Research On Acid Cross-linking And Rheological Properties Of Ground Cross-linking

Combing acid fracturing with proppants has become one of the most important measures to reform the carbonate reservoir,and the key problem of acid system to realize high fracture conductivity and multi-fractures is to select a good high-temperature resistant acid system.According to the domestic and foreign acid system’s problem,such as being broken after shearing,separation of hydrochloric acid and large amount of cross-linker and so on,a novel high temperature resistance and low dosage of new cross-liker in this paper was developed based on numerous laboratory researches.The specific formulation was that,20%Hydrochloric acid+0.8%thickener SRAP-1+0.8%cross-linking agent SRACL（2:10）+2%high temperature corrosion inhibitor SRAC-1+0.2%ferrous ion stabilizer DFI-1+1.0%cleanup additive SRCU-1+0.05%capsule breaker JSP-8.The results show that the cross-linking time of the system is about 89s,indicated that the system has a good crosslinking-delay properties.After 2h of constant temperature shear at 140℃and170 s^-1,the viscosity was still maintained up to 60mPa·s,and the system has a good temperature and shear resistance performance,which could meet the requirements of field case.So,this cross-linked acid system has a good application prospect.In addition,the sand-carrying properties,temperature and shear resistance,rheological properties,and acid-rock reaction kinetic parameters of the cross-linked acid system were evaluated and studied.According to different thickener concentration and cross-linker concentration,the rheological parameters were also evaluated.The relevant empirical formulae have been obtained from the analysis,which has certain guiding significance for the optimal design and on-site construction of carbonate acid pressure.