Guar Gum Facturing Flowback Fluid Reuse Factor Analysis And Eliminationmethod Research

At present,fracturing technology has been widely used in reservoir reconstruction of low permeability oilfield,while guanidine fracturing fluid is the mainstream system of fracturing fluid.Because of its complex nature of the composition of the drainage,the treatment is more difficult,has brought to the field of oil field development can not avoid pollution.In addition the configuration of guanidine fracturing fluid requires a lot of fresh water resources,to some remote water areas brought some economic pressure.Therefore,the repeated use of guanidine fracturing backflow has always been the hotspot and difficult point of oilfield development.The present situation of the recovery and reuse of guanidine gel fracturing fluid can not be effectively carried out,and the influence analysis and elimination method of recirculation Research is very important.The paper firstly had synthetical analyses on compositions and properties of fracturing flowback fluid in sites,and contents and physicochemical property characteristics of essential components in fracturing flowback fluid were defined.Then,critical factors influencing guar gum fracturing flowback fluid recycling in northwest region were determined by research of single factor experiment,and Studying these main factors and mechanism to eliminate the influence of these unfavorable factors to do the basic preparation.Through "ozone oxidation-flocculation sedimentation" pretreatment and synthetic retarded crosslinking agent to eliminate the guanidine gum fracturing fluid flowback of the main factors influencing the reuse.Ultimately,a set of process in fracturing flowback fluid recycling were formed.Through the study above,the conclusions were as follows:(1)The characteristics of fracturing flowback fluid in northwest region were concluded with stable system,high pH,and high iron content and low salinity.(2)The key factors of influencing factors of guar gum fracturing flowback fluid recycling were pH,Ca2+,Fe3+,crosslinking agent residue,breaking agent residue and solid particles.(3)“Ozone oxidation-flocculating settling-filtration” can eliminate negative influence of the pH,Fe3+,Ca2+ and solid particles.(4)The optimum dosages of "ozone oxidation-flocculation settling-filtration" treatment of fracturing flowback fluid were: ozone oxidation for 30 min,PAC 800 mg/L,coagulant aid PAM 4 mg/L,flocculating settling for 30 min.Processing after fracturing fluid flowback pH is 6.32,the removal rate of suspended solid is 98.95%,Fe3+content is 1.61 mg/L.(5)Preparation of slowcrosslinking agent: The first step reaction is 14.9g hydroxyethyl ethylenediamine,8.9g epichlorohydrin,5g sodium hydroxide,reaction temperature 50 ?,reaction time 8h Preparation of intermediates;second Step Reaction To 23.8 g of intermediate,add 50 g of boric acid mixed ester,add 10 g of pentaerythritol and 5 g of sodium hydroxide.Heat the reaction to 150 ° C for about 2 hours.Press the reaction under reduced pressure for 1 h,add16.1 mL of water to stir evenly.(6)“Ozone oxidation-flocculating settling-filtration”after processing fluid flowback,change the crosslinking agent,forming gel fracturing fluid system,the temperature of 80 ?,the shear rate is 170 s-1,the viscosity of fracturing fluid in 185mPa·s.;In temperature 80 ?,gel breaking time is 2 h,and gel breaking liquid viscosity of 2.37 m Pa s.,residual mass concentration of 325 mg/L.Basic meet the fracturing fluid flowback fluid recycle performance requirements.(7)A set of process in fracturing flowback fluid recycling were formed which was “ozone oxidation-flocculating settling-filtration”.