Virtual Hydraulics™ Engineering Success into · PDF fileand design critical well drilling hydraulics under simulated downhole conditions. It is used to monitor and predict: • downhole

1 3/24/2015 Confidential Information © 2011 M-I SWACO

Virtual Hydraulics™Engineering Success into HDD

Sam Rowdon

HDD Manager – Asia Pacific


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



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.



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



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)



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



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.



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



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.



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



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



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



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



Virtual Hydraulics Model – Hole Geometry



Virtual Hydraulics Model – Bit Nozzle Diameter and Flow Rate



Virtual Hydraulics Model – Directional Profile



Virtual Hydraulics Model – Fluid Rheology



Virtual Hydraulics Model – Lithology/Soil Profile



Virtual Hydraulics Model – Hole Cleaning & Operating Parameters



Virtual Hydraulics Model – Results



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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Virtual Hydraulics™ Engineering Success into · PDF fileand design critical well drilling hydraulics under simulated downhole conditions. It is used to monitor and predict: • downhole