Integrated Petrophysics for Reservoir Characterisation – Details

Benchmark Petrophysics Training

Integrated Petrophysics for Reservoir Characterisation

Course Contents

Course Objectives
Course Contents include
How you will feel after Integrating …
A Comprehensive Course Manual !
The Central Role of Petrophysics is to INTEGRATE !
Objective of Formation Evaluation
Four log calibrations ensure correct HPV’s ..this is what we will do (Deakin&Smith 2003)
Reservoir schematic
Data Hierarchy and Upward Calibration:
Logs Provide a Vehicle for Data Integration
The Concept of Data Hierarchy
Data Hierarchy Criteria
Calibration projects high value data into larger reservoir volumes using more continuous data
Adopt a problem solving philosophy
MICROPRACTICAL Logs, Core, Salinity & Rw
Poor Reservoir is More Sensitive to Error
Major Petrophysical Difficulties
Data Sources: Diverse data with the same result
create confidence (redundancy)
Hetrogeneous reservoirs require measurements at the required answer scale, or multiple finer scale measurements to describe them
Improper core sampling for core-log calibration
RCA should be at fixed depth spacing – like log data
A Basic Problem for Petrophysics
Deterministic vs. Probabilistic Petrophysics
Quick Look: Borehole, invasion and symbols (Schl. Gen-3)
Conventional Logs: Caliper; Gamma Ray
Conventional Logs: In spectral GR tools total GR is split into POTA, THOR & URAN by detection of different energy GR’s
Conventional Logs: Spontaneous Potential, MicroResistivity
Conventional Logs: Multi-depth Resistivity, Compressional Sonic
Conventional Logs: Density, Neutron
Conventional Logs: Density Tool receiver GR energies
Conventional Logs: Density, Neutron
Conventional Logs: Porosity, Sw, Perm, Pay
Clastics Wireline Logging (SLB mnemonics)
Operations Petrophysics: Chronological Tasks and Responsibilities
Environmentally Correct Logs
Compute Vsh
Compute Ø
Micropractical
Compute Sw
Compute k
Compute Netpay
Log Data Preparation
Missing Data
Log to Log Depth Matching
Environmental Corrections
Merge LWD and Wireline
Log Normalisation
Seismic Petrophysics Log Editing Process dt, rhob
Core Data Preparation
Core to Log Depth Matching
Vetting Special Core Data
Preliminary Zonation

LITHOLOGY and CLAY CONTENT: Vcl , Vsh
Objective
Distinction Between Clay and Shale
Uses of Vclay , Vshale
Importance
Common Problems
Non-Radioactive Fines and Radioactive Non-fines
Gas and other Non-Shale Influences Vshale Logs
Is Vclay / Vshale Relevant to Reservoir Beds?
Lack of Core Calibration and a Certain Vshale = Zero Reference
Scales of Heterogeneity in Core Calibration
Lithology, Vcl, Vsh Input Data
Bulk Volume Irreducible from Magnetic Resonance Logs, mbvi, bvf
Movie
Vshale, Vclay & Capillarity from Laser Particle Analysis Grain Size Distribution
Clay Volume from Core Plugs or Trims, Vclcore
Clay Volume from Thin Sections, Vcltx
Thin Section Limitations
Core Photographs and Descriptions
X-Ray Diffraction and Scanning Electron Microscope
Mudlogs and Lithlogs
Workshop: Quick Look Log Analysis MS Excel sheet with equations: vsh, Ø
Log Integration
Method
Shale Volume from Gamma Ray: Vshgr
Non-linear Vsh
Shale Volume from Density-neutron: Vshdn
Shale Volume from Density-sonic: Vshds
Shale Volume from Resistivity: Vshres
Vshgr, Vshdn, Vshds or Vshres ?
Thomas-Steiber clay distribution

