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7/27/2019 SCR-Slow Circulation Rate
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10/12/13 Slow Circulation Rate
www.drillingformulas.com/slow-circulation-rate-sc/
Slow Circulation Rate is a circulation rate which will be used
in well kill operation. Typically, slow
circulation rate pressure (SCR) is recorded from each particular
flow rate and the pressure represents
pressure loss of the system while circulating. Since there are
so many pressure gauges on the rig, you may
get confused on the figures. In order to be at the same page for
every personnel on the rig, the SCR
should be recorded by the pressure gauge that we will use for
killing the well.
There are a lot of reasons why we should kill the well with slow
rate rather than a drilling rate as
follows:
To minimize friction pressure
To allow time to weight up mud if you use wait and weight
method
To reduce pressure on surface equipment
To allow degasser to separate gas from the mud
To reduce needs for fast choke operation
To allow personnel to think if something goes wrong
Lets get an idea how to get pre-recorded SCR.
1. Turn pump on at slow speed as 10, 20, 30 and 40 spm
2. Record pressure without rotating or moving drillstring
3. Each pressure recorded at particular pump speed is SCR.
Please always remember that SCR that you take for each time
representing pressure loss at that time. I
dont recommend you to use it to estimate the initial circulating
pressure.
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7/27/2019 SCR-Slow Circulation Rate
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10/12/13 Slow Circulation Rate
www.drillingformulas.com/slow-circulation-rate-sc/
Lets me e xplain why There are some errors in pre -recorded SCR
which can make you in a
trouble.
Pre-recorded SCR may not reflect current pressure due to
drilling mud properties change.
The depth of pre-recorded SCR is not the same as the current
drilling depth.
SCR may be changed due to unknown condition down hole as BHA
mechanism, plugged jets, etc.
How can we get ICP without using pre-recorded SCR?
In order to get the initial circulating pressure, you just
simply bring the pump up to speed by holding casing
pressure constant until you reach kill rate. Additionally, you
will be able to calculate the actual SCR by
calculation.
Lets take a look at the e quation below.
ICP = SIDPP + SCR
Where; ICP is Initial Circulating Pressure.
SIDPP is Shut In Drill Pipe Pressure.
SCR is Slow Circulation Rate pressure.
Therefore, SCR = ICP SIDPP
If you would like to check SCR, the following time is when you
should check SCR.
Check before drilling out of casing shoe
Check after tripping back to the bottom
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7/27/2019 SCR-Slow Circulation Rate
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10/12/13 Slow Circulation Rate
www.drillingformulas.com/slow-circulation-rate-sc/
Check when mud properties are changes
Check at least two times each shift at the drilling depth at
that time
