The development and application of bi-functional clay inhibitor of CYY-2

with the constant discovery and gradual development of low-permeability and water-sensitivity formation, reservoir protection is especially important for improving water-injection development efficiency and enhancing working level of low-permeability reservoir, which will be a critical sector in enhancing development quality of low-permeability and water-sensitivity reservoir. Combined with the understanding of clay mineral expansion theory, starting from hydratability, polarity and oxidability of adopted materials, one type of bi-functional clay inhibitor, CYY-2, is developed which has the function of swelling prevention and swelling shrinkage, and property evaluation is carried out by adopting different methods and measures. Test results indicated that: by using this bi-functional clay inhibitor, the swelling prevention rate of magcogel and natural core powder could reach to 91.7% and 89.8%, swelling shrinkage of which could reach to 61.3% and 81.5%; in the natural flowing experiment, core damage ratio was declined from 86.3% to 12.8%, and the core permeability could be raised by 3 times averagely; in the field experiment of 5 wells, effective rate of 80%, the well effect, is reached. With the extension of injection time of injecting wells, injection pressure rose constantly, injection allocation request was not finished, which influenced the overall reservoir development effect. So reservoir protection is important to deal with the above problems.