1.11.2.overviewintroduction

FORMATION EVALUATION Đánh giá thành hệ, đặc tính vật lý - thạch học và đá chứa

11/7/2020

Faculty of Geology & Petroleum Engineering - HCMUT

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1. Overview and Introduction 1.1. Outline & Course Information

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Faculty of Geology & Petroleum Engineering - HCMUT

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Content

Introduction to formation evaluation methodology. At the end of this course, students should be able to determine rock and fluid properties, and evaluate petroleum-bearing formations, using coring and core analysis, rock catalogs, mud logging, and drill stem and wireline formation testing.

Course Description:

The purpose of this theoretical and practical course is to introduce petrophysical and transport properties of rocks, methods of their determination in lab from cores and in oilfields from wireline logging. This course gives abilities to determine main rock properties in lab and practical understanding of the interpretation of wire line tools and techniques, open and cased hole log analysis methods for the determination of lithology, porosity, fluid content and movement, and net pay. Both, qualitative (quick look) and quantitative analyses methods are covered. Practical examples are used throughout and case histories are used to demonstrate specific aspects. Several laboratory works are performed for coring with determination of rock properties. 11/7/2020

Faculty of Geology & Petroleum Engineering - HCMUT

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Course learning outcomes

 Describe different rock properties such as porosity and permeability based on basic definition.  Measure porosity and permeability of different rocks in Laboratory.  Identify the physics of logging tools.  Interpret individual wire-line log data.  Interpret different wire-line log data by cross-plotting.  Calculate hydrocarbon-in-place based on formation evaluation interpretation.  Define the fundamentals of special core analysis such as capillary pressure and relative permeability.  The physio-technology application of special core analysis.

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Faculty of Geology & Petroleum Engineering - HCMUT

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Course Structure

1. Formation Evaluation Introduction

6. Formation Evaluation by Wireline Logs

2. Reservoir description

6.1. Rock Catalogs

3. Mudlogging

6.2. Synergistic Formation Evaluation 6.3. Clean Formation Evaluation

4. Rock Properties 4.1. Coring and Core Analysis 4.2. Fundamental Rock Properties 4.3. Tour of Core Analysis Laboratory 5. Formation Testing 3.1. Wireline Formation Testing 5.2. Drill Stem Test (DST)

6.4. Mineral Logging Parameters 6.5. Porosity–Lithology Techniques

Crossplots

Quick

Look

6.6. Shaly Sand Evaluation 6.6. Prediction of Productivity 6.8. Nuclear Magnetic Resonance Logs 6.9. Computed Logs 6.10. Formation Evaluation through Casing 6.11. Design of Evaluation Programs 6.12. Log Quality

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Faculty of Geology & Petroleum Engineering - HCMUT

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Assessment

•Overall Purpose –to encourage you to revise, learn, read more broadly –to test your understanding and learning - not just your ability to recall (that is assumed) •Assessment Summary –The course will be assessed with a weighting of •10% in-class tests, •10% assignments, •10% practical project, •20% middle exam, •50% final exam. 11/7/2020

Faculty of Geology & Petroleum Engineering - HCMUT

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Assessment

•In-class tests, –mainly for illustration/practice of final exam style Questions –provide some timely feedback on how you go with them •There will be 2 in-term tests that will count towards the final assessment. Dates of the in-term tests will be given via MyUni two weeks in advance. Approximate schedules are –5th week –9th week •There are 3 assignments. •Alternative test dates for students who cannot be present on the date of the test on medical and compassionate grounds can be requested through the Course Coordinator. 11/7/2020

Thai Ba Ngoc – Faculty of Geology & Petroleum Engineering - HCMUT

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Useful Text 1. Fundamentals of Formation Evaluation, Donald P.Helander, 1983 2. Heriot Watt University - Formation Evaluation, 2008 3. Basic Well Logging and Formation Evaluation, Prof. Jurgen Schon, 2015 4. Formation evaluation UTM, 2013. 5. Openhole Log Analysis and Formation Evaluation, SPE, 2012 6. Well Logging and Formation Evaluation, Toby Darling, 2005 11/7/2020

Faculty of Geology & Petroleum Engineering - HCMUT

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ENJOY IT !

