Jiaxian Qiu,Yingrui Bai,Jinsheng Sun,Liyao Dai,Shaofei Lei,Fan Liu
Aiming at the lack of plugging agent for oil-based drilling fluid leakage in fractured formation, an oil-based gel-plugging agent with high structural strength and strong thermal stability was synthesized based on monomer polymerization and crosslinking. According to the preparation experiment, when the total concentration of methyl methacrylate (MMA) and butyl acrylate (BA) is 30% and the ratio is 6:4, the oil-based gel solution can be completely gelatinized from 80 to 200°C, which has high gel strength and controllable gelation time. The effects of total concentration of BA and MMA, the ratio of BA and MMA, synthesis temperature, oil-based drilling fluid invasion, shear effect, and fiber concentration on gelling performance were systematically studied. Fourier transform infrared molecular structure analysis showed that the oil-based gel contained benzene ring group and ester characteristic group. From the rheological properties of oil-based gel with 30% gelling agent at 160°C, it could be seen that the elastic modulus G ′ of 10 Hz is 232 kPa, which is much larger than the storage modulus G ″ is 99 kPa, which reflects the solid properties and has good elasticity and high strength. The displacement experiment of sand filling pipe and dynamic and static plugging experiment of high temperature and high pressure shows that the oil-based gel has high bearing capacity in fractures and sand filling pipe. The bearing pressure is 3.01 MPa in 6 mm fractures, and the bearing pressure gradient is 0.602 MPa/cm.
In this study, macadamia oil-based oleogels were prepared using monoglyceride stearate (MG) as a gelator with a low critical gelation concentration (3.0 wt%). The physical properties of the oleogels were evaluated by polarized light microscopy, Fourier transform infrared spectroscopy , differential scanning calorimetry , X-ray diffraction, texture and rheological analysis. And the lipid digestion and oxidative stability of the macadamia oil were determined by pH titration and accelerated oxidation test, respectively. The results showed that the hardness, oil binding capacity, and thermal stability of the oleogels increased with increasing MG concentration, which was attributed to the formation of a network of MG crystals held together by van der Waals interactions and hydrogen bonds. Rheological analysis indicated that all the oleogels exhibited a thermally reversible solid-to-liquid transition and viscoelastic behavior at ambient temperatures. Moreover, the formation of oleogels increased fatty acid release during in vitro lipid digestion and improved the oxidative stability of the macadamia oil. In addition, the potential application of these oleogels as replacements for saturated fats in foods was demonstrated by creating a chocolate product where the cocoa butter was replaced with macadamia oil-based oleogels with a high degree of unsaturation. These results can provide guidance for the preparation of macadamia oil-based oleogels, which may increase their application in foods.
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