Study On The Formulation And Performance Optimization Of High Temperature Fracturing Fluid

With the exploration and development of oil and gas field,the oil and gas reservoirs are changed to deep and ultra-deep well,reservoir geology becomes more complex,wells are often unproductive.Fracturing has become one of the important technical measures for reservoir stimulation,Choosing high temperature fracturing fluid system with good performance is the key to realize deep well fracturing reconstruction.At present,it is difficult to predict pressure in the tight reservoir in domestic oil fields?especially in the middle and western regions?;Meanwhile,The fracturing fluid system cannot meet the actual field demand,the main problems of fracturing fluid system are:poor temperature resistance,poor shear resistance,poor filtration compatibility and high cost.In this paper,the crosslinking performance,compatibility and rheological properties of high temperature fracturing fluids were studied;besides,160 high temperature fracturing fluid systems were optimized and evaluated.Besides,it has been successfully applied in acidizing fracturing of shunbei well in Tarim basin,Xinjiang.In this paper,a kind of high temperature resistant and slow acid solution system was developed through experiments,which realized multi-stage alternating acid pressure,the crosslinked acid base solution can be used as gelling acid,and the crosslinking agent can be added as crosslinked acid.The formula of crosslinked acid:20%HCl+1%SRAP-1+2.5%SRAI-1?high temperature corrosion inhibitor?+0.5%synergist+1%SRAF-1?iron ion stabilizer?+1%SRAD-1?demulsifier?+0.8%cross-linker SRAC-2A and delayed crosslinker SRAC-2B?2:10?.The comprehensive performance evaluation shows that the system has good hanging and no deacidification in 10 days,the viscosity has good stability,which is beneficial to the field pumping.The viscosity of gelling acid was about 30m Pa?s after 120 minutes of constant temperature shear at 160,170 s^-1.The cross-linking time of the cross-linked acid is about 93s,which has a good property of delayed cross-linking;Under the condition of160,170 and s^-1,the viscosity is 65m Pa?s after 90 minutes of constant temperature shear,there is no deacidification,the crosslinking state is still good,add the glue breaker and then the crosslinked acid fracturing fluid breaks the glue quickly,it is beneficial to backflow and reduce the pollution of formation and it can meet the requirements of slow acid fracturing fluid for high temperature reservoir,realizing the integration of acid fluid system,and greatly facilitate the field construction.In this paper,high temperature resistant acid fracturing fluid was also optimized,the addition of hydrochloric acid,crosslinking acid and proportion,corrosion inhibitor and weighting agent were optimized,concluded that 120?resistance acidic fracturing fluid formula.The formula of acid fracturing fluid:5%HCl+0.6%thickener+0.3%inhibitor+0.3%SRAC-2A and SRAC-2B?1:3?.Its performance was evaluated comprehensively,it has good temperature and shear resistance,good compatibility and can break rubber quickly and has certain guiding significance to the field construction of high temperature reservoir fracturing.