production logging...

Production Logging Core

Learning Objectives

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

Present the principles of cased‐hole evaluation tools

Present typical applications and justification forrunning cased‐hole evaluation tools

Present conveyance methods for running cased‐hole evaluation tools in the field

Objectives and Domain of Application

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Production Logging Core ═══════════════════════════════════════════════════════════════════════════════════

©PetroSkills, LLC. All Rights Reserved. _________________________________________________________________________________________________________

1

Section Overview

From a few basic sensors, production logging tools have evolvedto a family of tools each with sensors designed to makemeasurements that, once interpreted together, provide accurateflow rates estimates for multiphase flow and determine preciselywhere the various fluids are entering (or exiting) the borehole.

As well trajectories continue to grow in complexity, progressingfrom vertical to deviated and horizontal and introducing newchallenges in completion design and flow assurance, thedevelopment of new production logging technologies has helpedfor the understanding of downhole completion efficiency.

Production Logging Introduction

Logs are run after the well is completed.• Surface flow measurements are usually not adequate to assess the

efficiency of the downhole production or injection system.• Logs are run in order to acquire a range of downhole

measurements.• Usually, requested and analyzed by Production Engineers.

Purpose is to diagnose well integrity and evaluate fluid flowinside and (possibly) outside the pipe along the well path.

• Most common application of production logging is to obtain thedownhole well flow profile and measurement of fluid flowdistribution.

• Numerous other applications, such as the detection and evaluationof tubing leaks and channels behind casing.

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Also Referred to as Cased Hole Logging

Performed in production (or injection) wells

Usually performed in cased and cemented hole or in slotted liner, screen and gravel pack wells

Intrusive well data acquisition with or without a rig on location

Timing of Well Log Acquisition

Cased Hole Logging

Perforation Evaluation Cement and Corrosion EvaluationProduction LoggingSaturation Monitoring

Workover / Rigless

ResistivityDensity, PorositySonicLithologyFormation Pressure TestingFluid SamplingSeismic Walkaway LogsBorehole ImagingNuclear Magnetic ResonanceCoring

Drilling Rig

OH Logging LWD

OH Logging LWDCH Logging or OH Logging/LWD

Production Logging Investigation – Examples

Evaluation of each layer contribution (CPI*)

Layer 1

Layer 2

Layer 3

Well “A”

* Computer Processed Interpretation

Water

Oil

GasCOPYRIGHT



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Evaluation of each layer contribution

Identification of possible cross-flow (CPI)Depth

m

3960

3970

3980

3990

4000

4010

4020

4030

4040

4050

4060

4070

4080

4090

4100

GR

GAPI-5 60

Z FLOW

rps-6. 8

In terp re ta t ion # 1TEMP 98si,I1 [°C]35 100

PPR E 98si, I1 [ba r]

Ve loc ity matc hVAPP 98si,I1 [m/ min]-6. 14

. . .

QZ T

m3/ D-20 280

QZ I

m3/ D-200 120

Q

m3/ D-150 350

Layer 1

Layer 2

Layer 3

Well “B”

Negative flowfrom layers 1 & 2,

back intodepleted reservoir

(thief zone)



Identification of possible cross-flow

Determination of water (gas) breakthroughDepth

m

3400

Z GR

GAPI0 2800

SPIN

rps-30 30

W PRE

bara122 138

W TEP

°C128 132

Density matchWFDE ,I1 [g/ cc]

. ..

Veloc ity matc h..... .

QZT

B/ D-1000 9000

QZI

B/ D-500 5000 Well “C”

Gas breakthrough from this layer

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Identification of possible cross-flow

Determination of water (gas) breakthrough

Mechanical well condition diagnosis

Channeled Cement

Channel

Water

Sand

OilSand

Tubing, Casing, Packer Leaks

Cracks

Water

Sand

OilSand

Blast Joint Leak

Gas

Sand

Oil

Sand

Thief Zone

Oil

Sand

Oil(Low

Pressure)

High speed digital wirelinetelemetry technology is utilizedto transmit data for real timedata acquisition

Adapted to instant interpretationand troubleshooting

Sensor data is stored on non-volatile flash memory until it is downloaded at the surface

Intelligent memory tools run byslick line

Do not require engineer atsurface

Production Logging Tools Conveyance: SRO & MPLT

Surface Read Out (SRO) Memory PLT (MPLT)

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Injector Head

Riser

BOP

CT Reel

To Logging Cabin

Cable

Logging Tool

Coiled Tubing

Production Logging Tools Conveyance: Coiled Tubing

Coiled Tubing Advantages:

1. All conventional tool combinations and services may be run on the coiled tubing logging string.

2. Continuous data recording is possible while running in and logging out of the borehole.

3. Mud treatment or formation stimulation can be undertaken through the coiled tubing, while the logging tools are in the well, allowing the in-situ evaluation of treatments to take place.

Production Logging Tools Conveyance: Tractor

Courtesy Welltec

Connects to the wireline through mono or multi cable heads

Top Connector

Wheel Sections

Wheel sections can be optimized to maximize speed or traction

Connects to the mono or multi line logging tools below the Well Tracker

Bottom Connector

Electrical tools used to push the tool string into hole, overcoming wireline's disadvantage of being gravity dependent.

Engineered to be used in high-angle and horizontal wells to deploy downhole tools previously conveyed by coiled tubing or drillpipe.

Intelligent tractors can be run through complex completions and long horizontal sections.

Permits well data to be acquired during downward, as well as upward, passes.

Automatically monitored and controlled from surface so it achieves much greater flexibility than traditional systems.

Used to convey logging and perforating tools or to gather detailed information about downhole conditions.

