North Sea




FourPhase was requested by a well service company to assist in a coiled tubing (CT) well clean out operation which was
to be performed offshore for a major North Sea Operator. Initial scope of the operation included solids separation from
return flow during CT clean out of three wells. However, during the operation, the scope was expanded to also include
post-clean out production test on two of the wells. The aim of the test production was to remove accumulated solids
from the wellbore and to identify potential flow rates in correlation with sand lifting rates. This would provide data for
optimizing well production and establishing operational boundaries.
Operational considerations:
– High rates of solids were expected from one of the wells scheduled for CT clean out after fracking. High rates of
returning proppants could potentially result in high erosion.
– Limited access to empirical data prior to production testing operation.
– Limited knowledge about the solids in wellbore – amount, size/composition of particles and expected solids rates
while producing wells.


FourPhase 5K DualFlow unit was used in a CT operation allowing for safe removal of fracturing proppants and other
types of solids. Minimal real estate due to deck load limitations and good separation efficiency were critical, therefore
5K DualFlow (2m X 2m X 3.2m) was mobilized.


DualFlow has shown excellent separation efficiency during CT clean out and flowback operations. The total amount
of solids separated during post-fracking clean out and flowback operation from one of the wells was 23 044kg with the
separation efficiency of 96,5% during post-fracking clean out and 99,8% during flowback operation. During well CT
clean out operations and test-production, the overall combined separation efficiency of the DualFlow unit was never
below 98,1%.
Key operational outcomes:
– No recorded HSE incidents.
– No recorded equipment downtime.
– 26 351kg of solids, including fracturing proppants, removed.

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