14b-horizontal drilling equipment and controlling power point

8/14/2019 14b-Horizontal Drilling Equipment and Controlling Power Point

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SURVEY INSTRUMENTSSURVEY INSTRUMENTS

Survey instruments areSurvey instruments are

used to measure theused to measure theinclination and azimuth ofinclination and azimuth of

the wellthe well


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Survey InstrumentsSurvey Instruments

Magnetic surveys use the earthMagnetic surveys use the earthss

magnetic field to determine themagnetic field to determine the

azimuth of the wellboreazimuth of the wellbore

The magnetic north pole is not thesame as the geographical north pole


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Declination is the difference between

the the magnetic north pole and thegeographical north pole

It is either an east or west declinationEast declination is added to the

azimuthWest declination is subtracted from

the azimuth


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If the wellbore is

using gridcoordinates, theazimuth will also

have to beadjusted by thedifferencebetween truenorth and grid

north


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For magnetic survey instrumentsFor magnetic survey instruments

you must use nonyou must use non--magneticmagnetic

(monel) drill collars(monel) drill collars

The survey instrument must beplaced within the collars to minimize

magnetic interferenceNear the middle but not precisely the

middle


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The number of collars depends upon

the geographical location of the well

Where the horizontal intensity of the

earths magnetic field is a minimum,more non-magnetic drill collars will be

required


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The horizontal intensity of the earths

magnetic field is a function of themagnetic dip angle

Magnetic field strength x cos(magnetic dip angle) = horizontalcomponent

Alaska 57,500 gammas x cos(80.6)= 9,391 gammas

Gulf Coast 50,500 gammas x

cos(59.7) = 25,478 gammas


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Zone I requires fewer non-magnetic

drill collars

Zone II requires more non-magnetic

collarsThe number of collars also depends

upon the inclination and direction of

the well


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Use 18' collar in areaUse 18' collar in area

below Curve Abelow Curve A

Use 25' foot collar inUse 25' foot collar inarea below Curve Barea below Curve B

Use 30 foot collar inUse 30 foot collar in

area below Curve Carea below Curve C

Use tandem (18' +Use tandem (18' +

25') collars in areas25') collars in areasabove Curve Cabove Curve C

ZONE I


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Use 30' collars inUse 30' collars inarea below Curve Aarea below Curve A

Use 60' collars inUse 60' collars inarea below Curve Barea below Curve Bwith packedwith packed

bottomholebottomholeassemblyassembly

Use 60' collars inUse 60' collars in

area below Curve Carea below Curve Cwith near bitwith near bitstabilizer onlystabilizer only

Use 90' collars inUse 90' collars inarea above Curve Carea above Curve C

ZONE II


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Use 60' collars inUse 60' collars inarea below Curve Aarea below Curve A

with packedwith packedbottomholebottomholeassemblyassembly

Use 60' collars inUse 60' collars in

area below Curve Barea below Curve Bwith near bitwith near bitstabilizer onlystabil izer only

Use 90' collars inUse 90' collars inarea below Curve Carea below Curve Cwith anywith anybottomholebottomhole

assemblyassemblyZONE III

DIRECTION ANGLE FROM MAGNETIC N OR S


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TotcoTotco surveyssurveys

Inclination only and are not directionalsurveys

Run on most vertical wells


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Types of survey instrumentsTypes of survey instruments

Magnetic

Gyroscopic

COMPASS ELECTRONIC

MAGNETIC

CONVENTIONAL RATE OR

NORTH SEEKING

RING LASER INERTIAL GRADE

GYROSCOPIC

SURVEY INSTRUMENTS


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CompassCompass

Singleshot

Multishot

Both use a compass and camera.

The camera takes a picture of the

compass at various depths within thewellbore


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Steering ToolSteering Tool

MWD (Measurement WhileMWD (Measurement While

Drilling)Drilling)

EMS (Electronic Multishot)EMS (Electronic Multishot)


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All electronic survey tools useAll electronic survey tools use

the same instruments tothe same instruments to

measure the inclination andmeasure the inclination and

azimuthazimuthAccelerometers to measure the

inclinationMagnetometers to measure the

azimuth


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Probe Axis

Accelerometer/Gravity

Magnetometer/Earths Field

ToolfaceAlignment

Inclination Gx, Gy, Gz

Azimuth Bx, By, Bz

Toolface Gx, Gy or Bx, By


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The difference is how theThe difference is how the

instrument gets the informationinstrument gets the information

to the surfaceto the surface

Steering tool was the first electronicinstrument and used a single

conductor wireline


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The steering tool isThe steering tool is

oriented in a muleoriented in a mule

shoe sub (UBHOshoe sub (UBHO

sub). The key in thesub). The key in the

MSS is aligned withMSS is aligned withthe bend in thethe bend in the

motor so that themotor so that the

orientation of theorientation of theMSS is the same asMSS is the same as

the motor.the motor.