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Wire Line Lubricator and Surface Equipment

1

2

3

4

5 6

78

9

14

1110

12

13

Surface Equipment1. Wireline Stuffing Box2. Upper Section3. Quick Union4. Rope Blocks5. Telescoping Gin Pole6. Middle Section7. Lower Section8. Bleed‐Off Valve9. Wireline Valve10. Wireline Pulley11. Swage (Tree Connection)12. Weight Indicator13. Load Binder and Chains14. Wellhead Adapter

The logging tools string assembly is run by slick line into the well through a well extension called a lubricator.

The lubricator is assembled from 8-foot sections of heavy-wall tube generally constructed with integral seals and connections.

The top of the lubricator assembly includes a high-pressure grease-injection section and sealing elements.

Lubricator installed on top of tree & tested

Tools placed in lubricator

Lubricator pressurized to wellbore pressure

Top valve of christmas tree opened to enable tools to fall or be pumped into wellbore under pressure

Lubricator sections are routinely used on the assembly of pressure-control equipment for other well intervention operations, such as

coiled tubing.

(a)Tool

closed

Tubing

Casing

Spinner shaft

Centralizer arms

Spinner Blade

Protective centralizer

cage

(b)Tool open

Composite Production Logging Tool Geometry

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(a)Tool

closed

Tubing

Casing

Spinner shaft

Centralizer arms

Spinner Blade

Protective centralizer

cage

(b)Tool open

Wells with surface pressure typically have a completion tubing of relatively small internal diameter ID, compared to the casing size across the reservoir.

Cased hole toolstrings for live wells are

typically sized at 1-11/16" (42.9 mm) in order to pass through the smallest nipple

in a 2-3/8" (60.3 mm) tubing. The configuration of the tool string is determined from the objectives of the logging program and the composite Production Logging Tool (PLT) is assembled from various tools according to specific local needs.

The tool string is run in collapsed condition through tubing and opens to full operational configuration when reaching full casing diameter below mule shoe.

Composite Production Logging Tool Geometry

(6.9

)

(13.

8)

(20.

7)

(27.

6)

(34.

5)

(41.

4)

(48.

3)

(55.

2)

(62.

1)

(69.

0)

(mPa)

(18)

(36)

(54)

(73)

(91)

(109)

(127)

(145)

(163)

(181)

(200)

(218)

(236)

(254)

(272)

(290)

(308)

(kg

)

(0.32 cm)

(0.25 cm)

(0.23 cm)

(0.21 cm)

(0.18 cm)

Wire Line Lubricator Height Adjustment

Lubricator length should account for additional sinker bars allowing downward movement of the logging string.

Examples:

0.092" (2.3 cm) OD wire2000 psi WHP → 25 lbs min

(11 kg)

3/16" (.48 cm) OD braided wire2000 psi (13.8 mPa) WHP → 75 lbs min

(34 kg)

Note: Sinker bar weight given is at balance point. Add weight as desired to obtain downward movement.

Note: Sinker bar weight given is at balance point. Add weight as desired to obtain downward movement.

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General Production Logging Guidelines

Need prognosis with detailed well schematic

Need team effort between operator and servicecontractor

Appropriate well pressure control equipment defined

Need company representative always on location

Need measurement checks with corrected depths

Agree on findings, write down, discuss, concur

Put together clues to develop answers

Issue recommendations from log findings

• Summaries of wellcompletion details

• Full productionhistory

• All open hole logs• PVT data

Forward planning will ensure maximum long term use of log data.

General Production Logging Guidelines

Agree on findings, write down, discuss, concur

Why the logging is undertaken Previous production-logging summary Current well-completion data with a wellbore sketch Collars used for perforation Depth reference point Most recent well-test data Anticipated total depth, bottom hole pressure, and temperature

A second form completed at the time of logging lists: Logs run and their order Run number String logged and its status for each run Status of other strings or annuli Logging direction and speed Tool calibration checks Intervals where re-runs were logged

A good rule is to prepare a preliminary summary that specifies:

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Quality control is paramount, and careful attention must be focused upon three parts of the logging operation:

1. Procedure 2. Tool calibration3. Depth control

There are three pervasive myths about Production Logging:

A production log can be run by anyone1

Misconceptions About Production Logging

NO !

Just like open hole logging tools, production logging tools should be run in complementing suites so that one log can be compared with another.

It is rare that a single log identifies a problem sufficiently to prescribe a remedial action.


Only one logging tool is needed2


NO !

A production log can be run by anyone1 NO !

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Production Logging devices are measuring parameters which do not provide immediate concrete answers to specific questions.

Information derived from one log is usually reinforced by another log. The assembly of all information generates the value of the final data.

The answer (anomaly) will jump out from a casual scan of the log3


NO !



NO !

NO !


Experience with specific devices in specific areas is an important factor for effective analysis.

1. Select the proper combination of tools.2. Establish a relevant operating procedure.3. Monitor data quality.4. Interpret results.



NO !



NO !

NO !

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Production Logging devices are measuring parameters which do not provide immediate concrete answers to specific questions.

Information derived from one log is usually reinforced by another log. The assembly of all information generates the value of the final data.

Just like open hole logging tools, production logging tools should be run in complementing suites so that one log can be compared with another.

It is rare that a single log identifies a problem sufficiently to prescribe a remedial action.

Quality control is paramount, and careful attention must be focused upon three parts of the logging operation:

1. Procedure 2. Tool calibration3. Depth control


Experience with specific devices in specific areas is an important factor for effective analysis.

1. Select the proper combination of tools.2. Establish a relevant operating procedure.3. Monitor data quality.4. Interpret results.





NO !

NO !

NO !Through the next presentations, we will show how the diagnosis of individual well production issues is dependent on understanding tools characteristics, their selection and log interpretation.

