MWD I

�� Technology Services Group

16178 West Hardy Road, Houston, Texas 77060

Telephone: 281.260.5700 Facsimile: 281.260.5780

www.computalog.com

Training CurriculumCRCM_111_revA_0203

Mud PulseMeasurement While Drilling IMeasurement While Drilling I

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MWD I Mud Pulse I Course #111

Course Outline

Day One Precision Drilling Services Overview 0.5 hour Corporate Structure Technology Strategy Computalog Drilling Services Overview 0.5 hour Technology Review & Future Developments MWD & Directional System Overview 1.5 hours “State of the Art in MWD” Rig Components and Functions (if necessary) Directional Drilling Fundamentals 2.5 hours BHA Configuration – types, tool placement Motors – description, parts, application Bits/Hydraulics – description, parts, application Petroleum Geology Primer 3 hours Petroleum Geology Fundamentals Transportation and Deposition Sedimentary Rock Classifications Origin of Hydrocarbons Hydrocarbon Migration Hydrocarbon Accumulation

1 MWD MP I CROL_111_revB_0203

Day Two MWD Gamma Logging 3 hours Applications Overview Gamma Ray Theory Sensor Hardware Functions Environmental Effects on the Gamma Ray Measurement Sensor Response versus Lithology & Fluid Type Data Interpretation Factors Affecting Gamma Log Quality Applications Details MWD Surveying Fundamentals 5 hours Directional Surveying Essentials Other Sources of Survey Data (mechanical magnetic & gyroscopic) Sensor Response Magnetic Declination, Grid Convergence, Grid Systems OTF Calculations, NMDC Spacing Survey Quality Control Techniques Well Plan Parameters and Survey Terminology


Day Three MWD Operations 4 hours Surface Equipment Description & Function Hardware Description & Function

Positive Pulser Negative Pulser Driver DAS Gamma

Toolstring configurations Surface Software Configuration & Operation Downhole Software Operations MWD Demonstration & Practical Application 4 hours Surface Equipment Assembly Battery Testing (STU) MWD Assembly/Disassembly Tool Programming / Rotation Check Placement in BHA Initialize Surface System for Bit Run Depth System Hydraulics/Detection Generate Report


Day Four MWD Demonstration & Practical Application (continued) 4 hours Surface Equipment Assembly Battery Testing (STU) MWD Assembly/Disassembly Tool Programming / Rotation Check. TFO Placement in BHA Initialize Surface System for Bit Run Depth System Hydraulics/Detection Generate Report MWD Practical Application (students hands-on) 4 hours NOTE: Students are required to practice after hours and be able to perform,

build-up, testing, toolface offset, etc. for Practical Exam

Day Five Lithium Battery Safety (Course #080) 5 hours LBS - Exam Mud Pulse MWD – Final Practical Exam 3 hours

Day Six Mud Pulse MWD – Final Written Exam 3 hours


1

j u s t b r u t e s t e e l

T S E : P D N Y S E : P D S

PeopleTechnologyService

m o r e t h a n . . .

Corporate Mission Statement

• Precision Drilling Corporation is an innovative, performance oriented, integrated oilfield drilling and energy service company

• We are committed to providing

• Technologically advanced equipment and expertise

• A safe operating environment

• Quality service to the oil and gas industrial businesses

• Strong balance sheet

2

A Global Presence

Operational and Sales Headquarters

Rental and Production Group

ContractDrillingGroup

TechnologyServices

Group

Precision Drilling Corporation has grown to be a multifacetedinternational oilfield service and equipment supplier with a diverse revenue base.

Precision Drilling Corporation

3


Rental & Prod. ServicesRental & Prod. Services Technology Services GroupContract Drilling Services

Precision DrillingLimited Partnership

Precision Drilling International

Precision WellServicing

Live WellServicing

Columbia OilfieldSupply

Fleet CoilTechnologies

Rostel Industries

LRG Catering

Monterro OilfieldServices

Energy Industries

CEDA International

Computalog WirelineServices

Northland EnergyServices

Computalog DrillingServices

BecField DrillingServices

Polar CompletionsEngineering

United DiamondLtd.

Advantage EngineeringServices (R & D)

Fleet Cementers

Plains PerforatingChallenger/Silverline

Integrated Services

Contract Drilling Group

• 244 drilling rigs in Canada and international

CAN Int’l• Conventional 207 10• Super Single TM 14 3• Coil tubing 9 1

• 260 service rigs

• 19 rig assist snubbing units

• A full complement of associated drilling support services

4

Precision Coiled Tubing Rigs

• Cisco 2000 coil rig currently in field trials

• 3 1/2” coiled tubing enables drilling up to 2000m

• Deepest rated coil rig in the world

The largest service rig contractor in Canada260 service rigsDiverse rig fleet Rig capabilities from shallow to ultra deep

Well Servicing

5

Live Well Services

Hydraulic rig assist snubbing

Workovers in water sensitive formationsProblem well workCompletionsUnderbalanced drillingLow pressure gas wellsHigh kill fluid purchase

Drilling Support Services

Rostel Industries Ltd.• Machine and fabrication shop

for in-house equipment repair service

LRG Catering Ltd.• Owns, manages and

caters 75 camps for on-site field personnel

Columbia Oilfield Supply Ltd.• Purchasing arm for

general oilfield supplies

6






Live WellServicing



Rostel Industries

LRG Catering


Energy Industries

CEDA International






United DiamondLtd.


Fleet Cementers


Integrated Services

Rental and Production Group

• Industrial maintenance and turnaround services

• Packaging, sales, lease, rental and servicing of natural gas compression

• Wellsite trailers, downhole drilling equipment and surface oilfield equipment

7

CEDA International Corporation

• One of the largest provider of industrial services in Canada

• History of long term relationships

• Expansion of services to the US

• Currently have operations in five US states

Montero Oilfield Services Ltd.

• Largest oilfield rental supplier in Canada

• 22 branches and stocking points

• Patented Vapour Tight Oil Battery

8

Energy Industries Inc.• Second largest compressor

packager in Canada

• Compressor packages ranging from 100 to 5000 hp

• Manufacturing space increased by 70%

• Frick Rotary Screw Compressor with capabilities to 1,500 hp






Live WellServicing



Rostel Industries

LRG Catering


Energy Industries

CEDA International






United DiamondLtd.


Fleet Cementers


Integrated Services

9

Computalog Wireline Services• 237 wireline units Cdn Int’l

• Cased Hole 88 87• Open Hole 24 13• Slick Line 9 16

• Complete range of open hole and cased hole services

• Aggressive capital build program to increase capacity and upgrade fleet

• Significant investment in new technology • Micro imaging tool (HMI)• Mono/dipole sonic (MDA)• Array induction• Acoustic casing inspection• Production logging• Spectral gamma ray• Dual laterolog

Computalog Drilling Services• Global provider of directional

drilling services• Acquisition of BecField and

Geoservices’ drilling services business expands international network

• Complete drilling services• Directional drilling• Mud pulse and EM MWD• Logging while drilling (LWD)• Directional surveying• Drilling motors• Engineering and well planning

• Continuing development of new technology

10

United Diamond Polycrystalline Diamond Compact (PDC) Drill Bits

• One piece steel body for ease of manufacturing which reduces manufacturing costs

• Unique cutter placement delivers increased penetration rates

• Bits being run in Canada, United States, Venezuela, Argentina, Indonesia and the Caribbean

• Offshore trials successfully completed in Indonesia and offshore east coast Canada

Northlands Energy Global Underbalanced Drilling (UBD)

• Recently awarded two UBD contracts in southern Mexico

• UBD helps turn once uneconomic projects into profitable ones

• Equipment deployed in the North Sea, Middle East, Asia Pacific and throughout North and South America

• Commercial 5,000 psi RBOP TM

• Industry leader in inert gas generation

11

Fleet Cementers Pressure Pumping Services• Cementing• Acidizing• Hydraulic Fracturing

• Nitrogen Pumping• High Pressure Foaming• Coiled Tubing Service

Polar Completions Engineering Services & Manufacturing

Providing and servicing a complete product line of downhole completion, production and service equipment based on our own propriety designs as well as other world wide recognizable standards.

