1 3/24/2015 Confidential Information © 2011 M-I SWACO
Virtual Hydraulics™Engineering Success into HDD
Sam Rowdon
HDD Manager – Asia Pacific
2 3/24/2015 Confidential Information © 2011 M-I SWACO
Engineering Success into HDD
HDD – How does it work?
HDD Phases
Pilot Bore
Drill string is guided along a predetermined path
with drill cuttings (spoil) returning to the entry pit
(rig side).
Reaming/Hole Opening Phases
Pilot head is removed and replaced with a reaming
tool to increase the size of the borehole. Often in multiple passes. Drill cuttings return to exit pit (pipe
side) and eventually rig side.
Product Pullback
Product pipe is connected via a closed pulling head
and swivel to a reamer and pulled back into the
formed borehole
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Engineering Success into HDD
HDD – What are the Benefits?
• Process for installation of pipelines with minimal
requirements for excavation
• Less environmental impact
• Less disruption
• Improved outcome
• Often the most cost effective solution
• Feasible where other methods are not.
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Engineering Success into HDD
HDD – What are the risks?
Hydro-fracture
• Damage to infrastructure
• Environmental Damage
Cost Overruns
• Additional fluid demand
• Lost equipment
• NPT
Failure of Objective
• Product pipe not installed
• Product pipe damaged in installation
• Product pipe not installed to specification
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Engineering Success into HDD
HDD – Why does Hydro-fracture Occur in HDD?
• During the three HDD phases drilling fluid must
be pumped at all times to provide a number of critical functions.
• To make drilling fluid flow pressure is required
• If the surrounding soil is unable to contain this the pressure exerted on it by the drilling fluid in
the borehole it will fracture.
Soil Fracture Gradient (Measured in Psi/Kpa)
• Function of depth
• Soil density
• Water table depth
• Soils cohesive properties
(Delft Geotechnics- Soil Cavity Expansion Model)
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Engineering Success into HDD
If pressure is the source of the problem why pump fluid?
Drilling Fluids provide a number of critical roles in
any HDD installation.
• Transportation of drill cuttings from the borehole
• Suspension of cuttings during static periods
(pumps off)
• Transmission of hydraulic energy
• Lubrication and cooling
• Stabilisation of the borehole
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Engineering Success into HDD
HDD – Downhole Pressure, Formation Pressure and Fracture Gradient
• In an HDD drilling operation fluid pressure within
the borehole is exerted against the formation.
• If the borehole pressure is too low we risk a
ground water influx and collapse
• If the borehole pressure is too high we risk exceeding the confining overburden pressure
and hydro-fracture.
• The aim to keep the fluid pressure above the formation pressure (pore pressure) but below the
overburden pressure (fracture gradient)
• The borehole pressure “window” gets bigger with increased depth.
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Engineering Success into HDD
HDD – Sources of Downhole Pressure?Internal borehole pressure comes from two sources:
1. Hydrostatic – applied when static and circulating
vertical column Ht (m) x g x fluid density (SG)
2. Annular Pressure Losses
Borehole Pressure when circulating
= 1. Hydrostatic Mud Pressure + 2. Annular Pressure Loss
Annular Pressure Loss is a function of:
• Borehole Geometry
• Section Length
• Fluid viscosity (both Plastic Viscosity and Yield Point)
• Pump rate
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Engineering Success into HDD
HDD – The source of the problem is pressure but how can it be controlled?
Reactive Steps
• Change fluid viscosity
• Alter pump flow rate
• Back-ream to regain flow
What are the implications?
1. Loss of critical drilling functions
2. Loss of annular velocity
3. NPT – trial and error
Proactive Steps
• Design Feasibility (can HDD crossing be achieved?)
• How much pressure can we exert on the
formation?
• Computer modelling – Virtual Hydraulics™
1. Can the design fluid clean the hole at a given
flow rate.
2. How much pressure will be exerted to pump the fluid at a given flow rate.
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Engineering Success into HDD
Virtual Hydraulics™
VIRTUAL HYDRAULICS™ software is a
proprietary suite of programs used to evaluate and design critical well drilling hydraulics under
simulated downhole conditions.
It is used to monitor and predict:
• downhole pressures
• hole-cleaning,
• monitor and predict the hydraulics and rhelogical behavior of synthetic-, oil-, and
water-base drilling fluids
Originally employed in oil field drilling applications the software is now being utilized on HDD
crossings
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Engineering Success into HDD
Virtual Hydraulics™ - Modelling the for Design
Preliminary Design and Geotechnical Investigation
Calculation of maximum allowable installation pressure
HDD Equipment Selection
What is available in the industry
Fluid design for formation suitability
(multiple formulations built in lab)
Virtual Hydraulics™ Model
Can the hole be cleaned using this equipment and fluid?