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(6.9)

(13.8)

(20.7)

(27.6)

(34.5)

(41.4)

(48.3)

(55.2)

(62.1)

(69.0)

(mPa)

(18)

(36)

(54)

(73)

(91)

(109)

(127)

(145)

(163)

(181)

(200)

(218)

(236)

(254)

(272)

(290)

(308)

(kg)

(0.32 cm)

(0.25 cm)

(0.23 cm)

(0.21 cm)

(0.18 cm)

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Downhole Production Logging Tools

Production Logging Core

Learning Objectives

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

Demonstrate the principles and operation of the logging toolsassociated with flowmeter tools

Demonstrate the principles and operation of the basic temperaturelogs

Demonstrate the principles and operation of basic radioactivetracer logs

Discuss the added value of running a downhole video log inaddition to production logs

Present the principles and operation of basic spinner flowmeterlogs

Present the principles and operation of the gradiomanometer log

Illustrate the performance of cased hole logs in single phase flow

Understand the interest of running multiple tools within aProduction Combination Tool

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Major Through-Tubing Cased Hole Production Tools

Casing Collar Locator Log Gamma Ray Log Caliper Noise Logs Temperature Logs Radioactive Tracer Logs Spinner Flowmeter Logs Pressure Logging Tool Gradiomanometer Logs

Not Covered

This Section

Pulsed Neutron (TDT) Logs

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Casing Collar Locator (CCL)

Permission to publish by the Society of Petroleum Engineers of AIME.Copyright 1983 SPE-AIME.

Counting Pipe Collars is a Common Application


Counting Pipe Collars is a fundamental need for depth correlation

Co

llar

loca

tor

Su

b. 2

ft (.

61

m)

Bottom magnet

Top magnet

High impedance amplifier & voltmeterCOPYRIGHT



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kvalverde

Stamp


Counting Pipe Collars is a Common Application


Counting Pipe Collars is a fundamental need for depth correlation

Co

llar

loca

tor

Su

b. 2

ft (.

61

m)

Bottom magnet

Top magnet

High impedance amplifier & voltmeter

Initially correlated in depth by using a specific open hole log (usually the Neutron-Density or Gamma Ray log)

Subsequent cased hole runs can be correlated by using only the CCL

The CCL is a short tool that is run immediately below the cable head

Requires an electrical feed through to communicate with thesensors of the remaining tools

9000'

9100'6'

9050'

Depth

(2743 m)

(2758 m)

(2774 m)(1.8 m)

A BCollar Logs

Remember: Different reading due to cable stretch

Typical Casing Collar Recorder – CCL Log


A. Running in hole

B. Pulling out of hole

Limitations

Robust and rugged instrument.

1. Flush joint casing joints may bedifficult to detect.

2. Some non-magnetic CorrosionResistant Alloy (CRA) materials willnot provide collar indications.

3. Some pipe manufacturers provide veryconsistent pipe lengths, and thus novariation in casing pipe joint length.

4. Small diameter CCL’s (centralized)may not detect collars in largediameter casing strings.

Advantages

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The Gamma Ray (GR) Tool

Gamma Ray (GR) Tool

Generally use a scintillatorcrystal and photomultiplierreceiver for maximum logquality

Log reflects the shalecontent of rocks, asradioactive elements tendto concentrate in claysand shales

“Clean” formations usuallyhave low radioactivity

At least one GR tool willbe run during the openhole logging program

• Subsequent cased holeGR logs can becorrelated to this log

The GR sonde detectormeasures gammaradiation

Gamma Ray: correlation with open hole logs• Continuously measures and records natural radioactivity in the

formations adjacent to the wellbore using radioactive decay of:– Potassium, uranium, and thorium elements

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Gamma Ray (GR) Tool

Drill Collar

Gamma Ray Detectors

Dual Detectors

Bank A Bank B

Gamma Ray: correlation with open hole logs• Continuously measures and records natural radioactivity in the

formations adjacent to the wellbore using radioactive decay of:– Potassium, uranium, and thorium elements

Gamma Ray (GR) Tool

Drill Collar

Gamma Ray Detectors

Dual Detectors

Bank A Bank B

Generally use a scintillator crystal and photomultiplier receiver for maximum log quality

Log reflects the shale content of rocks, as radioactive elements tend to concentrate in clays and shales

“Clean” formations usually have low radioactivity

At least one GR tool will be run during the open hole logging program

• Subsequent cased hole GR logs can be correlated to this log

The GR sonde detector measures gamma radiation

Main applications• Depth control for cased hole wireline operations• Precision depth correlation

– When radioactive sources have been introduced at a particular casing depth or by perforating charge

• Sometimes a Gun-GR tool is used with perforating guns

Advantages• Simple tool requiring minimal interpretation

Limitations• GR definition or variation may be low over intervals of interest,

making correlation difficult– Can be the result of poor natural variations of gamma ray strength

– Signal suppression due to sensing multiple through strings– Centralized small diameter tool inside a large casing

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The Caliper Tool

Monitors wellbore condition (open or cased hole)

After a drilling phase, caliper data are integrated to determine the volume of the open hole

Caliper offers a qualitative indication of the condition of the wellbore and the degree to which the mud system has maintained hole stability

Very useful with any Production Logging run

The caliper measurement point corresponds exactly to the measurement point of the flowmeter impeller

Caliper

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Blades

Caliper

A B

Moving caliper

arm

or multi-finger types

Caliper tool: Variable resistance

Caliper arm

Variable resistor

Blades Monitors wellbore condition (open or cased hole)





Caliper

A B

Moving caliper

arm



Caliper arm

Variable resistor

Main Applications Limitations

1. Correct the flowmeter readings for diameter variations due to either heavily scaled tubulars or differences in open hole completions