Eskimo II Packer

Harpoon Bridge Plug

Hi-FloRetainer

• ISO 9001 Registered Quality Assurance System

• API - 5CT Certified

12

Advantage Engineering LWD/MWD

Technical Benefits:• Highest flow rating• Highest pressure rating• Shortest tool length• Reliability and accuracy

High Temperature Azimuthal Gamma Ray

High Temperature Lithium Batteries

Provide customers with a better understanding of the reservoir during drilling operations

m o r e t h a n . . .

m e e t s t h e e y e

Technology Overview

ContractDrillingServices

Rental &Production

Services

TechnologyServicesGroup


Computalog

Wireline Drilling Services

Ft. Worth AdvantageEngineering

Computalog Operations Locations

Mexico

Colombia

Argentina

Brazil

UK

Indonesia

Poland

IndiaUAE

USA

Canada

Saudi Arabia

Lithuania

Venezuela

Peru

France AustriaGermany

Portugal SpainSyria

Computalog R&M Locations

Nogales, Mexico

Jakarta, Indonesia

Mumbai, IndiaAbu Dhabi, UAEHouston, Texas

Edmonton, Canada

Ojeda, Venezuela

Paris, FranceHanover, Germany

Lafayette, Louisiana

$0

$10

$20

$30

$40

97 98 99 00 01 02

Computalog Research and Development Growth

MWD-LWD-DD Market Projection

$2.5

$2.0$2.3

$2.6

$3.2$3.6

$0.0

$0.5

$1.0

$1.5

$2.0

$2.5

$3.0

$3.5

$4.0

1998 1999 2000 2001 2002 2003

1998 - 2003 MWD/LWD/DD Global Market

Source: RJ & A estimates

billions

Market Share for Drilling Services

Total 2001 Global MWD/DD/LWD Market: $2.6 Billion

26.5%

27.0%

26.1%

9.5% 6.5% 4.4% HalliburtonAnadrillBHIOtherPathfinderComputalog

2001 LWD Competitive Analysis

Directional/Gamma Ray2 mhz ResistivityDensity w PeNeutron PorosityCaliperSonic

Annular PressureVibrationPore Pressure Prediction

Oriented Gamma RayElectromagnetic PulserSAGD RangingSpectral Gamma RayHigh Pressure ToolsHigh Flow Tools4-3/4 Rotary Steerable

X = under development

CL HAL SLB BHI PATH

XXXXXX

XXX

X

XXXXXX

X

X

XXXXXX

XXX

XXX

XXXXXX

XXX

X

X

XXXX

XXX

XXXXXXX

1970 1975 1980 1985 1990 1995 2000 2005

Maturity of Industry LWD Fleet Core Technology

Current Industry Core Technology

ComputalogNext Generation

Technology

LWD System Design Objectives

1) Develop the industry’s most reliable LWD system

2) Design emphasis on the global Deepwater drilling market1) Industry’s highest Flow Rating for LWD

2) Industry’s highest Pressure Rating for LWD

3) Industry’s shortest Tool Length for LWD

3) Design the most accurate, fit-for-purpose logging tools

MWD/LWDSystem Overview

Azimuthal Spectral Gamma RayMulti-depth/Frequency Resistivity

Azimuthal Bulk Density/Pe

Neutron Porosity

Near Bit MeasurementsRT Analysis Software

Formation Evaluation

Bore/Annular Pressure

Vibration SeverityTri-axial Vibration

RT Analysis Software

Rotary Steerable

Drilling Engineering

Data Transmission

Posi

tive

Pul

se

Neg

ativ

e Pu

lse

Elec

trom

agne

tic

Future Direction and Opportunities

• Continuous Data (EM, Optical Fiber)• Underbalanced Drilling

• Direct Reservoir Properties (Pressure, Gas, Temperature)

• Deepwater Dual Gradient Drilling• Advice and Automated Systems

• Link Drilling Data to Rig Operations

1

Directional Drilling Fundamentals

March 2002

Introduction to Directional Drilling

• Directional drilling is defined as the practice of controlling the direction and deviation of a well bore to a predetermined underground target or location.

2

Directional Wells

• Slant• Build and

Hold • S-Curve• Extended

Reach• Horizontal

Applications of Directional Drilling

• Multiple wells from offshore structure• Relief wells• Controlling vertical wells

3


• S-Curve


• Extended-Reach Drilling

• Replace subsea wells and tap offshore reservoirs from fewer platforms

• Develop near shore fields from onshore, and• Reduce environmental impact by developing

fields from pads

4

Directional Drilling Tools

• Steerable motors• Instrumented motors for geosteering applications• Drilling tools• Surveying/orientation services• Surface logging systems• At-bit inclination


• Sidetracking

• Inaccessible locations

5



• Drilling underbalanced

• Minimizes skin damage,• Reduces lost circulation and stuck pipe incidents,• Increases ROP while extending bit life, and• Reduces or eliminates the need for costly

stimulation programs.

6

Directional Drilling Limitations

• Doglegs• Reactive Torque• Drag• Hydraulics• Hole Cleaning• Weight on Bit• Wellbore Stability

Methods of Deflecting a Wellbore

• Whipstock operations• Still used

• Jetting• Rarely used today, still valid and inexpensive

• Downhole motors• Most commonly used, fast and accurate

7

Whipstock Operations

Jetting

8

Effect of Increased Bit Weight

• Increase Weight on Bit –Increase Build Rate

Effect of Increased Bit Weight

• Decrease Inclination -Decrease Weight on Bit

9

Reasons for Using Stabilizers

• Placement / Gauge of stabilizers control directional• Stabilizers help concentrate weight on bit• Stabilizers minimize bending and vibrations• Stabilizers reduce drilling torque less collar contact• Stabilizers help prevent differential sticking and

key seating

Stabilizer Forces

10

Directional Control

• BHA types

• Building assembly • Dropping assembly• Holding assembly

• Design principles

• Side force• Bit tilt• Hydraulics• Combination

Building Assemblies

• Two stabilizer assemblies increase control of side force and alleviate other problems

11

Building Assemblies

Dropping Assemblies

• To increase drop rate:• increase tangency length• increase stiffness• increase drill collar weight• decrease weight on bit• increase rotary speed

• Common TL: • 30 ft• 45 ft• 60 ft• 90 ft

12

Dropping Assemblies

Holding Assemblies• Designed to minimize side force and decrease

sensitivity to axial load

13

Stabilization Principle

• Stabilizers are placed at specified points to control the drill string and to minimize downhole deviation

• The increased stiffness on the BHA from the added stabilizers keep the drill string from bending or bowing and force the bit to drill straight ahead

• The packed hole assembly is used to maintain angle

Special BHA’s

• Tandem Stabilizers• Provides greater directional control• Could be trouble in High Doglegs

• Roller Reamers• Help keep gauged holes in hard formations• Tendency to drop angle

14

Application of Steerable Assemblies

• Straight - Hole• Directional Drilling / Sidetracking• Horizontal Drilling• Re - entry Wells• Underbalanced Wells / Air Drilling• River Crossings

Steerable Assemblies

• Build

• Drop

• Hold

15

Mud Motors

Turbine PDM

Commander TM PDM Motors

16

Motor Selection

• These are the three common motor configurations which provide a broad range of bit speeds and torque outputs required satisfying a multitude of drilling applications• High Speed / Low Torque - 1/2 Lobe• Medium Speed / Medium Torque - 4/5 Lobe• Low Speed / High Torque - 7/8 Lobe

Components of PDM Motors

• Dump Subs• Motor Section• Universal Joint Assembly• Adjustable Assembly• Bearing Assembly

17

Dump Sub Assembly

• Hydraulically actuated valve located at the top of the drilling motor

• Allows the drill string to fill when running in hole

• Drain when tripping out of hole• When the pumps are engaged, the valve

automatically closes and directs all drilling fluid flow through the motor

Dump Sub

• Allows Drill String Filling and Draining

• Operation- Pump Off - Open- Pump On - Closed

• Discharged Ports• Connections

18

Motor Section

• Positive Displacement Motor ( PDM )

• Lobe Configurations

• Stages

Performance Characteristics

Motor Section

• Positive Displacement MotorPDM

19

Universal Joint Assembly

• Converts Eccentric Rotor Rotationin to Concentric Rotation

– Universal Joint

» Flex Rod

Constant Velocity Joint --

Adjustable Assembly

• Two Degree and Three Degree

• Field Adjustable in Varying Increments to the Maximum Bend Angle

• Used in Conjunction with Universal Joint Assembly

H = 1.962 o

20

Bearing Assembly

• Transmits Bit Axial and Radial Loads to the Drill String

• Thrust Bearing• Radial Bearing• Oil Reservoir• Balanced Piston• High Pressure Seal• Bit Box Connection

Motor Specifications

• Motor Specifications• Dimensional Data• Ultimate Load Factors• Performance Charts

21



22

Performance Charts

Operational Constraints

• Servicing- Hours

• Drilling Fluid-Percentage Sands - 0.5 %- Percentage Solids - 5 %

• Circulation Rate• Full Load ( Differential Pressure)

23

Operational Constraints Cont’d

• Temperature - 200 Degrees F• Motor Stalling• No Spudding

Disadvantages of PDM

• Low Maximum Temperature Capability

• Susceptible to Oil Based Mud Damaged

24

Operational Features

• Stabilization• Off - set Pad• Rotor Bypass

Stabilization

• Improves Well - bore Straightness and Control

• Screw - on Stabilizer• Integral Blade Stabilizers

25

Offset - Set Pad

• Adjustable PAD Located Below Adjustable Bend

• Oriented with Center of Pad on Low Side of Bend

• Provides Lower Point on Drilling Motor to Increase Build Rate Capacity

Rotor Bypass

• Used to Increase the Flow Rate Through the Drilling Motor Beyond the Capacity of the Power Section

» All Multi - lobe Motors from 3 3/8’’ and Larger Use Ported Rotors

» May be Field Installed if Required

26

Trouble Shooting

• Pressure Increases• Pressure Losses• Lack of Penetration

Pressure Increases

• Bearing Pack Seized• Motor or Bit Plugged• Tight Hole

27

Pressure Losses

• Twist - off• Dump Sub Inoperable• Stater Worn Out• Washhing

Lack of Penetration

• Bit Wear• Stator Wear (Weak Motor)• Internal Motor Damage• Incorrect WOB• Formation Change• Stabilizer Hanging Up

28

Motor Performance Test

Motor History

29

Motor Service Report

Planning a Directional Well

• Geology• Completion and Production• Drilling Constraints

30

Geology

• Lithology being drilled through • Geological structures that will be drilled • Type of target the geologist is expecting • Location of water or gas top• Type of Well

Completion and Production

• Type of completion required (“frac job”, pumps and rods, etc.)