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1. Overview and Introduction 1.2. Introduction to Formation Evaluation

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DEFINITION

Formation Evaluation is the analysis and interpretation of well log data, drill stem tests, etc. in terms of the nature of the formations and their fluid content

OBJECTIVES

The objectives of Formation Evaluation are: • To ascertain if commercially producible hydrocarbons • are present, • To determine the best means for their recovery, • To derive lithology and other information on formation characteristics for use in further exploration and development.

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Faculty of Geology & Petroleum Engineering - HCMUT

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1.2.Formation Evaluation Introduction What is Formation Evaluation? • Formation Evaluation (FE) is the process of interpreting a combination of measurements taken inside a wellbore to detect and quantify oil and gas reserves in the rock adjacent to the well. FE data can be gathered with wireline logging instruments or logging-whiledrilling tools • Study of the physical properties of rocks and the fluids contained within them. • Data are organized and interpreted by depth and represented on a graph called a log (a record of information about the formations through which a well has been drilled). 11/7/2020

Faculty of Geology & Petroleum Engineering - HCMUT

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1.2.Formation Evaluation Introduction Why Formation Evaluation? • To evaluate hydrocarbons reservoirs and predict oil recovery. • To provide the reservoir engineers with the formation’s geological and physical parameters necessary for the construction of a fluidflow model of the reservoir. • Measurement of in situ formation fluid pressure and acquisition of formation fluid samples. • In petroleum exploration and development, formation evaluation is used to determine the ability of a borehole to produce petroleum. 11/7/2020

Faculty of Geology & Petroleum Engineering - HCMUT

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1.Formation Evaluation Introduction The E&P process

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FE Technologies • Surface Logging • Well Logging • Coring • Formation Testing • Well Testing Disciplines • Geosciences • Drilling • Production (feasibility) • Reserve evaluation

FE Technologies • Surface Logging • Well Logging • Coring • Formation Testing • Well Testing Disciplines • Geosciences • Drilling • Reservoir Engineering • Production (design) • Reserve certification

FE Technologies • CH Logging • Reservoir Monitoring & Surveillance Disciplines • Geosciences • Drilling • Reservoir Engineering • Production (optimization)

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1.2.Formation Evaluation Introduction Formation Evaluation Process

Main steps of the process are:

• Planning of the well data acquisition, • Acquisition phase with quality control, • Pre and/or post processing, • Interpretation, • Integration.

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1.Formation Evaluation Introduction Pressure analysis

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1.2.Formation Evaluation Introduction GEOSTEERING The intentional directional control of a well based on the results of downhole geological logging measurements rather than three-dimensional targets in space, usually to keep a directional well bore within a pay zone. In mature areas, geosteering may be used to keep a well bore in a particular section of a reservoir to minimize gas or water breakthrough and maximize economic production from the well 11/7/2020

Faculty of Geology & Petroleum Engineering - HCMUT

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1.Formation Evaluation Introduction Interpretation/Integration Integrated interpretation of well data can strongly reduce uncertainties in Formation Evaluation and in Reservoir Characterization studies. Integration is a combination and coordination of separate and diverse elements or units into a more complex or harmonious whole. Since it implies the creation of a more complete or harmonious whole, integration can therefore be considered as a process whereby extra value is produced. (Integrated Reservoir Studies – Luca Cosentino – Edition TECHNIP - IFP)

Extra value gained through integration can be expressed either in more complex but verified geological models or as a higher reliability in a simplified but stable model. 11/7/2020

Input Geological Model Res.Modeler, Res.Engineer, Geologist SCAL, PC, Kr, Phi & k, Sw logs, Rock Types