2. Locate packer seats in open hole sections

3. Determine restrictions for future tubing or casing work (workover planning)

4. The caliper data can be used independently for determining general internal corrosion, paraffin buildup, or mineral scaling

• Normal two or four arm calipers will only give general indications of corrosion and other more sophisticated tools need to be run to examine the corrosion issues furtherCOPYRIG

HT



21

Blades Monitors wellbore condition (open or cased hole)





Caliper

A B

Moving caliper

arm



Caliper arm

Variable resistor

Main Applications Limitations

1. Correct the flowmeter readings for diameter variations due to either heavily scaled tubulars or differences in open hole completions

2. Locate packer seats in open hole sections

3. Determine restrictions for future tubing or casing work (workover planning)

4. The caliper data can be used independently for determining general internal corrosion, paraffin buildup, or mineral scaling

• Normal two or four arm calipers will only give general indications of corrosion and other more sophisticated tools need to be run to examine the corrosion issues further

Multi-finger Calipers• Motorized Centralizers to ensure effective centering force

– Equipped with rollers to prevent casing and tubing damage

For cased hole logging, the caliper will give indications about: • Conditions inside the casing• Damage• Scale• Paraffin deposits

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Noise Log

• Hydrodynamic characterization of reservoirs

• Identification of production and injectionintervals

Noise Log

• Well integrity analysis

Spectral Noise Logging (SNL) is an acousticnoise-measuring technique used in oil and gaswells for:COPYRIG

HT



23

Noise Log

Spectral Noise Logging (SNL) • Records acoustic noise generated by fluid or gas flow • Tool listens passively to downhole noise such as gas bubbling up

through liquid in the wellbore– Behind pipe, a channeling flow passes through “tight spots”, which

cause higher velocities, sudden pressure reductions and significant flow turbulence

– The noise-logging tool listens for noise associated with the turbulence

• The tool includes piezoelectric crystal transducers which convert the oscillating pressure of wellbore sound to corresponding oscillating voltage

– The oscillating voltage is applied to a speaker at the surface, as well as each of four high-pass filters

• Each high-pass filter detects nothing below its filter range• Log noise filters for 200, 600, 1000 & 2000 Hz• Two-phase flow occurs at about 200 to 600 Hz• High rate single phase flow occurs above 1000 Hz• Sound is highly attenuated by gas• Tool works best for low rate gas leaks

Noise Spectrum

200

600

1,000

2,000

Differential Pressure

Single phase

Two phase

Rel

ativ

e am

plit

ud

e

Frequency, hz

Rel

ativ

e am

plit

ud

e

Frequency, hz

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Noise Spectrum

200

600

1,000

2,000

Differential Pressure

Single phase

Two phase

Rel

ativ

e am

plit

ud

e

Frequency, hz

Rel

ativ

e am

plit

ud

e

Frequency, hz

High noise amplitudes indicate locations where the flow path is submitted to turbulence

The noise log has been used as an indicator of channeling behind pipe

• Flow through channel is indicated on a noise log by the presence of high amplitude noise at places where restrictions in the channel causes throttling of fluid

Flow through a leak results in a pressure drop that generates detectable noise

Noise Log Principle

Piezoelectric Crystal

Microphone

2000

1000

600

200 HZ

5.7

14.1

27.3

55.0

Millivolts

High PassFiltersCOPYRIG

HT



25

Noise Log Principle


Microphone

2000

1000

600

200 HZ

5.7

14.1

27.3

55.0

Millivolts

High PassFilters

Filter’s output consists of positive excursions from neutral alternating with negative excursions

Amplitude is measured two ways1. Measure from peak of positive excursions to trough of following

negative excursion– “Peak to peak” amplitude

– “Standard gain” or “Standard sensitivity” recording

2. Measure from the peak of a positive excursion to neutral– “Peak” amplitude

– “One-half standard gain” recording

Noise Log Principle


Microphone

2000

1000

600

200 HZ

5.7

14.1

27.3

55.0

Millivolts

High PassFilters

Filter’s output consists of positive excursions from neutral alternating with negative excursions

Amplitude is measured two ways1. Measure from peak of positive excursions to trough of following

negative excursion– “Peak to peak” amplitude

– “Standard gain” or “Standard sensitivity” recording

2. Measure from the peak of a positive excursion to neutral– “Peak” amplitude

– “One-half standard gain” recording

Measurements• A single station measurement lasts 3 to 4 minutes• Relocating the tool requires 1 minute• Thus, the logging rate is approximately 15 stations per hour, and

a 4-hour logging run accommodates 60 measurements• 30 measurements are used for a course-measurement grid, with

successive measurements separated by 1/30th of the total survey interval

• The remaining 30 measurements are used for detailing areas of interest

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Noise Log Interpretation

Single Phase Leak Gas into Liquid Leak

A – Noise Level PeakMillivolts

B – Noise Level Peak to PeakMillivolts

DE

PT

H

Noise Log Interpretation

Single Phase Leak Gas into Liquid Leak

A – Noise Level PeakMillivolts

B – Noise Level Peak to PeakMillivolts

DE

PT

H1. Sound reflects downward at interface2. The tool sensor is built for coupling

to liquid rather than gasCOPYRIG

HT



27

A well was drilled through two gas zones

• Plugged and abandoned, and the wellhead cut at the sea floor

Six months later• An internal gas blowout reached

the mudline, causing the sea to churn

• A relief well was drilled to kill the uncontrolled zone

A well was drilled through two gas zones• Plugged and abandoned, and the wellhead cut at the sea floor

Six months later• An internal gas blowout reached the mudline, causing the sea to

churn• A relief well was drilled to kill the uncontrolled zone

(762)

(1067)

(1372)

(914)

(1219)

(762)

(1067)

(1219)

(1372)

(914)

