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Older Spud Can Penetration at Platforms
01 February 2018
Hi,
I would like to know any selction criteria for Jackup Rigs to mitigate the hazard of spud can penetrations for intervention work required alongside a platform. The ideal case would be to use the same rig for anywork overs and stuff.
Or alternatively do all Kepple Rigs have the same foot print and all La Toreanue Rigs have a similar foot print.

Thanks in advance.



3 answer(s)
davidaiii
Well Engineer
Shell
Total Posts: 6
Join Date: 02/10/14

HI... the industry rule for assessing this is called SNAME 5-5. “Guidelines for Site Specific Assessment of Mobile Jack-up Units” and gives the calculations required for assessment.

Used to be that the rig contractors had to perform this study work for insurance purposes prior to moving to certain locations Study work then performed by specialist consultants feeding in geomechanics and metocean to verify rig suitability at a location. You might be able to get more information from them. The consultant will for sure have a detailed database of spudcan shape and spacing and can go onto analyse if rig can remain stable in required operating/metocean conditions.

Companyrep
Drilling Specialist/Well Engineer/Training Consultant
Kingdom Drilling
Total Posts: 352
Join Date: 10/01/05

Jov, 

The amount of leg penetration is dependent on soil properties, vertical reaction of the legs, and footing area. The greater the footing area, the lower the penetration under same circumstances. (PA: I cant image rigs are the same or soil will be the same each time a rig is taken there! This must be accounted for)

The amount of soil penetration should be checked against the footing structural capabilities and scour characteristics of the site. (PA: one surely needs a geo-mechanical analysis of shallow soils to conclude this?) 

Proper planning with regards to soil information and predicted penetration curves should be done. (This is important to be done each time so plan plan plan!)

If during actual preloading the leg penetrations are recorded (penetrations vs. footing reaction curves), then this information can be used to improve upon the prediction penetrations curves methodology.  (PA: Again it is important to assure this is properly doen and implemented each time?)

In summary even if one uses the same rig and the same spud cans. Hazards/risks will and may not likely be the same.  One has to be very careful as soil shall not be the same on successive penetrations (better worse for specialists to advise?)

Where points as highlighted above should be carefully and duly managed and controlled throughout each workedover and intervention. 

I would suggest resourcing a suitably qualified geomechanic person  or specialist to offer some advice regarding  a long term strategy how to manage measure monitor control and assure suitable foundation can be safely provided for each operational activity when a jack up is required to be alongside the platform.  


http://marinewiki.org/index.php/Jack-up_units

Hint: Type in spud can penetration into search toolbar and several papers can be found on this subject. 

Success


jackcran
Drilling Engineer
AWE
Total Posts: 2
Join Date: 13/11/15
Hi, 

I worked on a Bass strait program where deeper than expected penetration was experienced during the original drilling and it very much complicated rig selection for phase -2.

Platform type is an important factor as it determines the mitigation's and offset of the stage-1 & stage-2 JUR. 

-In general larger spud cans are better + designs vary in suitability for mud conditions /depth
-Review rig weight (imposed loads) : Can area
-Maximize distance from platform
-Spud can removal techniques, pre-inspection of jetting lines prior to taking the rig so that you are not in the situation of being stuck jetting for a long time at the end of the project through limited lines and therefore eroding a larger crater/more damage from the cans.
- Rock dump
- Matts 
- TAD variations in extreme cases

Hope this helps. 

jack 


Posted by

Jov Rodrigues

Senior Drilling Engineer

NRG Well Management Ltd

Total Posts: 17
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