vu stripping
DESCRIPTION
strippingTRANSCRIPT
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5/21/2018 VU Stripping
1/14
GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
Pdp Pan Pdp2 Pan2
H1H2
Ps= (H2-H1) (rmud-rgas)
Ps= safety margin for loss
of HH when influx enters
the DCs
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5/21/2018 VU Stripping
2/14
GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
Pdp Pan Pdp Pan2
DV
Pw= -------------- rmud
Ann.vol OH/DC
Pw= safety margin for loss
of HH mud.
Gas is expanding while
rising up the well bore
DV
V is taken opposite DC,
ie. Worst case
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5/21/2018 VU Stripping
3/14
GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
Pdp Pan
Pchoke1= Pan+ Ps+ PwLet Pchoke increase to above value
while stripping in stands dp.
Alternatively : Bring annular pressure to above value byusing the rigpumps.
Bleed of CE dp vol after each stand stripped
into striptank
When increase intriptank DV due to gas expansion
increase Pchoke1by Pw(50 psi)= Pchoke2
When increase intriptank DV due to gas expansion
increase Pchoke2by Pw(50 psi)= Pchoke3
Pchoke
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5/21/2018 VU Stripping
4/14
GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
Pchoke1
Triptank
Striptank
Stripping in stand no 1
Volume 1 CE drill pipe
Volume increase due to expansion
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5/21/2018 VU Stripping
5/14
GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
Pchoke1
Triptank
Striptank
After stripping in stand no 1
CE vol stand dp is bled
off to Srip Tank
Volume 1 CE drill pipe
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5/21/2018 VU Stripping
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GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
Pchoke1
Triptank
Striptank
Stripping in stand no 2
Volume 2nd CE drill pipe
Volume increase due to expansion
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5/21/2018 VU Stripping
7/14GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
Pchoke1
Triptank
Striptank
After stripping in stand no 2
CE vol stand dp is bled to ST
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5/21/2018 VU Stripping
8/14GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
Pchoke1
Triptank
Striptank
DV
When vol-increase in Triptank is equal
to DV make Pchoke2 = Pchoke1+50 psi
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5/21/2018 VU Stripping
9/14GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
Pchoke1
Assume worstcase scenario:
- Influx remains as one slug
-Loss of HH due to expansion
across smallest annular cross-sectional
area, in most cases this is OH/DC
After string is stripped to bottom succesfully
Pchoke has been increased by several Pw
Extra Back pressure has been applied
BHP>Po
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5/21/2018 VU Stripping
10/14
GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
Pchoke1 Use checklist as per EP 89-1500
Rig up as per checklist
Lubricate pipeRemove sharp tong dies
Minimise annular closing pressure
Fill up each stand
Install grey valve, open kelly cock
Bleed of CE dp vol from Trip to Striptank
Monitor Triptank level increase for vol DVCalculate Pw
Calculate Ps
Ensure all returns go to triptank
Avoid annular leakage
Avoid surgepressures
Use Range of accurate pressuregaugesRemove dp/csg protectors
Do NOT confuse strip and triptank
On BTM kill well using the Drillers Method
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5/21/2018 VU Stripping
11/14
GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
Pch
Questions:
What will happen with Pw and Ps when
there is no pipe in the hole?
Suggestions on action once bit is through
the influx??
How to operate if no stripping tank available?
Can we strip irrespective of wellbore pressurewhen there is no pipe in the hole?
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5/21/2018 VU Stripping
12/14
GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
closeopening
line
remove plug to ventopening chamberduring stripping
bar200
N2 precharge 400 ps i
ANNULAR
Clos ing l ine to TR
regulating valve
ballvalve
gauge
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5/21/2018 VU Stripping
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GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
TIME STAND
NO:
an
w
chPP
PP
an= ......
= ......
= ......
Level inTriptank
D VRemarks
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5/21/2018 VU Stripping
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GJS:/VUstripping.ppt
Combined Volumetric Stripping Method
Pchoke1
Triptank
DV
When vol-increase in Triptank is equal
to DV make Pchoke2 = Pchoke1+50 psi
ABOVE EXPECTED INCREASE DUE
TO CE displacement of the dp
WITHOUT STRIPTANK