Noise Log Application: Internal Well Blowout

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Radioactive Tracer Logs

Radioactive Tracer Logs

Use peak-to-peak transit time

Require precise well diagram

Techniques: controlled time and interval

Typically use iodine I-131 (8 day half-life)

Investigates only about 1 ft (0.31 m) deep outside casing

Good for relatively low injection rates

Mostly used on water injection wells

Accurate logging of sequence of events essential

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Radioactive Tracer Tool

Shot = 20 cc

CCL

Ejector Port

Top Gamma Detector

Bottom Gamma Detector

Radioactive Tracer Log: Tracer Loss Method

Timed Logging Runs to Detect Radioactive Fluid Location

Tracer Loss Measurement• Peak = slug position

• Signal amplitude proportional to flowrate

D

C

B

A

Run No. 14 min

Run No. 26 min

Run No. 38 min

Run No. 410 min

Run No. 512 min

Run No. 614 min

Run No. 716 min

Run No. 818 min

Run No. 920 min

(1494)

(1524)

(1518)

(1512)

(1506)

(1500)COPYRIGHT



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Radioactive Tracer Log: Velocity Shot

Recorder on time drive detector stopped @ 4900' (1494 m)

Ejector @ 4895' (1492 m)

Start Time

Reaction time in casing “A” = 10 sec

Material clears tool in 33 sec

Material channeling to 4900' (1494 m)outside casing

Material being

flushed

into formation

(1494)

(1524)

(1518)

(1512)

(1506)

(1500)

(1497)

(1503)

(1509)

(1515)

(1521)

Radioactive Tracer Guidelines

Caliper any open hole and run base log

Log above injection zone, check flow rate

Use two gamma ray detectors and centralize tool string

Space to get reasonable tool detection times (> 10 sec)

Use controlled times to find injection zones

Use controlled interval to find flow rates

Investigate all identified anomalies

Document results

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Temperature Log

Temperature Log

Temperature log• Simplest, most accurate, and most widely applicable production log

Temperature gradient changes are caused by natural phenomenawithin the earth’s crust, and fluid movement

Two curves:• Gradient curve – temperature vs depth• Differential curve – derivative of temperature with depth

Temperature logs will be run both with the well flowing and shut in

Gas expansion cooling is about 1°F (0.5oC) / 40 psi (276 kPa)

High water flow heating is about 3°F (1.5oC) / 1000 psi (6895 kPa)

Qualitative data help derive “where”, not “how much”

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HRT = High Resolution TemperatureHRT = High Resolution Temperature

Temperature Log

CCL

Electronic cartridge

Bridge

Temperature-sensitive resistor

Geothermal Gradient Variation

Temperature in well depends on factors such as:

• Temperature of surrounding formations

• Wellbore flow conditions• Heat transfer characteristics

of completion• Fluid movement near the

wellbore

The temperature distribution in the earth’s crust is called the Geothermal Temperature Profile

• The temperature trend in the earth’s crust increases with depth, leading to a geothermal temperature profileGeothermal Gradient Varies Due to Rock

Properties Through Layers

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Local Geothermal Gradient

In desert conditions, surface temperature may initially decrease, reach a neutral point, and then increase

The geothermal temperature profile varies significantly from area to area, and the slope of the geothermal temperature varies from formation to formation

COOKING LAKE

Example of Geothermal Gradient

Knowledge of the geothermal temperature profile is necessary for temperature log interpretation

• Record one baseline log within a well shut-in and stabilized, before production start-up

The geothermal gradient is generally assumed to be constant when interpreting temperature logs in a given area

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Temperature Log Applications

Detect changes in surrounding temperature

Identify annulus cement top after cement hydration

Detect cooling effects of expanding gas (Joule-Thomson effect)

Confirm operation of gas lift valves

Help evaluate fracture treatments

Identify true reservoir temperature for other studies, such as PVT

Identify flow behind pipe (qualitative indication only)

Identify leaks in completion (packer, tubing, etc)

Qualitative evaluation of fluid flow by comparing with geothermal and/or shut in gradients

Limitations: Quantitative interval flow rates cannot be determined

Time lapse techniques during successive shut-in passes effective for identifying relative volume of produced/injected fluids

Temperature Log

Temperature profiles can be used to indicate where fluids are entering the wellbore

Geothermal gradient

Flow without gas entry

Flow with gas entry

Asymptote

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Geothermal gradient logged after cementing a casing

string to identify cement top while cement is curing

(Exothermic setting reaction)

Logged Temperature Gradient

TEMPERATURE

INCREASE

CEMENT TOP

Logged Temperature Gradient

Logged Geothermal Gradient to Identify Lost Circulation

If an initial (base line) temperature log has been recorded (Run #1),

Then, after a small fluid volume has been pumped into the well,

Run #2 shows a gradient shift occurring above the lost circulation zone providing evidence of a leak from an old or corroded casing.

Temperature

Increase

Lost circulation zonee.g., leak in old casing

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(3200)

(3505)

(3658)

(3810)

(3962)

(4115)

(4267)

(4328)

(24.5 cm)

Temperature Log Example

Hot fluid flow behind casing from source hereApparently, cross flow to about 11,000 ft (3353 m)

Initial Temperature Log

• Log illustrates estimated normal thermal gradient and increased sustained temperature (fluid flow upwards outside pipe)

• Interpretation: high temperature fluid flow behind casing from 13,850 ft (4,221 m)

Before & After Remedial Work

Before Remedial WorkoverAfter Remedial Workover

Temperature Logs

Temperature and Noise Logs

Before After

Noise Logs

(3200)

(3505)

(3658)

(3810)

(3962)

(4115)

(4267)

(4328)

(24.5 cm)(3505)

(3383)

(3414)

(3444)

(3475)

(3536)

(3566)

(3597)

(3627)

