Mudline Suspension (MLS)

Mudline Suspension

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

2. SURFACE BOP INSTALLATION LOCATION

3. MUDLINE SUSPENSION SYSTEM A s 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)

4. 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 .

5. THE MUDLINE HANGER SYSTEM CONSISTS OF THE FOLLOWING COMPONENTS Butt-weld sub Shoulder hangers Split-ring hangers Mudline hanger running tools Temporary abandonment caps and running tool Tieback tools

6. 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 .

7. 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.

8. 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)

9. 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.

10. TEMPORARILY ABANDONING THE WELL

11. Temporary abandonment caps and running tool

12. 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

13. 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 .

14. OFFSHORE WELLHEAD Mudline suspension Subsea wellhead

15. MUDLINE TREE Reverse installation

16. WELLHEAD CLASSIFICATION A CCO R D I N G TO T H E W E L L LO C AT I O N Wellhead for land drilling. Surface location offshore. – Jack-up, platform (Mudline Suspension sys.) Subsea wellhead. A CCO R D I N G TO T H E W E L L H E A D D E S I G N Spool Wellhead System Unitized Wellhead System

17. 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.

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

19. 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.

20. COMPONENT REQUIREMENTS APPLICABLE TO ALL WELLHEADS Produc t Servic e Lev e l (PSL) d efines t h e 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).

21. Produc t Servic e Lev e l Rating

22. WELDED B U T W E L D 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 S L I P - O N W E L D Used to make a connection between different diameters.

23. 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 secondary seals.

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

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