Preparation and Performance of the Hyperbranched Polyamine as an Effective Shale Inhibitor for Water-Based Drilling Fluid

Seeking effective solutions to control and mitigate the interaction between drilling fluids and clay formations has been a challenge for many years, and various shale inhibitors have shown excellent results in problematic shale formations around the world. Herein, the hyperbranched polyamine (HBPA) inhibitor with a higher ratio of amine groups and obvious tendentiousness in protonation was successfully synthesized from ethylenediamine, acryloyl chloride and aziridine by five steps, in which the metal-organic framework (MOF) was employed as a catalyst for ring-open polycondensation (ROP). The structure and purity were confirmed by nuclear magnetic resonance hydrogen spectroscopy and high-performance liquid chromatography (HPLC) respectively. The HBPA displays more excellent performance than EDA and KCl widely applied in the oil field. After aging at 80°C and 180°C, the YP of a slurry system containing 25 wt.% bentonite and 2 wt.% HBPA are just 8.5 Pa and 5.5 Pa (wt.%: percentage of mass), respectively. The swelling lengths of 2 wt.% HBPA are estimated to be 1.78 mm, which falls by 70% compared with that of freshwater. Under a hot rolling aging temperature of 180°C, the HBPA system demonstrates a significant inhibition with more than 85% shale cuttings recovery rate and is superior to conventional EDA and KCl. Mechanism analysis further validates that the HBPA can help to increase the zeta potential.

Numerical Study on the Blade Channel Vorticity in a Francis Turbine

A relevant way to promote the sustainable development of energy is to use hydropower.Related systems heavily rely on the use of turbines,which require careful analysis and optimization.In the present study a mixed experimental-numerical approach is implemented to investigate the related mixed water flow.In particular,particle image velocimetry(PIV)is initially used to verify the effectiveness of the numerical model.Then numerical results are produced for various conditions.It is shown that an increase in the guide vane opening can reduce the extension of the region where the fluid velocity is 0 at the inlet of the runner blade,i.e.,it can counteract the generation of the channel vortex;an increase in the guide vane opening also contributes to mitigate the pressure acting on the runner blade;no matter what the working conditions are,the surface pressure is usually higher than that on the suction surface,and there is a cliff-like drop of pressure at the tail of the blade,which indicates that the runner blade tail is more prone to develop backflow.

30 GHz GeSn photodetector on SOI substrate for 2 µm wavelength application

We report the demonstration of a normal-incidence p-i-n germanium-tin(Ge_(0.951)Sn_(0.049))photodetector on silicon-on-insulator substrate for 2μm wavelength application.The DC and RF characteristics of the devices have been characterized.A dark current density under−1 V bias of approximately 125 mA/cm^(2) is achieved at room temperature,and the optical responsivity of 14 mA/W is realized for illumination wavelength of 2μm under−1 V reverse bias.In addition,a 3 dB bandwidth(f_(3dB))of around 30 GHz is achieved at−3 V,which is the highest reported value among all group III–V and group IV photodetectors working in the 2μm wavelength range.This work illustrates that a GeSn photodetector has great prospects in 2μm wavelength optical communication.