• Enhanced recovery completion requirements• Wellbore positioning requirements for future

drainage/production plans• Downhole temperature and pressure

31

Drilling

• Selection of surface location and well layout• Previous area drilling knowledge and

identifies particular problematic areas

Drilling

• Casing size and depths• Hole size• Required drilling fluid• Drilling rig equipment and

capability• Length of time directional services

are utilized• Influences the type of survey

equipment and wellpath

32

Planning

• Build rates• Build and hold profiles should be

at least 50m• Drop rate for S-curve wells is

preferably planned at 1.5 o/30m • KOP as deep as possible to

reduce costs and rod/casing wear• In build sections of horizontal

wells, plan a soft landing section

Planning

• Avoid high inclinations through severely faulted, dipping or sloughing formations

• On horizontal wells clearly identify gas / water contact points

• Turn rates in lateral sections of horizontal

• Verify motor build rates

33

Planning

• Where possible start a sidetrack at least 20m out of casing

• Dogleg severity could approach 14o/30m coming off a whipstock

• Identify all wells within 30m of proposed well path and conduct anti-collision check


1

Factors That Affect ROPFactors That Affect ROP

• Bit selection• Weight on bit• Rotary speed• Drilling fluid properties• Hydraulics• Formation properties

Roller Cone BitsRoller Cone Bits

• Roller Cone Bit Crushes

• Offset Roller Cone Bit Crushes & Scrapes

2

Bit Tooth Cutting ActionBit Tooth Cutting Action

• Diamond bit plows

PDC Bits Shear or SlicePDC Bits Shear or Slice

3

Typical Specifications and Operating Guidelines for Natural Diamond Bits Run on Downhole Mud MotorTypical Specifications and Operating Guidelines for Natural Diamond Bits Run on Downhole Mud Motor

Increased Drillstring StressIncreased Drillstring Stress

• High RPM• High Torque• High WOB

4

Mud Motor & TurbineMud Motor & Turbine

Horizontal WellboresHorizontal Wellbores

5

Bent Sub & Bent HousingBent Sub & Bent Housing

Purpose of Drilling MudPurpose of Drilling Mud

Mud properties• Density• Viscosity• Solids• Fluid loss• Oil content

6

System HydraulicsSystem Hydraulics

Pressure Losses Occur• Surface system• Drillpipe• HWT drillpipe• Drill collars• MWD• Motor• Bit• Annulus

As Overdurden IncreasesAs Overdurden Increases

• Pore pressure typically increases

• Mud weight increases

7

Bit TendenciesBit Tendencies

• With a formation dip of 45° or more, the bit tends to slide down-dip • Bit trends

up-dip when the formation dip is less than 45°

• Bit trends up-dip when the formation dip is less than 45°

WOBWOB

• Decreased weight on bit will cause a rotary assembly to drop angle

8

Offset LedgesOffset Ledges

• Drilling through alternating hard and soft formations can produce offset ledges

1

PETROLEUM GEOLOGY PRIMER

Rocks and Minerals

• Igneous• Sedimentary• Metamorphic

2

Two Basic Kinds of Texture

• Clastic Texture

• Crystalline Texture

The Rock Cycle

3

Igneous Rock

• Igneous rocks are formed from magma. • Two principal types of igneous rock

• Intrusive (plutonic), those that have solidified below the surface

Granite

• Extrusive (volcanic), those that have formed on the surface

Lava

Sedimentary Rock

• Exposed surface rock is subject to weathering and erosion

• Weathering breaks down the structure• Erosion is the removal of weathered rock

4

Sedimentary Rock

• Sedimentary rocks cover 75% of the land surface.

• Because sedimentary rocks are capable of containing fluids they are of prime interest to the petroleum geologists

Shale

Metamorphic Rock

• Rock changed by pressure and heat• Shale can become slate

• Limestone can become marble

• Metamorphism results in a crystalline texture which has little or no porosity.

• About 27% of the earth’s crust is composed of metamorphic rocks.

5

The Crust

• The crust is the cool skin worn down by weather, with basins collecting the remains of once-living organisms

Sedimentary Transport & Depositional Environments

6

Sedimentary Transport

• Gravity works through water, wind, or ice• A river flows sediments downstream while

undercutting its banks• Tectonic forces raise lowlands above sea

level, ensuring a continuing supply of exposed rock for producing sediments

• Gravity ultimately pulls sediments to sea level

Mass Movement

• In high elevations • Severe weathering • Instability of steep slopes

• A large block of bedrockmay separate along deepfractures or bedding planes• Rockslide or avalanche

7

Stream Transport

• The distance a sedimentry particle can be carried cepends on:• Available stream energy• Size• Shape• Density

Stream Transport

• Laminar: smooth flowing• Turbulent: tumbling, swirling, chaotically• Spherical particles are more difficult to carry

than randomly shaped ones• The more dense a particle is, the faster it will

settle out• Lighter particles settle on top of heavier ones

8

Depositional Environments

• Continental• Transitional• Marine

Continental Environments

• Fluvial deposits• Lacustrine environment• Desert environment• Glacial deposits• Aeolian deposits

9


• Fluvial deposits• Desert environment


• Glacial deposits• Aeolian deposits

10

Transitional Environments

• Marine deltas

• Beaches

Marine Environments

• Shelf environments• Continental shelf• Epeiric sea• Reef

11

Outer Continental Environments

• Continental slope

Sedimentary Rock Classifications

12

Sedimentary Rock Classifications

• Lithification• Deposited beyond the reach of erosion• Diagenesis (physical and chemical changes)

• Compaction• Sediments accumulate over time in the ocean• Weight is increased by thousands of feet of more sediment

layers• Pore space is reduced as water is squeezed out

• Cementation• The crystallization or precipitation of soluble minerals in

the pore spaces between clastic particles.

Clastics

• Conglomerates

• Sandstones

• Shales

13

Evaporites

• Gypsum

• Halite

Carbonates

• Limestone

• Coal

• Chert

14

Origin of Hydrocarbons

putalog

Hydrocarbons

• Originally oil seemed to come from solid rock deep beneath the surface

• Scientists showed oil-rocks were once loose sediment piling up in shallow coastal waters

• Advances in microscopy revealed fossilized creatures• Chemists discovered certain complex molecules in

petroleum known to occur only in living cells• That source rocks were shown to originate in an

environment rich with life clinched the “organic theory”

15

Chemical Factors

• Petroleum occurs in such diverse forms as • thick black asphalt or pitch, • oily black heavy crude, • clear yellow light crude, • and petroleum gas

• Variations are due to differences in molecular weight• Despite those differences the proportions of carbon

and hydrogen do not vary appreciably • Carbon comprises 82-87% and hydrogen 12-15%

Chemical Composition of AverageCrude Oil & Natural Gas

Element Crude Oil Natural Gas

Carbon 82 – 87% 65 – 80%

Hydrogen 12 – 15% 1 – 25%

Sulfur 0.1 – 5.5% 0 – 0.2%

Nitrogen 0.1 – 1.5% 1 – 15%

Oxygen 0.1 – 4.5% 0%

16

Chemical Factors

• Petroleum is only slightly soluble in salt water• It floats but is often found in an oil-water emulsion• Some petroleum contains hydrocarbon molecules

with 60-70 carbon atoms• Molecules with up to four carbon atoms occur as gases• Molecules having five to fifteen carbon atoms are liquids• Heavier molecules occur as solids

• Methane, the simplest hydrocarbon, has the chemical formula CH4. • Four is the maximum number of hydrogen atoms that can

attach to a single carbon atom

Hydrocarbon Chains

putalog

17

Biological Factors

• Petroleum contains solar energy stored as chemical energy

• Radiant energy of the sun converts to complex molecules of hydrocarbons

• Coastal waters support an elaborate community of organisms

• The simplest of these organisms are the first to capture and convert the sun's energy

Biological Factors

• Simple microscopic organisms: • Protozoa (animals) • Algae (plants)• Algae uses the sun’s energy to synthesize food

from water and carbon dioxide

• Other organisms consume the algae and convert the simple carbohydrates into more complex foods, such as proteins and fats

• These are eaten by still larger organisms

18

Biological Factors

• The food chain contributes waste products, and every organism that is not eaten eventually dies

• Bacteria plays an important role in recycling • Aerobic (oxygenated) oxidizes organic matter• Anaerobic (reducing) takes oxygen from dissolved sulfates

and organic fatty acids producing sulfides and hydrocarbons

• Aerobic decay liberates certain hydrocarbons that some small organisms accumulate within their bodies, the anaerobics are more important in oil formation

Biological Factors

• Organic waste materials and dead organisms sink to the bottom, preserved in an anaerobic environment

• Accumulation and compaction help seal the organic matter off from dissolved oxygen

• Transformation into petroleum is accomplished by the heat and pressure of deeper burial

• Examples of where anaerobic environments exist:• Deep offshore• Salt marshes• River deltas• Tidal lagoons

19

Physical Factors

• Pressure increases about 1 pound per square inch (psi) per foot of depth

• Temperature rises about 1.5°F for every 100 feet of depth• Certain chemical reactions occur quickly at 120°-150°F

• Long-chain molecules are broken into shorter chains• Other molecules are reformed, gaining or losing hydrogen• Some short-chain hydrocarbons are combined into longer

chains and rings • The net result is that solid hydrocarbons are converted into

liquid and gas hydrocarbons

The Petroleum Window

• The set of conditions under which petroleum will form• Temperatures between

100°F-350°F • The higher the temperature,

the greater the gas proportion • Above 350°F almost all of the

hydrocarbon is changed into methane and graphite

• Source beds (or reservoirs) deeper than about 20,000 feet usually produce only gas

20

Source Rocks

• Source Rock• Organic material that has been converted into petroleum

• Reservoir Rock• Rock in which petroleum accumulates

• The best source rocks are shales • Other source beds are limestone, evaporites, and rocks

formed from freshwater sedimentary deposition• Petroleum is found in a variety of forms and chemical

complexities

Hydrocarbon Migration

21

Migration

• Primary migration• Movement of hydrocarbons out of the source rock

• Secondary migration• Subsequent movement through porous, permeable

reservoir rock by which oil and gas become concentrated in one locality

Primary Migration

• Effective porosity is the ratio of the volume of all the interconnected pores to the total volume of a rock unit

• Only the pores that are connected with other pores are capable of accumulating petroleum

• Effective porosity depends upon how the rock particles were deposited and cemented

22

Primary Migration

• A rock's permeability is a measure of how easily fluids can pass through it

• The basic unit is the Darcy; l/1000 of a Darcy is a millidarcy (md)

• The permeability of sandstones commonly ranges between 0.01 and 10,000 md.

