SPE Distinguished Lecturer
Deepwater well design has not really evolved in the last half century. A major design deficiency is the shallow setting depth of the initial conductor casing not leveraging the increasing fracture gradient below the seafloor.The initial conductor setting depth is limited to about 400 feet below the seafloor due to the technical limitations of the jetting process.Jetting uses bit and mud motor technology without pipe rotation to “push” the conductor casing into the formation without pipe rotation which is insufficient for drilling harder sediment. The result is premature slimming of well architecture in the riserless interval leading to narrow drilling operating pressure windows deeper in the well. This deficiency in well design and inefficient mitigation of shallow hazards are reasons deepwater operators may fall short of their well construction objectives.
This presentation makes the case for casing drilling as a viable replacement for jetting in the initial conductor. Unlike jetting, casing drilling is a more mechanically efficient drilling system not limited by mud motor output as it uses casing rotation to drill. Casing drilling is well proven in land and shallow water operations for top hole drilling efficiency, reducing flat times and mitigating hazard intervals in a single trip. This talk will discuss transitioning casing drilling to the deepwater riserless interval where it can be an enabling technology to deepen the initial conductor depth based on fracture gradient, a mitigant for shallow hazards, and a means providing deepwater operators a more optimal well design for a successful outcome.