Abstract: The paper made a calculation on the 51 polymer flooding wells, infilled well patterns and oil wells of basic well patterns in Sazhong region in Daqing oilfield, applying the equation of attenuating well pressure build-up curves and the result indicated that (1) the number of wells with straight-line portion calculated with classical send-log methods account for only 23.5% of the total, while the wells with straight-line portion calculated with attenuation equation account for 98%; (2) attenuation curve equation can be not only used to determine the parameters of the stable formation permeability,but can also identify effectively the near-well bore contamination and interpret the abnormal phenomenonof formation pressure and injection to production ratio in some parts of the field.

Key words: attenuation, pressure build-up curve, formation pressure, Permeability, immediate vicinity of well-bore