EC-Drill® Eliminating Casing Strings as a Standard Approach in Deepwater Drilling

The narrow operating envelope in deepwater wells requires frequent casing/liner setpoints which makes the well design more complex. The casing/liner strings comes at a high cost by themselves, and the wells take longer to complete. In this case study EC-Drill® was used in Gulf of Mexico (GOM).

Challenge

Reducing casing points in Deepwater Drilling. A common challenge for Deepwater wells is the need for multiple sections.

The narrow operating envelope in deepwater wells requires frequent casing/liner setpoints which makes the well design more complex. The casing/liner strings comes at a high cost by themselves, and the wells take longer to complete

Solution

EC-Drill® takes advantage of the Dual Gradient effect it creates when lowering the Riser Level – and the starting point of the fluid column. The resulting pressure profiles in the well matches the trend of the operating window enabling the sections to be extended.

In addition to eliminating a liner/casing the sections can in some cases be drilled conventionally by keeping the riser level fixed at a reduced level removing the need to operate with a Constant Bottom Hole (CBHP) approach

Challenge Solved

EC-Drill is now used to eliminate Liner/Casing strings as a standard approach by benefiting from the Dual Gradient effect it creates. The wells are planned and executed accordingly which simplifies the well design and reduces the time to drill and complete them. The extended sections can in some cases be drilled conventionally going beyond the CBHP approach.

Even with Fracture Gradients at the shoe being lower than the Pore Pressure further down in the section it is straightforward to drill and complete the sections

Conclusion

• EC-Drill established eliminating Casing/Liner in Deepwater drilling as a standard approach by utilizing the Dual Gradient Effect.
• EC-Drill enables drilling in negative operating windows
• EC-Drill proven as both enabler and optimizer
• EC-Drill “more than MPD” going beyond only CBHP approach