Abstract: The Bozhong 19-6 condensate gas field development project has encountered multiple sets of complex and weak formations during drilling in the Tertiary strata. The complex geological conditions are mainly manifested in the fault loss formed by tectonic movement,with the Dongying group as the main formation. When serious leakage occurs,a variety of leakage characteristics are often the same. At the same time,the coexistence of narrow density window and multiple pressure systems also affects the safety of downhole operation. Therefore,this paper analyzes the leakage characteristics and difficulties encountered during drilling in the Bozhong 19-6 condensate gas field development project. The characteristics of regional leakage are analyzed and the regularity in the process of well leakage treatment is summarized. The technical measures based on the concept of “prevention first,combination of prevention and blockage,scientific management and efficient plugging” are put forward,and successfully applied in the well leakage treatment field,which has positive significance for improving the operation efficiency and ensuring production safety in this area.

Key words: Bozhong 19-6, well leakage treatment, mature fault, narrow density window