During the process of the longterm water injection development, there was
a phenomenon of coexisting of regional lowpermeability reservoirs and largepore reservoirs in Changqing Oilfield, which made it difficult to
measure and interpret the water injection profile logging data. As a result, it was difficult to determine the amount of water absorbed by each
sublayer. Based on the wellbore pressure system of the injection well, the pressure loss at each stage of the water flow process and the seepage
characteristics of the water absorption layer were analyzed to determine the sensitive parameters affecting the logging acquisition. In addition,
the influence of water injection volume adjustment and large pore formation characteristics on water injection profile logging data acquisition
was analyzed and the appropriate size of isotopes was determined. The results show that when the pressure difference of water injection layer was
large, the isotope would enter the layer quickly, which would cause the distortion of measurement; when the pressure difference of water injection
layer was small, the isotope was difficult to enter the formation, and it would cause wellbore pollution, which made the collected data
inconsistent with the actual water injection situation and lowered the effect of water injection. Therefore, the key to successful logging and
reservoir protection was to bring isotopes into the reservoir position and reduce the damage to the reservoir by reasonable pressure difference of
water injection formation. This analysis can improve the accuracy of log interpretation results of water injection profile, reveal intralayer
contradictions, evaluate water injection effect, and provide measures for effective treatment of low permeability oilfields in the later stage of
development.