Output Interpretati on

Upscaled model

Kr & Pc model

Res.Engineer, Geologist, Petrophysicist PVT data

Oil characteristics

Res.Engineer Contacts, MDT/RFT Petrophysicist, Geologist, Res.Engineer

Fluid Regions

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GOALS OF FORMATION EVALUATION

To evaluate the presence or absence of commercial quantities of hydrocarbons in formations penetrated by, or lying near, the wellbore.  To determine the static and dynamic characteristics of productive reservoirs.  To detect small quantities of hydrocarbon which nevertheless may be very significant from an exploration standpoint.  To provide a comparison of an interval in one well to the correlative interval in another well 

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Methods     

Mud logging Coring Wireline Logging Testing Sampling

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Mud Log • Immediate interpretation of what the drill bit has penetrated and whether there are any hydrocarbons present (a show). • Making maps of the subsurface geology.

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Coring - Conventional • Taking a core requires that the regular drill bit be removed from the hole. It is replaced with a "core bit", which is capable of grinding out and retrieving the heavy cylinder of rock. • The core bit is usually coated with small, sharp diamonds that can grind through the hardest rock. A core bit cuts very slowly. • A core is a solid cylinder of rock about 4-5 inches in diameter, and a single core will usually be about 30 feet long.

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Faculty of Geology & Petroleum Engineering - HCMUT

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Coring - Conventional

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Slab Core- HCMUT Faculty of Geology & Petroleum Engineering Whole Core

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Coring - Sidewall • This method is cheaper than the conventional coring. • Cores can be taken in hours, instead of days. • In sidewall coring, a slim wireline coring tool is run into the hole. The tool may be of two general types; either "rotary sidewall" or "percussion". • Typically, cores about 1" in diameter and 1" to 2" long can be retrieved with this method.

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Faculty of Geology & Petroleum Engineering - HCMUT

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Coring - Sidewall

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Coring - Sidewall

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Faculty of Geology & Petroleum Engineering - HCMUT

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INTRODUCTION LOGGING?

-

WHAT

• In situ meas. (vs. depth) of • Rock properties • Fluid properties • When • Openhole (before casing) • While drilling (LWD / MWD) • After drilling (wireline) • Cased hole • Interpretation for • Geological properties • Petrophysical properties • Production properties 11/7/2020

IS

Casing

Open hole

Baker-Atlas

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VALUE AND LIMITATIONS OF WELL LOG DATA Strengths • Provides remotely sensed values of reservoir properties and fluids • Among the most abundant reservoir data • Presentation results fairly well standardized • Allows evaluation of lateral (map) and vertical (cross section) changes in reservoir properties and fluids Limitations • Indirect measurements • Vertical resolution • Depth of investigation 11/7/2020

Faculty of Geology & Petroleum Engineering - HCMUT

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OPEN HOLE LOGGING MEASUREMENTS

• Active • Acoustic - ∆tc, ∆ts, Ac, As • Nuclear - ρb, φN, Pe, τ1, τ2 • Electromagnetic - R, tPL, EATT 11/7/2020

LOGGING TOOL

• Passive • Caliper • Gamma Ray • Spontaneous Potential (SP)

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CASED HOLE LOGGING MEASUREMENTS • Passive • Gamma Ray • Temperature • Flow Velocity • Caliper • Active • Acoustic • Nuclear • Electromagnetic • Mechanical 11/7/2020

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SOME QUESTIONS ADDRESSED BY LOG INTERPRETATION • Geophysicist / Geologist • Are the tops as predicted? • Are potential zones porous? • Formation intervals? • Lithology? • Hydrocarbons? • What type of hydrocarbons? • Commercial quantities?

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• Reservoir Engineer • How thick is the pay zone? • How homogeneous is the zone? • Porosity? • Permeability? • Production Engineer • Which zone(s) to complete? • What production rates? • Any water production? • Is zone hydraulically isolated? • Will well need stimulation? • What stimulation would be best?

