Open Hole Logging Operations Basics...

Introduction to Petrophysical Data and Open Hole Logging Operations Basics

Petrophysical Data and Open Hole Logging Operations Basics

Learning Objectives

By the end of this lesson, you will be able to:

Understand the role of Petrophysics and why it is critical to theoil and gas business

Understand the relationship of Petrophysics to Geology,Geophysics, and Reservoir Engineering

Complete basic calculation of oil volume in a reservoir andexplain which petrophysical parameters are required

Recognize the difference in the Static (Geologic) Model and theDynamic (Reservoir Simulation) Model

Identify key parameters of the Earth Model and what a “normal”pressure gradient is in psi/ft and ppg

Petrophysical Data and Open Hole Logging Operations Core ═══════════════════════════════════════════════════════════════════════════════════

©PetroSkills, LLC. All Rights Reserved. _________________________________________________________________________________________________________

1

COPYRIGHT

What is Petrophysics?

Petrophysics is derived from the Greek word petra meaning "rock" and physis meaning "nature"

As defined by an SPE Reprint, petrophysics is “… the study of the physical and chemical properties of rocks and their contained fluids. Petrophysics uses rock properties and relationships among these rock properties to identify and evaluate hydrocarbon reservoirs, source rocks, seals and aquifers”

Gus Archie is the known as the “Father of Petrophysics”

Petrophysics plays a fundamental role in description, characterization and evaluation of rock-fluid packages

Why Petrophysics is Fundamental

Petrophysics consists of:• Geology• Reservoir Engineering• Mechanical Engineering• Drilling• Geophysics

Petrophysics

Geophysics Geology

ReservoirEngineering



2

COPYRIGHT

Give Me a Few “Glue” Examples…

Attic hydrocarbons• Produces out of the Gething sandstone

– Fine-grained sandstone

– Contains approximately 3 percent potassium feldspar

• A zone that looked like silty shale was first drilled through.• As drilling continued, the drilling fluid was carefully engineered and

resulted in an exceptionally prolific wet gas reservoir.• The life of the field was extended by 30 years because it consisted

of attic hydrocarbons.

Reservoir compartmentalization• On the inshore blocks of Angola

– Series of anastomosing channels which cut across from each other

– Each bounding surface of the channels serve as a vertical or lateral permeability barrier

– It was assumed that the entire package was hydrocarbon bearing

• Pressure tests, repeat formation tests or drill stem tests were run– Did not produce uniformly– Pressure and gas-oil ratios were variable

• Different reservoirs were identified using core and rock typing• Core and log data were integrated to determine continuity and

connectivity.

What is a Petrophysicist?

A petrophysicist is a petrophysical engineer

A petrophysicist is responsible for planning, acquiring and interpreting borehole data.

• Data sources include mudlogs and openhole and cased hole well logs.



3

COPYRIGHT

Stage or Phase1. Rank Exploration2. Field Discovery3. Field Development4. Secondary Recovery5. Tertiary Recovery6. Field Maintenance7. Field Abandonment8. Remediation

The Petrophysics Continuum

1

2

3

4

5

6

7

8K

NO

WL

ED

GE

IN

CR

EA

SE

PR

OB

LE

MS

IN

CR

EA

SE

Key Learning Points

Petrophysics Applies at All

Levels!

Petrophysical Data Sources

Reservoir characterization requires competent integration of data from many sources!

• Cuttings• Hydrocarbon Analysis• Cores• Logs• Fluid/Pressure Tests



4

COPYRIGHT

The Petrophysical Scene – Multiple Scales

Phase Activity Formation Evaluation Method

1. Exploration Define Structure Seismic, Gravity, Magnetics

2. Drilling Drill Well Mud Logging, Coring, MWD, LWD

3. Logging Log Well Open-hole Logs

4. Primary Evaluation Log Analysis and TestingSidewall Cores. VSP, Wireline FT, DST

5. Analysis Core & Fluid Analysis Laboratory Studies

6. FeedbackRefinement of Seismic Model Time/Depth Calibration

Integrated Field Study Log/Core Calibration

7. Exploitation Producing Hydrocarbons Material Balance Analysis

8. Secondary Recovery

Production Logging Production Log analysis

Assisted Lifting Flood Efficiency Analysis

Water or Gas Injection Micro-rock Property Analysis

9. Abandonment Economic Decisions

Phase Activity Formation Evaluation Method

1. Exploration Define Structure Seismic, Gravity, Magnetics

2. Drilling Drill Well Mud Logging, Coring, MWD, LWD

3. Logging Log Well Open-hole Logs

4. Primary Evaluation Log Analysis and TestingSidewall Cores. VSP, Wireline FT, DST

5. Analysis Core & Fluid Analysis Laboratory Studies

6. FeedbackRefinement of Seismic Model Time/Depth Calibration

Integrated Field Study Log/Core Calibration

7. Exploitation Producing Hydrocarbons Material Balance Analysis

8. Secondary Recovery

Production Logging Production Log analysis

Assisted Lifting Flood Efficiency Analysis

Water or Gas Injection Micro-rock Property Analysis

9. Abandonment Economic Decisions

Petrophysics Related Activities

Highlighted in yellow are most critical petrophysical phases



5

COPYRIGHT

Oil Vol = A*h*(N/G)*porosity*(1-Sw)

