Integrated Petrophysics for Reservoir Characterisation – Details

Benchmark Petrophysics Training

Integrated Petrophysics for Reservoir Characterisation

Course Contents

 

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COURSE OBJECTIVES

 

Course Objectives

Course Contents include

 

INTRODUCTION & PRINCIPLES

 

Intro: How you will feel after Integrating …

Intro: A Comprehensive Course Manual !

Intro: The Central Role of Petrophysics is to INTEGRATE !

Intro: Objective of Formation Evaluation

Intro: Four log calibrations ensure correct HPV’s ..this is what we will do (Deakin&Smith 2003)

Intro: Reservoir schematic

Intro: Data Hierarchy and Upward Calibration: Logs Provide a Vehicle for Data Integration

Intro: The Concept of Data Hierarchy

Intro: Data Hierarchy Criteria

Intro: Calibration projects high value data into larger reservoir volumes using more continuous data

Intro: Adopt a problem solving philosophy

MICROPRACTICAL Logs, Core, Salinity & Rw

Intro: Poor Reservoir is More Sensitive to Error

Intro: Major Petrophysical Difficulties

Intro: Data Sources: Diverse data with the same result create confidence (redundancy)

Intro: Hetrogeneous reservoirs require measurements at the required answer scale, or multiple finer scale measurements to describe them

Intro: Improper core sampling for core-log calibration

Intro: RCA should be at fixed depth spacing – like log data

Intro: A Basic Problem for Petrophysics

Intro: Deterministic vs. Probabilistic Petrophysics

 

QUICK LOOK

 

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

Guide: Clastics Wireline Logging   (SLB mnemonics)

 

Quick Look: Invasion profiles indicate mobile fluids & permeability – oil base mud

Quick Look: Why porosity logs are plotted backwards

Quick Look: Mudlog, rate shows and apply chromatograph ratios

Quick Look: Compute Vsh

Quick Look: Compute Vsh

Quick Look: Compute Ø

Quick Look: Density-Neutron crossplot Ø, safe!

Quick Look: Compute Ø

Quick Look: Compute Sw

Quick Look: Compute Sw

Quick Look: Compute k

Quick Look: Aquifer, Transition Zone and Hydrocarbon Zone

Quick Look: Compute netpay, h …

Quick Look: Default Equation Sequence

Quick Look: The backbone of log analysis..

Quick Look: Caution..  reviewers beware!

 

Recommended Evaluation Sequence

 

DATA PREPARATION

 

Data Prep: Project Preparation – Collect and tabulate all data for each well

Birthplace of The Manual … step by step

Data Prep: Log Data Preparation

Data Prep: Merge LWD and Wireline

Data Prep: Sometimes LWD is better than Wireline

Data Prep: Log Normalisation

Data Prep: Rock Physics (seismic) – log editing: dt, rhob process summary

Data Prep: Core Data Preparation & Vetting

 

VSHALE AND LITHOLOGY

 

Vsh: Clay and Shale

Vsh: Common Uses of Vclay, Vshale

Vsh: Importance

Vsh: Common Problems

Vsh: Magnetic Resonance and other inputs

c:\data\courses\zzMRIL.avi Click to play

Vsh: Cores and Cuttings

DAY1 1100h Begin Quick Look Log Analysis Practical

Vsh: CGR clean & CGR shale values from 5 & 95 percentiles

Vsh: Conventional wisdom: True Vsh < Linear Vshgr

Vsh: Density-neutron

Vsh: Some more equations.. see Notes

Vsh: Advantages of Vshgr

Vsh: Thomas-Stieber clay distribution..  assumes sand Øt is reduced by dispersed clay in pores, Tertiary clastics

Lith: Lithoscanner and spectral GR tools

c:\data\courses\zzLithoScanner.wmv Click to play

As a Reviewer of Petrophysics: Check Vshale

 

Recommended Evaluation Sequence

 

POROSITY

 

Ø: Objective of Log Derived Porosity

Ø: The Effect of Porosity Error is Significant, Even in Fair Reservoir Quality Sand

Ø: Common Porosity Problems

Ø: Pre-emptive action for Badhole

Morning report: “Successfully cemented rig in-place”

Ø: Importance and Problems of Core Porosity

Ø: Significance of grain density, rhog

END DAY 1

 

Day1 Recap, Questions, Debate

Ø: RCA, typical laboratory process

Ø: Core Cleaning and Drying

Ø: Recommended RCA procedure

Ø: Gas expansion porosity Boyle’s Law Porosimeter

Ø: Advantages of Gas Expansion Porosity

Ø: Porosity compaction with increasing Net Confining Pressure

Ø: Core Overburden Porosities

Ø: Core Uniaxial Compaction Correction

MICROPRACTICAL: Which quicklook porosity?

