Abstract:In this study, modified xanthan gum was prepared by esterification of xanthan gum (XG) with poly(maleic anhydride/1-octadecene) (PMAO) in order to improve the shearing and thermal degradation performance. The structure and molecular weight (M w ) of the modified xanthan gums (named as PX) and XG were characterized by FT-IR, 1 H NMR, and static light scattering. The radius of gyration (R g ) and hydrodynamic radius (R h ) of these polymers in aqueous solution were obtained by light scattering measurement. From … Show more
“…The absorption peaks that appeared at 1624 and 1728 cm –1 were caused by symmetric and asymmetric stretching vibration of CO. These results are in agreement with reported data. − For the XG- g -AAA curve (curve b), the peaks at 1040 and 2930 cm –1 are characteristic absorption peaks of XG retained by the graft copolymer. The broad absorption band at 3436 cm –1 was due to the overlap of O–H stretching of XG and N–H stretching of AM .…”
Xanthan gum (XG) was widely used as an oilfield chemical treatment agent because of its environmental protection and diverse functions. With the increased drilling depth and formation complexity, the shortcomings such as poor solubility and low resistance to temperature were gradually exposed. In this study, a modified XG derivative XG-g-AAA was synthesized by grafting XG with acrylic acid (AA), acrylamide (AM), and 2-acrylamido-2-methylpropane sulfonic acid (AMPS). The chemical structure of XG-g-AAA was determined by Fourier transform infrared spectroscopy and nuclear magnetic resonance ( 1 H NMR). Then, the solubility, high-temperature rheology and filtration properties, resistance to Na + /Ca 2+ , and compatibility were investigated. Results show that (1) both in aqueous and salt solutions, XG-g-AAA can completely be dissolved within 15 min. The significant improvement of the solubility of XG-g-AAA makes it more suitable for field use. ( 2) XG-g-AAA is less sensitive to high temperatures, and the viscosity decay decreased by 23.3 and 21.3% than XG at 150 and 180 °C, respectively. XG-g-AAA-based drilling fluid is a high-quality drilling fluid with significant shear thinning behavior, and the power-law model is the optimal model to describe its high-temperature rheology. Within 150 °C, 1.5% XG-g-AAA can maintain a reasonable value of the flow behavior index (n) (0.55−0.69), filtration volume (<11.6 mL), and sufficient gel strength (GS). At 150−200 °C, 3% XG-g-AAA is recommended. The value of n was in the range of 0.45−0.62, and the fluid loss was within 10 mL. However, 3% XG-g-AAA cannot provide enough GS at 200 °C; thus, a shear strength-improving agent is recommended to be added. (3) XG-g-AAA showed excellent contamination tolerance and compatibility. It could resist 2 wt % CaCl 2 and 35 wt % NaCl at room temperature and 0.75% CaCl 2 and 5% NaCl after 150 °C aging. (4) XG-g-AAA showed compatibility with sulfonated drilling fluids and could replace commercial fluid loss agents in the formula. Furthermore, the high-temperature fluid loss control mechanism was discussed by analyzing the effects of XG-g-AAA on the bentonite layer spacing, particle size distribution, stability of the colloidal system, and mud cakes.