where:• Area A = 1000 sq. ft.• Thickness, h = 100 ft

• Net to Gross, N/G = 60%

What is the oil volume “in place” in this “subsurface reservoir”Oil Vol = __ bbls? And, what inputs are from petrophysical data?

HCVOL= A*h* (N/G)*por*(1-Sw)

where:• A = 1000 sq. ft., h = 100 ft, N/G = 60%, Por = 20%, Sw = 10%

• HCVOL = 1000 x 100 x .6 x .2 x .9 = 10800 ft3

• cu ft x .1781 bbl/ft3 HCVOL= 1923 bbl oil

• Oil Vol = 1923 bbls.

The Hydrocarbon Volume and Petrophysical Data

• Porosity = 20%• Water Saturation, Sw = 10%

Key Parameters in Earth Model

In order to use logs and cores to understand the Earth; corrections are needed for:

• Pressure• Water Salinity• Temperature• Water Density• Borehole/Formation

Environment



6

COPYRIGHT

Earth Model: Temperature and Pressure Gradients

Geothermal Gradient• Gradual increase of temperature with increasing depth

(e.g., 1ºF/100ft)

Petrophysical Effects• Influences on logs

– Activity level of ions in subsurface waters increase with depth

– Drilling mud properties can change with depth

– Certain wireline tools are effective only within certain temperature ranges

• Influences all facets of well design

Overburden Pressure –gradual increase of pressure with increasing depth in the earth's crust (e.g., 1.1psi/ft)• OP = FP + GP

• Petrophysical Effects• Fundamental control on

phi-k (porosity-permeability)• Significant influence on well

design • Influences logs

– Certain wireline tools are effective only within certain pressure ranges

Hydrostatic Pressure –gradual increase of pressure in a fluid column: • 0.43 psi/ft (fresh water)

• 0.465 psi/ft (“normal pressured” salt water)

• 0.35 psi/ft for (oil) • 0.08psi/ft for gas

Earth Model: Pressure Gradients



7

COPYRIGHT

Important inputs for many petrophysical applications include:

• Formation Temperature• Formation Pressure• Fluid Densities

These corrected parameters are used for:• Log Analysis• Completion Planning• Producibility Estimates

Temperature and Pressure Gradient Summary

Where Does Petrophysics Fit in Reservoir Analysis?

The task for reservoir scientists (geologists, petrophysicists, engineers) is to locate hydrocarbon reservoirs and evaluate the oil and gas recoverable volumes.

• Requires detailed description, characterization of reservoir rocks and associated seals/aquifers

• Data Sources – Seismic Data – 2D, 3D and 4D– Geological Interpretation of Facies and Rock Types

– Petrophysical Data – Logs, Cores, Test Data

– Production Data– Fluid Properties Data



8

COPYRIGHT

Petrophysics Integral to Reservoir Analysis

1. Seismic analysis

2. Define container (trap size)

3. Petrophysical characteristics

4. Geologic modeling (and rock typing)

5. Mapping, volumetric determination

6. Model validation

7. Interwell modeling

Key Learning Points

Integrating petrophysics occurs in all

steps!

Petrophysics – An Important Piece

Petrophysical answers are indirect

Also true of static and dynamic reservoir models

When appropriate subsurface data is gathered, the results are valid and lead to good business solutions

There is never a “unique” solution but integration of all data narrows down the solutions to a set of “valid” ones.

BUT, Only a Piece

GeologyEngineering

Petrophysics Geophysics



9

COPYRIGHT

How Does Petrophysics Integrate?

