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deepwater 'shallow string' cementing
17 January 2014
In shallow 'deepwater' flow environments due to lack of formation integrity, competence and where narrow margins between pore and fracture commonly exists.  

100-300psi above normal overpressure is all that is expected from potential flow zones. i.e. >8.66ppg and up to 9.0-9.3ppg depending on depth below mud line. (Ref for this IADC deepwater well control guidelines.)

With the section safely, drilled, and section tripped either conventionally or usual a dual gradient system e.g. annular cuttings loading, weighted sweeps, pump and dump, mud recovery etc.

Cementing often the greatest challenge to end each drilling phase.

What drives a prefernce for Foam (dominant in Gulf of Mexico) vs a light weight designer cement (dominant elsewhere world-wide) is then often debated in these deepwater 'flow prone' environments.

To allow a decision to be made on a current project,

What pro's and cons of these cementing methods, current knowledge, experience, best practise and ref to these systems and proceses used/applied by forum members is greatly appreciated.

regards,
2 answer(s)
Ahmaid
senior drilling engineer
Kuwait Energy
Total Posts: 14
Join Date: 29/11/13
Dear Peter,
we need to support the decision with calculating the pore and frac pressure curves for the well profile using electric logging or seismic data if the previous is not present.
this is to define the level of integrity of the formation regarding the cement weight. it might be a losses problem due to high permeability and not formation strenght.
in this case using lost circulation additives with cemening slurries will be helpful, regardless how much lcm will be used.
planning with the cement company after performing these priliminary calcuations will guide us to the useful design and job pressure profile against the frac and pore pressures.
after that, we can look to the operational complication of each case.
I have attached a presentation to guide you for calculation the fracture pressures from the logging data (Source Applied Drilling Engineering)
Thanks
Ahmed
Documents uploaded by user:
Fracture pressure calculations.pptx
BoraiElSemari
BP
Total Posts: 5
Join Date: 28/05/08

The problem with foam if you shut down the N2 will escape from slurry and may compromise the slurry stability, high risk of shallow water flow, specially these jobs is big and to stop is high probability. I like litcreet ,it requires more focus onshore during blending and transportation  to avoid contamination and adding to that more care on the batches separation with lap tests .

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