文档介绍：HOLE PROBLEMS
Avoid hole problems and
stuck pipe if at all possible
to reduce costs
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Lost Circulation
Lost circulation
¾Lost circulation occurs when the
effective hydrostatic (mud weight,
friction losses and cuttings
concentration) es greater than
the formation pore pressure plus the
resistance to flow of the fluid through
the formation
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Hole Problems
Lost circulation
¾While drilling, all
the fluid pumped
into the drill
string returns to
the mud tank at
the surface
¾It is a closed
system
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Hole Problems
Lost circulation
¾Lost circulation
is when all or a
portion of the
circulating fluid is
lost to the
formation
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Hole Problems
Lost circulation
¾Lost circulation
is when all or a
portion of the
circulating fluid is
lost to the
formation
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Lost Circulation
Can loose
ciltiitirculation into
primary or
secondary
porosity
Generally,
primary porosity
will range from 8
to 30% for
reservoirs
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Lost Circulation
Secondaryyy porosity is porosit y
generated by altering the rocks
such as the dolomitization of
limestone or fracturing
¾Fractures
¾Vugs
¾Oolite
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Lost Circulation
Permeability is a measure of the
resistance to flow of a fluid
through a rock
¾Measured in Darcys or millidarcys
¾MtMost reservoi ihrs have less than one
Darcy of permeability and will not
accept wh o le mu d (w ith so lids )
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Lost Circulation
Lost circulation
¾Shallow formations with high porosity
and permeability that will accept
whole mud
−Shallow sands
−Increase viscosity and/