Transcript Lesson 9

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Lesson 17
Flow Drilling
Mudcap Drilling
Snub Drilling
Closed Systems
Read: UDM Chapter 2.8-2.11
pages 2.180-2.219
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Flow Drilling
• Flow drilling refers to drilling operations in
which the well is allowed to flow to surface
while drilling.
• All UBD operations are really flow drilling
operations, but the term is usually applied to
drilling with a single phase mud, and no gas
is injected except by the formation.
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Drilling fluid selection
• Density is determined by:
– maximum pressure <= to formation pressure
– minimum pressure dictated by wellbore
stability
• Pressure limitations of diverter and BOP
equipment
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Surface Equipment
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Surface Equipment
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Surface
Equipment
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Surface Equipment - RBOP
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Surface Equipment - RBOP
sealing element
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Surface Equipment
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Sizing Flare line
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Sizing Flare line
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Sizing Flare line
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Sizing Flare line
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Surface Pits
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Primary Oil Separation Pit
Secondary Oil Separation Pit
Skimmer System Safety
Drilling Fluid Pit
Oil Transfer Tank
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Operating Procedures
• Mechanical objective is to control the well
at the surface to maintain underbalanced
conditions.
• Maximum tolerable surfaces pressures
should be established before drilling starts.
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Mudcap Drilling
• Utilized with uncontrollable loss of
circulation during flowdrilling operations.
• Higher pressures than can be safely handled
with the rotating head or RBOP.
• Not necessarily underbalanced.
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Mudcap Drilling
• Driller loads the annulus with a relatively
high density high viscosity mud and closes
the choke with surface pressure maintained
• Drilling is then continued “blind” by
pumping a clear non-damaging fluid down
the drillstring through the bit and into the
thief zone.
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Mudcap Drilling
• Applications:
– Sustained surface pressures in excess of 2000
psi
– Sour oil and gas production
– Small diameter wellbores
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Mudcap drilling
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Fluid Volume Requirements
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Fluid Volume Requirements
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Fluid Volume Requirements
• Annular volumes will depend upon whether
the operator desires continuous or periodic
injection of annular fluids or whether a
floating mudcap is to be used.
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Fluid Volume Requirements
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Fluid Volume Requirements
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Fluid Volume Requirements
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Snub Drilling
• UBD operation utilizing a snubbing unit or
coiled tubing unit.
• Expense is justifiable if very high formation
pressures are anticipated, and uncontrollable
loss of circulation is expected.
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Harold Vance Department of
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Harold Vance Department of
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Harold Vance Department of
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Harold Vance Department of
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Closed Systems
• Refers to UBD operations with a specific
surface system.
• A pressurized, four phase separator and a
fully closed surface system, is used to
handle the returned fluids.
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Fig. 2.70
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Fig. 2.71
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Fig. 2.72
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Other Surface Equipment
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Cuttings Filter
Heater
Degasser
Flare Stack/Pit
Production Tank
Water Tank
Solids Tank
Instrumentation
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