Evaluation Of Acid Resistance And Sealing Channeling Performance Of CO₂-driven Weak Gel System

Along with the continuously go deep into the water injection development,comprehensive water cut rising,more and more high water cut oil well number,characterized by low recovery degree,low utilization rate of resources,low development efficiency,CO₂ flooding can improve oil recovery,not only can solve the problem of geologic sequestration,protect the atmospheric environment,inhibit the greenhouse effect,has a broad application prospect.In CO₂displacement process gas channeling phenomenon,as a new type of weak gel flooding sealing channeling blocking agent is widely used in CO₂,but CO₂gas dissolved in acid etching effect of weak gel system to system,this paper carried out the CO₂ flooding weak gel system performance evaluation of the resistance to acid and sealing channeling and set up CO₂ flooding weak gel acid and performance evaluation method.Based on the experimental method of CO₂ flooding weak gel system to evaluate resistance to acid,acid performance evaluation standard to evaluate mainly from two aspects of dynamic and static,static evaluation mainly through the experiment in different temperature and pressure and salinity under the condition of weak gel system of microstructure,the law of the rheological and viscoelastic observation and test,the evaluation results that weak acid conditions contribute to form weak gel network structure,increase the system's energy storage modulus;At a low shear rate?0?100s-1?,the CO₂ flooding gel system is a pseudoplastic fluid.At a high shear rate?100?1000s-1?,the CO₂ flooding weak gel system behaves as an approximate Newtonian fluid.With the increase of experimental time in CO₂ environment,the energy storage modulus of the weak displacing gel system increased first and then decreased sharply.The dynamic evaluation is mainly based on the core simulation experiment of the parallel sealing performance of cores with different permeability and different permeability levels by the CO₂ flooding weak gel system.The evaluation result indicates that the effective duration of the system in the formation condition?85?and 20MPa high-pressure CO₂ environment?is 30d,which is not suitable for depth profile control.In this paper,through the evaluation of the acid resistance of CO₂ weak displacing gel system,the method of establishing the relationship between the static stability evaluation results and the blocking performance evaluation results of CO₂ weak displacing gel is established to evaluate the acid resistance and blocking performance of CO₂ weak displacing gel.