The document discusses mudline suspension systems used for offshore drilling. It describes how the system allows the weight of the well to be transferred to the seabed and provides a disconnect capability. Key components include butt-weld subs, shoulder hangers, split-ring hangers, mudline hangers, and temporary abandonment caps. The system also allows the well to be temporarily abandoned when drilling is finished and reconnected later for completion.

1. MLS (Mudline suspension Sys.)
Offshore Drilling
Dr. Esmaeili
S.Hamidreza Shobeyri
ME, Petroleum Engineering (Drilling)
IAU ( Central branch, Tehran 2018, April)

4. SURFACE BOP INSTALLATION LOCATION

5. MUDLINE SUSPENSION SYSTEM
• As jack up drilling vessels drilled in deeper water, the need to transfer
the weight of the well to the seabed and provide a disconnect-and-
reconnect capability became clearly beneficial. This series of hangers,
called mudline suspension equipment, provides landing rings and
shoulders to transfer the weight of each casing string to the conductor
and the sea bed.
• The mudline suspension system also allows the well to be temporarily
abandoned (disconnected) when total depth (TD) is achieved (when
drilling is finished at total depth)

6. MUDLINE SUSPENSION SYSTEM
• A casing suspension system that allows a well to be drilled using
a surface BOP, surface wellhead and surface drilling equipment.
The mud line suspension equipment provides for individual casing
hangers to be installed with each casing string that interconnects
with each other at a pre-set point below the mud line.

7. THE MUDLINE HANGER SYSTEM
CONSISTSOFTHEFOLLOWING COMPONENTS
• Butt-weld sub
• Shoulder hangers
• Split-ring hangers
• Mudline hanger running tools
• Temporary abandonment caps and
running tool
• Tieback tools

10. MUDLINE HANGER SYSTEM
• Each mudline hanger landing shoulder and landing ring
centralizes the hanger body, and establishes concentricity around
the center line of the well. Concentricity is important when tying
the well back to the surface.
• In addition, each hanger body stacks down relative to the
previously installed hanger for washout efficiency.

11. MUDLINE HANGER SYSTEM
(hanger and running tool)
Washout efficiency is necessary to clean
the annulus area of the previously run
mudline hanger and running tool. This
ensures that cement and debris cannot
hinder disconnect and retrieval of each
casing riser to the rig floor upon
abandonment of the well.

12. A hanger collet for a
midline casing suspension
system in the form of a
hollow cylinder. Vertical
slots (32,34) create a
serpentine form which is
radially collapsible. Flow
space behind the legs (30)
permits a flow path for
running and cementing.
Casing hanger collet
(Split-ring hangers)

13. TEMPORARILY ABANDONING THE WELL
• After each casing string is disconnected from the mudline
suspension hanger and retrieved to the rig floor in the reverse
order of the drilling process, threaded temporary abandonment
caps or stab-in temporary abandonment caps (both of which
makeup into the threaded running profile of the mudline hanger)
are installed in selected mudline hangers before the drilling vessel
finishes and leaves the location. The temporary abandonment caps
can be retrieved with the same tool that installed them.

14. TEMPORARILY ABANDONING THE WELL

15. Temporary abandonment caps and running tool

16. The mudline suspension system has been designed to accommodate
tying the well back to the surface for surface completion, and it also
can be adapted for a subsea production tree. A tieback tubing head can
be installed to the mudline suspension system at the seabed, and a
subsea tree can be installed on this tubing head.
RECONNECTING TO THE WELL

17. RECONNECTING TO THE WELL
• A mudline suspension system also
incorporates tieback tools to
reconnect the mudline hanger to
the surface for re-entry and/or
completion.
• A surface wellhead system is
installed, and the well is completed
similarly to the method used on
land drilling operations.

19. OFFSHORE WELLHEAD
• Mudline suspension
• Subsea wellhead

20. MUDLINE TREE
Reverse installation

21. WELLHEAD CLASSIFICATION
ACCORDING TO THE WELL
LOCATION
• Wellhead for land drilling.
• Surface location offshore.
– Jack-up, platform (Mudline Suspension
sys.)
• Subsea wellhead.
ACCORDING TO THE WELLHEAD
DESIGN
• Spool Wellhead System
• Unitized Wellhead System

22. DIFFERENCE BETWEEN THE LAND
WELLHEADS AND A THE JACKUP MUDLINE
• The main difference between the wellheads used in the land
drilling application and the jackup drilling application (with
mudline) is the slip- and-seal assembly
• Because the weight of the well now sits at the seabed, a weight-set
slip- and-seal assembly is not used. Instead, a mechanical set
(energizing the seal by hand) is used, in which cap screws are
made up with a wrench against an upper compression plate on the
slip-and-seal assembly to energize the elastomeric seal.

23. A MECHANICAL-SET SLIP-AND-SEAL
ASSEMBLY

24. COMPONENT REQUIREMENTS
APPLICABLE TO ALL WELLHEADS
• Standard temperature ratings are defined by an
operating range.
– Conventional operations span -60 to 121⁰C in 8 ranges (K, L, P, R, S, T, U, V).
K and U are the largest and overlap the other ranges.
– Elevated temperature operations span -18 to 345⁰C in 2 ranges (X, Y). Y has
the highest temperature rating.

27. COMPONENT REQUIREMENTS
APPLICABLE TO ALL WELLHEADS
• Product Service Level (PSL) defines the degree of
testing applied to the wellhead component.
–PSL-1 is the baseline.
–PSL-2, PSL-3, PSL-3G, and PSL-4 include additional and
ever more stringent requirements to confirm component
suitability for challenging operations (e.g. high pressure,
elevated temperature, sour).

28. Product Service Level Rating

31. WELDED
BUT W ELD
• connecting two lengths of pipe of the
same unit weight (kg/m) and diameter.
• joining different lengths of wellhead
piping
• where a casing extension or repair is
required at surface.
• Seal + Connection
SLIP- ON W ELD
• Used to make a connection between
different diameters.

32. STUDDED
• one component that has studs threaded into its housing and a second component with
a flange bolted to the studs.
• Uses:
– Typically used in any high pressure (i.e., 2000 psi to 30,000 psi) or higher risk operations.
– Used in any operations where there are requirements to shorten the height or length of the
wellhead components.
– Used in any operations where there is a need to reduce the bending moment on equipment.
– Along with flanged connections, studded connections allow for the installation of a test port
to meet requirements of pressure testing between primary and secondaryseals.

33. SEALS
• Seal composition:
– Elastomer and Graphite / CarbonSeals.
– Metal Seals.
• Seal types:
– Primary Seals
– Secondary Seals
• If both are installed the wellhead can be pressure
tested.

34. REFERENCES
Http://Petrowiki.Org
Http://Www.Glossary.Oilfield.Slb.Com/
Cameron Mudline Suspension System.
http://www.nustar-tech.com/Product_Mudline1.html