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WHAT DOES AN OPEN HOLE LOG COST? IT DEPENDS ON... • Well type • Vertical/Deviated • Deep/Shallow • Hot/Normal • Measurements • Depth charge • Survey charge • Time / location / special procedures • Land/offshore • Service charge • Equipment availability • Rig time • Wireline/LWD 11/7/2020

Faculty of Geology & Petroleum Engineering - HCMUT

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TYPICAL OPEN HOLE WIRELINE COSTS Land Service Charge

$6-10K

$1-3K

Depth Charge (per msmt-foot)

30-50¢

50-100¢

Survey Charge

30-50¢

50-100¢

Rig Time

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Offshore

$4K/day

$12-25K/day jack-up $100K+/day floater

Faculty of Geology & Petroleum Engineering - HCMUT

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LOGGING IS COMPARITIVELY INEXPENSIVE! Vertical Land Well Costs

Trouble 15%

Misc. 7%

Wireline Logging 8%

Mud 20%

Rig Time 25% Steel 25%

Total cost to drill a well: $75 to $200 per foot! 11/7/2020

Faculty of Geology & Petroleum Engineering - HCMUT

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WIRELINE LOGGING EQUIPMENT

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DETAILS OF WIRELINE LOGGING RIGUP

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Modified from Halliburton (EL-1007)

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LOGGING CABLE

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LOG PRESENTATION - THE HEADING • Well location 

Depth references



Date of log



Well depth



Casing shoe depth



Bit size



Mud data



Type  Properties  Resistivities Max. Temperature 

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LOG PRESENTATION - LINEAR GRID Track 1

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Depth track

Track 2

Track 3

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LOG PRESENTATION - LOG GRID Track 1

Depth track

Track 2

n

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2x10

Track 3

n+4

2x10

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LOG PRESENTATION - HYBRID GRID Track 1

Depth track

Track 3

Track 2

n

2x10

n+2

2x10

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LOG PRESENTATION - COMMON DEPTH SCALES • Correlation • 1:500 or 1:1000 • 2 in. (1:600) or 1 in. (1:1200) • Heavy lines every 100 ft. or 50m • Light lines each 10ft or 5m • Routine • 1:200 or 1:240 (5 in) • Heavy lines every 50 ft. or 5 m • Medium lines each 10 ft. or 5 m • Light lines each 2 ft or 1 m

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CHOOSING A LOGGING TOOL It is necessary to choose the right tool to get the desired measurement. Considerations: • Type of well ( wildcat or development ) • Hole conditions ( depth, deviation, hole size, mud type ) Examples: • Oil based mud : Induction tool • Water based salty mud : Laterolog Tool • Formation fluid content (fresh/salt connate water) • Economics (cost of the job, rig time involved)

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Faculty of Geology & Petroleum Engineering - HCMUT

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TYPES OF LOGS TO BE RUN • Logging suites generally include one resistivity and one porosity device • The logging string will also have other tools like the gamma ray, SP and caliper tools • However, logging suites usually have two porosity devices to give more information about rock type, hydrocarbon type and porosity • Other considerations – to estimate permeability or to take fluid samples – require other special tools like the formation testers

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Faculty of Geology & Petroleum Engineering - HCMUT

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NOMENCLATURE FOR ZONES IN AND AROUND THE BOREHOLE

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Modified from Halliburton (EL-1007)

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TOOL CALIBRATIONS • A logging tool collects data that are converted to porosity, resistivity, and other values • Each tool is calibrated to an industry standard • This ensures that each tool, irrespective of the type of tool or tool history or service company, reads the same value when logging the same formation (normalization may still be required between log) • Check tool calibrations before and after a logging job to ensure good quality log data 11/7/2020

Faculty of Geology & Petroleum Engineering - HCMUT

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LOG QUALITY CONTROL • Check all calibrations before and after job • Record a repeat section of about 200 ft to ensure validity of data and to explain abnormal curve response • Compare log response with offset well logs • Keep hole conditions (hole size, mud type, tool centralization) in mind when interpreting log data • Ensure that logging speeds are as recommended by the service company.

