In this study, a series of amidocyanogen silanols (HASes) modified by methacryloxy propyl trimethoxyl silane (MPS) with polyethylene polyamine was introduced as potential shale inhibitors, thus providing the development and application of high-temperature resistant shale inhibitors in water-based drilling fluids. One shale inhibitor was selected based on cuttings dispersion tests. The results indicated that the shale inhibitor prepared with tetraethylenepentamine and MPS with the mole ratio of 1:2 (named HAS-8) was the best. The inhibition performance of HAS-8 was evaluated with the cuttings dispersion test, linear swelling test, and bentonite inhibition test, and was compared with the performance of currently available polyamine inhibitors. The results indicated that HAS-8 can effectively inhibit the hydration swelling and dispersion of clay, and that its temperature resistance is significantly better than that of polyamine inhibitors. The inhibition mechanism of HAS-8 was investigated with X-ray diffraction, adsorption measurement, and thermogravimetric and transmission electron microscope analysis . The mechanism is the adsorption on the clay surface and the intercalation of the interlayer, which inhibited the surface hydration and osmotic hydration of the clay. In field application of Bei 9 well, the HAS-8 effectively inhibits the hydration of water-sensitive cuttings and maintains the wellbore stability of the shale formation , providing a guarantee for safe and fast drilling.
Jingjing Zhou,Changqing He,Lin He,Xincheng Zhang,Ying Tian,Hong Sui,Xingang Li
Emerging nano-demulsifiers are efficient functional materials for separating emulsions. However, the size effects of nanoparticles on demulsification and the mechanisms of enhanced demulsification by nano-modification are still unclear. Herein, a nano-demulsifier (SiO 2 -mANP) was prepared by modifying carboxyl-modified aliphatic nonionic polyether (mANP) with nano-SiO 2 . Compared to single polyether, the SiO 2 -mANP significantly reduced the demulsification temperature from 60 °C to room temperature . The demulsification efficiency of the asphaltene-stabilized water-in-oil emulsion reached 91.0% within 10 min at room temperature (dehydration over 99.5% in less than 2 min at 60 °C). The size effects study showed that smaller SiO 2 -mANP nanoparticles (∼10 nm) performed better in demulsification due to their superior diffusion ability in continuous phase and greater adsorption at the oil-water interface. The electrostatic potential (ESP) and independent gradient model (IGM) were used for the first time to analyze the changes in non-covalent interactions between demulsifiers and water. Nano-modification facilitated the formation of more non-covalent interaction sites, notably hydrogen bonding sites such as silanol groups. This rearranged the molecular surface ESP of the demulsifier. As a result, the non-covalent interactions between demulsifier and water were greatly enhanced, leading to a significant reduction in the coalescence time of water droplets. This primary study on the size effects and non-covalent interactions of nano-demulsifiers will provide guidance for the design and development of highly efficient demulsifiers.
Zihan Zhou,Yunwen Wu,Huiqin Ling,Jie Guo,Su Wang,Ming Li
3D NAND flash memory with vertically stacked cells has been developed to break through the limits of technology nodes. However, during the selective etching process, it is difficult to ensure the byproducts diffuse away from the trenches in the multistacked layers. Once saturated, the byproduct causes abnormal redeposition on the SiO 2 layers. This problem has restricted the development of high-density 3D NAND memory. To solve this problem, the composition and formation mechanism of the redeposited layer must be clarified. In this study, a ternary-wafer system comprising a Si 3 N 4 /SiO 2 /Si 3 N 4 stack was fabricated to study the redeposition mechanism, and the morphology, elastic properties , and chemical composition of the redeposited layer were clarified. The redeposited layer consists of spherical particles with elastic surfaces (average Young’s modulus of 24.17 GPa). The particles were confirmed to comprise colloidal silica gel covered by silanols . By considering the chemistry of silica , the redeposition mechanism was proposed as follows: colloidal silica gel is formed by the aggregation of silicic acids from Si 3 N 4 etching, which adsorb onto the SiO 2 layer through oxide bridges and hydrogen bonding . Our work will contribute to the development of high-density 3D NAND memory.
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