Modification Of Xanthan Gum And Its Fracturing System And Rheological Properties

China has abundant reserves of unconventional resources and huge economic value.At the same time,the development of unconventional LPG can fill the vacancy caused by the shortage of conventional LPG.At present,the measure widely used in oilfield stimulation is hydraulic fracturing,and fracturing fluid thickener as a part of hydraulic fracturing is also a hotspot for scholars.First,using 3-chloro-2-hydroxypropyltrimethylammonium chloride,propylene oxide as modifier and xanthan gum(XG)etherification reaction to obtain cationic xanthan gum(CXG)and cationic hydroxypropyl xanthan gum(HCXG).Through the exploration and optimization of single factor experiments and orthogonal experiments,the apparent viscosity of the HCXG solution with a mass fraction of 0.4%under the optimal synthesis conditions is 6.27 times and 2.27 times that of XG and CXG solutions,respectively.The structure of the product was characterized by infrared spectroscopy,nuclear magnetic resonance and X-ray diffraction(XRD).The rheological properties of XG,CXG and HCXG solutions and their performance indexes as fracturing fluids were studied.Infrared,nuclear magnetic and XRD test results show that the cationic etherifying agent and hydroxypropyl have been successfully connected to XG;the rheological properties of HCXG solution and the performance of the base fluid of fracturing fluid are better than those of CXG and XG solution.Afterwards,the performance of xanthan gum was further optimized using hypergravity technology to obtain hypergravity modified xanthan gum(CHCXG).After a single factor optimization,its viscosity has been further improved compared with HCXG,and it is increased by 28.98%again at 0.4%compared with HCXG solution.Subsequent rheological and base fluid performance tests also proved that its comprehensive performance was further strengthened,and the reaction time under optimal conditions was also shortened by 0.5h compared to before.At the same time,the formulation of organic zirconium cross-linking agent suitable for xanthan gum was explored and optimized through a single factor.Finally,the optimal modified xanthan gum was cross-linked with a self-made organic zirconium cross-linking agent,and the rheological properties of the organic zirconium cross-linked hypergravity modified xanthan gum fracturing system were tested.The results show that,compared with HPG jelly,CHCXG jelly system has more excellent viscoelasticity and temperature resistance.