The practice and knowledge of drilling deepwater well in west Africa

JDZ B-1 is the first deepwater well drilled by SINOPEC as an operator, which is located at JDZ(Nigeria-Sao Tome Principe Joint Development Zone) in Gulf of Guinea, and its water depth is 1 655 m. There are a lot of challenges in drilling this deepwater well, such as complex formation, low formation fracture pressure, small margin between formation fracture pressure and pore pressure, hole stability, especially the pay zone is only 778 m below mud line. Based on the challenges in drilling and deepwater drilling technology, optimized the well structure design and took reasonable measures while drilling operation, and successfully solve problems and got required information about this well. The success will exert great effect on deep water drilling in the future, and also provide a good reference to the development of drilling techniques in this area and in China.