POROSITY: Ø
Objective
Importance
Common Problems
Badhole Conditions
Minimising Badhole Conditions
Effective Porosity
Shale
Gas
Unknown Grain Density
Lack of Density Tool
Workshop: Quick Look Log Analysis MS Excel sheet with equations: Rw, Sw, k, Netpay

DAY 2

Morning Daily Recap, Questions, Debate

Non Shale Corrected Density-neutron Total Porosity
Porosity Input Data
Conventional Coring Criteria
Core Porosity and Grain Density, Øcore, rhog
Recommended Routine Core Analysis procedure

Core Porosity Method
Core Overburden Porosities
Log Integration
Total and Effective Porosity: Øt, Øe
Carbonates: Intergranular and Vuggy Porosity, Øv
Fracture Porosity, Øf
Density Total Porosity, Ød
Mean Grain Density Determination
Grain Density in Complex Lithologies
Correct rhog, neutron & sonic matrix in shales
Fluid Density, rhof
Magnetic Resonance Total Porosity, Ømrt
Magnetic Resonance Effective Porosity, Ømre
Shale Corrected Neutron Total Porosity, Øn
Neutron Porosity Method
Shale Corrected Density-Neutron Total Porosity, Ødn
Gas Zones
Micropractical

Shale Corrected Sonic Total Porosity, Øs
Sonic Porosity Method
Limitations of Multiple Linear Regression Porosity, Ømlr
Probabilistic Porosities
Badhole Conditions
Shale Volume Derived Porosity, Øvsh
Water Saturated Resistivity Porosity, Øro
Two Stage Minimum Porosity: Øs, Øvsh
Effective Porosity Equations, Øe

What is Effective Porosity?

Mainstream Petrophysics Effective Porosity

Traditional log analysis Effective Porosity
Magnetic Resonance Porosities, Øe, Øt

Vary rhog with shale
Recap – Summary of Typical Porosity Evaluation

FORMATION WATER RESISTIVITY: Rw
Rw Input Data
Recovered Formation Water
Well Tests
Reservoir Temperature, Tres
Wireline Formation Tester Water Samples
Archie Apparent Water Resistivity, Rwa
Certain water zones, Sw100
Micropractical
Archie Apparent Flushed Zone Water Resistivity, Rmfa
Resistivity Ratio Apparent Water Resistivity, Rwrr
SP Logs
Origin of SP
Determining Rwsp
Rwsp Recipe
Rw Catalogues
Wireline Formation Tester Water Gradients
Integration of Rw Values

Workshop: DST-Core-Log Reconciliation

WATER SATURATED RESISTIVITY: Ro
Summary of Common Problems
Special Core Analysis ‘m’ Not Equal To In-situ ‘m’
Invalid Ø, a, or m or Rw and Sw100 zones
Øsca ¹ Ørca ¹ Ølog
Ro Equation Inputs
Total Porosity, Øt
Formation Water Resistivity, Rw
Cementation Exponent ‘m’
‘m’ Objective
Pickett Plot
‘m’ Importance
‘m’ Input Data
Electrical Special Core Analysis Laboratory ‘a’ and ‘m’
Problems with Laboratory ‘m’ values
Log Analysis Water Zone ‘m’
Carbonates: Øv and Water Zone ‘m’
Problems with Log Analysis ‘m’ values
‘m’ Log Integration

Workshop: DST-Core-Log Reconciliation: SCAL m vs. Water Zone m

DAY 3

Morning Daily Recap, Questions, Debate

RESISTIVITY SATURATION: Swrt
Summary of Common Problems
Absence of Conventional Core Calibration
Core Analysis ‘n’ Not Equal To In-situ ‘n’
Freshwater Shaly Sands
Formation Heterogeneity Un-Resolved by Rt
Sw Equation Inputs
Formation True Resistivity, Rt
Which Logging Tool?
Rt Problems
Inadequate or Inappropriate Rock Volume Resolution
Deep Invasion
Shoulder Beds
Horizontal and Vertically Resistivity in Laminated Beds (3DEX)
Groningen and Delaware Effects
Cased Hole Resistivity Tool (CHFR) xx
Saturation Exponent, ‘n’
‘n’ Objective
‘n’ Importance
Laboratory ‘n’ Problems
Wettability – Containing the Problem
Laboratory ‘n’ Input Data
Electrical Special Core Analysis Laboratory ‘n’
Guidelines for Improved Laboratory ‘n’
Micropractical

