Optically Transparent and Color-Stable Elastomer with Structural Coloration under Elongation.

Optically transparent and colored elastomers with high toughness are expected to play an important role in the construction of advanced medical materials, wearable displays, and soft robots. In this study, we found that composite elastomers consisting of amorphous SiO2 particles homogeneously dispersed in high concentrations within a biocompatible acrylic polymer network exhibit optical transparency and bright structural colors. In the composite elastomers, the system in which the SiO2 particles form a colloidal amorphous array hardly changes its structural color hue despite deformation due to elongation. Furthermore, the composite elastomer of the SiO2 particles with the acrylic polymer network also results in high mechanical toughness. In summary, we have shown that the elastomer that exhibits fade-resistant structural coloration formed from safe materials can combine stable coloration and mechanical strength independent of their shape. This is expected to have new potential in future technologies to support our daily life.

Nano-Film-Forming Plugging Drilling Fluid and Bridging Cross-Linking Plugging Agent Are Used to Strengthen Wellbores in Complex Formations.

Lost circulation is one of the great challenges during the drilling process as it can not only increase the risk of drilling operations but also cause an increase in drilling costs, thus greatly affecting the drilling efficiency. Wellbore strengthening has been widely used to prevent lost circulation, which ultimately expands the mud density window by increasing the formation fracture pressure. This paper proposes a combination of "preventive" wellbore strengthening and "remedial" wellbore strengthening to prevent leakage and plug and stabilize wellbores by means of summarizing the characteristics of lost circulation and wellbore instability in the Hasan area. The formula of the bridging cross-linking plugging agent is determined by experiments as well slurry + 8-10% granular material + 3-5% fiber material + 2-4% elastic material + 0.5-1% cementing material. The formula of the nano-film-forming plugging drilling fluid is determined to be 3% bentonite + 0.2NaOH + 0.2% KPAM + 3% SMP + 1% PB-1 + 2% SMNA-1 + 2% lubricant SMLUB-1 + 1% modified nano-SiO2 particles. Then, the performance evaluation of the composite system is carried out by the high-temperature and high-pressure plugging simulation evaluation device. The results show that the bridging and cross-linking plugging agent can effectively block the 1-3 mm crack, the pressure-bearing capacity is greater than 10 MPa, and the anti-liquid return capacity is greater than 4 MPa. The nano-film-forming plugging drilling fluid has lower fluid loss and better rheological properties.

Wellbore Flow Model and Process Optimization for Gas-Lift Leakage Drilling for Shallow Shale Formations.

The shallow surface karst landform in the Nanchuan-China shale gas area, with developed caves and underground rivers, frequently lost circulation during the drilling operation. To solve the issue, first, according to the actual drilling engineering, this paper analyzes the geological factors and drilling and completion characteristics, optimizes the construction plan, and suggests a new technology for gas-lift leakage drilling based on double-wall drill pipes. Second, a distributed coupling improved Beggs-Brill gas-liquid-solid multiphase flow model is established. This model is used to complete the optimization design of the gas-lift leakage penetration construction scheme of the well sy20-2. Finally, the accuracy, process feasibility, and effect of the model are verified after the field application. The test results show that this method can establish a full drilling fluid circulation without plugging the leakage, control the leakage rate to within 0.5 m3/h, more than 90% reduction in the loss of circulation, and significantly shorten the nonproduction time limit with good application prospects.

Bioinspired Color Elastomers Combining Structural, Dye, and Background Colors.

Organisms that alter body color undergo color change in response to environmental variations and stimuli by combining chromatophores that develop colors by various mechanisms. Inspired by their body color changes, we can develop sensors and optical materials that change colors in response to multiple stimuli, such as mechanical and light stimuli. In this study, we report on bioinspired composite elastomers that exhibit various color changes as the pigment color, structural color, and background color change. These composite elastomers exhibit structural colors due to their fine structures in which fine silica particles form colloidal crystals, and the structural colors reversibly change as the elastomers elongate. Furthermore, photochromic dyes can reversibly change color depending on the wavelength of irradiated light when they are introduced to the composite elastomers. Since the structural color is one of the three primary colors of light and the pigment color is the color that corresponds to the three primary colors of a pigment, each color becomes vivid when the background color is black or white. Thus, we clarify that the composite elastomers exhibit various color changes due to the combination of structural color change in response to the mechanical stimulus, pigment color change in response to light irradiation, and background color change.