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The mule shoeThe mule shoestinger is orientedstinger is oriented

in reference to thein reference to thehigh side on thehigh side on thesurvey toolsurvey tool

When the stingerWhen the stingerenters the MSS, itenters the MSS, it

is rotated until itis rotated until itlines up with thelines up with theorientation of theorientation of the

MSS and motorMSS and motor


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In order to make a connection,In order to make a connection,

the steering tool had to be pulledthe steering tool had to be pulledfrom the holefrom the hole

It was time consuming and thereIt was time consuming and therewas a possibility of getting stuckwas a possibility of getting stuckwhile tripping the wireline (nowhile tripping the wireline (no

circulation)circulation)

A side entry sub was developedA side entry sub was developed

to minimize connection timeto minimize connection time


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With the sideWith the side

entry sub, theentry sub, thewireline passeswireline passes

from inside thefrom inside the

drill string todrill string to

outside the drilloutside the drill

string (annulus)string (annulus)


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With the wirelineWith the wireline

outside the pipeoutside the pipenear the surface,near the surface,

the steering toolthe steering tool

did not have todid not have to

be pulled tobe pulled to

make amake aconnectionconnection


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Drilling with aDril ling with a

side entry subside entry subThe kellyThe kellybushings are onbushings are on

a stand to keepa stand to keepfrom damagingfrom damagingthe wirelinethe wireline

A stand wouldA stand wouldnot be requirednot be required

with a top drivewith a top drive


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Development of the MWD spelledDevelopment of the MWD spelled

doom for the steering tooldoom for the steering toolbecause the drill string could notbecause the drill string could not

be rotated with the wireline in thebe rotated with the wireline in theholehole

A wet connect system wasA wet connect system was

developed to allow rotation ofdeveloped to allow rotation ofthe drill string without pulling thethe drill string without pulling the

steering toolsteering tool


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The wirelineThe wireline

enters the top ofenters the top ofthe swivelthe swivel

While rotating,While rotating,

the wet connectthe wet connectis not connectedis not connectedto the toolto the tool

It is reconnectedIt is reconnectedwhile surveyingwhile surveying

or slidingor sliding


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Steering tools are still usedSteering tools are still used

where the MWD may not bewhere the MWD may not beapplicableapplicable

Underbalanced drilling

Cannot pulse a compressible fluid

LCM in the mud

Plugs the pulser and other parts of MWD

High temperature

Steering tool can be run in a heat shield


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MWD pulses the mud system toMWD pulses the mud system to

send information to the surfacesend information to the surfacePositive pulse

Negative pulse

Continuous wave

Also have electromagnetic MWDwhich uses radio waves to send

information


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MWD

Pressure Pulses

in Drill Pipe

Surface Computer

Transducer

On Standpipe


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Directional MWDDirectional MWD

tooltoolThis is a positiveThis is a positive

pulse systempulse systemIt is powered by anIt is powered by an

alternator wherealternator where

some may besome may be

powered bypowered by

batteriesbatteries

S I t t


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Positive pulsePositive pulse

a restriction ina restriction inthe MWD causesthe MWD causes

an increase inan increase in

pressurepressure

11s and 0s and 0ss

TimePres

sure

Positive Pulse

S I t tS I t t


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Negative pulseNegative pulse

uses a valve inuses a valve inthe side of thethe side of the

MWD to bypassMWD to bypass

some of the fluidsome of the fluid

reducing thereducing the

standpipestandpipepressurepressure

TimePress

ure

Ne ative Pulse

S I t tS I t t


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ContinuousContinuous

wave modulateswave modulatesthe frequency tothe frequency to

generate 1generate 1s ands and

00ss

Time

Pr

essure

Continuous Wave

S I t tS I t t


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ElectromagneticElectromagnetic

MWD uses radioMWD uses radiowaveswaves

Works inWorks incompressiblecompressible

fluidsfluids

(underbalanced(underbalanceddrilling)drilling)