100-1000 md10-100 md1-10 md<1 md

Very GoodGoodFairPoor

Permeability• Permeability can vary with direction of flow• Pore connections may be less numerous, narrower, or less

well aligned in one direction than another• In rocks formed from well-sorted beach sands, grains that

are not spherical are often aligned perpendicular to the beach

• Stream channel sands are aligned in the direction of stream flow and often contain horizontal sheets or stringers of less permeable clay

• Fluids move more easily through such rocks parallel to grain alignment or clay stringers than across them

23

Secondary Migration

• Hydrocarbons are moved through permeable rock by gravity• Compressing pore spaces containing fluid • Causing water containing hydrocarbons to flow • Causing water to displace less dense petroleum

fluids upward

• Flow can mean movement of a few inches a year, which can add up to many miles in a geologically short time

Hydrocarbon Accumulation

24

Accumulation

• Oil collects in places it cannot readily flow out of• a structural high point • a zone of reduced permeability

• As accumulation occurs, distinct zones of gas, oil, and water appear

Trapping

• Formation permeability sealing off a reservoir is never absolutely zero

• Enough pressure and fluidity may force hydrocarbons into tight formations previously excluded

• Tight formations may prevent vertical migration – leading to horizontal migration

25

Effective Permeability

• Rock permeability to a given fluid when another fluid is also present

• Water has seven times the ability of oil to cling to the grains of porous rock

• Interstitial water reduces the space available for oil• narrows the passages between pores• lowers the rock's effective permeability to oil

Relative Permeability

• The ratio of effective to absolute permeability • 1.0 = rock with oil but no water • 0.0 = rock with water but no oil

• Encountering higher fluid pressure • may overcome the water's resistance to the passage

of oil • may increase the effective permeability of the

formation by opening tiny fractures

26

Horizontal Movement

• Interstitial water with oil droplets moves slowly through horizontal sandstone beneath a layer of relatively impermeable shale

• The oil droplets tend to concentrate in the upper levels of the sandstone because of their buoyancy

Diagonal Movement

• If the tilt is upward in the direction of flow • The oil tends to rise updip with the flow of water

• If the oil rises against the flow of water• The water flows downdip

27

Movement Within an Anticline

• Water flows updip into the anticline, then downdip• Oil rises with the incoming water and moves

preferentially toward the crest• Concentration is near the highest point • To accumulate oil, the anticline must be closed

• Plunge in both directions along its axis• Dip toward both flanks

Differentiation

• Petroleum reservoirs are water-wet • Oil is not in contact with the rock grains because

they are coated with a film of water• Most oil fields have 50-80% maximum oil

saturation• Above 80%, the oil can be produced with very little

water mixed in• Below 10%, the oil is not recoverable

28

Hydrocarbon Reservoirs

• Hydrocarbon reservoirs divide into two or more zones

• With oil and water, oil will occupy the upper zone• This zone has maximum oil saturation• The oil-water contact is not a sharp line

but a transition zone

• Oil saturation increases gradually from near 0% at the base to 50%-80% at the top


• Natural gas is dissolved in the oil and to some extent in the water

• Reservoir conditions sometimes allow undissolved gas to create a gas cap above the oil zone

• The wetting fluid in a gas cap is usually water but occasionally oil

• The transition zone between oil-gas is thinner than the oil-water

29


• Some reservoirs contain gas but not oil• This gas is called non-associated gas• The transition zone is a gas-water contact• The water contains gas in solution

• Free methane remains in a gaseous state even under great pressure

• Ethane, propane, and butane, are gases at the surface are often found in a liquid state under reservoir conditions

Types of Traps

• Structural• Anticlines• Faults

• Stratigraphic• Shoestring sand• Beach sand• Lens• Bioherm• Pinchout• Permeability changes

30

Types of Traps

• The basic requirements for a petroleum reservoir are• A source of hydrocarbons• Porous and permeable rock enabling migration• Something to arrest the migration and cause accumulation

• Anticlines are not the only geologic situations for hydrocarbon accumulation

• Two major groups of hydrocarbon traps • structural, the result of deformation of the rock strata • stratigraphic, a direct consequence of depositional variations• *hydrodynamic, trapped by the force of moving water

• Most reservoirs have characteristics of multiple types

Structural

• Anticlines• Created by tectonic deformation of

flat and parallel rock strata• A short anticline plunging in both

directions along its strike is classified as a dome

• Faults• Most faults trap oil and gas by

interrupting the lateral continuity of a permeable formation

Anticline Structure

Impermeable Bed

Sealing Fault

31

Stratigraphic

• Lateral discontinuity or changes in permeability are difficult to detect• Stratigraphic traps were not studied until after most of the

world's structural oil field discoveries • They still account for only a minor part of the world's

known petroleum reserves

• Stratigraphic traps are unrelated to surface features• Many stratigraphic traps have been discovered

accidentally while drilling structural traps

Lens

• Isolated body of permeable rock enclosed within less permeable rock

• Edges taper out in all directions• Formed by turbidity underwater slides • Isolated beach or streams sand deposits • Alluvial fans, and other deposits

Lens Traps

32

Pinchout

• Occurs where a porous and permeable sand body is isolated above, below, and at its updip edge

• Oil or gas migrates updip to the low-permeability zone where the reservoir "pinches out"

PinchoutTraps

Combination Traps

33

Timing and Preservation of Traps

Conclusions

• The petroleum geologist's job is finding oil and gas that can be produced for commercial profit

• Most of what he needs to know is hidden beneath the surface

• Powerful tools and techniques exist for revealing the secrets of the earth's crust

• To the geologist's trained eye and mind, the same rocks that hide the resource also provide subtle clues about its location


•1

1

GAMMA RAY SENSOR ESSENTIALS

2

Gamma Ray Sensor Topics

• Applications Overview• Gamma Ray Theory• Sensor Hardware• Environmental Effects on the Gamma Ray

Measurement• Sensor Response versus Lithology & Fluid Type• Data Interpretation• Factors Affecting Gamma Log Quality• Application Details

•2

3

Applications Overview

• Lithology Identification • Formation Thickness and Tops• Stratigraphic Correlation• Geosteering• Locating Radioactive Tracer Tags• Estimating Shale Volume (for correcting

other formation evaluation data)

4

Gamma Ray Measurement Theory

• “Passive” detector of natural radioactive decay occurring in various formations

• Can be run in any environment – air, any salinity fluid, oil-based fluids, open hole or cased hole wells

• Indicates matrix clay content, but DOESNOT directly reveal fluid contents (i.e., gas, oil, water)

•3

5

Isotopes• Atoms with the same number of

protons but different numbers of neutrons are called isotopesof the same element

• The number beside each isotope is the sum of the protons and neutrons in its’ nucleus and is called the atomic weight

• The three most common gamma emitting isotopes found in the earth’s crust are Potassium-40, Thorium-232, & Uranium-238

8

Gamma Ray Interactions• Photoelectric Effect: In this interaction the energy of the x-ray or

gamma-ray is completely transferred to an atomic electron which is ejected from its atom. The x-ray or gamma-ray no longer exists after the collision.

• Compton Effect: The x-ray or gamma-ray loses only part of its energy in its interaction with an atomic electron. The electron is ejected from its atom. The x-ray or gamma-ray of reduced energy and the electron fly off in different directions

• Pair Production: Gamma-rays with an energy greater than about 1.2 MeV may interact with an atomic nucleus to form an electron positron pair. The gamma-ray energy is completely converted into the mass and kinetic energy of the electron and positron with only a very small amount going to the nucleus in order to conserve momentum.

