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Underbalanced Drilling and Managed Pressure
Connections
June 2012
1
Summary of Presentation
 Rig setup on EWG 103 for Underbalanced Drilling Operations
- Designed as a light fluid drilling vertical rig
- Converted to do underbalanced air drilling
- Airpack & hard lines
 Managed Pressure connections
2
Rig setup
3
Easternwell 103 – Rig Setup for Underbalanced Drilling
Strata float
To Well
Stand-pipe
Bypass line
Blooie line
Test Separator
Choke Line
Kill Line
Mud Tank
Choke manifold
Mud Pump #1
Stand-pipe
manifold
M d Pump
Mud
P
#2
Mist
Pump
Compressor
Compressor
Compressor
4
Primary
Jet
Booster
CFM Meter
P&T
transmitter
Killing Well By-pass
BOP Stack and Well Head
Rotating head and
Bearing Assembly
Annular Rams
Air Cross
Ai
C
Drilling
D illi
Spool
Pipe Rams
Drilling Spool
B-Section
5
A-Section
Air Compressors and Boosters
 3 Compressors: 1350 cfm @ 350 psi
each (+ one spare)
To booster
From compressors
Compressor
Compressor
6Compressor
Booster
 1 Booster: 1400 psi & ~ 2000 CFM
 Monitored in the Air-pack manifold
 Orifice Plate (CFM)
 Pressure
 Relief Valves
 Mist Pump
Air-pack Manifold
mufflers
CFM Meter
Psi reading
P&T
transmitter
Vent
Main air flow
to stand-pipe
Metering
Orifice Plate
(CFM reading)
di )
Line to spare mist
pump (TDC)
7
Addition of Airpacks in the Circulating System
Mist
Pump
Air from
Air-pack
Fluid from
C
Cement
/
Mist Pump
Mist into line
up to stand
pipe
8
Blooie Line and Primary Jet
Relief line from
Choke Manifold
Blooie Line
Degasser Blooie Line
Primary Jet
(from stand-pipe
Manifold)
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Sample Catcher
Underbalanced drilling operations
 Directional drilling in 75 degree inclination well with motor
 Average drilling rate is 10m/hr including connections time
Average drilling rate is 10m/hr including connections time
 Managed pressure connection time ranges from 10 minutes to 20 minutes
20 minutes  Monitoring bottom hole pressure with pressure while drilling sub
 Normal reservoir pressure is 2 – 4ppg, drilling with circulating BHP ranging from 400 – 450 psi. BHP ranging from 400 450 psi
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Managed Pressure Connections
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Managed Pressure Connections
 Formation pressures ranges from 250 – 500.  To minimise bottom hole pressure cycling (of up to 500 psi) between circulating ((drilling) and static (connection) modes, a connection procedure was developed for ll )
(
)
l
f
building up and shutting in casing pressure (SICP) before diverting the air flow to the primary jet.  Based data from EM‐MWD package with a Pressure While Drilling sub in the BHA. BHA measurement indicated significant pressure cycling being applied to the coal formations between drilling and connection mode.  This pressure cycling could possibly lead to borehole instability and breakout, resulting in stuck BHA while having static pipe in hole during connections. Cycling of coals could also cause hole issues while running pre‐perforated liner.  Managed pressure connection procedures is developed to reduce BHP fluctuations between drilling and connection modes to below a target of 100 psi. 12
First Trial of Managed Pressure Connections - Fairview Concept 10 Wells
Wells
Casing
Policy
Fairview 508
Fairview 509
Fairview 506
9-5/8” @ 129.5m (MD/TVD)
9-5/8” @ 130.2m (MD/TVD)
9-5/8” @ 130m (MD/TVD)
7” @ 1231m / 653m
7
(MD/TVD)
7” @ 1250
7
1250.5m
5m / 658.8m
658 8m
(MD/TVD)
7” @ 1252m / 648
7
648.6m
6m
(MD/TVD)
6-1/8” Production Hole to TD 6-1/8” Production Hole to TD 6-1/8” Production Hole to TD
W ll TD
Well
1544.5m MDRT
734.5m TVDRT
1613m MDRT
738.4m TVDRT
1630m MDRT
745.9m TVDRT
Survey at
Well TD
Inclination = 64°
Azimuth = 346.4°
Inclination = 76°
Azimuth = 34°
Inclination = 73.8°
Azimuth = 331°
Formation
Pressure
275 psi (2.4 ppg EMW)
225 psi (1.94 ppg EMW)
264 psi (2.28 ppg EMW)
Target Formations TVD
A Coal
673 1 tto 673
673.1m
673.7m
7 (0
(0.6m)
6 )
674 tto 675
674m
675m (1
(1m))
656 tto 656
656m
656.9m
9 (0
(0.9m)
9 )
B Coal
681.3m to 687m (5.7m)
684m to 688.3m (4.3m)
686.4m to 692.8m (6.4m)
D Coal
707.6m to 711.1m (3.5m)
710.1m to 715m (4.9m)
714m to 717.5m (3.5m)
E Coal
728.8m to 729.5m (0.7m)
732.8m to 733.9m (1.1m)
740m to 740.2m (0.2m)
13
Bottomhole Pressure Behaviour in Air Drilling
Pf = Friction Pressure
Phyd = Fluid hydrostatic Pressure
Connection after Drilling Phase (A) – Performed without locking SICP
Connection after Drilling Phase (B) – Performed with locking SICP
14
Procedure for minimizing BHP fluctuations
 Determine hydrostatic pressure of fluid in annulus (Phyd)
Phyd = BHP – SICP (assume formation P of around 250 psi)
Phyd = 264 – 130 = 134 psi
Based on the pumping rates and the drilling fluid properties,
 Circulating
g BHP while drilling
gp
production hole in Fairview 506 = 440 p
psi
 SICP to be locked in connections = Circ. BHP – Phyd
= 440 psi – 134 psi
= 306 psi
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Managed Pressure Connections
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Air Drilling Setup – Drilling 6-1/8” Production Hole
Standpipe Manifold
Flow path
Fl
th off air
i / mist
i t / foam
f
through standpipe manifold
(highlighted in RED) while
drilling 6-1/8”
6 1/8 Production hole
Valves 1, 2, 5 – CLOSED
Valves 3 & 4 – OPEN
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Air Drilling Setup – Making a Connection
Standpipe Manifold
Flow path of air / mist / foam
through standpipe manifold
(highlighted in RED) while making
connection.
Pressure trapped in the drill string
is released through secondary jet
(highlighted in GREEN)
Valves 1, 3, 5 – OPEN
Valves 2 & 4 – CLOSED
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Bottomhole Pressure Behaviour in Air Drilling
BHP behaviour in Fairview 508 well
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Bottomhole Pressure Behaviour in Air Drilling
BHP behaviour in Fairview 509 well
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Bottomhole Pressure Behaviour in Air Drilling
Formation Pressure
BHP behaviour in Fairview 506 well – Adopted procedure
to lock in SICP during connections
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Thank you
22