte layer. The modified cathode material exhibits significant improvement in rate performance and cycling stability up to 4.5 V at elevated temperatures. Scanning electron microscopy and X-ray diffraction techniques prove that the flexible polymer coating layer effectively suppresses the mechanical degradation and crystal structure changes during cycling.
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