MWD

Antenna Array

S I t tS I t t


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Positive pulsePositive pulse

The positive pulse is more tolerant of

LCM and mud solids

It is also less affected by pump noise;however, it has the lowest data

transmission rate

S I t tSurvey Instruments


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Negative pulseNegative pulse

The negative pulse system has a slightlyhigher data transmission rate and pump

noise is still not as much of a problem

It uses less power

There must be enough pressure differential

between the tool and the annulus for it towork properly, which means jet selection

can be limited

More LCM tolerant



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Continuous waveContinuous wave

The significant advantage of the

continuous wave is that the data

transmission rate is substantiallyhigher

Pump noise is more difficult to filter

out

Less LCM tolerant



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Electromagnetic MWDElectromagnetic MWD

A transmitter in the tool transmits theelectromagnetic waves and the

waves are picked up at the surfacewith an antenna array

Data transmission rates are not

substantially different than mud pulse

MWD



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Electromagnetic MWD does not workas deep as mud pulse MWD and is a

function of the resistivity of theformations

It works better in fresh waterformations

The signal is attenuated across from

evaporite formations such as salt anddoes not work while in the evaporitezone. Once the transmitter gets

below the zone, it will work again



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EMS or electronic multishotEMS or electronic multishot

It stores the information in a computerchip (memory)

Once the tool is retrieved from thehole, the survey data is downloaded

into a computer

The tool is usually dropped into the

drill string before making a trip



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The EMS is programmed to wait a

specific amount of time before takingthe first survey, which gives it time to

get into the non-magnetic drill

collar(s)

After it takes a survey, one stand of

pipe is pulled from the holeAt preset intervals, the EMS will take

another survey



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The drilling crew waits until the EMS

takes a picture at each stand whiletripping out of the hole

The survey operator keeps track ofwhich surveys are at each depth

When the EMS is retrieved from the

hole, the surveys are matched to thedepth from the drill string tally



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Gyroscopic toolsGyroscopic tools

Conventional Gyro

Rate or North Seeking Gyro

Ring Laser Gyro

Inertial Grade Gyro

COMPASS ELECTRONIC

MAGNETIC


NORTH SEEKING


GYROSCOPIC

SURVEY INSTRUMENTS



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ConventionalConventional

gyro or free gyrogyro or free gyroGet directionGet direction

only and notonly and notinclinationinclination

Inclination isInclination is

still withstill withaccelerometersaccelerometers

SPIN AXIS

OUTER GIMBAL AXIS

INNER

GIMBAL

AXIS



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ConventionalConventional

gyro or free gyrogyro or free gyroGet directionGet direction

only and notonly and notinclinationinclination

Inclination isInclination is

still withstill withaccelerometersaccelerometers

SPIN AXIS

OUTER GIMBAL AXIS

INNER

GIMBAL

AXIS



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The gyro is a littleThe gyro is a little

more complicatedmore complicatedthan just a spinningthan just a spinning

massmass



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A conventional gyro had to beA conventional gyro had to be

referenced. You have to knowreferenced. You have to knowwhich way the axis is pointingwhich way the axis is pointing

when it is startedwhen it is startedThe conventional gyro has driftThe conventional gyro has drift

due to imperfections in the gyrodue to imperfections in the gyroand the earthand the earths rotation, systems rotation, system

shocks, bearing wear, etcshocks, bearing wear, etc



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The drift is measured beforeThe drift is measured before

running the gyro in the holerunning the gyro in the hole

While surveying, the drift isWhile surveying, the drift is

checked at regular intervalschecked at regular intervalsThe survey data is corrected forThe survey data is corrected for

drift for the final surveydrift for the final survey



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Rate integrating or NorthRate integrating or North

Seeking GyroSeeking Gyro

COMPASS ELECTRONIC

MAGNETIC


NORTH SEEKING


GYROSCOPIC

SURVEY INSTRUMENTS



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Survey Instrumentsy

It is a gyroIt is a gyro

with only onewith only onedegree ofdegree of

freedomfreedom

SPIN AXIS

INNER

GIMBALAXIS

BASE PLATE



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Su ey s u e sy

DeterminesDetermines

which waywhich wayis northis north

withoutwithoutreferencingreferencing



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yy

Automatically adjusts for driftAutomatically adjusts for drift

electronicallyelectronicallyMore accurate than theMore accurate than the

conventional gyroconventional gyro



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yy

The rate gyro measures theThe rate gyro measures the

forces acting on the gyro and theforces acting on the gyro and theaccelerometers measure theaccelerometers measure theforce of gravityforce of gravity

