Dynamic Well Control_Slide printing.pdf

Drillbench® Dynamic Well Control

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 3

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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 6

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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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Dynamic Kick Tolerance

A dynamic model will disperse a kick over a much longer section of the annulus whilst drilling as circulation continues. The dynamic model also accounts for absorption of the gas into any oil based fluid systems. Dynamic Kick Tolerance Calculations result in a more realistic design and allows casing setting depths to be optimized.

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Dynamic Kick Tolerance Kick Tolerance for 14-3/4" hole at 2215m MDDF (drilled kick) 6500 ECD at TD of Section (psi) LOT Equivalent Pressure (psi) Mud Weight in use (ppg)

6400

Dynamic Kick Tolerance (psi) Kick Tolerance Single Bubble Model (psi)

6300

Pressures (psi)

LOT 16.50 ppg 6200

6100

ECD 15.91 ppg 6000

5900

Mud Weight 15.50 ppg

5800

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Kick Size (bbl)

Dynamic Kick Tolerance Calculations result in a flatter line for volumes allowing larger kick volumes to be controlled. 12

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Dynamic Kick Tolerance

Dynamic Kick Tolerance Calculations result in a flatter line for volumes allowing larger kick volumes to be controlled. 13

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Dynamic Simulations

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.

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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 the closure/shutdown of a unit. Human factor.

Duration: The time it takes to for the unit 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  Comparison among different scenarios.

Methane WBM Gas Breakout

Methane OBM

Black Oil OBM

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Exercise Setting up Input file and do calculation 26

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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 27

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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 the same. You have one phase envelope describing the transition/equilibrium point. Gas/multiphase/oil regions. The important part is that the compositions does not change and even 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 equilibrium constant 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. 28

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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 – – – –

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Compressibility Thermal expansion Rheology Solubility of gas

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Verification 145

P r e ssure (b a r)

Pressure [bar]

150

Pressure

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Simulated

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Measured 125 0

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in )

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Time (min)

2000

1500

Simulated Measured

F lo w o u t (l /

Flow out [l/min]

40

1000

Flow 500

0 0

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Time (min) Copyright ©2001-2012 NExT. All rights reserved

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Applications  All wells  Kick tolerance  Casing design – Setting depths – Pressure

 Surface capacity  Well control procedures  Post analysis  Education / training

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