Integrated Geology-Engineering Early Warning Technologies for Lost Circulation of Fractured Reservoirs in Bohai Oilfield

In order to solve the problems of downhole leakage caused by faults and fractures in the drilling process of fractured reservoirs in Bohai Oilfield, integrated geology-engineering early warning technologies for lost circulation were proposed. Using large and medium-scale fault characterization in post-stack seism, special treatments such as filtering and fault enhancement were carried out to optimize attributes, fuse multiple attributes, finely describe small and medium-scale fractures, and a three-dimensional spatial distribution model of multi-scale fractures was established. In the design of the wellbore trajectory, drilling in the layers with leakage was avoided. The model was used to develop risk warnings before drilling and guide drilling operations in taking countermeasures for preventing and plugging leakage. During the drilling process, the tracking technology for lost circulation risk was implemented, and the prediction results of the risk were adjusted and fed back in real time. As a result, the wellbore trajectory was optimized in a timely manner, and a dynamic technology for avoiding layers with leakage while drilling was formed, which fully guaranteed the safety of drilling operations and reduced operating costs. The above-mentioned technologies such as risk prediction before drilling, tracking for lost circulation during drilling, and real-time optimization of the wellbore trajectory while drilling were successfully applied in Lvda X Oilfield and avoided leakage sections of the faults in one trip. The integrated geology-engineering early warning technologies for lost circulation can effectively minimize drilling risks and ensure operational safety in fractured reservoirs, which provides technical support for increasing reserves and production of Bohai Oilfield.