The combined readings of theThe combined readings of theaccelerometers and the gyroaccelerometers and the gyro

allow calculation of theallow calculation of theinclination and azimuth of theinclination and azimuth of the

wellborewellbore



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yy

Ring laser gyro uses lasers toRing laser gyro uses lasers to

get directionget directionMore accurate than rate gyro butMore accurate than rate gyro but

is 5 1/4is 5 1/4 (133.4 mm) OD and(133.4 mm) OD andcannot be run in drill pipecannot be run in drill pipe

COMPASS ELECTRONIC

MAGNETIC


NORTH SEEKING


GYROSCOPIC

SURVEY INSTRUMENTS



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y

The sensor is comprised of threeThe sensor is comprised of three

ring laser gyros and three inertialring laser gyros and three inertial

grade accelerometers, mounted tograde accelerometers, mounted to

measure X, Y and Z axismeasure X, Y and Z axis



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y

It is more accurate than a rate orIt is more accurate than a rate ornorthnorth--seeking gyroseeking gyro

The survey tool does not have to beThe survey tool does not have to bestopped to take a survey sostopped to take a survey so

surveys are quickersurveys are quickerIn its simplest form, the ring laserIn its simplest form, the ring laser

gyro consists of a triangular blockgyro consists of a triangular blockof glass drilled out for 3 heliumof glass drilled out for 3 helium--neon laser bores with mirrors at theneon laser bores with mirrors at the

120 degree points120 degree points -- the cornersthe corners



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CounterCounter--rotating laser beamsrotating laser beams -- oneone

clockwise and the other counterclockwise and the other counter--

clockwise coexist in this resonatorclockwise coexist in this resonator

At some point, aAt some point, a photosensorphotosensormonitorsmonitors

the beams where they intersectthe beams where they intersectThey will constructively or destructivelyThey will constructively or destructively

interfere with oneinterfere with one--another depending onanother depending on

the precise phase of each beamthe precise phase of each beam



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If the RLG is rotated about its centralIf the RLG is rotated about its centralaxis, the clockwise and counteraxis, the clockwise and counter--

clockwise beams will experienceclockwise beams will experienceopposing Doppler shifts, one willopposing Doppler shifts, one willincrease in frequency and the other willincrease in frequency and the other will

decrease in frequencydecrease in frequencyThe detector will sense the differenceThe detector will sense the differencebetween the frequencies from whichbetween the frequencies from whichprecise angular position and velocityprecise angular position and velocitycan be determinedcan be determined

This is known as theThis is known as the SagnacSagnac effecteffect



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Inertial grade gyro is the sameInertial grade gyro is the same

gyro used for navigationgyro used for navigationIt has a 10 5/8It has a 10 5/8 (270 mm) OD and(270 mm) OD and

cannot be run in casing smallercannot be run in casing smallerthan 13 3/8than 13 3/8 (339.7 mm)(339.7 mm)

COMPASS ELECTRONIC

MAGNETIC


NORTH SEEKING


GYROSCOPIC

SURVEY INSTRUMENTS



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Often called the Ferranti toolOften called the Ferranti tool

The tool uses three rate gyrosThe tool uses three rate gyrosand three accelerometersand three accelerometers

mounted on a stabilized platformmounted on a stabilized platformThe most accurate surveyThe most accurate surveyinstrument availableinstrument available

It not only measures theIt not only measures theinclination and direction of theinclination and direction of the

well; it also measures the depthwell; it also measures the depth



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Accuracy of survey toolsAccuracy of survey tools

Magnetic surveys can suffer frommagnetic interference, hot spots inthe non-magnetic drill collars,

declination correction errors (chartsand programs are not perfect),problems associated with higherlatitudes, and even sun spot activity(magnetic storms)



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Film based surveys cannot be read

accuratelyFor a conventional gyro surface

referencing, drift and tool

misalignment can be a problemWith the other gyros, quality control is

the biggest issue

The tools must be properly calibratedand then checked again at the end of

the survey



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Survey accuracy as

reported by de

Lange, et. al. (SPE

17213)

