To meet the escalating demand for oil and gas exploration in microporous reservoirs, it has become increasingly crucial to develop high-performance plugging materials. Through free radical grafting polymerization technology, a carboxymethyl chitosan grafted poly (oligoethylene glycol) methyl ether methyl methacrylate acrylic acid copolymer (CCMMA) was successfully synthesized. The resulting CCMMA exhibited thermoresponsive self-assembling behavior. When the temperature was above its lower critical solution temperature (LCST), the nanomicelles began to aggregate, forming mesoporous aggregated structures. Additionally, the electrostatic repulsion of AA chains increased the value of LCST. By precisely adjusting the content of AA, the LCST of CCMMA could be raised from 84.7 to 122.9 °C. The rheology and filtration experiments revealed that when the temperature surpassed the switching point, CCMMA exhibited a noteworthy plugging effect on low-permeability cores. Furthermore, it could be partially released as the temperature decreased, exhibiting temperature-switchable and self-adaptive plugging properties. Meanwhile, CCMMA aggregates retained their reversibility, along with thermal thickening behavior in the pores. However, more detailed experiments and analysis are needed to validate these claims, such as a comprehensive study of the CCMMA copolymer’s physical properties, its interaction with the reservoir environment, and its performance under various conditions. Additionally, further studies are required to optimize its synthesis process and improve its efficiency as a plugging material for oil and gas recovery in microporous reservoirs.Keywords:temperature-switchable;intelligent fluid;adaptive;rheological properties;filtration loss
Yiming Gao,Ying Jiang,Wenjing Hu,Haizhen Jiang,Jiusheng Li
Mechanical operation could be seriously affected by friction and controlling it by oil lubrication has been considered as an effective way. Good lubricant additives are very necessary to avoid the friction damages, and to find or design new additives is always a challenge. In this study, a systematic investigation of using cholesteryl liquid crystals (LCs) as lubricant additives to obtain exceptional tribological behaviors was performed. In total, four cholesteryl LC compounds were synthesized targetedly and their thermal and mesogenic properties were studied to see the inherent relationship between the mesogenic phases and antifriction and antiwear performance. Through a series of tribological and related tests, including the UMT TriboLab test, three-dimensional optical microscopy, oil film thickness and viscosity tests, etc., the effect of the mesogenic phases and structures of the synthesized cholesteryl LCs on their tribological properties as lubricant additives was investigated and a related mechanism was analyzed. The result showed that within and close to the mesogenic phase temperature ranges, which we called as effective temperature ranges of LC additives (TEF), the LCs presented better tribological behaviors, meaning they could be used in special lubrication applications that need to be confined in certain temperature scopes; however, the ester groups with long alky tails could help dissolve in base oils and adsorb onto the friction pairs. Among the four LCs, LC-D with a long perfluoroalkyl tail brought widest mesogenic phase with considerably enhanced lubrication performance and increased oil film thickness, viscosity, and thermal stability, indicating that the perfluoroalkyl group could be well used in the structural modification of LC additives to give unexpected tribological performance. This study, in conjunction with our experimental data, suggested that the liquid crystals may be evaluated as potential friction modifiers for temperature-controllable lubrication and also shed a fresh light on the development of novel liquid crystal lubrication materials.
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