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