The inertial gradegyro is the most

accurate survey

instrument followedby the ring laser

gyro

0 30 60 90

0.5

1

2

5

10

20

50

100

200

500



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The accuracy of therate or north seekinggyro is similar to themagnetic tools(electronic) with goodquality control

Note that themagnetic tools aremore accurate if the

wellbore is north/southas opposed toeast/west

0 30 60 90

0.5

1

2

5

10

20

50

100

200

500


00


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Above an inclinationof 30, theconventional gyro isless accurate than theMWD withoutsubstantial quality

controlWith higher

inclinations, the error

associated withsurveys can besubstantial

0 30 60 90

0.5

1

2

5

10

20

50

100

200

500

Survey UncertaintySurvey Uncertainty


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Wolff andWolff and DeWardtDeWardt is oneis one

systematic survey error modelsystematic survey error modelused to predict the ellipse ofused to predict the ellipse of

uncertainty (actually an ellipsoiduncertainty (actually an ellipsoidsince it is in three dimensions)since it is in three dimensions)

Their work has since beenTheir work has since beenrefinedrefined



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Generally, the inclination of aGenerally, the inclination of a

survey is relatively accuratesurvey is relatively accurate

because it is only affected bybecause it is only affected by

depth measurement and thedepth measurement and the

accuracy of the toolaccuracy of the tool

The direction of the well is moreThe direction of the well is more

inaccurate due to accuracy ofinaccurate due to accuracy ofthe tools, magnetic interference,the tools, magnetic interference,

magnetic storms, etc.magnetic storms, etc.



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As the inclination of the wellAs the inclination of the well

increases, the error in theincreases, the error in thevertical and horizontal planevertical and horizontal plane

increasesincreasesMost survey errors areMost survey errors are

systematic rather than randomsystematic rather than randomwhich means they accumulatewhich means they accumulate

rather than cancel each other outrather than cancel each other out



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Ellipse ofEllipse ofUncertainty atUncertainty at

TD showingTD showingpossiblepossiblelocation oflocation ofwellborewellbore

Spider mapsSpider maps

are used to plotare used to plotexisting wellsexisting wellsand futureand future

wellswells



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The size of theThe size of the

ellipse ofellipse ofuncertaintyuncertainty

increases withincreases with

depthdepth



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WellboreWellbore

showing ellipseshowing ellipseof uncertaintyof uncertainty

with depthwith depth

0

2000

4000

6000

8000

10,000

12,000

-1000 -3000

-5000-7000

-5000

-3000

-1000

N E

SW



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While drillingWhile dril ling

wells, we try towells, we try tostay out of thestay out of theellipse ofellipse of

uncertainty ofuncertainty ofother wells toother wells toavoid a collisionavoid a collision

using a travelingusing a travelingcylindercylinderproximityproximity

analysisanalysis



82/110

The travelingThe traveling

cylinder showscylinder showsthe proximity ofthe proximity of

other wells whileother wells while

drillingdrilling



83/110

Bottomhole assemblies areBottomhole assemblies are

oriented with survey toolsoriented with survey toolsThe orientation of the BHA isThe orientation of the BHA is

called the toolfacecalled the toolfaceToolface is magnetic below anToolface is magnetic below an

inclination of 5 degrees andinclination of 5 degrees andgravity toolface above 5 degreesgravity toolface above 5 degrees



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30

45

60

75

90

105

120

135

150

165180

195

210

225

240

255

270

315

285

300

330

345

INCLINATION

AZIMUTH

60.0

3.6

15

45

Left

Hole Direction 60

Magnetic Toolface

High Side

Gravity Toolface

30

45

60

75

90

105

120

135

150

165180

195

210

225

240

255

270

315

285

300

330

345

INCLINATION

AZIMUTH

60.0

8.3

15

45

Left



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If the inclination of the wellboreIf the inclination of the wellboreis above 5 degrees, the BHA canis above 5 degrees, the BHA can

be oriented using gravitybe oriented using gravitytoolface even with magnetictoolface even with magnetic

interference (provided theinterference (provided theazimuth of the wellbore isazimuth of the wellbore isknown)known)

If the inclination is less than 5If the inclination is less than 5degrees, a gyro surveydegrees, a gyro survey

instrument will have to be usedinstrument will have to be used



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Singleshot and steering tools use theSingleshot and steering tools use the

mule shoe sub method (UBHO) to getmule shoe sub method (UBHO) to getthe orientation of the BHAthe orientation of the BHA

