Abstract:

The evaluation of water flooded layer using the old data is very difficult in high water cut reservoir. In this research, the idea of establishing the relationship between water content and resistivity in target section to realize the evaluation of old wells under water flooded condition was adopted. For the same type of depositional sand body, the initial resistivity and initial water content was picked up from the drilling data of the sand body in different historical stages during the development to establish the empirical formula for the relationship between water content and resistivity. And then, the current remaining oil saturation of the old wells could be calculated by the Archie formula. Therefore, a rapid interpretation method for old wells under water flooded condition based on the water content and resistivity was put forward. Based on the new method, the ZW Oilfield with more than 30 years of development history was chosen as the example. The evaluation of the water flooded degree of old wells in the 6th sand group of first member of Sanduo Formation in the typical block, ZW12 fault block, was made. Meanwhile, through the calculation of the oil saturation of the closed coring wells, well-ZJ1 and well-ZJ4, the accuracy of this method was verified. It was proved that this method has high practicability in the rapid qualitative—semi-quantitative evaluation of old wells in high water cut reservoir under the water flooded condition.

Key words: high water cut reservoir, water content, resistivity, evaluation of old wells under water flooded condition, ZW12 fault block, Sanduo Formation