Synthesis And Property Analysis Of Hdrophobic Modified Guar Gum

Hydraulic fracturing is a common method in improving the hydrocarbonproductivity. The proppant was carried from the ground to the fractures by theviscoelastic fracturing fluid, and then the fractures could be supported orextended. Hydrocarbons can flow to the bottom hole along the supportedfractures, and the aims of improving the production may be achieved. Thefracturing fluid gel is often made up of water-soluble polymer, crosslinker,gelbreaker and other additives. The guar gum (GG) or its derivant such ashydroxypropyl guar,carboxy methyl guar,carboxy methyl hydroxypropyl guarcan be used as thickener. The concentration of the thickener usually very highand the high concentration may cause huge friction, reduce the efficiency of thepump in the process of pump note. This will also make more difficulty inpreparing the solution and increase the residue. The reduction of the thickenercan improve the station in some degree. In this paper, we have obtained series ofmodified guar gum to meet the requirements of the fracturing. The structure andrheological property were analyzed in order to reduce the concentration of thethickener. Two kinds of modified guar gum were successfully prepared:The one was synthesized with GG as material and bromododecane asetherifying agent by suspension polymerization method. The aqueous solutionand the gel of the modified guar gum were also prepared. The structure and theproperty of the modified guar gum were analysized by means of FT-IR, XRDand TGA. The apparent viscosity of the solution was tested by rotationalviscometer and the heat resistance and the viscoelasticity modulus of the gelwere also researched by rheometer. The results of FT-IR and XRD showed thatthe hydrophobic long chain had been introduced into the guar gum successfully.TGA indicated that the modified guar gum had higher thermal stability. With thesame concentration, the modified guar gum had better stability and higherviscosity than the unmodified. The rheology tests reflected that with different temperature conditions, the shear viscosity, the viscoelasticity modulus of the geland the heat resistance of the modified guar gum were both better than theunmodified. The modified guar gum could be used as thickener of fracturingfluid, and it could reduce its amount.The other one,2-hydroxy-3-butoxypropyl guar gum (HBPG), wassynthesized with GG as material, using n-butyl glycidyl ether (BGE) as thehydrophobic reagent, sodium hydroxide as catalyst and isopropanol assolvent.The structure of HBPG was characterized by means of FT-IR, XRD andTGA, meanwhile, the rheological property of the aqueous solution and the gel ofHBPG were discussed. The results showed that the hydrophobic modificationcould reduce the crystallinity and improve the thermal stability. Compared to GG,HBPG had better thickening property and the solution stability has significantlyimproved. The rheological property of the gel of HBPG was better than GG. Thegel of HBPG has good temperature resistance and shear stability properties.