SHALY SAND Swrt
Waxman Smits Equation Inputs
Cation Exchange Capacity (CEC) and Qv
Qv from Magnetic Resonance Logs, Qvmr
Qv from Archie apparent water zone ‘m’
Equivalent Conductivity of Exchange Cations, B
Waxman & Smits Cementation Exponent, mws (m*)
Waxman & Smits Saturation Exponent, nws (n*)
ImageLog Facies as Classes of Clay Distribution and B
Shaly Sand Swrt Log Integration
Is a Shaly Sand Equation Required ?
Log Data
Laboratory Electrical Data
Selecting a Suitably Structured Resistivity Swrt Equation
Core Sw Equation Inputs Do Not Guarantee Sw Output
Workshop: A-Z Integrated Evaluation: Ød, Rwa, Rw, m, Pickett Plot

CORE SATURATIONS
Oil Base Mud Core Sw and ‘n’ Calibration (Swobm)
Low Invasion Water Base Mud Core Sw and ‘n’ Calibration
Conventional Core Porosity and Permeability Sw and ‘n’ Calibration
Minimum Fluids Exchange
Conventional Core Fluid Saturations as Sw Constraints
1 Limitations of Conventional Core Fluid Saturations
Restored State Core
Well Tests as Sw Constraints
Reservoir Saturation Tool, RST

CAPILLARY PRESSURE SATURATION, Swpc
Capillary Pressure Derived Sw and ‘n’ Calibration
What Is Capillary Pressure?
Capillary Pressure Data Acquisition
Identifying Bad Capillary Pressure Data
Capillary Pressure Data Interpretation
The Reservoir Master Equation, [Sw-Ø-k-Height]
The J Function Method
The Regression Method
Individual Plug Curve Fit Methods, Skelt etc
Log Integration of Swpc
Problems with Capillary Pressure Derived Sw and ‘n’
Workshop: A-Z Integrated Evaluation: Sw_pc, core-log n, Sw, k, Netpay

DAY 4

Morning Daily Recap, Questions, Debate

MAGNETIC RESONANCE SATURATION, Swmr
Magnetic Resonance Tool’s Swi

RECONCILLIATION OF Swrt via n
‘n’ Log Integration
Implied Sw Constraint from Electrical versus Capillary Pressure ‘n’ values ?
Field Example of Data Integration Constraining ‘n’
Earth Tide Downhole Pressure Variations and Netgas Porosity xx
Sw Logical Constraints
Resistivity Ratio, Swrr
Log(Rt/Rxo) v SP Movable Hydrocarbon Indicator

BASE CASE SATURATION – THE Sw DECISION TREE
SATURATION DERIVATIVES
Movable Oil Saturation, Som
Residual Oil Saturation, Sor
Log / Core Minimum Rt for Maximum Water Cut – Netpay

