This document provides an introduction to well control from Kingdom Drilling Services. It discusses primary and secondary well control, including maintaining pressure and monitoring flows. Loss of primary control can occur through pressure changes or lost circulation. Secondary control indicators include increased flow rates or mud pit volume changes. Methods for controlling kicks include circulating or bullheading. The document also covers well control terms, blowout prevention, shallow well hazards, and lost circulation detection and remedies.

1. Drilling & well engineering
Introduction to Well Control
Peter Aird: Kingdom Drilling Services.

2. 2009 rev 1 Kingdom Drilling Services
Well control
• Primary
– Prevention, where 1oz of primary control
prevention is generally far better than the cure?
• Secondary
– Safely managing and regaining control of the
well when primary control is lost.

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Drilling with ‘Primary’ control

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Primary control principles
• Primary well control
– Flow in/out
– Pressure
– Volumes
• Pumping
• Displacement
– Drilling parameters
– Mud logging

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Primary control loss?
1. Losing pressure column causing change in pressure
balance e.g. shallow water flow
2. Pressures induced causing a change in flow regimes
e.g. ECD, surge, swab, inducing lost circulation,
borehole ballooning etc.
3. Losing circulation causing loss of hydrostatic and
flow to occur e.g. drilling into an under-balanced or
depleted formation
4. Loss of measurement and control causing losses or
gains to occur e.g. swab pressure causing pressure
reduction less than formation pressure.

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Primary control issues
1. Personnel at the required level of competency
2. Fit for purpose tools and equipment
3. Adequate supplies and materials
4. Systems for maintaining good records and
reports (and using them to learn)
5. Maintaining and controlling down hole pressures
EMW=MW +/- ECD
6. Monitoring, evaluating and determining swab,
surge, pressure effects etc.
7. Tripping and circulating practices

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Loosing ‘ Secondary’ control

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Secondary control indicators
• Increase in flow rate?
• Gain or loss in mud pit
volume?
• A drilling break and >
ROP
• Pump pressure reduction

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Well control contributors
1. Degree of under-balance or overbalance
2. Formation permeability
3. Length of the formation exposed
4. Time the formation is allowed to flow or
lose.

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Secondary methods
• Circulating
– Weight and weight
– Drillers method
– New methods
• Non circulation
– Bull-heading
– Volumetric

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Well Control terms
• Kick
– Unplanned entry of FORMATION fluids into the wellbore, of
sufficient volume quantity to require shutting in the well.
• Lost circulation
– Unplanned loss of DRILLING fluids to the wellbore, of sufficient
volume quantity to require shutting in the well. Often then
associated with a ‘Kick’
• Blowout
– Loss of control of wellbore ‘drilling and/or formation fluids’
resultingin severe lost circulation and/or a kick

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Wells out of control

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Blow out preventers ‘BOP’

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Drilling Instrumentation
• Drilling
• Tripping
• Well control
– Kicks
– Loss circulation
• Wellbore difficulties
– Hole cleaning
– Instability
– Stuck pipe

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Blowouts

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Blowouts

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Well Control
• Blowout
– Surface
– Underground
• Blowouts caused by
– equipment failure
– human error

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• Shallow well control
• Over pressured zones.
• Low fracture pressures
• Shallow prospects
Shallow well control hazards
36" Pipe

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Shallow well control drilling
1. Operating margins between pore
pressure and formation integrity is small
2. Penetration rates are difficult to control
3. VOLUME control can be very difficult
indeed.
4. Dynamic gas invasion can quickly occur
5. Gas above BOP can quickly result

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Prediction, detection, prevention
• Geophysical prediction,
• Pore pressure, fracture
gradient prediction,
• Operational strategies,
– Drilling, tripping, cementing
• Remedial operations
– Well flow dynamics

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Seismic systems
Seismic systems; target depths 50-500 metres
Mini seismic source Very good
3D high resolution Very Good
Seismic systems; target below 200 metres
2D high resolution Good
3D seismic Can be good
3D seismic re-processed Can be good

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Shallow well control prevention
• Site specific location for lowest risk
– Multidisciplinary approach
• Subsurface geo-hazard avoidance
• Geo hazard mitigation

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Shallow well control detection
1. Drilling trends
2. Pressure while drilling monitoring and control
3. LWD/MWD (Resistivity, gamma) detection
4. Increase/decrease in mud flow and/or volumes
5. “Best” Connection & Tripping practices
6. Safe and/or dynamic circulating procedures

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Pressure management

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Flow show’s
• Losses & gains
– While drilling
– Drilled
– Swabbed / surged
– High pressure – low volume
– Well instability

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Tripping and circulating
• Every effort must be made to ensure control
and stability of the well bore at all times
while tripping, circulating and/or when
applying rotating practices.
• “Best Practices” must be maintained and
controlled at all times.

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Special considerations
• Casing design and setting depths
• Mud programme
• Cement programme
• Fishing, milling, casing cutting
• WBM, OBM, SBM, Brines
• Well servicing, work-over, re-completion

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Well Control
• Engineers in office can aid in
well control by:
– Provide pressure profiles for all
pending wells
– Provide offset information such
as logs, bit records, mud reports,
drilling records.
– Provide support and assistance
personnel on location.

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Lost circulation detection
1.Establish loss rate.
2.Check all surface
equipment
3.Check no mud has been
dumped/transferred or no
solids control equipment has
been switched on.
4.Check that the riser slip
joint packing is not leaking.

