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Coiled Tubing Drilling surface setup
08 November 2019
Dear All,

I'm looking for a good guide and recommendations about Coiled Tubing Drilling for milling out cement plugs and composite bridge plugs in 4.5" Liner through existing 4.5" completion string (set in 9-5/8" casing).

Since EMW is around 17.8ppg (P=5320psi) and there are open perforations between the plugs, I need a good surface setup to separate returns (brine, oil, gas) at the surface (we will use water or 1.05ppg brine during drilling).


3 answer(s)
Well Engineering Consultant and Instructor
SPREAD Associates
Total Posts: 41
Join Date: 23/03/16

You are underbalanced drilling. You will need to ensure that reservoir fluids and flow volumes can be handled at surface A 0.455 psi/ft brine in a 0.925psi/ft formation pressure is a very large drawdown which could mean a very large reservoir inflow.

Recommend that you do some hydraulics modeling to understand bottom hole and surface pressures and then size the separation spread accordingly, Make sure that you understand how to retrieve the BHA to surface with potentially large surface pressures using strippers and BOP.

The gas and oil will also change drag characteristics of the coil so you will also need to make sure that you have overpull and weight available to pull out and run in the hole.
Technical Director / Trainer
SPREAD Associates
Total Posts: 10
Join Date: 31/03/20
Send me a little bit more info such as
size of CT
Size of Motor
Type of bit
We followed same type scenario in CBM wells in QLD, and as we were limited to pump rates of 1.25bbl per min we had to be very careful not to load up the annulus with solids.
Suggestion without knowing all the facts is to drill have the plug and pump a HiVis sweep and not take any more bites until all solids returned to surface.
In terms of separation at surface i suggest using a regular well test spread and burner boom/pit with the focus on saving your brine as opposed to anything else.



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Managing Director (
Relentless Pursuit Of Perfection Ltd.
Total Posts: 468
Join Date: 10/01/05
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