Tight reservoirs, characterized by low porosity, low permeability, and difficulty in fluid flow, rely on horizontal wells and large-scale hydraulic fracturing for development. During fracturing, a significant volume of fracturing fluid is injected into the reservoir at a rate far exceeding its absorption capacity. This not only serves to create fractures but also impacts the recovery efficiency of tight reservoirs. Therefore, achieving the integration of fracturing and enhanced recovery functions within the working fluid (fracturing-enhanced recovery integration) becomes particularly crucial. This study describes the concept and characteristics of fracturing-enhanced recovery integration and analyzes the types and features of working fluids. We also discuss the challenges and prospects faced by these fluids. Working fluids for fracturing-enhanced recovery integration need to consider the synergistic effects of fracturing and recovery; meet the performance requirements during fracturing stages such as fracture creation, proppant suspension, and flowback; and also address the demand for increased recovery. The main mechanisms include (1) enlarging the effective pore radius, (2) super-hydrophobic effects, and (3) anti-swelling properties. Fracturing fluids are pumped into fractures through pipelines, where they undergo complex flow in multi-scale fractures, ultimately seeping through capillary bundles. Flow resistance is influenced by the external environment, and the sources of flow resistance in fractures of different scales vary. Surfactants with polymerization capabilities, biodegradable and environmentally friendly bio-based surfactants, crosslinking agents, and amino acid-based green surfactants with outstanding properties will unleash their application potential, providing crucial support for the effectiveness of fracturing-enhanced recovery integration working fluids. This article provides important references for the green, efficient, and sustainable development of tight oil reservoirs.
Over the years, the abuse of antibiotics has increased, leading to their presence in the environment. Therefore, a sustainable method for detecting these substances is crucial. Researchers have explored biomass-based carbon dots (CDs) to detect various contaminants, due to their low cost, environmental friendliness, and support of a circular economy. In our study, we reported the synthesis of CDs using pinecones (PCs) and pinebark (PB) through a sustainable microwave method. We characterized the PCCDs and PBCDs using X-ray diffraction, Raman spectroscopy, Transmission Electron Microscope, and Fourier transform infrared, Ultraviolet-visible, and photoluminescence (PL) spectroscopy. The PCCDs and PBCDs were tested for the detection of amoxicillin (AMX) and tetracycline (TC). The results indicated that the sizes of the PCCDs and PBCDs were 19.2 nm and 18.39 nm, respectively, and confirmed the presence of the 002 plane of the graphitic carbon structure. They exhibited excitation wavelength dependence, good stability, and quantum yields ranging from 6% to 11%. PCCDs and PBCDs demonstrated “turn-off” detection for TC and AMX. The limits of detection (LOD) for TC across a broader concentration range were found to be 0.062 µM for PCCDs and 0.2237 µM for PBCDs. For AMX detection, PBCDs presented an LOD of 0.49 µM.
15 November 2021 in Frontiers in Environmental Science
Methylene blue (MB) is a common pollutant in wastewater of printing and dyeing industry. At present, ozone oxidation is commonly used in the treatment of printing and dyeing wastewater. Ozone is used for oxidation reaction directly and indirectly. However, the reaction rate is not fast enough. In this study, the attapulgite (ATP) was modified by tetrabutyl titanate-ethanol solution. The TiO2/ATP nanocomposite with high catalytic activity was prepared. The synthesized samples were subjected to characterized by X-ray diffraction (XRD) and Fourier Transform infrared spectroscopy (FTIR). The morphology and particle size of the particles were observed by scanning electron microscopy (SEM). The TiO2/ATP nanocomposite was calcined at 300°C for 2 h, and the degradation rate of 80 mg/L methylene blue was 99.8%. The experimental results show that the ozone, temperature and mass transfer factors are excluded, and the effects of temperature, MB concentration and pH on the degradation of methylene blue are investigated. The optimal reaction conditions are as follows: The ozone concentration is 0.067 g/min; the ozone flow rate is 0.15 NL/min; the stirrer rotation speed is 550 r/min; the catalyst is 0.1 g; the temperature is 50°C; Based on the results, the reaction mechanism was derived and the kinetic study of the experiment was carried out.
20 March 2023 in Industrial & Engineering Chemistry Research