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Faculty of Geology & Petroleum Engineering - HCMUT

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DRILLING DISTURBS FORMATION • Drilling and rock crushing  Damage zone • Mud systems and invasion  Oil based mud Small conductivity mud Damaged zone Shallow invasion Thin cake  Water based mud Moderate to very conductive mud Shallow to deep invasion Thin to thick cake 11/7/2020

Mudcake

Invading filtrate

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MUD FILTRATE INVASION Invaded Zone (Rxo)

Uninvaded Zone (Rt)

Wellbore Mud (Rm)

Uninvaded Zone (Rt)

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Mud Cake (Rmc)

Modified from J. Jensen, PETE 321 Lecture Notes

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COMMON TERMINOLOGY Borehole Rm : Borehole mud resistivity Rmc : Mudcake resistivity Invaded zone Rmf : Mud filtrate resistivity Rxo : Invaded zone resistivity Sxo : Invaded zone water saturation Uninvaded zone Rw : Interstitial water resistivity Rt : Uninvaded zone resistivity Sw : Uninvaded zone water saturation 11/7/2020

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PASSIVE MEASUREMENTS • Caliper • Spontaneous Potential • Gamma Ray • Natural • Spectral

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CALIPERS • Uses • • • •

Hole volume Mudcake (permeability) Tool corrections Crude lithology indicator

• Properties

• two, three, or four arms • linked or independent

• Calipers may disagree (limitations) • non-circular hole • deviated wells

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THE SP TOOL SHALE

SAND

• One electrode • Insulators on either side • Surface ground electrode – at a stable potential

SHALE 11/7/2020

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REVERSED SP

5

TYPICAL SP RESPONSES

(+)

4

3

1

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NORMAL SP

2 (-)

– BASED ON THE DIFFERENCE BETWEEN Rw and Rmf. 1.

Rmf >> Rw - Amplitude large and negative

2.

Rmf > Rw - Amplitude negative but not large

3.

Rmf = Rw

4.

Rmf < Rw - Amplitude positive but not large

- No SP deflection

5. Rmf << Rw - Amplitude large and positive

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GAMMA RAY LOGS • Correlation • Lithology indicator; exploration for radioactive materials • Evaluation of shale content • Paleoenvironmental indicator • Open or cased hole; any fluids • Fracture detection

• Properties

Rock Formations

GR Tool

• Uses

• Measures natural gamma radiation • random fluctuations

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GR RESPONSE IN COMMON FORMATIONS 0

• Shales often radioactive

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100 API units

Shaly sand

• Clays • Trace and heavy minerals

• Sandstones may be radioactive

• Non-clay minerals, e.g., mica, feldspar • Clays

• Units

• GR calibrated to standard • Response in “mid-continent shale” equals 200 API units • Calibration pits

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Shale Very shaly sand Clean limestone Dolomite Shale Clean sand Coal Shaly sand Anhydrite Salt Gypsum

Volcanic ash

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PASSIVE LOG CORRELATION • GR, SP, and CAL

• often correlate • different measurements • different reasons

• Correlation helps

• GR instead of SP in OBM • Easier detection of shales • Facilitates “zonation”

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POROSITY TOOLS • Sonic (acoustic) • Density • Neutron

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SONIC PRINCIPLE

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Ray, 2002

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FAMILY OF NUCLEAR TOOLS GR

Particle

Neutrons

Source

Natural GR

Emitted GR

Emitted Neutrons

Application

Shaliness Correlation

Porosity Density Lithology

Porosity Gas Oil

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GR tools

Density tools

Neutron tool

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DENSITY & POROSITY MEASUREMENTS COMPENSATED DENSITY LOG

• Uses – Density – Porosity – Lithology 63 • Curves – Bulk density (ρb and ∆ρ) – Pe