•4

9

Gamma Ray Shielding

• Gamma ray energy is attenuated(reduced) most effectively by collisions with dense materials

• For example, lead is a more effective gamma shield than the human body

10

Gamma Ray Sensor Hardware

• Two most commonly found gamma ray detectors in MWD tools:

Geiger-Mueller Tubes

Scintillation Detectors

•5

11

Geiger-Mueller Tube• Consists of a gas-filled (99% Neon, 1%

Bromine) tube containing electrodes, between which there is a 1000 volt potential

• When gamma radiation passes through the tube electrons are knocked from the tube inner lining. They collide with the Neon atoms creating an electron “avalanche” which causes a drop in voltage on the inner electrode

• Bromine is used as a “quenching gas” to stop the reaction

• Each voltage cycle is registered as a count

+1000 v

+1000 v

1 count

12

Advantages of GM Tubes

• Sturdy construction (no glass or flimsy components)

• Low current consumption (less than 1 mA)• Can withstand high shock and vibration• Temperature rated up to 200 °C (must be used in

high temperature tool design)

•6

13

Disadvantages of GM Tubes

• Very inefficient counter (less than 5% of all gamma rays are counted by the tube)

• Low efficiency means multiple tubes must be utilized to yield accurate data

• Using multiple tubes increases the length of the sensor, decreases its vertical resolution, and increases costs

• Cannot be used to perform “spectral analysis”

14

Scintillation Detectors• Consists of a Sodium Iodide (NaI)

crystal, photomultiplier, and amplification circuitry

• When gamma radiation passes through the crystal structure it deposits energy within the crystal

• This energy is released in the form of “visible” light

• The intensity of the light flash is directly proportional to the energy deposited in the crystal

•7

16

Advantages of Scintillation Detectors

• Very efficient counter (greater than 50%)• High efficiency means a single detector can be

used, reducing module length and cost• Smaller detector length improves vertical

resolution• Can be used to perform “spectral analysis”.

(Unfortunately the Gamma module’s downhole software does not support this function; LWD spectral gamma in development)

17

Disadvantages of Scintillators

• Not as shock and vibration resistant as GM tubes• Cannot withstand temperatures greater than 165 °C• Require considerably more power than GM tubes

•8

18

Sensor Response• Shale vs. “Not Shale”• Shales can contain high

percentages of potassium and thorium rich clay components

• Volcanics (igneous) can yield values higher than shales

• Most reservoir rocks have low gamma response

20

Lithology Components

Reservoir Rocks:Sandstone (silicone dioxide, SiO2)Limestone (calcium carbonate, CaCO3)Dolomite (calcium magnesium carbonate, CaMg(CO3)2)

•9

21

Lithology Components

Non-Reservoir Rocks:Illite Clay (Potassium aluminum silicate hydroxide fluoride, KAl2(AlSi3O10)(F, OH)2) – main component of shalesCoal (organic matter H,C)Sodium Chloride (NaCl)Calcium Sulphate Dihydrate (CaSO4.2H2O)

22

Data Interpretation• Low gamma response can

indicate potential reservoir rock

• Used by geologist to identify “marker beds” and formations tops

• Gamma data is NOT used to identify hydrocarbons (resistivity, neutron, density, sonic)

•10

24

Data Interpretation

• Lithology response is different between shale and sandstone

• No change in gamma response despite the change in fluid type through the formation

25

Data Interpretation

• A “Dirty Sandstone” indicates that the percentage of shale is greater than 50% within a zone

•11

26

Data Interpretation

• Limestone is typically “cleaner” than sandstone

• Gamma response is still unaffected by fluid type as the lithology changes

27

Data Interpretation• Chalk, Dolomite, Coal, Salt,

Anhydrite, and Gypsum are all lithologies which appear as “clean” zones to the gamma sensor

• Anhydrite and Gypsum are usually found as caprock over Salt domes; neither of these is a reservoir rock

• Chalk and Dolomite are reservoir rocks but typically have low porosity and their permeability is usually due to fracturing

• Coal is not a reservoir rock

•12

28

Factors Affecting Gamma Log Quality

• Calibration• Depth of Investigation• Vertical Resolution• Sample Period vs. Logging Speed• Collar Attenuation• Borehole Conditions

29

Calibration

• Removes “bias” from the detector response• Compensates for collar attenuation• All gamma sensors should read the same

API (or AAPI) value under the same conditions

•13

30

• The standard unit for gamma ray measurement is the “API” and is defined as 1/200 of the log deflection when the tool is between the two lower concrete zones of low and high radiation in the pit

• The radioactive concrete (center section) is composed of 12 ppm uranium, 24 ppm thorium, and 4% potassium and has approximately twice the radioactivity of an average shale

• “Apparent” API units must be used if the module cannot be run in the API test pit

What is an “API”?

31

Depth of Investigation• The maximum radial distance from which the detectors can measure

gamma counts • Dependent upon the travel distance of a gamma ray• Typically, 50% of the measured gamma rays come from a radius of 4” (10

cm)• The stated depth of investigation of the gamma module is 9 - 12” (23 - 30

cm)

•14

32

Vertical Resolution• The thinnest vertical bed that

the sensor can fully resolve• “Resolve” is defined as being

able to determine the actual value of the formation

• Typically based upon 3 times the length of the detector

• Gamma module vertical resolution is stated to be 12” (31 cm)

Shale

Shale

detector 4”

33

Effect of Detector Length on Gamma Response

• The smaller the detector length the thinner the bed that can be “resolved”

• As the logging speed increases, the actual gamma value provided by the sensor becomes much less accurate

•15

34

Sample Period vs. Logging Speed

• If logging speed is too fast for the sample period (time constant), the depth correlation of the data will be incorrect

• If drilling rate is too slow for the sample rate, the data will be statistically “noisy”

• “Noisy” data can be smoothed, whereas low accuracy data cannot be improved

35

Sample Period vs. Logging Speed

• Notice how much better the bed definition and depth correlation is for the curve on the left (720 ft/hr) versus the curve on the right (2700 ft/hr)

•16

36

Collar Attenuation

• Drill collar reduces the gamma ray intensity by a factor of 5 to 10 depending on the collar thickness

• This loss of count rate can directly affect gamma ray accuracy and indirectly affect bed resolution

• Gamma factors compensate for collar attenuation and detector bias

37

Borehole & Formation Effects

• The environment between the formation and the detector will have a major effect on the count rates seen by the module– Formation Density– Mud Weight (barite, cuttings load)– Mud Additives (KCl)– Hole Size (washout, collar-to-bit ratio)

•17

38

Formation Density

• The higher the formation density, the higher the attenuation of the gamma rays will be as they travel through the matrix

• Matrix Densities:– Sandstone = 2.65 g/cc– Limestone = 2.71 g/cc– Dolomite = 2.87 g/cc– Average Shale = 2.5 g/cc

39

Mud Weight

• Barite is used to increase mud weight• Barite density is 5.5 g/cc• Barite acts as a “shield”• The higher the mud weight (i.e., the thicker

the shield) the higher the attenuation of formation gamma rays

•18

40

Mud Additives

• The addition of certain salts and chemicals to the mud system will affect the gamma ray sensor response

• For example, adding Potassium Chloride (KCl) salt to the mud will cause an increase in gamma counts

41

Hole Size Changes (Washout)

• If the annular flow rate exceeds critical velocity the washout effect greatly increases due to the turbulent nature of the fluid

• Washout effectively moves the formation further away from the detectors, reducing the overall count rate relative to a gauge hole

•19

42

Hole Size Changes (Shale Hydration)

• Swelling of shales high in montmorilloniteclay moves the formation closer to the detectors, increasing the overall count rate relative to a gauge hole

• Oil-based mud and certain chemicals added to the mud can inhibit shale hydration

43

Gamma Ray Accuracy• One-foot bed resolution is the minimal

acceptable criteria• Sample Period & Drilling Rate are the

key factors controlling accuracy

•20

44

Stratigraphic Correlation• Gamma data can be

used to correlate formation tops to determine the area extent and thickness of the reservoir

45

Geosteering

• Geosteering is the evaluation of formation evaluation and survey data from an actively drilling horizontal well resulting in an interpretation which provides essential steering information to the geologist

• Information needed to accurately steer a horizontal wellbore includes position of the bit within the stratigraphic section, formation dip rates and fault cuts with direction and throw.

•21

46

Geosteering Applications using the Gamma Ray Sensor

• maintaining wellbore placement within a reservoir

• maintaining specified distances from contacts or bed boundaries

• detecting lateral reservoir faults or facies changes

48

Shale Volume Estimation

• Determine the “shale baseline” GR value• Determine the “clean reservoir” GR value• Determine the GR value of the zone of

interest• Shale Volume is the ratio between the zone

value and the spread between the clean and shale lines

•22

49

Shale Volume Example

VSH (%) = GRlog – GRclean X 100GRlog – GRclean

VSH (%) = 50 – 25 X 10075 – 25

VSH (%) = 50%

Shale Baseline (75 api)

Clean Line (25 api)

Zone of Interest (50 api)

1

SURVEYING ESSENTIALS

Inclination

• Inclination is the angle, measured in degrees, by which the wellbore or survey instrument axis varies from a true vertical line

• An inclination of 0° would be true vertical

• An inclination of 90° would be horizontal.

2

Hole Direction• Hole direction is the angle,

measured in degrees, of the horizontal component of the borehole or survey instrument axis from a known north reference

• This reference is true north, magnetic north, or grid north, and is measured clockwise by convention

• Hole direction is measured in degrees and expressed in either azimuth form (0° to 360°) or quadrant form (NE, SE, NW, SW)

Measured Depth

• Measured depthrefers to the actual depth of hole drilled as measured from the surface location, to any point along the wellbore or to total depth.