For most MWD tools, the offsetFor most MWD tools, the offset

between the MWD toolface and BHAbetween the MWD toolface and BHAtoolface is measuredtoolface is measured

The difference is entered into theThe difference is entered into thesurface computer and the computersurface computer and the computercorrects the toolface data sent by thecorrects the toolface data sent by the

MWDMWD



87/110

The toolface is an indication ofThe toolface is an indication of

which way the wellbore will turnwhich way the wellbore will turnIf the toolface is set at high sideIf the toolface is set at high side

with a bent housing motor, thewith a bent housing motor, thewellbore will only buildwellbore will only build

inclination and will not turninclination and will not turnunder ideal conditionsunder ideal conditions



88/110

If the toolface is set at 45If the toolface is set at 45 left asleft as

in Figure 5in Figure 5--21, the wellbore will21, the wellbore willbuild inclination and turn to thebuild inclination and turn to the

leftleftThe amount of build and turn willThe amount of build and turn will

depend upon the amount of holedepend upon the amount of holedrilled and the dogleg severity ofdrilled and the dogleg severity of

the motorthe motor



89/110

If the toolface is set 120If the toolface is set 120 right,right,

the wellbore will drop inclinationthe wellbore will drop inclinationand turn to the rightand turn to the right



90/110

Theoretically, if the toolface wasTheoretically, if the toolface was

set at 90set at 90 right, the wellboreright, the wellborewould not build or drop andwould not build or drop and

would only change azimuth bywould only change azimuth byturning to the rightturning to the right



91/110

However, gravity and formationHowever, gravity and formation

tendencies do have an affect ontendencies do have an affect onthe motor and the assembly willthe motor and the assembly will

likely drop some inclinationlikely drop some inclinationespecially when the wellbore isespecially when the wellbore is

at higher inclinations but it isat higher inclinations but it is

formation dependentformation dependent



92/110

When changing both holeWhen changing both hole

inclination and direction, it isinclination and direction, it isbest to change the direction firstbest to change the direction first

if the inclination is lowif the inclination is lowThe azimuth will change faster atThe azimuth will change faster at

the same DLS when thethe same DLS when theinclination is lowinclination is low



93/110

When kicking off in a verticalWhen kicking off in a vertical

hole, it is best to get the azimuthhole, it is best to get the azimuthestablished before trying to buildestablished before trying to buildtoo much inclinationtoo much inclination

It is actually relatively easy toIt is actually relatively easy toaccomplish when usingaccomplish when using

magnetic toolfacemagnetic toolfaceIn Figure 5In Figure 5--21, the inclination is21, the inclination is

3.63.6 and the azimuth is 60and the azimuth is 60



94/110

30

45

60

75

90

105

120

135

150

165180

195

210

225

240

255

270

315

285

300

330

345

INCLINATION

AZIMUTH

60.0

3.6

15

45

Left

Hole Direction 60

Magnetic Toolface

High Side

Gravity Toolface

30

45

60

75

90

105

120

135

150

165180

195

210

225

240

255

270

315

285

300

330

345

INCLINATION

AZIMUTH

60.0

8.3

15

45Left



95/110

If the target azimuth is 340If the target azimuth is 340, the, the

toolface is set on 340toolface is set on 340 or a toolfaceor a toolfacesetting of 80setting of 80 left (60left (60 to zero plus 20to zero plus 20

to 340to 340))

Initially, the wellbore will be turningInitially, the wellbore will be turning

mostly to the leftmostly to the left

As the azimuth of the wellbore turnsAs the azimuth of the wellbore turnsleft, the toolface is left on 340left, the toolface is left on 340 andand

the toolface angle is decreasingthe toolface angle is decreasing



96/110

When the azimuth of theWhen the azimuth of the

wellbore reaches 340wellbore reaches 340, the, thetoolface will be pointed straighttoolface will be pointed straight

up or to high sideup or to high sideThe toolface angle is notThe toolface angle is not

constantconstant



97/110

When using gravity toolface orWhen using gravity toolface or

high side at higher inclinations,high side at higher inclinations,it is easier to use a constantit is easier to use a constant

toolface angletoolface angleToolface angle is an approximateToolface angle is an approximate

number because the toolfacenumber because the toolfacecannot be kept constant in thecannot be kept constant in the

fieldfield



98/110

The toolface angle will vary by atThe toolface angle will vary by at

leastleast 1515The directional driller will onlyThe directional driller will only

pick up the BHA and reorientpick up the BHA and reorientwhen the toolface angle gets toowhen the toolface angle gets too

far offfar off



99/110

The longer the drill string, theThe longer the drill string, the

more difficult it is to keep amore difficult it is to keep aconstant tool faceconstant tool face