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From Halliburton (EL – 1007)

ρe

φD

ρb

ρc

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DENSITY PRINCIPLE • Detect GR’s from the source which have been scattered back by the formation Formation Hydraulic sonde

Caliper arm

Skid

Low Density Windows Stabilizer

Cesium Source

Detectors Gamma rays

Near Detector

Gamma ray Tungsten emitting source Shield 11/7/2020

Tungsten Bore Liner

Far Detector

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PRINCIPLE • Gamma rays emitted from radioactive source • Gamma rays collide with electrons in formation, losing energy • Detectors measure intensity of backscattered gamma rays • High energy GR relate to - Density • Low energy GR relate to - Lithology

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NEUTRON LOGS Uses of neutron logs • Identify porous zones • Determine porosity • Identify gas in porous zones Where neutron logs can be used • Any borehole • Open or cased • Liquid- or air-filled

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Depth of investigation • 6-12 inches for CN

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NEUTRON MEASUREMENT ρb

• Uses

• Lithology Porosity

Pe

φN

∆ρ

• Curve φN

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NEUTRON TOOL PRINCIPLE • Source AmBe 15-20Cu 5MeV

• Detects neutrons from the source which have been scattered back by the formation 11/7/2020

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•The neutron tool employs a dual detector design to compensate for mudcake, lithology, etc. •Still, corrections are required for the NPHI values •NOTE : The tool is pressed against the borehole wall to minimize mud effects 11/7/2020

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LIFE OF A NEUTRON - 1 • Neutrons emitted from source • Neutrons interact with Hydrogen in formation • Neutrons loose energy • Neutrons are absorbed or reflected back to detectors

• High counts = Low porosity • Low counts = High porosity 11/7/2020

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LIFE OF A NEUTRON - 2 •

•

•

•

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Source AmBe 15-20Cu 5MeV neutrons Collisions cause neutrons to lose energy Energy loss due mainly to hydrogen Therefore tool measures amount of hydrogen in formation, ie., water, oil 71

NEUTRON SCATTERING

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Energy transfer to the nucleus is a maximum if the collision is head-on and the nucleus has the same mass as the neutron. The only atom that has the same mass as a neutron is hydrogen.

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Thermal Neutrons • The neutron tool responds primarily to the presence of hydrogen • The more hydrogen, more neutrons slowed to the thermal level and captured by the formation • Other minerals also have a small effect on the neutron tool, which requires compensation

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RESISTIVITY Resistivity • The voltage required to cause one amp to pass through a cube having a face area of one square meter • Units are ohm-m 2 / m; usually ohm-m (Ω.m)

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𝟏𝟏 Resistivity = Conductivity

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RESISTIVITY – DEFINITION OF THE OHM-METER

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From Halliburton (EL 1007)

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RESISTIVITY OF EARTH MATERIALS 𝟏𝟏 Resistivity = Conductivity

Increasing Resistivity

(2) Gas

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(3) Oil (4) Fresh Water (5) Salt Water

Increasing Conductivity

(1) Rock

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FACTOR AFFECTING RESISTIVITY • Resistivity of water • Porosity of the formation, • Pore geometry - tortuosity • Lithology of the formation • Degree of cementation, and • Type and amount of clay in the rock From J. Jensen, PETE 321 Lecture Notes

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Rock containing pores saturated with water and hydrocarbons Non-shaly rock, 100% saturated with water having resistivity, Rw

Rt φ= 20% Sw = 20%

Cube of water having resistivity, Rw

Ro

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(1) (2) (3) (4) (5)

Rock Gas Oil Fresh Water Salt Water

Rw φ= 100% Sw = 100%

Increasing Conductivity

Increasing Resistivity

φ= 20% Sw = 100%

F = Ro

Rw

=

a

φm

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