Development And Evaluation Of High-temperature Silanization And Etherification Guar Based Fracturing Fluids

The hydrocarbons resource are very rich in China,and the development prospects is broad.Now,the majority of reservoir need to fracture to increase production capacity.Fracturing fluid directly influences the effect of fracturing as working liquid.Thickener is one of the main components of fracturing fluid,and has been widely studied.Guar and its derivatives are the most popular thickener,such as GG?HPG?CMHPG and so on.However,they have obvious shortcomings,such as poor temperature-stable ability and shear resistance,high levels of the residue,high cost and so on.Based on the situation of study on development of thickeners,starting from the chemical modification of guar gum,screened the aid of fracturing fluid and made performance evaluations.The main results are below.(1)By chemical modification of guar gum,developed the silanization guar gum(SGG),and characterized SGG by IR and SEM.(2)By study of the best conditions of modification,the optimum conditions of preparing SGG was conformed as the ratio of 40:1 of the reactants,100? of reaction temperature and 2h of reaction duration.(3)Based on the experiment,optimization the main agent,including temperature cross-linking agent,clay stabilizer,temperature stabilizer,cleanup additive and gel breaker,and optimized for the SGG fracturing fluid system.(4)By the rheological experiments,evaluation the stability of the high temperature silanization guar gum fracturing fluid system.After shearing 2 hours by 170s-1 in 160?,the viscosity of high temperature silanization guar gum fracturing fluid is still greater than 50mPa.s,which showed that this fracturing fluid could be applied to the reservoir of less than 160?.(5)Evaluation the gel breaking performance and the residue levels of the high temperature silanization guar gum fracturing fluid system by experiment.The result shows that this fracturing fluid system can be completely broken;the residue levels were 560mg/L and the residue levels the surface tension is less than 28mN/m after this system was broken;the fracturing fluid system possesses good proppant carrying ability.(6)Evalutation fracturing fluid system compatibility with formation fluid and evaluated the damages of the high temperature silanization guar gum fracturing fluid system to formation permeability.The results show compatibility of two kinds of fluid is favorable,and that this fracturing fluid system is harmful to formation permeability to some extent(7)By chemical modification of guar gum,developed the etherification guar gum(EGG),and characterized EGG by IR and SEM.(8)By study of the best conditions of modification,the optimum conditions of preparing EGG was conformed as the 200mL of water,2g of guar gum,1mL of sodium hydroxide solution(10%Wt),0.18g of 1,3-dichloropropanolratio,32.5mg of tetrabutylammonium bromide,70 ? of reaction temperature,6h of reaction duration and 30minutes of alkalization duration.(9)Based on the experiment,optimization the main agent,including temperature cross-linking agent,clay stabilizer,cleanup additive and gel breaker,and optimized for the EGG fracturing fluid system.The result demonstrated that the high temperature SGG fracturing fluid system could be applied to the reservoir which temperature below 160?.