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

What is MPD in Drilling and Completion?

Managed Pressure Drilling (MPD) is a technique for adjusting the pressure in the well. Initially MPD was used primarily to enable drilling wells in environments deemed undrillable with conventional methods. The usage of MPD has expanded to include other areas such as 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 You Need to Know

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 utilizing 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 default approach with 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.

With an MPD system rigged up it is wise to investigate if it can benefit more than just drilling or completion.

There have been cases where the initial thought for acquiring an MPD system centered around drilling efficiencies, only to discover that the largest 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 for 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 will have a uniform pressure profile throughout the section. SBP generate profiles with higher pressure at shallow depths (Shoe) and lower pressure deeper down (Bit). CML generate profiles with lower pressure at shallow depths (Shoe) with increasing pressure deeper down (Bit).

4. Different MPD methods have different approaches.

This relates mainly to their difference in pressure profiles. The pressure profiles vs the section specific operating window determines the opportunities and limitations for drilling and managing the pressure during completions.

The different MPD methods naturally favour different drilling environments; a SBP system can more easily increase the pressure in the well (drilling in a pressure ramp) whereas a CML system can more easily reduce the pressure in the well (drilling in a depleted zone).

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

With SBP MPD a separated lower completion assembly is 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 will use a higher density completion fluid – both of which may affect the completion.

6. MPD can increase rig time (displacements and tripping).

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

CCS and SBP rely on a fluid density being statically underbalance which requires displacements (drilling fluid, tripping fluid, cementing fluid) and or stripping in/out at reduced trip speed. The CML method removes this flat time by eliminating the need for displacements and enables higher tripping speeds.

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

Dynamic Pore Pressure Tests (DPPT) and Dynamic Formation Integrity Tests (DFIT) are probably the best-known benefits.

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

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

For completion there is for example the ability to add pressure 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. Bridging documents may be required for new well control procedures and crew training is required. The rig integration varies according to both rig and type of MPD method.

9. MPD can simplify and improve the well design.

This applies especially for deepwater wells with CML, where two of the upper sections are drilled as one section. This is now established as a standard 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 will generate less 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 increase the production rate through improved completion.

This is documented with Open Hole Gravel Pack cases using MPD (CML) in the North Sea and Gulf of Mexico. In these cases, the gravel packing was completed once a full screen out was achieved instead of ending the gravel packing when inducing losses.

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

Conclusion

Managed Pressure Drilling (MPD) offers a versatile solution for overcoming the challenges of drilling in complex environments while maximizing production through improved completion. By allowing precise pressure management, MPD not only enhances drilling efficiency but also transforms completion strategies, enabling approaches that would otherwise be impractical.

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

Ultimately, a collaborative and well-planned approach to utilizing MPD can lead to optimized operations, reduced costs, and improved safety, making it an invaluable tool for modern drilling and completion engineers.

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.