3

Magnetic Toolface• Magnetic toolface is the direction, in the

horizontal plane, the bent sub scribe line is pointing with regard to the north reference (Grid, Magnetic, or True)

• Magnetic Toolface = Dir Probe Mag Toolface + Total Correction + Toolface Offset

• Magnetic orientation is used when the inclination of the wellbore is less than 5° to 8°

• When the inclination is below this amount, the survey instrument cannot accurately determine the highside of the instrument for orientation purposes

• The toolface will be presented in azimuth or quadrant form, referenced to magnetic north

• The magnetic toolface reading is whatever magnetic direction the toolface is pointed to

Gravity Toolface• Gravity toolface is the angular distance the bent sub scribe line is turned,

about the tool axis, relative to the high side of the hole

• Gravity toolface = Dir Probe Gravity Toolface + Toolface Offset

• If the inclination of the wellbore is above 5° to 8°, then gravity toolface can be used

• The toolface will be referenced to the highside of the survey instrument, no matter what the hole direction of the survey instrument is at the time

• The toolface will be presented in a number of degrees either right or left of the highside

4

Gravity Toolface• For example, a toolface pointed to

the highside of the survey instrument would have a gravity toolface of 0°

• A toolface pointed to the low side of the survey instrument would have a gravity toolface of 180°

• If the probe highside point was rotated to the right of highside, the gravity toolface would be 70° to the right.

Acid Bottle Inclinometer• This technique was originally used in

the mining industry from about 1870• A glass cylinder filled with

hydrofluoric acid was lowered down the drill string on a wireline until it rested on top of the bit or on a baffle plate at some point above the bit

• The acid bottle was left in this position for about 30 minutes to allow the acid to react and leave a mark on the side of the cylinder indicating the horizontal surface

• The glass was inspected back at the surface, and the angle of inclination was determined.

5

Pendulum Compass

• The pendulum is either suspended over a fixed grid or along a vernierscale and allowed to move as the inclination changes

Magnetic Float Compass• A mechanical compass uses a compass card

that orients itself to magnetic north, similar to a hiking compass needle, that always points to magnetic north

• The compass card uses an attached magnet to get its orientation. As the magnet is attracted to magnetic north, hole direction can be read

• Inclination is measured by means of a pendulum or float device

• In the float device, the float is suspended in a fluid which allows the instrument tube to move around it independently as inclination changes.

6

Basic Gyroscope Principle• A rotor gyroscope is composed of a

spinning wheel mounted on a shaft. It is powered by an electric motor and is capable of reaching speeds of over 40,000 revolutions per minute (rpm)

• The spinning wheel (rotor) can be “oriented” or pointed in a known direction. The direction in which the gyro is spinning is maintained by its own inertia. Therefore, it can be used as a reference for measuring azimuth

• An outer and inner gimbal arrangement allows the gyroscope to maintain its pre-determined direction regardless of how the instrument is positioned in the wellbore.

Gyro Application

• Gyroscopic surveying instruments offer an accurate means of surveying boreholes with extraneous magnetic influences, such as cased holes, production tubing, or near existing wells

• Gyroscopic sensors can be classified into three categories:

• Free gyroscopes (conventional)• Rate gyroscopes• Inertial navigation systems

7

Gyro Errors

• Drift– Shock– Bearing wear

• Temperature– Expansion of material

• lntercardinal Tilt Error or Gimbal Error– Angular motion vs.

Actual motion as Inclination Increases

• Drift– North Pole – 360o

24/hrs– Equator - 0o 24/hrs

MWD & Gyro Survey Comparison

8

ACCELERATION

ACCELEROMETER

UPPER MAGNET

TORQUER COIL

CHEMICALLY MILLEDHINGE

LEAD SUPPORT POSTS

LOWER MAGNET

QUARTZ PROOF MASS

CAPACITANCEPICKOFF

Quartz-Hinge Accelerometer

Fluxgate Magnetometer• Fluxgate magnetometers measure

components of the Earth’s magnetic field orthogonally, i.e., in the same three axes as the accelerometers.

• From this measurement, the vector components can be summed up to determine hole direction

• The magnetometer contains two oppositely wound coils around two Mu-metal rods

• As AC is applied to the coils, an alternating magnetic field is created, which magnetizes the Mu-metal rods

• Any external magnetic field parallel with the coil will cause one of the coils to become saturated quicker than the other, and the difference in saturation time represents the external field strength.

9

Earth’s Magnetic Field• The Earth can be imagined

as having a large bar magnet at its center, lying (almost) along the north-south spin axis

• Although the direction is magnetic north, the magnitude will be parallel to the surface of the Earth at the equator and point steeply into the Earth closer to the north pole

Earth’s Magnetic Components• M = Magnetic North• N = True North• Bv = Vertical component of the

local magnetic field• Bh = Horizontal component of the

local magnetic field• Btotal = Total field strength of the

local magnetic field• Dip = Dip angle of the local

magnetic field in relationship to horizontal

• Dec = Variation between the local magnetic field’s horizontal component and true north

• Gtotal = Total field strength of the Earth’s gravitational field

10

Dip Angle vs. Latitude• Lines of magnetic flux lie

perpendicular (90°) to the earth’s surface at the magnetic poles

• Lines of magnetic flux lie parallel (0°) to the earth’s surface at the magnetic equator

• Dip Angle increases as Latitude increases

• As dip angle increases the intensity of the horizontal component of the earth’s magnetic field decreases

Dip Angle vs. Latitude• At the magnetic

equator, Bh = Btotal, Bv = 0

• At the magnetic poles, Bh = 0, Bv = Btotal

• Bh is the projection (using the dip angle) of Btotal into the horizontal plane

Bh = Btotal

Bv = Btotal Bh = 0

Bh = Btotal(cos Dip)

Btotal

Bv = Btotal(sin Dip)

11

Survey Quality Checks

• Gtotal = (Gx2 + Gy2 +Gz2 ) 1/2

• Btotal = (Bx2 + By2 +Bz2 ) 1/2

(Bx * Gx) + (By * Gy) + (Bz * Gz)• MDIP = ASIN {----------------------------------------------}

Gtotal * Btotal

Survey Quality Check Limits

• Gtotal = Local Gravitational Field +/- 0.003 g

• Btotal = Local Magnetic Field +/- 350 nT

• MDIP = Local Dip Angle +/- 0.3°

12

Magnetic Declination• The Earth’s magnetic field varies by location on

the Earth and by time• The magnetic north pole is constantly moving,

although very slowly. Because of this, a survey referenced to magnetic north today will not be accurate at some time in the future

• However, we are able to compensate for this variable by applying a correction to a magnetic survey which references it to true north

• True north can also be thought of as geographic north or the spin axis of the Earth. The true north pole does not move

• A survey referenced to true north will be valid today and any time in the future

• The correction we apply to change a magnetic north direction to a true north direction is called declination.

Magnetic Pole Movement

13

Applying Declination

• To convert from Magnetic North to True North, Declination must be added:

True Direction = Magnetic Direction + Declination

Important Note:• East Declination is Positive & West Declination is Negative in both the

northern and southern hemispheres

Applying an East DeclinationThe formula for calculating a true north direction is:True Direction = Magnetic Direction + DeclinationWhere: East Declination is PositiveWest Declination is Negative

• For example, the magnetic direction is 75° and the declination is 5° east

The true direction would be calculated as:True Direction = Magnetic Direction + Declination80° = 75° + (+5°)

14

Applying a West Declination• If the magnetic direction is 120° and the

declination is 5° west , the true direction would be calculated as:

True Direction = Magnetic Direction + Declination

115° = 120° + (-5°)

Implications of an Incorrect Declination

• Since declination is a addition of degrees of correction to the magnetic hole direction, any mistakes made to the declination have serious consequences.

• For example, if you intend to apply a +18°declination but instead input a -18 ° declination, your reported hole direction will be wrong by 36°!

• This can potentially cost the company dollars off the profit margin and will cost you your job!!!

15

Undeclinating a True North Azimuth

• Necessary step if comparing declinated MWD surveys to singleshot data

• For example, if the true direction is 60° and the declination is 5° east, the magnetic direction would be calculated as:

Magnetic Direction = True Direction - Declination

55° = 60° - (+5°)

Grid Zones• Central Meridian bisects each

6° grid zone• To correct for the curvature

of the earth projected onto a flat plane we apply CONVERGENCE

• If directly on the central meridian or on the equator, the grid correction is ZERO

16

Grid Zones• Convergence correction

increases as location moves away from the equator and central meridian

• Convergence should not be more than 3°, otherwise the incorrect grid zone has been chosen

Maximum Grid Correction

Grid Zones

• For rectangular coordinates, arbitrary values have been established within each grid

17

Applying Convergence

• To convert from Grid North to True North, Convergence must be subtracted:

Grid Direction = True Direction – Convergence

Important Note:• East Convergence is Positive & West Convergence is Negative in the

Northern Hemisphere• East Convergence is Negative & West Convergence is Positive in the

Southern Hemisphere

Applying an East Convergence• If the grid convergence is 3° east and the

true direction is 70°, the grid direction would be calculated as:


67° = 70° - (+3°)

18

Applying a West Convergence• If the grid convergence is 3° west and the

true direction is 120°, the grid direction would be calculated as:


123° = 120° - (-3°)

Applying Declination and Convergence Simultaneously• Replacing the formula for a true north

direction in the grid north direction equation gives us the following formula:

Grid Direction = Magnetic Direction + (Declination –Convergence)

• If magnetic declination is 5° east and the grid convergence is 3° west, and the magnetic direction is 130°, the grid direction is calculated as:

Grid Direction = Magnetic Direction + (Declination -Convergence)

• 138° = 130° + (+5°) - (-3°)

19

Assumptions When Taking Surveys

• Drillstring is not moving up or down• Drillstring is not rotating• Pumps are off• No Drillstring Interference• No Casing or other Local Magnetic Interference• Declination, Dip and Btotal are constant

Sources of Inclination Errors

• Movement during a survey (axial or rotational) • Hardware Failure• Wrong calibration factors• Sensor measurement accuracy• Real-time Data resolution

