11 Things All Drilling and Completion Engineers Need to Know About MPD

Managed Pressure Drilling (MPD) was originally developed to enable drilling in wells where conventional methods struggle — typically due to narrow pressure margins, depleted formations, or deepwater conditions.

What is MPD in Drilling and Completion?

Managed Pressure Drilling (MPD) is a set of techniques used to precisely control bottom-hole pressure throughout drilling and completion operations. It is typically applied in wells with narrow pressure margins, deepwater conditions, or depleted formations — where maintaining stable bottom-hole pressure is challenging with conventional methods. MPD was originally introduced to make these wells drillable, but its application has since expanded to include cementing and completion.

Implementing MPD introduces additional complexity and may increase rig time, depending on the chosen method. In some cases, the completion assembly may require modifications or be split for MPD to be used.

In short, MPD can enable drilling in challenging environments and increase production through improved completion. While it can bring added operational flat-time and require changes to the planned completion, it all comes down to the specific well, choice of MPD method, and careful operational planning for both drilling and completion.

Check out: How Does CML MPD Work? 

11 Things to Consider When Using MPD

When considering MPD, investigating the different MPD methods and taking them into account early in the planning phase will go a long way. Ideally, the consideration should apply for both drilling and completion. Especially, completion can benefit greatly by MPD and result in improved production.

Here are some key points to keep in mind when considering MPD for drilling and completion:

Beyond holding a Constant Bottom Hole Pressure (CBHP) MPD can benefit from the Dual Gradient effect (DGE) and extend sections. In deepwater operations the Controlled Mud Level (CML) MPD is using the DGE to drill two sections as one and remove a casing string from the well design.

The completion method can also be changed with MPD. Beyond managing the pressure while circulating, different approaches otherwise deemed not possible can be used with the right MPD method.

2. MPD can benefit both drilling and completion

Once an MPD system is installed it is worth evaluating if it can benefit more than just drilling or completion.

In some cases, the initial thought for acquiring an MPD system centered around drilling efficiencies, only to discover that the greatest value was realized during completion activities.

Ideally, drilling and completion engineers should get together and evaluate the full spectrum of MPD capabilities and consider its application across the entire lifecycle of the well.

3. Different MPD methods have different pressure profiles

Whether drilling or completing with MPD - this is important to be aware of. The three most common MPD methods (Continuous Circulation System (CCS), Surface Back Pressure (SBP), Controlled Mud Level (CML)) all generate different pressure profiles in the well.

CCS provides a more uniform pressure profile throughout the section. SBP typically results in higher pressure at shallow depths (Shoe) and lower pressure deeper down (Bit). CML results in lower pressure at shallow depths (Shoe), with increasing pressure deeper down (Bit).

Graph showing how different MPD methods affect pressure profiles along the wellbore.

4. Different MPD methods have different approaches

This relates mainly to their difference in pressure profiles. The pressure profiles relative to the section-specific operating window determines wether the method can operate within the available pressure window – and therefore wether it is suitable for the section.

Different MPD methods are suited for different drilling environments. Methods based on surface backpressure typically increase pressure from the top of the system, making them suited for pressure ramp conditions. Controlled Mud Level (CML), on the other hand, enables pressure reduction and provides a more precise and flexible way to adjust bottom-hole pressure – which is often critical in depleted zones.

5. MPD may require changes in completion assembly and completion fluid

In methods based on surface backpressure, a separated lower completion assembly is typically run first to temporarily isolate the reservoir. The second assembly part is then run on pipe with compatible float valves.

With CML MPD any type or size of assembly can be run without requiring modifications.

SBP will use a lower density completion fluid, whereas CML can use a higher density completion fluid – both of which may affect the completion.

6. MPD can require additional time for displacements and tripping

Again, this depends on the MPD method. It is an important factor when evaluating cost vs. benefit – especially for deepwater wells.

Some MPD methods rely on a statically underbalanced fluid system, which requires displasements between drilling fluid, tripping fluid, and cementing fluid, as well as stripping operations at reduced trip speeds. The CML method removes the need for these displacements and enables higher tripping speeds, reducing the associated operational time.

7. There are side benefits with MPD for drilling and completion

In addition to pressure control, MPD can provide several operational side benefits.
Dynamic Pore Pressure Tests (DPPT) and Dynamic Formation Integrity Tests (DFIT) are among the most well-known benefits and can be performed with SBP and CML.

With CML comes the ability to trip faster, reducing rig time and minimizing open hole exposure time before the completion assembly, or casing, is in place.

CML also allows pressure to be adjusted as desired, regardless of what is in the well, from wireline to casing, without requiring modifications. It can also assist in freeing stuck pipe on the fly, as well as performing DFITS and DPPTS (the latter requires installation of control device in riser).

In completion operations, it also enables pressure to be applied when spotting a breaker fluid.

8. MPD brings added equipment and complexity

The amount of extra equipment (and resulting footprint) varies depending on the type of MPD method. The added equipment increases the complexity of the drilling and completion system of the rig. This may require updated procedures, bridging documents, and additional crew training. The rig integration varies according to both rig and type of MPD method.

9. MPD can simplify and improve well design

This applies particularly for deepwater wells using CML, where two of the upper sections can be drilled as one, allowing a casing string to be removed from the well design. This is now the default approach. By eliminating a casing string, the remainder of the well will have a simpler design.

Besides combining or extending sections, MPD can enable drilling sections with different hole sizes. The reservoir section can be of a larger or smaller hole if wanting to use different size of completion assembly.

10. MPD enables different types and densities of drilling and completion fluids to be used

Besides density the different fluids have different properties. For completion it can be beneficial to use a different type of brine. For drilling, the ability to use a drill-in fluid in the reservoir may reduce skin damage and improve a subsequent gravel packing.

When perforating, a heavier fluid can be used to ensure overbalance while CML can adjust the fluid level to stop losses afterwards.

11. MPD can significantly improve production through better completion execution

This is documented with Open Hole Gravel Pack cases using MPD (CML) in the North Sea and Gulf of Mexico. In these cases, gravel packing was completed upon achieving full screen-out, rather than being terminated due to losses.

Read more: MPD methods: Pros and Cons of CML vs SBP

Conclusion

Managed Pressure Drilling (MPD) offers a versatile approach to addressing the challenges of drilling in complex environments, while also supporting improved completion performance. By allowing precise control of bottom-hole pressure, MPD can enhance drilling efficiency and enable completion approaches that would otherwise be difficult to execute.

You should consider the specific MPD methods, their associated complexities, and the potential benefits across the full well lifecycle.

Ultimately, a well-planned and collaborative approach can contribute to more efficient operations, reduced costs, and improved safety.

Worth noting - there are several additional aspects to keep in mind when evaluating using MPD. Regulatory compliance, crew training and rig integration are other points which needs to be addressed.