(3658)

(3688)

(3719)

(3749)

(3780)

(3810)

(24.5 cm)

(19.4 cm)

(24.5 cm)

(3505)

(3383)

(3414)

(3444)

(3475)

(3536)

(3566)

(3597)

(3627)

(3658)

(3688)

(3719)

(3749)

(3780)

(3810)

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TemperatureD

epth

GeothermalGradient

Injection

Injection Zone

Shut-in

Typical Water Injection Well

Water Injection Well – Temperature Log

This log illustrates • The water injection

temperature profile

And,• The shut-in (1 hr)

temperature profile as the warmer formation increases the temperature of the shut-in column of injected cold water

This log also indicates a possibility of channeling below the depth of the lowest perforations

(1524)

(1509)

(1522)

(1514)

(1530)

(1555)

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Friction

within rocks

Gas expansion

Channeling

Example of Thermal Anomaly

Gas

Gas or liquid?

Well Temperature Log

Production zones may or may not be clearly identified on a temperature log

When free gas is flowing from the reservoir, pressure drawdown will induce a significant cooling of the gas in the near-wellbore vicinity due to Joule-Thomson effect

• Gas entry locations are identified by cool anomalies on a temperature log

A

B

C GgradDTSProd-1RateRateCumRateCOPYRIG

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Temperature Gradient Flowrate Interpretation

Entry 1Q1

Entry 2Q2

Entry 3Q3

TL3

TL1

(Q1 + Q2 ) TL2 = Q1 T2 + Q2 TG2

Qi = Qi-1 (Ti - TLi) / (TLi - TGi)

TG2

TG3

T2TL2

T3

For more information, review the Romero-Juarez Method

which uses a similar gradient method

Temperature Gradient Flowrate Interpretation

Entry 1Q1

Entry 2Q2

Entry 3Q3

TL3

TL1

(Q1 + Q2 ) TL2 = Q1 T2 + Q2 TG2

Qi = Qi-1 (Ti - TLi) / (TLi - TGi)

TG2

TG3

T2TL2

T3

Qi = the flowrate from entry #i

TGi = the static geothermal temperature at depth of entry #i

TLi = the flowing fluid temperature at top of entry #i

For more information, review the Romero-Juarez Method

which uses a similar gradient method

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Temperature Logging Recommendations

Record a full (top to bottom) reliable geothermal gradient log (base line log) during the first Production Logging run

Routine: stabilize rate for 48 hours, log, shut in for about 24 hours

Record temperature profiles, well shut-in, at repeated time intervals

Log down and up, make re-runs (after 1-2 hrs), check log response

Analyze temperature log versus flowmeter log

Temperature profiles can be used for flow rate estimation

Document results and recommendations

Remember: in high rate gas wells, with low compressibility, the Joule-Thomson effect may be reversed and create a local heating at the fluid entry point (molecular friction effect)

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Spinner Flowmeter Tools

Continuous Flowmeter (CFM) Principle

The spinner flowmeter is the most commonly used device for measuring flow profiles, both in injection and production wells.

Impeller placed in well to measure fluidvelocity

• Signal period on output coil • Frequency of rotation F• Measures in rps

Characteristics• rps are filtered before recording• Spin direction is now presented on logs

Continuous Flowmeter Sonde (CFS)• Maximum Pressure (psi) 15000 (103 mPa)

• Maximum Temperature (°F) 350 (177 °C)

• Makeup Length (inches) 24.0 (61 cm)

Lower Bearing

Spinner

Pickup Coil

Upper Bearing

Electrical Connection Flowmeters must be centralized in the

wellbore so that accurate flow velocity of flow stream center can be determined

Use a caliper for accurate flowdetermination

To determine the minimum fluid velocityrequired for spinner to rotate:

1. Multiple up and down passes are madeand calibration chart is developed to determine fluid flow velocity and cable logging speed

2. Spinner velocity will be at fluid conditionsat the point of measurement and will need to be converted back to stock tank conditions during final calculations

Magnet

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kvalverde

Stamp

Temperature and Flowmeter Logs – Example 1

Increased flow

Dep

th

Temperature

Dep

thTemperature Log Continuous Flowmeter

G

TM

A’

A

T’

T

P

1° C.

M2


M1

T2

A2

A2T

T1P1

P2

Temperature Increased Flow

Temperature Log Continuous FlowmeterD

epth

Dep

th

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Anomaly


Formation Producing Liquid at MLiquid Entering Casing at M

Formation Producing Liquid at MLiquid Entering Casing Through

Perfs at M’

M M

M’

Flow Behind Pipe


Anomaly

Gas Expansion / Prod Rate at MLow Perm Rock Demonstrates More Cooling due to

Greater Pressure Drop at Formation / Borehole interface

M

Expanding from Formation into Formation / Casing at MGas Flowing from M with Little or No Expansion

Gas Expanding from Annulus into Casingthrough Perforations at M’

M

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Spinner Flowmeter Tools

Types: continuous, full bore, diverter

Calibration in hole required

Two-pass technique applied (log up and down)

Use together with gradiomanometer (density differences)

Slippage velocity and water holdup applied for calculation of two-phase flow rates Qoil and Qwater

Full Bore Flowmeter Sonde (FBS)

Early flowmeters were designed for low flowrates and adapted accordingly

• However, mechanical design involved flaws that sometimes induced operational complications

• These weaknesses led to the development of the Full Bore Flowmeter (FBS) tool

Maximum Pressure (psi) 20000 (138 mPa)

Maximum Temperature (F) 392 (200 °C)

Weight (lbs) 11 (5 kg)

Makeup Length (inches) 35.1 (89.2 cm)

Courtesy of Schlumberger

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Uses collapsible large spinner blades that unfold only when exiting the tubing

Run in collapsed position within centralizer arms while within the tubing

Centralizer arms protect spinner blades

• However, both are easily damaged

• Both expand to large fraction of casing inner diameter by unfolding when reaching the larger casing

Size of spinner blades allows largerflow cross section to be monitored










Uses collapsible large spinner blades that unfold only when exiting the tubing

Run in collapsed position within centralizer arms while within the tubing

Centralizer arms protect spinner blades

• However, both are easily damaged

• Both expand to large fraction of casing inner diameter by unfolding when reaching the larger casing

Size of spinner blades allows largerflow cross section to be monitored

The FBS tool is more complex than the

continuous flowmeter but tends to provide more

reliable flow data as the spinner blades cover a

larger fraction of the wholeflow path.