20

Sources of Azimuth Errors

• Magnetic Interference (axial or cross-axial)• Hardware Failure• Wrong calibration factors• “Bad” Inclination • “Bad” Highside Toolface• Mathematical Error (at 0° and 90° inclination)• Sensor measurement accuracy• Real-time Data resolution• Latitude, Inclination, Hole direction• Wrong Declination and/or Convergence

Survey Error Sources

1. Survey instrument/sensors2. Tool misalignments3. Hole conditions4. Well location5. Calculation method6. Survey personnel

21

Survey Quality Checks

• Gtotal = (Gx2 + Gy2 +Gz2 ) 1/2

• Btotal = (Bx2 + By2 +Bz2 ) 1/2

(Bx * Gx) + (By * Gy) + (Bz * Gz)• MDIP = ASIN {----------------------------------------------}

Gtotal * Btotal

Directional Sensor Package Spacing

• Non-Mag Spacing is used to minimize Drillstring Magnetic interference

22

World Map of Zones Used for NMDC Selection

All Zones Combined

23

Survey Terminology

Survey Terminology

24

Survey Calculations

• Accurate survey parameters can be calculated using simple trigonometric functions

Average Angle Calculation Method

25

Radius of Curvature Calculation Method

• Applies a “best fit” curve between survey stations

• More accurately reflects the shape of the borehole than Average Angle

Minimum Curvature Calculations

• Uses multiple points between survey stations to better reflect the shape of the borehole

• More accurate than the Radius of Curvature method

26

Calculation Methods

• Total Survey Depth @ 5,985 feet• Maximum Angle @ 26°• Vertical hole to 4,064 feet, then build to 26° at 5,985 feet• Survey Intervals approximately 62 feet

Vertical Projection (Section View)

KOP

TVD

Vertical Section

Build Section

Tangent Section

27

Vertical Projection Definitions• Kickoff Point – depth which the wellbore is intentionally

deviated from vertical along a specific direction .• Build Section – section of hole where the wellbore builds

inclination from vertical to a prescribed value.• Tangent Section – constant wellbore inclination and

direction is maintained.• True Vertical Depth – the actual length of hole drilled,

projected onto the vertical plane.• Vertical Section – the horizontal distance the wellbore

moves along the target direction.

Horizontal Projection (Plan View)

N

E

Latitude

Departure

Target Azimuth

ClosureVertical Section

Closure Azimuth

28

Horizontal Projection Definitions

• Departure – the horizontal distance the wellbore moves in an east/west direction.

• Latitude – the horizontal distance the wellbore moves in a north/south direction.

• Closure – the horizontal projection of the wellbore from the wellhead to the last survey station.

• Closure Azimuth – the direction of the closure projection.• Target Azimuth – the proposed direction of the wellbore

upon completion of the well.

Closure and Vertical Section

HOW TO DETERMINE

MUD PULSE & EM

TOOLFACE OFFSETS

1

NEGATIVE PULSE OFFSET TOOL FACE

OFFSET TOOL FACE (OTF) SHEET

This sheet is possibly the most important form that must be filled out correctly. All other work and activity performed by the MWD Operator means naught if the well must be plugged back with cement because of an incorrect OTF calculation (or the correct OTF not being entered into the TLW 2.12 software). Ensure that the OTF calculation is correct, entered into TLW 2.12 correctly and verified by the Directional Driller. The procedure for measuring the OTF is as follows: 1. Measure in a clockwise direction the distance from the MWD high side scribe to the motor high side scribe. Record this length into the OTF work sheet as the OTF distance. In the following example, this value is 351 mm. 2. Measure the circumference of the tubular at the same location where the OTF distance is being measured. Record this length into the OTF work sheet as the Circumference of Collar. 3. Calculate the OTF angle using the following formula: OTF Angle= OTF Distance x 360 Collar Cirumference From the above example, if the collar circumference is 500 mm, OTF Angle= (351/500) x 360 = 0.702 x 360 = 252.72o A sample form is as follows:

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NEGATIVE PULSE OFFSET TOOL FACE (O.T.F. MEASUREMENT)

Well Name: Enter in the Well Name here Date: Enter in date OTF taken LSD: Enter in the LSD here Time: Enter in time OTF taken Job #: Enter in the MWD job number here Run #: Enter in the run number

TOP VIEW OF MWD

MWD SCRIBE PROPER DIRECTION OF OTF

MEASUREMENT

MOTOR SCRIBE (HIGH SIDE)

O.T.F. Distance (Anchor Bolts to Collar Scribe): 351 mm Circumference of Collar: 500 mm O.T.F. Angle (Distance / Circumference) x 360: 252.72 degrees O.T.F Angle entered into Computer as: 252.72 degrees O.T.F. Distance measured by: Both MWD Operator Names O.T.F. Calculated by: Both MWD Operator Names O.T.F Entered into computer by: Both MWD Operator Names O.T.F. Measurement and calculation Witnessed by: Directional Driller(s) Name(s)

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NEGATIVE PULSE OFFSET TOOL FACE

252.72

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POSITIVE PULSE Toolface Offset

INTERNAL TOOL FACE OFFSET (TFO) SHEET

. Ensure that a zero OTF has een entered into TLW 2.12. The positive Tool Face Offset (TFO) sheet entries

se Pulser Set to High Side / Directional Driller: Enter the names f the MWD Operator and Directional Driller respectively.

value reported from the igh side tool face calibration from TLW 2.12.

Note: For the positive pulse MWD, the OTF is zerobare as follows: 1. Positive Pulo 2.Positive Pulse T.F.O. from PROGTM: Enter the T.F.O. h TFO internal toolface offset

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POSITIVE PULSE T.F.O. MEASUREMENT

ell Name: Enter in the Well Name here Date: Enter in date OTF taken W LSD: Enter in in time OTF the LSD here Time: Enter taken Job #: Enter in the MWD job number here Run #: Enter in the run number

ROTATE PULSER TO HIGH SIDE

PULSER KEY WAY

PROPER DIRECTION

OF TFO

EAS REME T

Positive Pulse Pulser Set to High Side: Witness

DAS HIGH SIDE TAB

ame of MWD hand

M U N

N

Directional Driller: ctional hand Witness Name of Dire Positive Pulse T.F.O. from PROGTM: 163.25 degrees Gravity Tool Face (gtface) Should Equal Zero: 0.00 degrees Motor Adjustment: 2.12 / G degrees/setting Alignment of Mule Shoe Sleeve Key to Motor Sc e: Name of 2nd Mrib WD hand Witness O.T.F.=0, Entered in ut Name of MWD hand to Comp er by: All Calculations Witnessed by: Signature of Directional Driller

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OTF – External Drill Collar Offset Magnetic Declination Toolface switch over

MWD - Positive Pulse

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EM MWD Toolface Offset

agnetic Declination M

The “Bearing Display” GEOGRAPHIC radio button must be selected for the Declination value to be applied (by the surface software) to the transmitted magnetic hole direction.

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Toolface Offset

Zero tool face offset G4 – this is the internal ofalways

fset for the CDS probe; this value must ber from 0 to –360; this value is applied by the be entered as a NEGATIVE num

– this is the external (drill collar) offset; mu the muleshoe boltholes to the m

hole, measure from the CSGx locking bolts to the men using a bipod measure from the tool carrier scribeline to the m

surface software. Tool face offset DC st be measured clockwise (looking toward bit) from ud motor scribeline (if using a stinger). For slim ud motor scribeline. Wh ud motor scribeline.

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The main page software display can be checked to verify that the appropriate declination nd toolface off transmitted data.

a set are being applied to the

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Toolface Offset Summary Mud Pulse System Negative Pulse Positive Pulse

Internal Offset

DAS highside is mechanically oriented to align with pulser anchor bolts

Directional Probe (DAS) Determine offset as per procedure and PROGTM into the DAS

None

External Offset

Surface Software Measure clockwise from anchor bolts to motor 0° to +360° values permitted

Surface Software Typical: Muleshoe sleeve is aligned with motor scribeline, therefore offset = 0° Optional: If muleshoe sleeve is not aligned with motor scribeline, calculate offset as per procedure 0° to +360° values permitted

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EM System Electromagnetic Telemetry

Internal Offset

Surfac

etermine offset as per procedure and always enter value as a IVE number. (Zero toolface offset G4, “Job Data” screen)

e Software

DNEGAT 0° to -360° values permitted S ipod: Measure clockB

scribeline. 0° to +360° values pe tinger: Measu

itted.

e stamp/pressure port/bolt combo values permitted.

