The relationship between management safety commitment and patient safety culture. International Nursing Review, 58: 249-254.

Exploring deep and ultradeep wells has rapidly become more significant to meet the global demand for oil and gas. The study of rheological and filtration-loss properties is essential to designing drilling muds and determining their performance under operational conditions. Rheological and filtration-loss properties of drilling muds were found to have a negative impact when exposed to elevated temperatures in the wells. In this study, an amphoteric polymer (abbreviated to PEX) was synthesized and characterized using a combination of analyses: FTIR, SEM, 13 CNMR, and TGA. The synthesized PEX was used as an additive in water-based drilling muds to improve rheological properties and reduce fluid loss at elevated temperatures (180−220 °C). The experimental results demonstrated that inclusion of an optimal concentration of PEX (0.3 wt %) into the drilling mud formulation increased the rheological properties by 62.3% and decreased the filtration loss by 63.5% at an aging temperature of 180 °C. Moreover, PEX was found to perform superbly compared to polyanionic cellulose (PAC-LV) and polyacrylamide (PAM), the widely used drilling mud additives. PEX not only improved the rheological properties and reduced the filtration loss behavior but also bolstered the thermostability of the drilling mud formulation. It was concluded that the rigidity and amphoteric nature of PEX accounted for the exceptional performance and temperature resistance for PEX-drilling mud formulations. Succinctly, PEX exhibits admirable properties in smart drilling mud formulations for drilling operations under high-temperature geothermal conditions. Moreover, in terms of rheological models, the Herschel−Bulkley model adequately described the rheological properties of all the studied drilling mud formulations.

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The application of fiber in the completion fluid can improve the rheological properties of the completion fluid and the plugging quality of the production layer by the completion fluid and reduce the damage of the filtrate to the reservoir formation. However, there are few studies on the influence of fibers on the rheological properties of completion fluids and the flow behavior in pores. In this paper, plant fiber, mineral fiber, and synthetic fiber are discussed. Carbon fiber, bamboo fiber, polypropylene fiber, and polyester fiber are selected as research objects. The dependence of the rheological property of polymer solution on fiber type, fiber concentration, temperature, and shear rate is evaluated. The evaluation is carried out by observing the microscopic state of the fiber through a microscope and a scanning electron microscope, testing the rheological property parameters of the fiber with an OFITE 900 rheological tester, and fitting with the Herschel−Bulkley model. The results show that polypropylene fiber and carbon fiber have the best dispersion in polymer solution. The higher the fiber content, the greater the influence of fiber on the rheological properties of the solution. Compared with the other three fibers, carbon fiber has the greatest influence on the rheological properties of polymer solution. When the temperature is lower than 70 °C, the influence of the fiber on the rheological properties of the solution is not affected by the temperature. When the temperature exceeds 70 °C, the carbon fiber and polypropylene fiber are affected by the temperature, and the viscosity of the polymer solution is increased. The flow behavior of fiber suspensions in pores varies with the flow factor n. Carbon fiber suspensions are most conducive to the transition of polymer solution to plate laminar flow, which can improve the bearing capacity of plugging materials.

Oil-well cement-based materials have inherent brittleness; therefore, they cannot be directly used to seal oil and gas wells for a long time. To improve the elasticity of oil-well cement-based composites, a flexible epoxy resin system was developed. The flexibility, TG, and SEM of the cured resin system were evaluated. At the same time, the resin was added to oil-well cement-based materials to improve its elasticity. The compressive strength and elastic modulus of resin cement stone were tested, and the microstructure was analyzed by XRD, TG, and SEM/EDS. The results showed that the structure of the cured resin is compact, the thermal decomposition temperature is 243.9 °C, and it can recover its original shape after compression. At the curing age of 28 days, the compressive strength of cement-based composites containing 30% resin decreased by 26.7%, while the elastic modulus significantly decreased by 63.2%, and the elasticity of cement-based composites was significantly improved. The formation of hydration products (e.g., calcium silicate hydrate, and calcium hydroxide) in the resin cement slurry is obviously lower than that of pure cement, which is the reason for the decrease in compressive strength. The flexible structure of polymer particles and polymer film formed by epoxy resin is distributed inside the cement stone, which significantly improves the elasticity of oil-well cement-based composites. The results of this paper are helpful for the design of elastic cement slurry systems.

The surface hydrophilicity of thermoplastic rubber (TPR) is poor, and the effect of using it directly in oil well cement is not good. TPR was modified by different silane coupling agents, and the hydrophilicity of the modified TPR was studied by Fourier-transform infrared (FT-IR) spectroscopy and dispersion stability photography. The application effect of modified TPR in oil well cement slurry was also evaluated. The fracture surface morphology of TPR cement stone was observed by macrophotography and scanning electron microscopy (SEM). The results demonstrated that the hydrophilicity of TPR particles was improved after modification with silane coupling agent 3-methacryloxypropyltrimethoxysilane (KH570), and its application effect in cement slurry was excellent. Compared with the pure cement paste, the compressive strength of the cement paste with addition of TPR modified by KH570 was reduced, but the flexural strength and impact strength of the cement paste were effectively enhanced. Moreover, the modified TPR greatly improved the deformation capacity and decreased the elastic modulus of the cement paste. The modified TPR particles formed a plastic polymer network structure in the cement stone and penetrated the cement hydration products, filling in the cement paste to form a flexible structural center. Thus, it improved the mechanical properties and reduced the brittleness of cement paste.

e brittleness and the poor resistance to external load of oil well cement impede the development of oil and gas wells. To overcome these deficiencies, latex powder or rubber and their hybrid combinations were used to modify the oil well cement. e conventional properties, mechanical properties, and scanning electron microscopy (SEM) images of the modified cement were analyzed. In comparison with latex powder-incorporated cement and rubber-incorporated cement, a significant improvement of fluid loss, flexural strength, impact strength, and elasticity of the cement slurry was observed when using the hybrid combinations of 3 wt.% latex powder and 2 wt.% rubber, although this synergistic effect was not remarkable on the compressive strength and the thickening time. ese evidences arose from the synergism between latex powder and rubber leading to the formation of a threedimensional network structure and a flexible structure which subsequently improved the elasticity and toughness of cement stone. e improved elastic matrix has a buffering effect on external impact when the cement stone is subjected to an external load.

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