Synergistic Diverting Acid System and Its Application in Heterogeneous Carbonate Reservoir Stimulation

Zanazour Oilfield has the typical characteristics of large perforation interval span, large number of perforation intervals, large differences in physical properties between different layers, and uneven fluid production profile. In order to achieve uniform acidification requirements, improve fluid production profile, and increase the use of low permeability layers, a multifunctional diverting acid fluid system suitable for the characteristics of the Zanazour oilfield was developed. The system has the characteristics of temporary blocking and diverting, selective acidification, and energy-assisted flowing back and so on. Based on the reservoir and fluid characteristics, lithology and physical properties of the oilfield, three acid liquid systems with good compatibility and temporary plugging, diverting, deep acidification, and energy-enhancing flowing back were developed, and their properties were tested with laboratory tests. At the same time, in order to give full play to the advantages of different functional acid liquid systems and achieve the purpose of synergistic enhancement, selective foamed acid systems and technologies, as well as emulsified self-diverting acid systems and technology have been formed. The pilot implementation of the field experiments, through high construction success rate and significant better production increasing effect than that of conventional liquids, indicated that the multifunctional diverting acid system and synergistic acidification technology have better adaptability in the oil field.