Micropractical
CONTACTS, FLUID ZONES AND CAPILLARY PRESSURE
Objective
Hydrocarbon Types
Reservoir Capillary Pressure: Pc
Importance
Summary of Common Problems
Badhole Unknown Formation Pressure Gradients
Logs respond to Bulk Volumes Not Mobility
Marginal Reservoir
Lack of Density-neutron
Fluid Zone Input Data
Wireline Formation Pressure Gradients and Samples
WFT Problems
Supercharging
WFT Operation and Operational Recommendations
WFT Further Details
GeoTap MWD Formation Tester
Recovered Fluids: Tests, Wireline, Kicks
Kicks
Early Formation Pressure System, EFPS
While Drilling Formation Pressure Tester
rhob-npsc, dt-nphi, and rhob-dt will Detect Gas!
Calculated Sw
Bulk Volume Water, BVW
Bulk Density – Rt Trend
Rt/Rxo vs SP
Residual Hydrocarbons seen by Rmfa
Shale Corrected Density-neutron Separation
Non shale corrected Neutron-Sonic Separation for Gas Carbonates
Magnetic Resonance Log Hydrocarbon Typing
Core UV Visible Spectroscopy
Reservoir Master Equation’s prediction of Height
Chromatograph, Lithlog / Mudlog: Cut, Fluorescence, Stain
Quantitative Fluorescence Tool
IPL and Neutron Tools
Sonic Tool vp/vs
Maps and Cross Sections
Log Integration
Gas Zone
Oil Zone
Transition Zones
Residual Oil Zones
Coals and False Bulk Volume Hydrocarbon
Water Zone, Sw100 zones
Workshop: MDT Data Acquisition

PERMEABILITY: k
Objective
Importance
Relevance of Permeability to Special Log Processing
Common Problems
Dynamic Property Inferred from Static Properties
Inadequate Data for Analytic or Predictive Pore Typing
Core Ø – k Regression Applied with Log Effective Ø
Unidentified but Influential High Permeability Streaks
Invalid Low End Core kair
Shale and Extreme Low End Prediction
Unrecognised Sw > Swi Zones
Lack of k overburden data
k Input Data
Core Permeability
Conventional Air Permeabilities, kair
Klinkenburg Correction
Equivalent Overburden kbrine
Altered Core Permeabilities
Core Effective Permeability
Magnetic Resonance, kmr
Bulk volume hydrocarbon, bvh
Normalised Resistivity Ratio, RRn
Sidewall Core Laser Particle Analysis
WFT Permeability, kwft
Well Tests Permeability, kh
Well Test Problems
Permeability Averaging
Zonation
Pore Type Zonation: [Ø-Sw-k-Pc]
Core Capillary Pressure Data
Core Ø – k plots
Log Pore Typing Parameters
Is Facies Based Zonation Useful?
Borehole Image-log Facies Zonation
Other Log Permeability Predictors
Sonic Responses
Specific Surface Area
Log Integration
Timur Coates Permeability Equation
Understanding Components of Bound Fluid Volume and their Log Prediction
Fitting Timur Coates constants a, b and c
Summary of Conventional Log Permeability Evaluation
Effective Porosity, kpor
Saturation, ksw
Reservoir Master Equation Enables k from Sw as well as Swi
Clay / Shale Volume, kvsh
Multiple k Inputs: Accuracy versus Stability
Estimated Production Rates
Does your RE need stressed kbrine or kair? Ask
THE EFFECTIVE PERMEABILITY OF EACH PHASE: kw, ko, kg
kw ko kg:Swrt & SCAL rel.perm predicts kw, kg, pay & kh
kw ko kg: inputs used to match summed log data kh to summed DST kh
kw ko kg: Effective kg vs. kw, P10 & P90 versions and Linear kg-kw
Reviewers of Petrophysical Results: Check Permeability
Recommended Evaluation Sequence
Workshop: MDT Data Interpretation. Calibration of log analysis ko & kw to Well Test kh

DAY 5

Morning Daily Recap, Questions, Debate

NETPAY and NETROCK: N:G
Objective
Importance
Common Problems
Relevant Hard Data Usually Not Available
Different Understanding of Meaning and Function
Violating the integrity of the petrophysical results table
Impact of Marginal Bed’s Thickness and Location
Use Core-log Data not stand-alone Core data
Reservoir Geometry May Isolate Rock Volumes
N:G Input Data
N:G Non-Log-Inputs
Water Encroachment
Depletion
Permeability at Zero Movable Oil from Relative Permeability Data
Core Fluorescence
Capillary Threshold Height and Closure
Borehole Image Logs
Conventional Core Porosity Permeability Data
Well Tests and Production Data
Micropractical

