Predicting the effective mechanical property of heterogeneous materials by image based modeling and deep learning. Computer Methods in Applied Mechanics and Engineering

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Here we report a water-soluble acrylamide sulfonate copolymer for inhibiting shale hydrate formation. The copolymer, denoted as PANAA, was synthesized via copolymerization of acrylamide (AM), N,N-diallylbenzylamine (NAPA), acrylic acid (AA), and 2-(acrylamide)-2-methylpropane-1-sulfonic acid (AMPS). The performance of this new water-soluble copolymer for inhibiting shale hydration was investigated for the first time. The retention ratio of apparent viscosity of 2 wt % PANAA solution can reach 61.6% at 130 °C and further up to 72.2% with 12 000 mg/L NaCl brine. The X-ray diffraction studies show that the addition of copolymer PANAA (5000 mg/L), in combination with a low loading of KCl (3 wt %), remarkably reduces the interlayer spacing of sodium montmorillonite (Na-MMT) in water from 19.04 to 15.65 Å. It has also found that these copolymer solutions, blending with KCl, can improve the retention of indentation hardness from 22% to 74% and increase the antiswelling ratio up to 84%. All results have demonstrated that the PANAA copolymer not only has excellent temperatureresistance and salt-tolerance but also exhibits a significant effect on inhibiting the hydration of clays and shale.

A modular b-cyclodextrin copolymer for clay stabilization was prepared from 2-O-(allyloxy-2-hydroxyl-propyl)-b-cyclodextrin (XBH), acrylamide (AM), 2-acrylamido-2-methyl propane sulfonic acid (AMPS), and sodium acrylate (NaAA) via redox freeradical copolymerization. The effects of reactive conditions (such as initiator concentration, monomer ratio, reaction temperature, and pH) on the apparent viscosity of the copolymer were investigated and the optimal conditions for the copolymerization were established. The copolymer obtained was characterized by infrared spectroscopy, scanning electron microscope, viscosity measurements, rheological measurement, core stress test, and X-ray diffractometry. The crystalline interspace of MMT could be reduced from 18.95323 Å to 15.21484 Å by copolymer AM/NaAA/AMPS/XBH. And this water-soluble copolymer also showed remarkable anti-shear ability, temperature resistance, and salt tolerance (1000 s À1 , viscosity retention rate: 35%; 120 C, viscosity retention rate: 75%; 10,000 mg/L NaCl, viscosity retention rate: 50.2%; 2000 mg/L CaCl 2 , viscosity retention rate: 48.5%; 2000 mg/L MgCl 2 , viscosity retention rate: 42.9%).

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