“…The absorption peaks that appeared at 1624 and 1728 cm –1 were caused by symmetric and asymmetric stretching vibration of CO. These results are in agreement with reported data. − For the XG- g -AAA curve (curve b), the peaks at 1040 and 2930 cm –1 are characteristic absorption peaks of XG retained by the graft copolymer. The broad absorption band at 3436 cm –1 was due to the overlap of O–H stretching of XG and N–H stretching of AM .…”
Xanthan gum (XG) was widely used as an oilfield chemical treatment agent because of its environmental protection and diverse functions. With the increased drilling depth and formation complexity, the shortcomings such as poor solubility and low resistance to temperature were gradually exposed. In this study, a modified XG derivative XG-g-AAA was synthesized by grafting XG with acrylic acid (AA), acrylamide (AM), and 2-acrylamido-2-methylpropane sulfonic acid (AMPS). The chemical structure of XG-g-AAA was determined by Fourier transform infrared spectroscopy and nuclear magnetic resonance ( 1 H NMR). Then, the solubility, high-temperature rheology and filtration properties, resistance to Na + /Ca 2+ , and compatibility were investigated. Results show that (1) both in aqueous and salt solutions, XG-g-AAA can completely be dissolved within 15 min. The significant improvement of the solubility of XG-g-AAA makes it more suitable for field use. ( 2) XG-g-AAA is less sensitive to high temperatures, and the viscosity decay decreased by 23.3 and 21.3% than XG at 150 and 180 °C, respectively. XG-g-AAA-based drilling fluid is a high-quality drilling fluid with significant shear thinning behavior, and the power-law model is the optimal model to describe its high-temperature rheology. Within 150 °C, 1.5% XG-g-AAA can maintain a reasonable value of the flow behavior index (n) (0.55−0.69), filtration volume (<11.6 mL), and sufficient gel strength (GS). At 150−200 °C, 3% XG-g-AAA is recommended. The value of n was in the range of 0.45−0.62, and the fluid loss was within 10 mL. However, 3% XG-g-AAA cannot provide enough GS at 200 °C; thus, a shear strength-improving agent is recommended to be added. (3) XG-g-AAA showed excellent contamination tolerance and compatibility. It could resist 2 wt % CaCl 2 and 35 wt % NaCl at room temperature and 0.75% CaCl 2 and 5% NaCl after 150 °C aging. (4) XG-g-AAA showed compatibility with sulfonated drilling fluids and could replace commercial fluid loss agents in the formula. Furthermore, the high-temperature fluid loss control mechanism was discussed by analyzing the effects of XG-g-AAA on the bentonite layer spacing, particle size distribution, stability of the colloidal system, and mud cakes.
“…The authors further acknowledged its excellent salt tolerance as well as temperature resistance properties which could be benecial in oil recovery, pharmaceutical and food applications. 156 Tao et al 157 endorsed sodium trimetaphosphate (STMP), a non-toxic and water soluble cyclic triphosphate for the crosslinking of hydroxy groups of XG chains under alkaline condition to design hydrogel disks. One phosphorous group intertwined two sugar rings of different XG chains ( Fig.…”
Due to presence of hydroxy and carboxy functional groups, xanthan gum is amenable to various chemical modification for producing derivatives such as carboxymethyl xanthan and carboxymethyl hydroxypropyl xanthan with desirable properties for end use.
“…However, in recent years, the research on hydrophobically modified xanthan gum was mostly focused on the pharmaceutical field. − There were few studies on the petroleum industry, which were mainly involved the application in fracturing fluids. ,,− Therefore, this work studies the potential of hydrophobically associated xanthan gum as an oil-displacing agent to enhance oil recovery.…”
Section: Introductionmentioning
confidence: 99%
“…After shearing at 80 °C and 170 s −1 for 120 min, the viscosities of XG and HAXG solutions were 35.55 and 108.96 mPa s, respectively, indicating that the HAXG solution had better temperature and shear resistance. Wang et al 21 used the maleic anhydride/1-octadecene esterification method to prepare modified xanthan gum, which improved the performance on salt tolerance, temperature resistance, and shear endurance of xanthan gum. Sara et al 22 used the Williamson synthesis method to graft octyl groups onto the xanthan gum backbone and prepared hydrophobically modified xanthan gum derivatives with different degrees of substitution using ethanol and DMSO as two solvents.…”
Xanthan gum (XG) is one of the widely used biopolymers in oilfield development. It has low cost and will not pollute the environment. However, its limited temperature and salt tolerance restricts its application in high temperature and high salt reservoirs. An environmentally friendly hydrophobic associative polymer was prepared by grafting long-chain alkyl groups onto xanthan gum through an etherification reaction for enhanced oil recovery (EOR). The hydrophobically modified xanthan gum (MXG) was characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). Due to the hydrophobic association, MXG had excellent thickening, rheological properties, antiaging, temperature, and salt resistance properties. In the 30 g/L NaCl solutions, the viscosity of MXG (335 mPa s) was about 3 times that of XG (115.3 mPa s) at 65 °C. Whether in a high-salt solution (20 g/L NaCl) or reservoir injection water (mineralization of water is 7542 mg/L), modified xanthan gum can show good antiaging properties. The polymer flooding experiments showed that EOR of MXG is 25%, 7% higher than that of XG. The macroscopic mechanism of MXG flooding was studied. In summary, MXG has a wide range of applications in EOR.
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