WFTs
Hydrocarbon Pore Volume from Material Balance
N:G Log Inputs
Magnetic Resonance Logs
Invasion Profiles
0.5 Micron Mean Pore Throat Radius
Mudcake Build-up – Microlog
Mudcake Build-up – Caliper
Borehole Image-logs in heterolithic beds
Evaluated Saturation, Porosity and Clay / Shale Volume
Micro Spherically Focused and Microlateral Logs
Log Integration
Criteria: Why Permeability?
Determine Netpay first then Netrock
Determine the Cut-off from Direct Reservoir Observations If Possible
Netpay and Fluid Zones

SENSITIVITIES & UNCERTAINTY
Importance
Cutoff Sensitivities

XLS or Batch Recalculation Sensitivity Studies
P10 P50 P90 Geo-model Uncertainties

Reducing Sensitivities & Uncertainties Cost-Effectively

SEISMIC – PETROPHYSICAL INTEGRATION
Depth-Time Conversion
Synthetic Seismograms
Fluid Substitution
Seismic Attributes

REPORTING RESULTS
Objective
Importance
Common Problems
Field Petrophysical Reference – The Results Table

GEOLOGICAL MODELING
In-Out Petrophysical checks
Permeability upscaling key points
A Consistent Geo-model
10 Systematic Common Errors which Ruin Geo-models

WHY INTEGRATE ?

FORMATION EVALUATION RECOMMENDATIONS
Data Acquisition
Mud
Core
Core Description
Core Analysis
Logs
Saturation
Evaluation

CASE HISTORY: LOW POROSITY RESISTIVITY
Review of Core – Log – Well Test and Petrographic Data Integration
Problem
Data
Method
Key Findings
Conclusion: To be Announced

EQUATIONS
Lithology
M and N lithology parameters
Shale Volume from Gamma Ray
Shale Volume from SP
Shale Volume from Density-neutron
Porosity
Conversion of Laboratory to Reservoir Core Overburden Porosity
Density Porosity
Density-neutron Porosity
Density-neutron Gas Zone Porosity
Sonic Porosity
Porosity from Ro (water zones) assuming Rw and ‘m’
Effective Porosity
Formation Water Resistivity, Rw
Porosity, m Apparent Water Resistivity, Rwa
Resistivity Ratio Apparent Water Resistivity, Rwrr and equivalent NaCl (chart
Saturation
Formation Factor
Cementation Exponent
Waxman Smits prediction of water saturated resistivity, Ro
Resistivity Index
Saturation Exponent
Archie Saturation
Logarithmic Form of Archie Equation (where a = 1)
Archie Cementation Exponent from Water Zones
Sxo from Rmfa
Dual Water Model Saturation
Waxman & Smits Model Saturation
Equivalent Conductivity of Exchange Cations
Effective Concentration of Exchange Cations per Unit Volume of Pore Fluid
Actual BQv Required to Satisfy W-S Equation in water zones (Swt = 1.00)
Qv from Archie apparent water zone ‘m’
Waxman Smits mws from Archie m
Popoun & Leveaux ‘Indonesia’ Shaly Sand Saturation
J Function Correlation of Pore Types
Conversion to Height above Free Water Level
Mercury capillary pressure clay bound water correction
Saturation Exponent from log independent Sw (Swx)
Layer Sw for Mapping Wedge Zones
Rt for Economic Production (max. water cut)
Permeability
Darcy Permeability
Well Test Permeability Thickness
Empirical Klinkenberg Correction
Kbrine from Kair and CEC (Qv)
Example klog for Above Transition Zone
klog for Above Transition Zone – Log Data Only
Normalised resistivity ratio, RRn
Fractional Flow Equation

FIGURE CAPTIONS
REFERENCES
Petrophysicaly Related Websites
ABBREVIATIONS
ESSENTIAL SCHLUMBERGER CHARTS

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