Static model(Geologic model)

Dynamic model(Reservoir Simulation model)

(Borehole) Seismic

Core data

Mudlog data

LWD Wireline Logs

Reservoir monitoring

Open hole logs• Resistivity• Nuclear• Acoustic• Other

Cased hole logs• Nuclear• Production logs• Other

Field studies

Corrections:• Invasion• Layering• Deviation

Interpretation models incl. QC & Uncertainty

Static model(Geologic model)

Dynamic model(Reservoir Simulation model)

Learning Objectives

Understand the role of Petrophysics and why it is critical to the oil and gas business

Understand the relationship of Petrophysics to Geology, Geophysics, and Reservoir Engineering

Complete basic calculation of oil volume in a reservoir and explain which petrophysical parameters are required

Recognize the difference in the Static (Geologic) Model and the Dynamic (Reservoir Simulation) Model

Identify key parameters of the Earth Model and what a “normal” pressure gradient is in psi/ft and ppg



10

COPYRIGHT

Open Hole Logging Operations


Learning Objectives


Understand Wireline Logging operations, equipment, and procedures

Understand the role of Wireline Logging Engineers and Operators

Identify the major components of a wireline logging unit

Identify the primary open hole logging tools run for Petrophysical Evaluation

List the measurement units for the primary open hole logs

Specify the typical logging tools combinations run for Exploration and Development wells



11

COPYRIGHT

Equipment Conventional wireline open hole

logs

LWD – Logging While Drilling• Built into drill collars and

run near the bit

Wireline Logging Operations

Depth and Log displays

Calibrations and Accuracy

Wireline Logging

Surface Logging Unit

Logging Tool

Signal Conditioner

Sensor

Transmission Via Cable



12

COPYRIGHT

“Wireline Acquisition in 1927…”

First well run by Schlumberger in 1927

They devised a way to run electrodes into wellbores filled with water based mud

They invented the first electric resistivity log

• They named it Lateral Log

• Early logs were manually recorded as “station readings”

• The wireline wench was cranked by hand

The First Log

“… Data Acquisition Now”

Typical Land Wireline Unit Typical Off-Shore Wireline Unit

courtesy of Schlumberger

courtesy of Baker Hughes



13

COPYRIGHT

Wireline Logging Truck

A Modern Logging Unit

Computers

Wireline Winch



14

COPYRIGHT

Surface Acquisition Unit

Well Logs



15

Cap Rock

Water

Logging Tool

Blow Out Preventers(BOP)

Upper Sheave Wheel

Lower SheaveWheel

Logging truck withRecording equipment

Cable Drum Rig

Oil

COPYRIGHT

Courtesy: Weatherford, Intl.

Sidewall Sample Gun

Density Log (pad device)

4-Arm Dipmeter (pad device)

Induction Log with “standoffs”

Offshore Logging Unit

Land (Onshore) Logging Truck

Open Hole Logging Tools

Open Hole Logging Tools

Open Hole Logs Resistivity (Laterolog, Induction)

Nuclear (Density, Neutron)

Acoustic Nuclear Magnetic Resonance

Formation Imaging

Sampling (pressures and fluids)

Formation Properties Rock type

Porosity

Permeability Fluid type (oil, gas, water)

Fluid Volume (saturation)

Formation tops Fractures

Open Hole Logs Resistivity (Laterolog, Induction)

Nuclear (Density, Neutron)

Acoustic Nuclear Magnetic Resonance

Formation Imaging

Sampling (pressures and fluids)



16

COPYRIGHT

Log Heading Well and Tool Sketch

Short Tool Strings – The New Standard

Note: For a “Quad Combo” add an Acoustic Log

Conventional Logging Tools

Compact Logging Tools

Compact Triple Combo



17

COPYRIGHT

Learning Objectives

Understand Wireline Logging operations, equipment, and procedures

Understand the role of Wireline Logging Engineers and Operators

Identify the major components of a wireline logging unit

Identify the primary open hole logging tools run for Petrophysical Evaluation

List the measurement units for the primary open hole logs

Specify the typical logging tools combinations run for Exploration and Development wells



18

COPYRIGHT

MWD and LWD Acquisition(Measurement and Logging

While Drilling)


Learning Objectives


Understand the concept of Measurements While Drilling (MWD)and the difference between MWD and LWD

Identify five or more typical MWD and LWD measurements,respectively

Understand the terminology used for the different events andsections of a directional drilling well path

Describe the downhole placement of the MWD and LWDsensors with respect to the bit



19

COPYRIGHT

MWD Tools

MWD Sensors include:• Directional data• Weight on the bit (WOB)• Torque at the bit• Pressure at the bit

LWD Tools are run to acquire petrophysical data including:

• Gamma ray• Resistivity• Porosity• Acoustic• Logs specified in the evaluation

MWD and LWD, the Keys to Horizontal Drilling

Applications and Advantages:• MWD data include recording

“real time” petrophysical data during drilling

• LWD is sometimes called formation evaluation while drilling (FEWD)

• Real time data is useful in highly deviated and horizontal wellbores

• Measurements made early in invasion process

• Real time ability to change wellbore trajectories to reach target

Tool and Technology Development

Measurements While Drilling (MWD)

• Refers to measurements and data used to optimize the drilling process.

