Studies On Synthesis And Performance Evaluation Of New Clay Stabilizers Used For Fracturing In Changqing Oilfield

Clay minerals are widespread in the formation,such as montmorillonite,kaolinite,illite and so on.When they contact with water-based fracturing fluid,they are easy to cause the hydration and swelling of clay minerals,which bring the problems such as reservoir permeability decline,the effect of oil field exploitation.Aiming at such problems,the purpose of this study is to develop a good efficient clay stabilizer which has compatibility with fracturing fluid.This paper optimized the centrifuge method to determine the rate of the anti-swelling agent,studied the conditions of the laser particle size instrument used in the application of clay stabilizers performance evaluation,developed an evaluation device and method to evalue the waterwashing properties.In this paper,based on epoxy chloropropane,diethanolamine,dimethylamine,dimethyl ethanolamine and so on as raw materials,five types of polymers were synthesized such as quaternary ammonium salts,zwitterionic copolymer and biquatenary ammonium salts.Through the basic evaluation of the expansion rate and the compatibility with the fracturing fluid,the biquatenary ammonium salts are selected out.Through the exploration of the optimal synthetic conditions of GJ-3,the product of the synthesized under the best conditions is got,which is named the Top-3,through making complex formulation of Top-3 and KCl,ultimately the anti-swelling agent CsS-2 is got.Then its performances are studied on,such as the rate of the anti-swelling agen,the waterwashing properties,compatibility with fracturing fluid and so on.The GJ-3 is made of chloropropane,dimethyl ethanolamine and so on,The best optimum conditions were that Under the normal pressure the Trimethylamine hydrochloride(n):epoxy chloropropane(n):dimethyl ethanolamine(n)is 1.2:1.2:1,the reaction temperature is 40℃,the reaction time is 2h,the Optimum reaction pH is7.5-8.The product which is synthesized under the best conditions named Top-3.When adding the amount of 0.5%,the expansion rate of the COS-2 is as high as 81.5%.The expansion rate has no change when the COS-2 soaked at 90℃ for7 days.The stability of the COS-2 are good after being rinsed.The Compatibilities with formation water and otherfracturing fluid were good.When added to the fracturing fluid,the shear tese index and thermal stability of the fracturing fluid were good,which fully met the the index requirements.of the SY/T6376-2008 "the fracturing fluid general technical conditions".