It is usually more difficult toIt is usually more difficult tomaintain toolface orientationmaintain toolface orientationwith PDC bits because smallwith PDC bits because small

changes in bit weight make a bigchanges in bit weight make a bigdifference in torque, whichdifference in torque, which

changes the reactive torquechanges the reactive torque

ToolfaceToolface


100/110

( )( )

( )

=

2/tan

2/tanln180

tan

1

2

121

I

I

AATF

Equation for calculating constantEquation for calculating constant

toolface angle to changetoolface angle to changeinclination and azimuthinclination and azimuth

ToolfaceToolface


101/110

( )( )( )

0148

2/14tan

2/25tan

ln180

1048tan +=

=

TF

Example 5Example 5--1 on page 51 on page 5--2525

Need to change inclination fromNeed to change inclination from1414oo to 25to 25oo and change azimuthand change azimuth

from 10from 10oo

to 48to 48oo

similar tosimilar tosidetracking out of an existingsidetracking out of an existing

wellwell

ToolfaceToolface


102/110

Class ProblemClass Problem Problem 1 onProblem 1 on

page 5page 5--2828MD1 = 3000, I1 = 18

o,A1 = 309o

Need an inclination of 30o at an

azimuth of 288o. The DLS of themotor is 2o/100 feet. What is thetoolface angle required to hit theinclination and azimuth with onesetting? How many feet of hole will

have to be drilled?

ToolfaceToolface


103/110

Need to change inclination fromNeed to change inclination from

1818

oo

to 30to 30

oo

and change azimuthand change azimuthfrom 309from 309oo to 288to 288oo

Or 35Or 35oo LeftLeft

( )( )( )

{ } o1

1

356971.0tan

2/18tan

2/30tanln180

309288tan

==

=

TF

TF

ToolfaceToolface


104/110

Can use the dogleg severityCan use the dogleg severity

equation to determine theequation to determine themeasured depth to accomplishmeasured depth to accomplish

the changethe change( )( )

( )( )2

12

2

1221

1

2sin

2sinsinsinsin

1002

+

=

IIAAII

MDDLS

( )( )( )( ) ( )( )

( ) feet7281267.0sin200

2

2

1830sin

2

309288sin30sin18sinsin

10022

1

22

1

=

=

+

=

MD

MD

ToolfaceToolface


105/110

Can also think of it as looking atCan also think of it as looking at

the toolface indicatorthe toolface indicator

35o Left

I

A x sinIavg

( )( )( )MDDLSTFI = cos

( )( )( )

+

=

2sin

sin

21 II

MDDLSTFA

Gravity Toolface

ToolfaceToolface


106/110

Calculate the measured depthCalculate the measured depth

from the toolface anglefrom the toolface angle


( )( )( )

( )( )feet732

100/235cos

1830

cos

=

=

=

MD

MD

DLSTF

IMD

ToolfaceToolface


107/110

Example 5Example 5--2 on page 52 on page 5--2727

The survey tool is 60 feet off bottomand the survey is I1 = 28 andA1 =

63. The dogleg severity of the motor

is approximately 14/100. The

toolface angle has been set at 20

right.Estimate the inclination and azimuth

at the bit

ToolfaceToolface


108/110

The inclination at the bit must be

calculated first

I2 = I1 + I =28 + 7.9 = 35.9


( ) o89.760100/1420cos ==I

ToolfaceToolface


109/110

Calculate the azimuth at the bit

A2

=A1

+ A = 63 + 5.4 = 68.4

( )

+

=

2sin

sin

21 II

MDDLSTFA

( ) o43.5

2

9.3528sin

60100/1420sin=

+

=A

ToolfaceToolface


110/110

Check the calculations by calculating

the dogleg severity

DLS = 13.98/100 feet

( )( )( )( )

2

12

2

1221

1

2sin

2sinsinsinsin

1002

+

=

IIAAII

MDDLS

( )( )( ) ( )

22

1

2

2889.35sin

2

6343.68sin89.35sin28sinsin

60

1002

+

= DLS

14b-horizontal drilling equipment and controlling power point

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