Logging While Drilling (LWD)

• Refers to petrophysical log data that is recorded while drilling.

• It is an alternative to wireline logging.



20

COPYRIGHT

MWD & LWD Tools Have Different Uses

Measurement While Drilling (MWD) Tools Uses:

• Wellbore steering– Direction and azimuth

• Drilling parameters – WOB, torque, pressure

• Correlation resistivity• Gamma ray

Logging While Drilling (LWD) Tools Uses:

• Real time logging of petrophysical parameters:

– Resistivity, Density, Neutron Porosity, Acoustic, NMR, Formation Imaging

• LWD density and gamma ray have “azimuthal” capability

• LWD can include resistivity-at-bit (RAB)

Typical MWD Measurements

Torque

Weight on Bit (WOB)

Borehole pressure

Borehole Temperature

Tool Face Angle

Hole Deviation from Vertical

Hole Azimuth with respect to Geographic Coordinates

Gamma Ray (GR)



21

COPYRIGHT

Directional Drilling and Logging

Wireline logs are pulled down by gravity

Wireline logs can be run in wells drilled with water based muds with hole angles up to about 45° to 50°

Wells drilled with synthetic oil based muds (SOBM) run wireline logs in wells with hole angles up to 70°

For higher angles, other log conveyance methods must be used

Pipe conveyed logging uses special equipment

Kickoff Point (KOP)

2nd Build SectionLateral

Horizontal Departure

Tru

e V

erti

cal D

epth

MWD Tool String



22

COPYRIGHT

Tool & Technology Development

Key Technology developments in Well Logging:• Computer Processing 1960s• Nuclear logging refinements 1970s• NMR tools; established in the 60s but took several

decades to refine– First tool introduced by Numar (now Halliburton)

• LWD evolved from MWD measurements initially Gamma and Resistivity curve

– Now full suite of logs as for Wireline can be run on the pipe during the drilling process

– Key driver has been highly deviated and horizontal wells

• Early barrier was data transmission to surface– Key advance was Mud Pulse Telemetry 80s

LWD Measurements Available

Resistivity – shallow and deep

Gamma ray

Density

Neutron

Sonic

Borehole imaging

NMR (Nuclear Magnetic Resonance)

Formation Pressure

Fluid Sampler



23

COPYRIGHT

Dynamic Invasion Profile – Conceptual

Invasion frontDrilling mud

Wireline resistivity logs are typically run after significant exposure times to mud filtrate invasion

• May require invasion corrections

LWD resistivity data is measured soon after drilling

• Typically does not require invasion corrections

Deep Reading Parallel to Bedding

Major interpretation issue in shale gas, horizontal completions!



24

COPYRIGHT

MWD – LWD Summary

MWD: Real-time availability of drilling parameters

LWD: Real-time availability of petrophysical parameters

LWD: Resistivity, density, neutron, sonic and images comparable with wireline measurements

LWD: Invasion-free formation resistivity at bit

Petrophysical interpretation principles applicable regardless of the logging tool conveyance method

Example: Triple Combo

LWD Tools = $25K per day

Log with wireline = $500K + 2 days rig time

Deepwater well takes 2 weeks to drill and rig rate = $1M per day

In this case, LWD logging is less expensive.

However, if drilling on land at 60 days + $50K per day rig time, then wireline logging is less expensive.

Advantages of LWD data over Wireline data:

• Real time sonic and resistivity data can be used to predict increasing geopressures and alert the drillers to increase the mud weight to maintain safe drilling conditions.

• Real time resistivity and porosity logs can improve selecting the whole coring depth.

Learning Objectives

Understand the concept of Measurements While Drilling (MWD) and the difference between MWD and LWD

Identify five or more typical MWD and LWD measurements, respectively

Understand the terminology used for the different events and sections of a directional drilling well path

Describe the downhole placement of the MWD and LWD sensors with respect to the bit



25

COPYRIGHT

PetroAcademyTM Foundations of Petrophysics

Petrophysical Data and Open Hole Logging Operations Core

Mud Logging, Coring and Cased Hole Logging Operations Core

Gamma Ray and SP Logging Core

Porosity Logging (Density, Neutron and Sonic) Core

Formation Testing Core

Resistivity Logging Tools and Interpretation Core

Petrophysical Evaluation Core

Core Analysis Core Knowledge

Special Petrophysical Tools: NMR and Image Logs Core



26

COPYRIGHT

Open Hole Logging Operations Basics...

Documents

Transcript of Open Hole Logging Operations Basics...