Acidizing is commonly used to relieve damage and increase reservoir permeability.In carbonate reservoirs,this process is commonly performed using viscoelastic surfactant (VES)-based steering acids.VES steering acid formulations can respond to changes in[H⁺]and[Ca²⁺]to modulate the rheology of the surfactant solution.When the viscosity increases,the fluid changes its flow direction and forms wormholes.In this paper,a system for acid-liquid neutralization was constructed and tested using two commercial steering acids to investigate the rheology of the fluid at different degrees of neutralization and to simulate the behavior of the fluid as it flowed and reacted in a carbonate matrix.In addition,new responsive steering acids based on VES,named ZX,were developed and their linear and nonlinear rheology was investigated at different[H⁺]and[Ca²⁺],and their performance was evaluated in core replacement experiments.The experimental results showed that these novel steering acids formed desirable dominant wormholes.
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