Casing Program Design and Optimization for Deepwater Drilling and Application in JDZ Block of West Africa

摘要

JDZ Block in west of Africa is a strategic oversea deepwater exploration and development project for Sinopec who worked as an operator at the first time in this ultra-deepwater drilling project.Casing program design and optimization is the key point in drilling engineering plan.Deepwater drilling has the characteristics of special jet in technique for conductor; open hole drilling for surface casing section; low formation fracture pressure gradient in shallow formation, and higher uncertainty in formation pressure information.Therefore there are significant differences for casing design and optimization compared with shallow water and onshore drilling.The subsea wellhead mechanical stability and conductor setting depth, surface casing setting depth, casing program and setting depth under formation pressure uncertainties were detailed for deepwater casing design and optimization based on investigation of deepwater well structure.The paper presents cases study in JDZ block in west of Africa, the results show that approach suggested in this paper could be fitter for deepwater drilling than conventional methods, it can lower risk possibility and improve the operation efficiency.