EC-Drill® Enables Casing Elimination in Deepwater Wells in the Gulf of Mexico 

Executive Summary

In a deepwater well in the Gulf of Mexico characterized by a narrow operating window and complex well architecture, EC-Drill® enabled elimination of a planned liner section by leveraging the Dual Gradient effect.

The result:

• Extended drilling sections
• Simplified well design
• Reduced operational time
• Lower casing and liner costs

This case demonstrates how EC-Drill® enables a different approach to pressure management by reshaping the pressure profile to better match the well’s operating window.

The Deepwater Challenge: Why Are Multiple Casing Strings Required?

What makes deepwater wells difficult?

Deepwater wells are often characterized by:

• Narrow pressure margins between pore pressure and fracture gradient
• Multiple casing and liner set points
• Increasing complexity with depth
• High cost per additional casing string
• Extended drilling and completion timelines

The challenge is not unique to deepwater alone, but becomes more pronounced due to well depth and pressure constraints.

When the operating window narrows with depth, conventional drilling requires multiple casing points to stay within safe pressure limits.

Result:Increased number of sections, higher complexity, and increased cost.

Learn more: EC-Drill® Dual MPD system

Plot 1 – Deepwater Operating Window and Resulting Casing Scheme

Figure 1 – Conventional pressure profile: Illustration of the drilling pressure environment showing pore pressure (red), fracture gradient (blue), and hydrostatic pressure profiles (white) for different mud weights in conventional drilling.

As depth increases, the operating window narrows, making it difficult to maintain a single mud weight within safe limits. This requires multiple adjustments in mud weight and leads to additional casing or liner set points.

In this example:

• The pressure window narrows significantly with depth
• Different mud weights are required for each section
• Multiple casing/liner set points are introduced

Each additional casing string increases:

• Rig time
• Material cost
• Operational complexity

This has traditionally been accepted as standard well design practice.

The Solution: Using the Dual Gradient Effect to Extend Sections

How EC-Drill® changes the pressure profile

EC-Drill® creates a Dual Gradient effect by lowering the riser fluid level, effectively shifting the starting point of the hydrostatic column.

Figure 2 – EC-Drill® modified pressure profile: This illustration shows how EC-Drill® modifies the pressure profile in the well.

Compared to conventional hydrostatic pressure profiles (white lines), the adjusted pressure profile (green) better follows the operating window defined by pore pressure (red) and fracture gradient (blue).

This enables:

• Improved alignment with the operating window
• Reduced need for multiple mud weight changes
• Extension of drilling sections
• Potential elimination of casing or liner sections

Explore: EC-Drill® Controlled Mud Level technology

Plot 2 – Extending Sections Using the Dual Gradient Effect

Figure description: Comparison of conventional mud weight and EC-Drill® Dual Gradient pressure profile, illustrating how liner sections can be eliminated by extending drilling intervals.

The comparison shows:

• Conventional drilling requiring liner installation
• EC-Drill® enabling extended sections
• Reduced need for casing strings

In some cases, once the riser level is set at a reduced level, sections can be drilled without continuous CBHP operation.

Case study: EC-Drill® Dual MPD influx management

Challenge Solved: From Reactive to Engineered Well Design

By applying EC-Drill®, the well design can be fundamentally simplified.

Key outcomes:

• Liner and casing strings can be reduced or eliminated
• Sections can be extended beyond conventional limits
• Well architecture becomes less complex
• Time to drill and complete is reduced

Even in scenarios where fracture gradient at the shoe is lower than pore pressure deeper in the section, EC-Drill® enables controlled drilling and completion.

This represents a shift from reactive pressure management to engineered pressure profile design.

EC-Drill®: More Than Conventional MPD

EC-Drill® is not limited to conventional MPD approaches such as CBHP.

It enables:

• Dual Gradient drilling
• Drilling in negative operating windows
• Section extension
• Pressure profile optimization

It functions as:

• An enabler for wells that would otherwise be difficult or not feasible to drill
• An optimizer for improving efficiency in wells that are already drillable

Watch the Technical Webinar

Explore how EC-Drill® Dual MPD is putting an end to frequent casing and liner installations in deepwater drilling.

👉 Watch the webinar: Deepwater MPD – Introducing EC-Drill® Dual MPD

Conclusion

EC-Drill® enables a different approach to deepwater well design by leveraging the Dual Gradient effect.

By reshaping the pressure profile, it becomes possible to:

• Reduce or eliminate casing and liner strings
• Extend drilling sections
• Simplify well architecture
• Reduce overall well cost