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Drillbench® Dynamic Well Control
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History
Multiphase flow model
– Model originates from Rogaland Research
– Modeling has been supported by extensive verification work with
fullscale data; both experiments and real wells
– Continuous development by Schlumberger Integrated Solutions
(SIS)
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Dynamic Well Control
Kick Circulation
Kick Tolerance
Kill Sheet
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Dynamic Well Control Module
Model provides details on :
• Kick Circulation
• Circulating pressures
• Bottom Hole Pressures
• Casing Shoe Pressures
• Gas volumes
• Gas in solution and when the gas breaks out
• Choke Line Pressures
• Kick tolerance
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Type of Kick
Kick while drilling
Pore Pressure > ECD
– Formation pore pressure is higher than the dynamic bottomhole pressure
Kick during connections/pumps off
ECD > Pore Pressure > ESD
– Formation pore pressure is lower than the dynamic bottomhole pressure, but higher than the
static bottomhole pressure
Swab kick
ESD > Pore Pressure
– Formation pore pressure is lower than the static bottomhole pressure
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Circulating the Kick
2 method:
– Driller’s Method
– Wait & Weight Method
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Dynamic Well Control - Model Basic
Dynamic model
– A kick enters the well
– The well is closed in and well pressures stabilises
– The kick is circulated out
– A heavy kill mud is placed into the well
Conservation of mass and total momentum
– Mud
– Free gas
– Dissolved gas
– Formation oil
Equation set is solved by a finite difference technique with
– A set of sub models for physical properties
– Boundary conditions defined for various modes
Circulation
Closed in well
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Kick Tolerance
The maximum volume of influx that can be circulated out without breaking down the weakest
formation (Presumed to be at the last casing shoe, if no other information is available).
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SLB IPM Standards
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Kick Tolerance Consideration
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Kick Tolerance Consideration
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A dynamic model will disperse akick over a much longer section ofthe annulus whilst drilling ascirculation continues.
The dynamic model also accountsfor absorption of the gas into anyoil based fluid systems.
Dynamic Kick ToleranceCalculations result in a morerealistic design and allows casingsetting depths to be optimized.
Dynamic Kick Tolerance
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Dynamic Kick Tolerance Calculations result in a flatter line for volumes allowing larger kick volumes to be controlled.
5800
5900
6000
6100
6200
6300
6400
6500
0 10 20 30 40 50 60 70 80
Pre
ssu
res (
psi)
Kick Size (bbl)
Kick Tolerance for 14-3/4" hole at 2215m MDDF (drilled kick)
ECD at TD of Section (psi)
LOT Equivalent Pressure (psi)
Mud Weight in use (ppg)
Dynamic Kick Tolerance (psi)
Kick Tolerance Single Bubble Model (psi)
Mud Weight 15.50 ppg
ECD 15.91 ppg
LOT 16.50 ppg
Dynamic Kick Tolerance
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Dynamic Kick Tolerance Calculations result in a flatter line for volumes allowing larger kick volumes to be controlled.
Dynamic Kick Tolerance
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In well control simulations we provide the simulator which gives you a dynamic kill sheet and it allows to look at the possible scenario’s in minutes.
Whilst the well is being killed results of pressures and flow rates can be followed using the simulator.
Dynamic Simulations
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Facts to remember:
Concentration depends on operation – drilling will give a more
distributed kick than if it is swabbed in
– Influx rate
– Mud circulation rate
Gas dissolution process is transient
The conditions in HPHT wells are far above critical point
– One phase
– Infinite solubility
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Pressure Losses
Frictional pressure drop
– Laminar and turbulent flow
– Rheology models
– Pressure loss
Flow area changes
BHA / Bit
Choke valve / choke line
– Two-phase flow
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Geometry
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Geometry
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Geometry
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Geometry
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Surface Equipment
Delay: The time it takes to initiate theclosure/shutdown of a unit. Human factor.
Duration: The time it takes to for theunit to close/shutdown. Mechanical factor.
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Kick Detection Evaluation
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Reservoir – Influx Model
Two Model:
– Reservoir Model
– Constant Influx Model
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Reservoir Model vs. Constant Influx
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Choke Pressure During Kill
Gas Breakout
Methane
WBMMethane OBM
Black Oil
OBM
Comparison among different scenarios.
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Exercise
Setting up Input file
and do calculation
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PVT Models
Black Oil
– Correlations (several) – model gas & liquid
– Not very accurate
– May not be valid for HPHT conditions
Compositional– Base oil composition
Predefined alternatives Measured data
– Reservoir fluid composition
Predefined influx alternatives Measured data
– Equation of State
– Physical modeling
Measured Data (Tabular)
– Accurate
– Data is often unavailable
Predefined or custom fluid composition
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PVT Models
How to select the most appropiate one?
• Black Oil
– A system with liquid and gas where the composition of the liquid and the gas phase is thesame. You have one phase envelope describing the transition/equilibrium point.Gas/multiphase/oil regions. The important part is that the compositions does not change andeven if more gas is released as free, the remaining oil has the same composition.
Compositional
– In principle one phase transition curve for each component. You are referring to an equilibriumconstant for transition between phases for each component.
Note:
Compositional is to be used as default setting as all calculations will be done based on the «Equation of
State» while Black Oil is based on measurements of PVT properties at low to moderate pressures and
temperatures and to extrapolate to HPHT conditions is not recommended.
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Degasser Input
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Verification
Experimental work at Rogaland Research– Full scale research drilling rig– Laboratory tests
Tested a large number of HPHT muds – Field muds– Base fluids– Various fluid compositions
Max pressure 1500 bar Max temperature 220 °C Measured– Compressibility– Thermal expansion– Rheology– Solubility of gas
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Pressure
Flow
0 10 20 30 40 50 60 70
Time (min)
125
130
135
140
145
150
Pr e
ss
ur e
(ba
r )
Simulated
Measured
0 10 20 30
Time (min)
0
500
1000
1500
2000
Flo
wo
ut
(l/
in) Simulated
Measured
Verification
Flo
w o
ut
[l/m
in]
Pre
ss
ure
[b
ar]
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Applications
All wells
Kick tolerance
Casing design
– Setting depths
– Pressure
Surface capacity
Well control procedures
Post analysis
Education / training