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Lost circulation actions
• Establish dynamic and static loss
conditions. (instantaneous, gradual)
– Depth & formation type
– Establish loss rate
– Check surface equipment
– Check with logger / driller
– Check marine riser components
– Leaking casing?
• Losses on bottom of further up the hole?

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Curing Lost Circulation
• Reduce mud weight
• Reduce pressure effects
• Use lost circulation material
– Fibrous materials
– High Fluid Loss Slurries
– Reinforcing Plugs and Cement
• Special formulation’s

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Lost Circulation w/Flow
Well Flow AfterWell Flow After
Losses?Losses?
YesYes
Displace PillsDisplace Pills
Squeeze DPSqueeze DP
& Annulus& Annulus
Secure WellSecure Well
Hole onHole on
Vacuum?Vacuum?
Fill Pipe & AnnulusFill Pipe & Annulus
Until Pills ReadyUntil Pills Ready
LossesLosses
Cured?Cured?
YesYes
Circulate KickCirculate Kick
PillsPills
NoNo
NoNo
YesYes
Circulate KickCirculate Kick
SpecialSpecial
PillPill
LossesLosses
Cured?Cured?
LossesLosses
Cured?Cured?
NoNo
NoNo
YesYes
Circulate KickCirculate Kick

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Lost Circulation on Shut-in
Attempt CirculationAttempt Circulation
Determine Loss RateDetermine Loss Rate
Severe orSevere or
CompleteComplete
Losses?Losses?
NoNo ConventionalConventional
LCM Pills WhileLCM Pills While
Circulating KickCirculating Kick
Strip Pipe AboveStrip Pipe Above
Loss Zone?Loss Zone?
Displace PillDisplace Pill
Squeeze DPSqueeze DP
& Annulus& Annulus
LossesLosses
Cured?Cured?
YesYes
NoNo
Circulate KickCirculate Kick
Circulate KickCirculate Kick

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Lost circulation while cementing
• Reduce ECD’s
– Pump rate
– Mud, spacer, properties
• Treat the zone
• Add LCM to cement
• Pull the casing /liner

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Well Control Terminology
• Hydrostatic pressure
– = .052 x MW.ppg x TVD.ft

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Hydrostatic Pressure
• Derive HSP equation
• Calculate the HSP for each of the following:
– 10,000ft of 12.0ppg mud
– 12,000ft of 10.5ppg mud
– 5,000ft of 11.2ppg mud on top of 6,000ft of
16.5ppg mud

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Hydrostatic Pressure
• Derive HSP equation
– Area = A, sq.ft.
– Height = h, ft.
– Density = MW, ppg
• Weight of fluid =
– A*h (ft3)*62.4 lb/ ft3
*MW/8.33
– =62.4/8.33*MW*A*h
h
A
MW

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Hydrostatic Pressure
• This weight is equally distributed over an
area of A sq.ft or 144*A sq. in.
• Pressure = Weight (force)/area
• = 62.4*MW*A*h
• 8.33*144*A
• P=.052*MW*h where h=TVD

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Terminology
• Pressure Gradient
– psi/ft = .052 x MW
– ppg equivalent
• Formation Pressure
– Normal pressure
– Abnormal pressure
– Subnormal pressure

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Terminology
• Overburden pressure
– function of rock and fluid above zone of
interest
• Fracture pressure

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Terminology
• Pump pressure or
system pressure loss

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Terminology
• Slow Pump Pressure
• Taken:
– every tour by each driller
– pumps repaired or liners changed
– mud properties change
– every 500’ of hole
– change in BHA
– bit nozzles changed

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Terminology
• Surge pressure
• Swab pressure

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Terminology
• Shut-in drillpipe pressure - SIDPP
– FP = HSPdp + SIDPP
• Shut-in casing pressure - SICP
– FP = HSPcsg mud + HSPinflux + SICP
• Bottom-hole pressure - BHP
– BHP = HSP + SIP + Friction + Surge - Swab

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U-Tube Concept

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Basic Calculations
• Dia, in - cap, bbl/ft
dispCapacityWetdisp
IDODftwt
DCdisp
ftwt
DPdisp
ODID
AnnularCap
IDCapacity
pipehole







10292750
/
2600
/
1029
1029
22
22
2

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Basic Calculations
• Pump Output
– Duplex Pump
– Triplex Pump
   effRDLDSLTPOduplex  22
2000162.0
effLDSLTPOtriplex  2
000243.0

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Basic Calculations

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Basic Calculations
• Kill Weight Mud
– KWM = SIDPP/(0.052 x TVD) + OWM
– KWM = FP/(0.052 x TVD)

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Weight material to add to increase density
2.25/
60
)(2.25
64.17/
42
)(64.17
96.15/
38
)(96.15
7.14/
35
)(7.14
sxGalenaPitGain
KWM
OWMKWMMudVol
sxGalena
esxIronOxidPitGain
KWM
OWMKWMMudVol
esxIronOxid
sxIlmenitePitGain
KWM
OWMKWMMudVol
sxIlmenite
sxBaritePitGain
KWM
OWMKWMMudVol
sxBarite

















51. 2009 rev 1 Kingdom Drilling Services
Well Control Introduction Summary
• Well control cannot be like looking through
your rear view mirror
• It is about looking ahead, anticipating the
hazards and risks, ensuring you have plans
procedures and contingencies in place set to
handle any situation or circumstances the
well may present to you at the rig-site.
• Best practices exist so stick to them!

52. www.kingdomdrillng.co.uk
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