Can it be done without exceeding the maximum allowable installation
pressure?
Yes – Finalize Design and Specification
No - Redesign
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Engineering Success into HDD
Virtual Hydraulics™ - Modelling the for Construction
Contract AwardContractor Selects
Equipment
Fluid design for formation suitability
(multiple formulations built in lab)
Virtual Hydraulics™Model
Can the hole be cleaned using this equipment
and fluid?
Can it be done without exceeding the maximum
allowable installation pressure?
Yes – commence drilling
No – Redesign Drilling Fluid/Change equipment
selection
Onsite Calibration of Virtual Hydraulics
Onsite drilling fluid testing and real time
modelling
Informed decisions made on appropriate corrective procedures
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Engineering Success into HDD
Virtual Hydraulics Model – What data is needed?
• Downhole equipment
Fluid behaves differently through different hole geometries. VH simulate how it moves
inside and outside of the selected tooling.
• Bit nozzle # and diameter
Orifice pressure losses must be determined. Jet impact force determines cuttings size.
• Pump flow rate
Flow rate dictates pressure and is also a function of hole cleaning
• Hole ProfileDifferent angles are harder to clean than others. (30 – 60˚ from vertical worst case)
• Drill Fluid Rheology
Depending on velocity drilling fluid has different viscosity. A Rheogram must be input
to allow the model to simulate flow profiles through different hole geometry
• Formation Soil Details
Soil type dictates cuttings size and chemical makeup and impact of hole cleaning
function
• Operating Parameters
• Drill String rotation speed, ROP steering, rotation ROP and % time steering
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Engineering Success into HDD
Virtual Hydraulics Model – Hole Geometry
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Engineering Success into HDD
Virtual Hydraulics Model – Bit Nozzle Diameter and Flow Rate
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Engineering Success into HDD
Virtual Hydraulics Model – Directional Profile
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Engineering Success into HDD
Virtual Hydraulics Model – Fluid Rheology
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Engineering Success into HDD
Virtual Hydraulics Model – Lithology/Soil Profile
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Engineering Success into HDD
Virtual Hydraulics Model – Hole Cleaning & Operating Parameters
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Engineering Success into HDD
Virtual Hydraulics Model – Results
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Engineering Success into HDD
Virtual Hydraulics Model – Results Snapshot
Dril l i n g F lu id
DRIL PL EX HDD
Mu d Weig h t 9 lb /g al
T est T emp 21 °C
PV (@21°C) 12 cP
YP 32 lb /100ft²
L SY P 19 lb /100ft²
System Data
F lo w Rate 400 l /min
Pen etratio n Rate 20 m/h r
Ro tary S p eed 80 rp m
Weig h t o n Bi t 25 1000 lb f
Bi t No zzles 10-10- 0 - 0 - 0
0 - 0 - 0 - 0 - 0
Pressu re L o sses
Mo d i fi ed Po wer L aw
Dri l l S trin g 55 p si
Bi t 147 p si
Bi t On /Off 0 p si
An n u lu s 31 p si
Su rface Eq u ip 10 p si
U-T u b e E ffect 0 p si
T o tal S ystem 243 p si
ES D +Cu t ECD +Cu t
Csg Sh o e 9.00 9.33 11.17 11.51T D 9.00 9.33 30.56 30.89
VRDH - Version 3.3 Fann 35
File - Dunst ans Tingira.MDB,#1 Dat e: 3/12/2015
P ressu re Distrib u tio nBi t = 63.1 An n = 13.2 DS = 23.7
H C IB ed H t %
Hole CleaningIndex
V G G F P
0 100B ed V ol %
0 100 200
Va(ft/min)
T urb T urbLam
Top
Btm
Top
20 40
A nnul usD r i l l S t r i ng
Temperature(° C)
10 20 30 40
P VY PLS Y P
PV (cP)YP, LSYP (lb/100ft²)
0 10 20 30 40
E S DE C DE S D +C ut t i ngsE C D +C ut t i ngs
Density(lb/gal)
0 45 90
Angle(° )
8. 000 300
8
G eometryM D/TVD Csg O D/ID(m) (in)
FormationTop
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
Dep th(m)
MD: 300 mT VD: 8 m
Bi t S i ze: 8 in
Ro t(%)/S l id in g (%):60/40
Op erato r: Cal texWel l Name: T in g i ra
L o catio n : Eag le F arm
Co u n try: Au stral i a
VIRTUAL HYDRAULICS*
SnapShot*©1995- 2014 M- I SW ACO * Mar k of M- I SW ACO
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Engineering Success into HDD
Virtual Hydraulics Model – Navigator
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