Ø: The Ideal Model. Full core-log integration. Uses Øt & Øe linked via Qv, salinity (Juhasz 1988)

Ø: Advantages of Total Porosity, Øt

Ø: What is Effective Porosity? Øe

Ø: Mainstream Petrophysics Øe

Ø: Traditional Log Analysis Øe

Ø: Porosity measurements compared

Ø: Uncalibrated ‘Effective’ Porosity, Core calibrated total porosity and Bulk Volume Hydrocarbon

Ø: Carbonates: Density-Sonic porosity can indicate vugs, Øv

Ø: Log Integration.  rhog variations cause error in Density Porosity

Ø: Log Integration. Core-log plot determines apparent fluid density, rhof

Ø: Magnetic Resonance Porosities, Ømrt, Ømre

Ø: Neutron Porosity, Øn

Ø: Deriving Øn : 1. Matrix and Shale corrections

Ø: Kaolinite reduces GR’s ability to correct neutron

Ø: Advantages of Ødn and recap

Ø: Gas Zone Porosities

Reviewers of Petrophysics: Check Ø

 

Recommended Evaluation Sequence

 

Rw, FORMATION WATER RESISITIVITY

 

Rw: Formation Water Resistivity

Rw: Errors obscure resistivity derived pay

Rw: The Rw we Want and The Rw we Get

Rw: Sources of Rw    *=@Swi

Rw: Screen salinity data for Rw

Rw: Reservoir Temperature from well tests. End main build up period

Rw: Use WFT water samples to calibrate log Rwa’s

Rw: Archie Rwa  from clean 100% water zones

MICROPRACTICAL Compute Rwa, Rwrr

Rw: NaCl apparent (NaCla), a useful curve during exploration

Rw: Certain water zones, Sw100

Rw: Identify & Flag “Sw100” zones for Rwa, NaCla, ma, BQva etc..

Rw: Rwpc, Rwssp, Rwgrad

Reviewers of Petrophysical Results: Check Rw

DAY2 1100h BEGIN Practical Ques2 Core-Log Workshop : Reconcilliation..

 

Ro, WATER SATURATED FORMATION RESISTIVITY & m

 

Ro: Water Saturated Resistivity, Objective and Problems

Ro: Function of ‘m’

Ro: Ø^-m = Ro/Rw. Core-log common format ‘m’ definition plot

Ro: Pickett Plot: determines m, a*Rw and Sw from logs

Ro: Importance of ‘m’

Ro: How to pick SCAL plugs

Ro: Some Problems with Laboratory ‘m’ values

Ro: Laboratory SCAL m* variations

Ro: Sw100 Zone Log Analysis ‘m’

Ro: Determining m and m* from Sw100zone log data

Ro: Carbonates: Is Water Zone ‘m’ related to Øvugs ?

Ro: Investigate Poretype ‘m’ variations by:

Ro: ‘m’ Log Integration

Reviewers of Petrophysical Results:  Check Ro

Resume Practicals with Water Zone “m”..

 

Recommended Evaluation Sequence

 

Sw WATER SATURATION

 

Sw: Saturation

Sw: Uncertainty Increased by:

Sw: Common Problems

Sw: Archie – Basic Reference

Rt: Rt Squaring is Naive – a glance at core (Malay basin shaly sands)

Rt: Rdeep_lwd  Exceeds Invasion Corrected  Rt_lld

Rt: Vertical and Horizontal Resistivity for Rsand(3DEX)

END DAY 2

 

Day2 Recap, Questions, Debate

BIG    WEDNESDAY !