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Diverter Flowmeters

Diverter/Basket Flowmeter

Basket Size Small Large

Minimum Casing, in (cm) 4 ½ (11.4) 7 (17.8)

Maximum Casing, in (cm) 7 (17.8) 9 ⅝ (24.5)

Maximum Flow, bbl/d (m3/d) 1800 (286.2) 1000 (159)


Maximum Temperature (F) 350 (177 C)

Weight (lbs) Makeup Length (in) 60 (152 cm)

Maximum Flow (bbl/d)• Basket Open 2000 (318 m3/d)• Basket Closed 10000 (1589.9 m3/d)

Maximum Deviation () 60

Single phase (bbl/d) >100 (15.9 m3/d)

Qo in two phases (bbl/d) > 30 (4.8 m3/d)

Qw in two phases (bbl/d) >400 (63.6 m3/d)

Accuracy (%) 10

Exit Ports

Spinner

Hold-up Meter

Water Resistivity

Cell

DC Motor

The most accurate of the spinner devices when low total rates and multiphase flow occurs.

• Can detect flowrates as low as 10 to 15 bbl/d (1.6 to 2.4 m3/d).

– A typical 1-11/16-in (4.3 cm) tool has a barrel ID of approximately 1.45 in (3.9 cm).

– A flow of 10 bbl/d results in a velocity of 3.4 ft/min (1.04 m/min) inside the barrel.

– Because of the limited clearance between the spinner and the barrel, this velocity is enough to overcome friction and rotate the spinner.

– A flow of 100 B/D passes through the barrel at 34 ft/min (10.4 m/min) – enough to start the homogenization of the flow.

– In a casing, a rate of 2,000 bbl/d (318 m3/d)is needed to obtain the same effect around a continuous spinner.

– The tool can be calibrated directly for such flow.

Metal Petals

Diverter Flowmeters














Accuracy (%) 10

Exit Ports

Spinner

Hold-up Meter

Water Resistivity

Cell

DC Motor

Metal PetalsCOPYRIG

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Diverter Flowmeters














Accuracy (%) 10

Exit Ports

Spinner

Hold-up Meter

Water Resistivity

Cell

DC Motor









Metal Petals

Small clearance between the spinner and the ID of the barrel assures almost no diversion of flow around the spinner.

As the spinner rotates, it generates a specific number of voltage pulses per revolution.

• The pulse rate from the tool can be transmitted through the logging cable for surface recording and determination of corresponding revolutions per second.

Typical basket flowmeters are rated for 320 – 350°F (160 – 177°C) temperatures and 15,000 to 20,000 psia (103 to 138 mPa).

• 1.70-in (4.3 cm) tool accommodates 3,000 bbl/d (477 m3/d)

• 2.25-in (5.7 cm) tool: 5,000 bbl/d (795 m3/d)

• 3-in (7.6 cm) tool: 8,000 bbl/d (1272 m3/d)

Diverter Flowmeters














Accuracy (%) 10

Exit Ports

Spinner

Hold-up Meter

Water Resistivity

Cell

DC Motor









Metal Petals

Small clearance between the spinner and the ID of the barrel assures almost no diversion of flow around the spinner.

As the spinner rotates, it generates a specific number of voltage pulses per revolution.

• The pulse rate from the tool can be transmitted through the logging cable for surface recording and determination of corresponding revolutions per second.

Typical basket flowmeters are rated for 320 – 350°F (160 – 177°C) temperatures and 15,000 to 20,000 psia (103 to 138 mPa).

• 1.70-in (4.3 cm) tool accommodates 3,000 bbl/d (477 m3/d)

• 2.25-in (5.7 cm) tool: 5,000 bbl/d (795 m3/d)

• 3-in (7.6 cm) tool: 8,000 bbl/d (1272 m3/d)

Measurements are made with the tool stationary.

The tool is lowered to the deepest measurement depth, then opened.

After recording the measurement depth, the tool is pulled up (while open) to the next measurement depth.

The risk of diverting flowmeter getting stuck in the hole is higher than it would be for a continuous flowmeter.

• If the tool is stuck, the cable can be pulled loose and retrieved.

• If the flowmeter is stuck in casing, it may be least expensive to leave the tool in the hole.

• If the flowmeter is stuck in tubing, it may be necessary to pull the tubing.

