2. Content…
Intro
Indication the lost circulation zone
Why lost Circulation?
Classification of Loss Zone
Quant classification of lost circulation
Preventions…
Loss
Numerical approach
Restoring of loss zone
Locating Loss Zone
6. Indications of loss circulation
Flow back is questionable
Increased the weight of drill string
Pump speed increases
Bottom hole or vertical pressure head reduces
Pit volume variation
12. Classes of Lost Circulation
Seepage losses: From 1-10 bbl/hr and lost while circulating at the
normal drilling circulating rate
Partial losses: From 10-50bbl/hr and lost while circulating at the
normal drilling circulating rate
Severe losses: Greater than 50 bbl/hr and lost while circulating at
the normal drilling circulating rate
Total losses: When the mud level in the annulus cannot be seen or
the hole cannot be filled through the annulus. Total losses usually
occur in cavernous formations
14. Prevention of lost circulation
Adequate Hole cleaning
Avoiding restrictions in the annular space
Setting casing to protect upper weaker formations within a transition
zone (100% or irreducible water saturation)
Updating formation pore pressure and fracture gradients (log and
drilling data)
Maintain proper mud weight
Treating mud with lost circulation materials
Leak-off test and Formation Integrity test
18. Numerical Question?
During drilling of an 8.5 inch hole at 8000ft , a complete loss of
circulation was observed. Drilling was stopped and the mud level in
the annulus was observed to fall rapidly. The well was filled with
water of 8.3 ppg until the annular level remained stationary. If the
volume of water used was 65.7 bbl and mud density was 10 ppg,
determine the formation pressure and the new mud weight required
to balance the formation pressure. Assume the intermediate casing
to be 9.625 in, 40# set at 6000ft. Drill pipe is grade E, 5 inch OD?
23. Restoring of Lost Circulation
Trip out and wait
Identify the point of safety and trip out the drill pipe
Wait for 4-8 hours standard time and selection of LCM
Squeezing technique
Identify the thief zone and design LCM
Locate the pipe above the zone and squeeze the fluid blended
with LCM
24. Continue…
Blind drilling: fluid does not return to the surface
In order to identify the lost circulation…