 

n SATURATION EXPONENT

 

n: Function of ‘n’

n: Sw^-n = Rt/Ro Core-log common format ‘n’ definition plot

n: Importance of ‘n’

n: Some Problems with Laboratory ‘n’ values

 

WETTABILITY

 

Wettability: Wetting preferences dictate the distribution of oil and water within the pore network

Wettability: Effect of Core Cleaning on Saturation Exponent, n

Wettability: Containing the Problem

Wettability: The link between resistivity and Sw becomes problematic with mixed wettability  n* 3.4 Þ 1.8; EHC+48%

Wettability: Is your reservoir non-strongly water wet?

n: Improve your laboratory ‘n’ values..

MICROPRACTICAL  Sw equations predict Ro first … then compare with Rt

 

SHALY SAND EVALUATION

 

Shaly sands: Ro is suppressed in Shaly Sands for a given Ø

Shaly sands: Rt is suppressed in Shaly Sands for a given Sw

Shaly sands: Multiple Salinity Core Tests for Excess Conductivity, B*Qv and Waxman Smits  Fws

Shaly sands: Waxman & Smits, Swt

Shaly sands: Core Cation Exchange Capacity for Qv

Shaly sands: Qv, effective conc. clay exchange cations per unit pore vol.

Shaly sands: Øt – Qv relationships (log-log plot)

Shaly sands: NMR logs provide Qv estimate

Shaly sands: NMR logs provide this and more:

Shaly sands: Archie m = f.(Ø, Vsh) for apparent Qv.. no core (Qvm)

Shaly sands: Equivalent Conductivity of Exchange Cations, B

Shaly sands: Porosity vs WS Formation Factor aws = 1.33, mws = 1.86  (at overburden)

Shaly sands: Saturation vs W&S Resistivity Index:  nws = 2.17 ?

Shaly sands: Is ‘m’ a Function of Vshale ?  Sw100zone diagnostic plot

Shaly sands: Are ‘clean’ sands really clean ?  Does it matter ?

Popular Sw Equations

Choose a Suitably Structured Saturation Equation

Shaly sands: Selecting parameters for the Juhasz Qvn Eqn, 1  .. No core

Shaly sands: Selecting parameters for Juhasz Qvn Eqn, 2   No core

Shaly sands: For Freshwater Shaly Sands do this …

Shaly sands: Getting the right answer..

DAY3  1100h BEGIN Practical: DAY3  EVALUATIOn: Ø, Rw, ‘m’, ‘n’, Sw

 

n: ‘n’ as a core-log matching parameter Use best estimate of reservoir Sw for core-log integration

 

SW OIL BASE MUD CORE

 

Swobm: Oil Mud Core Sw & ‘n’

Swobm: Oil and Water mud core Sw compared to reservoir true Sw

Swobm: Partial Invasion of an Oil Mud Core leaving an un-invaded center

Swobm: Dean Stark apparatus used in the determination of oil mud Swcore

Swobm: Comparison of oil mud core and log derived Sw, Prudhoe Bay

Swobm: How to get Sw OBM core

Swwbm:  How to get Sw WBM core

 

Sw CAPILLARY PRESSURE

 

Swpc: What is Capillary Pressure?

Swpc: WFTs Provide FWL, Mobile Fluid Type and Actual Reservoir Capillary Pressure

Swpc: Porous plate apparatus used for air-brine capillary pressure data, Sw – Pc

Swpc: Wetting phase (water) desaturation with increasing Pc

Swpc: Core Overburden Electrical Properties in conjunction with porous plate Pc

Swpc: Capillary Pressure Measurement techniques

Capillary Pressure Saturations – 4 controls on Sh

Swpc: Are Pc Plugs Representative?

Have Anomalous plugs been identified?

BEGIN PM Practical DAY3  EVALUATION: Ø, Rw, ‘m’, ‘n’, Sw

Swpc: Converting Laboratory Pc  to Height

Swpc: Height positions the Pc-Sw data in the reservoir..

Swpc: Use RCA to project cap.press data into the reservoir

Swpc: e.g. Whole core would provide a log independent direct measure of EHC over gross interval

Swpc: Summary of J Function Sw from Pc data, Swj

Swpc: J Bundles Ø, k and Ht to correlate with Sw

Swpc: The Reservoir Master Equation J predicts Sw (carbonate, poor fit)

Swpc: Equation check:  Plot Swj vs Sw measured

Swpc: Log  Ø, Sw, k = Core Ø, Sw, k

Swpc:  QuickLook: arrange your Pc data like this

Swpc: Redisplay lab Pc results as a simple Sw-Ht grid

Swpc: Capillary Pressure Sw and ‘n’

Swpc: n from logged Rt and Cap.Pressure Data

Swpc: Capillary Pressure Saturations may be inaccurate

END DAY 3

 

Day3 Recap, Questions, Debate

 

Sw NMR, DIELECTRIC  & OTHERS

 

Swmr:  Magnetic Resonance Swi

Swik4:  Sw from log evaluation matches Swik4 from core Ø and k

c:\data\courses\zzDieScanr.wmv Click to play

 

SW WRAP UP

 

Swrt: Do we use the Log Integrated ‘n’ value for Swrt or not?