Sto mud motor scibeline. 0° to

External Offset

urface Software

wise from the tool carrier key to the mud motor rm

re clockwise from th +360°

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MWD OPERATIONS

Computalog

Computalog

Strip Chart Recorder (SCR)• The SCR is used to

record incoming pulses on paper for troubleshooting purposes

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Surface PC Backplane

• The surface PC provides the interface between the CID and the DAS

Computalog Interface Display (CID)•The CID receives pressure transducer inputs and decodes them before sending to the PC

•Allows communication with the DAS on the surface

•Sends messages to the RFD

•Sends voltage output to the SCR

•LED display showing surface sensor output

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Systems Test Unit (STU)

• The STU allows the operator to simulate real-time pulsing and to test the integrity of the the toolstring components

Setting the Compression Sleeve Gap

•The compression sleeve gauge is used to set the proper compression between the connectors in the toolstring components

•The compression should be set to 1/8”

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Tandem Sub, O-rings, & Backups

• The tandem sub acts as an “electronic” crossover between the toolstring components

• Backup rings should always be placed between the source of pressure and the o-ring

• Backup rings keep the o-ring from extruding out of the o-ring groove under high pressure and temperature

Pressure

Assembling the Components

• Offset the HS “Fat” Tab and the HS Slot slightly when pushing the modules together

• When they meet, rotate the modules until the tab slips into the slot

• The “click” is the sound of the two, spring-loaded connectors inside the modules coming together

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Fastening Tandems

• Once the modules have been connected, they should be secured with tool pins (nails)

Fastening Tandems• Once the nail has been

countersunk with a punch, a rubber grommet and a tandem screw are inserted into the tandem sub hole

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Fuse Packs• The negative pulse fuse pack is

single-sided; it has a 4-pin connector on ones side and is sealed with silicone on the other

• The positive pulse fuse pack has a 6-pin connector on one side and a 2-pin connector on the other; the 6 –pin connector goes toward the tool

Fuse Pack Taping

• The fuse pack should be secured to the module using high temperature Kapton tape

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TFO Procedure

• The pulser stinger keyway should be rotated to the highside position prior to determining the toolface offset

Installing the Poppet on the Positive Pulser

• With a calibrated torque wrench and a crescent wrench (as backup), apply 40 ft-lb of torque to the poppet

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Pressure Transducer

• Detects pulses at the standpipe that are generated by the downhole pulser

• Works on a 4 – 20 mA current loop; 4 mA equals 0 psi, 20 mA equals 5000 psi

Muleshoe Sleeve

• A muleshoe sleeve and muleshoe sub are used in the positive pulse configuration to align the highside of he DAS with the bend in the motor

Muleshoe Sleeve

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Anchoring the Muleshoe Sleeve

• Once the sleeve and motor are aligned, the sleeve is fixed into place with muleshoe bolts

• The bolts are torqued to 150 ft-lbs

Fractional Life Remaining (FLR)

FLR = 1 - (PI – PU) + PUPF1 PF2

FLR = fractional life remainingPI = plugged in hoursPU= pressured up hoursPF1 = power factor 1 (for NP 400, for PP 350)PF2 = power factor 2 (for NP Dir 140, NP Gamma 125, PP 110)


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DOWNHOLE SOFTWARE OPERATIONS

Computalog

Computalog

SELFTEST (DAS & CID)• Command causes the following actions:

– ROM checksum– RAM pattern test– EEPROM test– Peripherals test– Re-initialization of RAM from EEPROM or ROM– Software re-initialization (resetting stack and queue

pointers, etc.)

• The CID and DAS will perform a selftest on power up.

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USERID (DAS & CID)

• Allows the user of the device to change his security level within that device by entering a password

• Each security level one through five is associated with a unique password

• Default is 1• Level 3 password is “goatchow”; allows operator to

change programming variables• Current user level can be interrogated with the

USERLEV command

FLOWDET (DAS)

• The pressure sensor output is sampled at 100 Hz• Two averages are updated in real-time from these samples,

a long term average and a short term average• When mud flow goes from off to on, the output of the short

term average will increase more rapidly than that of the long term average. As soon as the short term average exceeds the long term average by a threshold value, flow is set to on. It works in vice-versa also

• Parameters are always “2, 10, 5000, 5000”

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INVSENS (DAS)

• Informs the DAS if the sensor is mounted inverse to normal conventions in the drillstring

• When set to “1” the DAS inverts the signs of the Y and Z axes

• “0” for negative pulse, “1” for positive pulse

POWERCON (DAS)

• DAS sensor power control switch, which is used to control the sensor power when not acquiring data

• If set to “1”, the sensor is powered continuously• If set to “0”, the processor will turn sensor power

off between acquire data commands in order to conserve power

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PSTRETCH (DAS)• DAS mud bus pulse stretch time in mud bus samples• Due to mechanical rise and decay times, the pressure

pulse produced by the pulser valve may be of longer duration than the electrical pulse sent to open and close the valve

• The electrical pulse sent to the pulser is therefore made to be Pwidth – Pstretch samples long in order to produce a pressure pulse approximately pwidthsamples long

• 12 for negative pulse, 18 for positive pulse

RSMASK (DAS)

• DAS rotation sensing switch, which controls whether rotation sensing is performed

• If RSMASK is enabled and the DAS senses rotation, it will disable transmission of toolface data

• “0” for Gamma, “1” for Directional

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SERNUM (DAS)

• Reads the 4-digit DAS serial number

SWTFLIM (DAS)

• The values used in determining whether gravitational or magnetic toolface is transmitted over the mud bus

• The first power on will default to magnetic toolface if the inclination is between the limits

• Default limits are 28, 30 which are 2.8° and 3.0°

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NCCBS (DAS)

• Control Blocks which dictate what data items will be transmitted by the DAS

• “7” for Directional, “8” for Gamma

NFCBS (DAS)

• Control Blocks which dictate the type of survey data that will be transmitted by the DAS

• “3” for raw directional data • “4” for raw directional data and gamma• “7” for calculated survey data

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TFO (DAS)

• Reports the internal toolface offset value in the DAS

RSTLOG (DAS)

• Resets the logging memory pointer to the top so that all 8192 bytes are available for new log data

• Once this command is issued, previous data stored in the logging memory is lost

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SETTIME (DAS)

• Allows the operator to adjust the DAS time• Current time format in the DAS• YY:MM:DD:HH:MN:SS• For example, SETTIME 02:03:06:13:13:13 for

March 6, 2002 at 13:13:13

GETTIME (DAS)

• Same format as SETTIME• Allow the operator to view the DAS time

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UNLOCKTM (CID)

• Allows modification of the mud bus telemetry parameters after a PROGTM command has been sent to the CID

• The user should be aware that unlocking and modifying the telemetry parameters during downhole operations will result in lost communications with the downhole DAS.

DATARATE (CID)

• An integer between 1 and 5 inclusive which selects the mud bus pulse width from the data rate versus pulse width table.

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MEASSYNC (CID)

• The delay in seconds between the time that the CID detects flow on and the time that the CID detects sync

• Mud parameters can affect how long it takes the pulse to travel from pulser to surface

• This value affects how the parameters SYNCDEL and SYNCSIZE are set

SYNCDEL & SYNCSIZE (CID)• Tells the CID how long to delay from pumps on before it

should look for the first sync pulse• The sync window (SYNCSIZE) is centered about the sync

delay• During the sync window the CID looks for the sync

signature sent from the DAS over the mud bus.• Both parameters are set based on the MEASSYNC value• SYNCDEL will typically need to be increased as the well

gets deeper• SYNCSIZE will typically need to be decreased as the well

gets deeper

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Relationship between Meassync, Syncdel, & Syncsize

Meassync

Syncdel

Voltage

Time

Syncsize

NUMCCBS (CID)

• Control Block definitions which tell the CID what transmitted data items to expect from the DAS

• “7” for Directional, “8” for Gamma• If the DAS and CID are not in sync with each

other (NCCBS and NUMCCBS the same) then no data will be processed by the surface system

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NUMFCBS (CID)

• Control Block definitions which tell the CID what type of survey data will be transmitted by the DAS

• “3” for raw directional data • “4” for raw directional data and gamma• “7” for calculated survey data• If the DAS and CID are not in sync with each

other (NFCBS and NUMFCBS the same) then no data will be processed by the surface system

PULSEPOL (CID)

• Lets the surface system know how the raw directional data is being encoded by the DAS

• When in a positive pulse configuration the DAS is run upside down; it inverts the signs of the Y and Z axes before transmission

• “0” for positive pulse, “1” for negative pulse

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SIGTHR (CID)

• “Signal Threshold” parameter tells the detection software what voltage level to start triggering pulse detection

• The incoming signal (as a voltage) must cross above the threshold to be considered as a pulse

• Set this value such that the mud pulse signal crosses the threshold but the background noise does not

AVNOISE (CID)

• Displays the average strength of the noise component of the incoming transducer signal

• Allows the operator to adjust the SIGTHR parameter to achieve better detection

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PROGTM (CID)• Sends the mud bus telemetry parameters from the CID to

the DAS over the bus and prohibits further modification of those parameters until an UNLOCKTM command is given

• If the user modifies any of these parameters while they are unlocked and then fails to send a PROGTM to the DAS, mud bus communication failure may occur as soon as an attempt is made to use the DAS downhole

• Communication failure is indicated by a CSTAT1 message when flow is turned on.

• Result of PROGTM is 0=successful, 1=unsuccessful

Mud Pulse Practical Exercise Student #1 Student #2 Student #3 Student #4 Student #5 Student #6 Student #7 Student #8Rig Up Surface EquipmentCID to PCCID to ToolCID to STUSTU to ToolBoot up PC and start Surface Software

Assemble Positive Pulse ToolstringConfiguration OrderVisually Inspect & Clean ConnectionsO-Ring LubricationTandem Sub CompressionConnect Components

Configure Surface Software for Roll TestPROGTM appropriate DAS settings (Basic)PROGTM appropriate CID settings (Basic)Verify battery voltage Describe battery depassivation procedurePulse up a full surveyPrint out on SCRPerform a 5-point Roll Test and Swing Test

Demonstrate Toolface Offset Procedure Obtain TFO value presently in DASDetermine TFO for current configuration Download to DASVerify correct TFO is downloadedPulse up toolface data to prove correct TFO

Download Tool as InstructedInsure all parameters used as instructedPulse up the data and verify it is appropriateProvide SCR and Printer output

Disassemble Positive Pulse Toolstring


Documents

MWD I