Can anyone provide me an educated guess about Conductor Pipe size, In the environment of 10m to 26m which Pipe size would be appropriate to use.
1) 24" external Dia - 1" wall thickness?? Or
2) 26" Ext Dia0 2" wall thickness??
We are in the process of performing the Geotechnical study of the soil
Casing design has
24"x185/8"x135/8x103/4x75/8- Well TD @ 16000ft.
Of if possible can anyone share the procedure to evaluate the designing forces to be applied for this Conductor Pipe Design.
As in what kind of Data is required to be analyzed to decide the size and wall thick ness of the Conductor pipe.
Appreciate your help
I’m from 2H Offshore, a company which specialises in the design and structural analysis of riser and conductor systems.
A typical analysis scope for a shallow water conductor system would include the following:
· Stability Analysis – to ensure the conductor won’t buckle under the vertical loads acting on the well (surface equipment and casings);
· Strength Analysis – to ensure the conductor (and casings) are not over-stressed and that the bending moment and tensile capacities of connections are not exceeded under the extreme loading conditions expected in that location;
· Wave Induced Fatigue Analysis – to ensure that the conductor is sufficiently sized to provide fatigue life for the duration of the operations.
I saw that VIV fatigue analysis has already been mentioned. In this particular case, due to the shallow water depth I wouldn’t expect VIV to be a concern but a short screening exercise can be carried out to confirm this. VIV is a concern in deeper waters (>120m) or where the string in the water column is particularly slender i.e drill string. For a water depth of 10-26m, the waves will be the main concern to the fatigue life.
Fatigue from installation has also been mentioned. If the conductor is to be driven, the fatigue life accrued during installation can be determined and considered alongside the wave induced fatigue damage. If the conductor is drilled and cemented, this analysis is not required.
The response of the system is based on the particular seastates expected to occur in that area, the currents and importantly the soil conditions. Data on the wave, current and soil conditions along with the sizes, weights and arrangement of the conductor system and surface equipment is also required to conduct analysis.
If you have any questions regarding the above, please just let me know.
It is Offshore well - Jack up rig - water depth 10m-26m -
Casing design has
Shallow well - 24"x185/8"x135/8x103/4x75/8- Well TD @ 16000ft.
Deep wells - 36"x24"x185/8"x135/8x103/4x75/8x5" Well TD-20000ft
the environmental conditions are not that severe!! no severe storms, tidal and current profile
Wellhead & BOP Stack will be surface , we will be using MLS and first casing-"structural" casing will be drilled and cemented.
Do we need to consider the loading and bending moments at the mudline water depth being very less i.e 10m - 26m
which companies supply Conductor pipe & Connectors analysis to determine the weight & grade of pipe and type of connector needed we are using GE Vetco and vallourec.
If any one can provide any excel sheet , for the design calculations, wil help a lot , or any SPE papers for reference.
Thanks and really appreciate your help,
Conductor design is driven by following:
Onshore or Offshore ?
Driven or drilled & cemented?
Welded or Threaded connectors
Well is expendable or potentially a Keeper? (with MLS capability) or production batch drill ?
Anticipated life of well vs fatigue analysis (above refers)
Water depth, quality of formation below mud line. are there expected to be losses in highly permeable formations that may be present below mud line ? or communication concerns between conductors in the instance of batch drill campaign ?
Typically Conductors with WT< 0.750" are drilled and cemented. if operator is considering driving conductor to setting depth then WT > 0.750" should be used in order to facilitate driving particularly of the shoe depth is > 45 m below mud line and prolonged hard driving is expected.
If there is a spud can penetration report for an offshore vocation this will typically contain Geotech info to perhaps 35 meters below mud line, from this one can gain an insight in the seafloor conditions immediately below the mud line. and using offset data for the local area if available, a fairly coherent impression of the conductor installation requirements can be determined.