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Spinner / Flowmeter Log Guidelines

Need to achieve stabilized flow rate

Calibrate tool

Record multiple passes at various speeds

Record stationary readings above and below perforations

Record repeat runs

The method is• Best for single-phase flow• Good for oil and water two-phase flow• Questionable under liquids and gas flow• Needs additional support (software, gauges, etc.) • Questionable for hole angles beyond 70°

Document all results

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Pressure Logging Tool

Pressure Logging Tool

Usually contained within the same housing as the temperature tool

Sensor (strain or quartz gauge) measures absolute pressure at logging point

Its resolution is limited by a potentiometer transmitting device which causes pressure changes to appear as discrete steps on the recording

Limitation: Quartz crystals need to be well protected or risk damage

Data to be used in combination with other production logging tool components

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Gradiomanometer

Gradiomanometer

Measures pressure differentials• Pressure differential is the sum of:

– Hydrostatic head

– Friction head– The difference in kinetic effect between the 2 bellows

Mechanism requires calibration with a known fluid

At normal fluid velocities friction is very low, an unless there is a change in flow velocity between bellows, there is no kinetic effect

Pressure differential as seen by the gradiomanometer is usually only due to the average fluid density

Most effective for identifying gas entry and locating standing water levels

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Gradiomanometer Components


Transducer

Upper Sensing bellows

Slotted Housing

Floating connecting tube

Lower Sensing bellows

Expansion bellows

Spacing2 ft

(0.61 m)

Readings to be corrected for hole deviation and possible friction

Limitation: Application is of limited interest in highly deviated or horizontal wellbores when stratified flow is present

Gradiomanometer Components


Transducer

Upper Sensing bellows

Slotted Housing

Floating connecting tube

Lower Sensing bellows

Expansion bellows

Spacing2 ft

(0.61 m)

Readings to be corrected for hole deviation and possible friction

Limitation: Application is of limited interest in highly deviated or horizontal wellbores when stratified flow is present

Hole deviation: Correction is applied by dividing reading by cosine of the deviation angle

Kinetic effect: Correction to absolute readings is required due to high downhole flow velocity

• Higher than 2000 bbl/d (318 m3/d) in 4-½" (11.4 cm) tubulars • Higher than 5000 bbl/d (795 m3/d) in 5-½" (14 cm) tubulars

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Gradiomanometer Log Interpretation

0.4 gm/ccFree gas + liquid

Zones

Hydrocarbon entry possibly with some water

Hydrocarbon entry possibly with some water

Gas or gas + liquidGas or gas + liquid

WaterWater

1.0 gm/cc water column either static

or moving

0.7 gm/cc oil, or gas + water, or oil + gas + water

ρw = 1.0 gm/ccρo = 0.7 gm/ccρg = 0.2 gm/cc

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Production Combination Tool (PCT)

Production Combination Tool

PCT Logging Tool Specification• Fullbore Flowmeter• Gradiomanometer• Caliper• Manometer• Thermometer• Casing Collar Locator• Gamma Ray

Great progress in production logging has been made with thedevelopment of tools to work under dynamic conditions

Combinations of tools• Flowrate meter• Fluid identification devices• Depth controlCOPYRIG

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Production Combination Tool

PCT Logging Tool Specification• Fullbore Flowmeter• Gradiomanometer• Caliper• Manometer• Thermometer• Casing Collar Locator• Gamma Ray

In open hole, the presence of a caliper is essential.

In cased hole logs, it is useful to obtain a diagnosis on the actual casing diameter.

When local conditions are unknown, this PCT configuration allows to record the maximum amount of relevant data to diagnose well flow conditions.

Run only those tools that are needed (‘Fit-for-purpose’ rather than ‘Nice-to-have’).

Flowmeter ‒ Quicklook Qualitative Analysis

Depthm

2310

2320

2330

2340

2350

2360

2370

2380

2390

2400

2410

2420

2430

2440

Z GRGAPI0 2000

CVELm/ min-40 40

SPINrps-11 15

CALin6.6 7.

W FDEg/ cc0.95 1.04

W TEP°C113.4 114

W PREpsia2100 2250

Possible corrosion

FluidEntries Fluid

Entries

FluidEntries

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Conventional Production Logging Summary

Essential recording tools for single- or two-phase flow:• Thermometer (Temperature log)

• Spinner flowmeter

• Gradiomanometer Density log

As a standard configuration downhole diagnosis tool, the CombinationLogging Tool usually includes:

• Thru-Tubing Caliper• Temperature log

• Spinner flowmeter

• Pressure log• Gradiomanometer Density log

Other logs include: • The Noise log is useful in specific applications to diagnose flow issues

• The Radioactive tracer is used in injection wells

• The Thermal Decay Time log (Pulsed Neutron) is a reservoir engineering tool to monitor water saturations over well life

All these tools provide valuable information to be analyzed by qualified analysts

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Downhole Video Alternative

Downhole Video Alternative to Production Logs

Advances in downhole video equipment now offer thismeasurement as an alternative to the new class of productionlogging measurements.

A downhole video log is a means to directly identify location offluid entries into the well, because almost all production wellscontain water through which the hydrocarbons are passing.

High rate water entries can also be detected from the imagedistortion caused by high levels of turbulence.

This approach is qualitative and does not fully replace productionlogging tools.

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Characterizing wellbore fluids Especially entry points

Inspecting downholemechanical equipment


Supplement fishing services

Detect casing or tubingleaks

Spot mineral deposits

Find scale corrosion and bacterial buildup

Examine the condition ofdownhole equipment

Inspect the operation ofdownhole equipment

In open hole wells, rockformations are easilyviewed by the camera

When drilling mud is used, mud is opaque and usually prohibits use of a video cameraCOPYRIG

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PetroAcademyTM Production Operations

Production Principles Core Well Performance and Nodal Analysis Fundamentals Onshore Conventional Well Completion Core Onshore Unconventional Well Completion Core Primary and Remedial Cementing Core Perforating Core Rod, PCP, Jet Pump and Plunger Lift Core Reciprocating Rod Pump Fundamentals Gas Lift and ESP Pump Core Gas Lift Fundamentals ESP Fundamentals Formation Damage and Matrix Stimulation Core Formation Damage and Matrix Acidizing Fundamentals Flow Assurance and Production Chemistry Core Sand Control Core Sand Control Fundamentals Hydraulic Fracturing Core Production Problem Diagnosis Core Production Logging Core Production Logging Fundamentals

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production logging...

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