Sw: Consider cutting rotary side-wall cores for Ø, k & Sw in OBM wells

Sw: One Common Use Equation Set – Log and Geo-model HPVs, kabs, koil                Core = Log = Geomodel (black)

Swrt: Other Sw checks

Sw: Base case:  The Sw Decision Tree

Sw: Alternative Methods for Sw Equation Parameters

Sw: Base case – Logical Constraints (reviewers)

Sw: Logical constraint:  At a given porosity, Swrt increases with increasing clays: the shaly sand equation (W&S) is not over compensating

Sw: Logical constraint:

Sw: Swrt  agrees with  Swpc

Recap.  Calibrate Swrt with:

Four log calibrations ensure correct HPV’s. This is what we have done (Deakin&Smith 2003)

Moved Hydrocarbon Saturation, Shm

Resistivity Ratio Sw, Swrr

Reviewers of Petrophysical Results: Check Sw

MICROPRACTICAL  Core analysis indicates Swi

What Rt = the maximum economic water cut?

 

Recommended Evaluation Sequence

 

MOBILE FLUID ZONES

 

Contacts, Fluid Zones & Capillary Pressure

FZ: Importance of Fluid Zone Evaluation

FZ: Fluid zones and their use during data extraction for geo.models

FZ: Fluid zone determination can be complex

FZ: Common Fluid Zone Problems

FZ: WFTs Provide Mobile Fluid Type, FWL and Capillary Pressure

FZ: Reservoir separation may be subtle

FZ: WFT Problems

FZ: Supercharging: WFT measured pressures may be above formation if permeability is low

FZ: Excess Pressure plots clarify FWLs and show actual reservoir capillary pressure

FZ: SLB’s Quicksilver probe

FZ: Saturn Probe <2mD formation

FZ: Mis-identified gradients from pressure barriers

FZ: WFT Operations Recommendations

FZ: WFT Operations Recommendations, contd

c:\data\courses\zzIFX.wmv Click to play

FZ: Think of kicks as unplanned well tests

FZ: Think of kicks as unplanned well tests … contd.

FZ: Find gas..  qualitative

FZ: Bulk Volume Water, BVW = Ø*Swi   (Buckles Number)

FZ:  Ø*Swi > Buckles Number indicates Fluid Zone = Transition Zone, Residual or Water

FZ: Use Multiple Hydrocarbon Indicators!

FZ: Use Probability of Mobile Hydrocarbon Tables

FZ: In Transition Zones Pc is low and Sw>Swi.  Water and oil both mobile

FZ: Different Reservoir Qualities yield

Different  TZ  thickness

Reviewers of Petrophysical Results:

Check Fluid Zones

DAY4 1100h BEGIN Practical

DAY4  WFT Data Acquisition

 

Recommended Evaluation Sequence

 

k PERMEABILITY & DERIVATIVES

 

k: Permeability Objectives

k: Importance of Permeability Prediction, klog

k: Well B’s Netpay is more permeable.

Compare your wells’ h or EHC like this

k: Problem:  Flow from Static Properties

k: Other Permeability Prediction Problems

k: Why core data rules  (permeameter)

k: Gas Slippage – Klinkenberg effect

k: Klinkenberg Permeability correction

(gas slippage)

Skip k: Low k plugs are more sensitive to overburden stress

k: The Effect of Oven Drying and Critical Point Drying on Illite Morphology

k: RCA kair > k_in-situ

k: Typical Relative Values for Various Measures of Permeability

k: Well Test Permeability, kh

k: Well Test Problems

k: The effective h may not be that at the well bore

k: Reservoir Rock Typing (RRT) for klog:

1) Facies, Image-log facies zonation

k:  Reservoir Rock Typing for klog

2) Data should cover cores and logs

k: Two Rocktypes: Same field, same well, same reservoir

k: Rocktypes:  J value vs. Sw trends help reveal separate rocktypes

k: Rocktypes: Log linear J Function plot, two trends.    Air/mercury data

k: Rocktypes: Porosity-perm trend disturbed by diagenetic leaching

k: Are Geo.Facies Useful for klog?

c:\data\courses\zzSTAR.avi Click to play

k: Permeability indicators, ranked

k: Log Integration for Permeability

k: Quick Look Permeability from cheap logs

k: Summary of Quick Look Perm. contd.

k: The ability of Sw to predict k exceeds Ø  Same core plugs.  (N.Sea cap.pres.data)

k: kair from log derived Ø & Sw irreducible, Chart K4

k: MICROPRACTICAL

Hydrocarbon Pore Volume indicates permeability Chart K-4

k: Advantages of HPV & Sw for klog

k:  klog = f.(vsh, Ø, Sw)

END DAY 4

 

Day4 Recap, Questions, Debate

k: Magnetic Resonance, kmr

k: Timur Coates permeability equation

k: Understanding Bound Fluid Volume BFV and logs

k: Timur Coates adds what’s missing in Ø-k transforms

k: TimurCoates equation vs Core

k: Does your RE need stressed kbrine or kair? Ask

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 and P90 versions and Linear kg-kw

Reviewers of Petrophysical Results:

Check Permeability

 

Recommended Evaluation Sequence

 

NET & NETPAY

 

Net: What is Netpay?

Net: Net Importance

Net: Accurately determining the Net cutoff can be crucial …

Net: ‘Net’ yields fluids

Net: Gross Ratio Problems

Net: Rt imported from Twin-well (200ft away) shows Water-flood Above and Below 1mD

Net: Depletion below 1mD = Net (RFTs)

Net: Strong Relationship Between Movable Oil Saturation after Water Flood and Permeability  indicating  Zero Movable Oil at 0.2mD

Misleading Data: How not to acquire SCAL data.

Exclusively high permeability samples create bias and preclude trends

Net: MICROPRACTICAL

Relative Perm data demonstrates the Netpay permeability cutoff

Net:  Core Fluorescence, Conventional Core and Well Tests

Net: Logs = non-pay or marginal, core = pay: Tested 11mmscfpd. This facies 35% Bulk Rock Vol.

Net: NMR locates movable fluids and delineates netpay in laminated shaly sands (low contrast pay)

Net: Invasion Profiles for Netpay

What is Netpay? Microlog indicates permeability, Vsh does not

Net: Netpay from Evaluated Sw, Ø, Vsh

Net: Log and Non-log Netpay, Netrock Indicators, ranked

Net: Why Permeability as Cut-off criteria ?

Net: PASS FLUIDS measured by Vclay – No!

Net: PASS FLUIDS measured by Porosity – No!

Net: PASS FLUIDS measured by Sh – better

Net: PASS FLUIDS measured by k – YES

Net: When Should Netrock be defined?

Net: Summary of Suggested Netpay / Netrock Method

Reviewers of Petrophysical Results:

Check Netpay

 

GEO-MODEL INPUT

 

Sensitivity Studies indicate what data to acquire and where to focus effort

Geo-model: Input Uncertainties – strictly petrophysical

Geo-model: Field Petrophysical Reference – The Results Table

c:\data\courses\zzXMAC.avi Click to play

Geo-model: Input Display:

How much oil does each well have and how permeable?

Geo-model: A Consistent Geo.model

Geo-model: Imagine your reservoir as a road cutting..

Geo-model: Checksums

Ensure EHC & kh are equal at all scales

Reviewers of Petrophysical Results:

10 Systematic errors which ruin your

geo.models (chronological)

Break for Lunch, continue Evaluation Recs after

 

Day5 Recap, Questions, Debate

 

RESISTIVITY CASE HISTORY (PhD)

 

Schematic of Problem Well A

Well A’s Sw logs profile suggests unacceptably complex capillary pressures

Well A Formation Fluid Pressures from FITs and DSTs

Petrophysical definition of conglomerate clast

Influence of Vclast on F, (Ro/Rw)

Why does this plot miss the point?

Well A: Key Findings1

Well A: Key Findings2

And the answer is …

THE END

 

BACKUP

 

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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