Production Logging Presentation

Production Logging for Field Engineers

PRODUCTION LOG

INTERPRETED LOG

prepared by: Ahmed Abu-Shloua

Why should we Production Log Wells? “In the year 2003 seven barrels of water are being produced for every barrel of oil. This trend is set to continue.” “Oil is a finite reserve, wells are getting older, we have to be more efficient” “It cost more to produce water than to produce oil” “The only way to find out what is happening downhole, for sure, is to lower tools to the bottom of the well and measure what is happening.”

What do we gain? •Information to assist in solving problems now and in the future. The AIM? •To maximise the ultimate oil / gas recovery. •To justify the cost of remedial work or even the development of an entire field.

PRODUCTION LOGGING FOR F.ENG.'S

What is the well producing? •OIL •GAS •WATER What do we want? Definitely Oil, Gas if we have a pipeline but not if it limits oil production. What do we not want? Water! Water costs more produce than oil because we have to dispose of it!

Production Profiling 14%

7%

24%

Injection Profiling Water Problems 10%

45%

Excessive Gas Problems Mechanical Problems PRODUCTION LOGGING FOR F.ENG.'S

An example of: Profiling a New Well KR A 4

0 GAM M -1 5 0 LSP D N -1 5 0 LSP D N -1 5 0 LSP D N -1 5 0 LSP U P

CCL tells us the perfs are in the right location

-1 5 0 LSP U P -1 5 0 LSP U P

1 510500 A R A Y (A P I ) C C L 150 3 0 F t / M (R P S ) 150 5 0 F t / M (R P S ) 150 7 5 F t / M (R P S ) 150 3 0 F t / M (R P S ) 150 5 0 F t / M (R P S ) 150 7 5 F t / M (R P S )

-1 0 -1 0 -1 0 -1 0 -1 0 -1 0

40 260 275 S P N R D N 3 0 F t / M (R P S ) T E M P E R A T U R E (D E G F ) 40 1500 1700 S P N R D N 5 0 F t / M (R P S ) P R E S S U R E (P S I A ) 40 4000 0 S P N R D N 7 5 F t / M (R P S ) F L U ID C A P A C IT A N C E 40 0 2 S P N R U P 3 0 F t / M (R P S ) D E N S I T Y (g / c c ) 40 S P N R U P 5 0 F t / M (R P S ) 40 S P N R U P 7 5 F t / M (R P S )

8100

8150

8200

Gamma Ray indicates that only the cleanest sands (below 30 API) are productive.

Temperature indicates cooling with gas production

8250

8300

Flowmeter shows that this section of perfs is not productive.

8350

8400

8450

8500

8550

PRODUCTION LOGGING FOR F.ENG.'S

Fluid ID tells us which fluids are being produced

An example of: Production Profiling To save money on an Exploration Well The oil company wanted to confirm the gas oil contact in this exploration well.

Where is the Gas / Oil contact?

The floating rig was costing $120,000 per day. To test 4 zones would be 10 days = $1,200,000.

(Remember gas production has a cooling effect and volumes are large)

A single test taking 2.5 days covering all 4 zones with a PLT job cost US$ 300,000

What would happen if the tools failed or the spinner did not work?. This well was making 5000 BOPD. If it was a production well and we had a mis-run the deferment of 12hrs oil would be $50,000. •Reliability is important financially and for our reputation. PRODUCTION LOGGING FOR F.ENG.'S

An Example of: Quantifying Water Production Excess water production will limit oil production Production Log Interpreted Data

PRODUCTION LOGGING FOR F.ENG.'S

An example of: Injection Profiling Spinner shows negative rotation as flow is negative This zone is ‘HOT’ No apparent injection into this zone BUT the temperature does not return to geothermal straight away which shows that there is a little injection but it is not measurable.

This zone is ‘NOT’ WHY?

Clue: Radio Active scale deposition occurs with water production. A. This well was once a producer and one zone watered out (but not the others) PRODUCTION LOGGING FOR F.ENG.'S

How our tools are used to measure the flowrates of oil, gas and water from each zone. MonoconductorWireline MBH Battery Housing MPL Memory PL Recorder

For Memory PLT exchange XTU with MPL and MBH

XTU Ultralink Controller SRO Telemetry Sub

Power Supply / Telemetry Panel with Printer

QPC Combined Quartz Pressure Casing Collar Location

PKJ Conducting Knuckle Joint

Ultralink SRO Telemetry

PSJ Swivel Joint

Parallel for Printer

USB for Data

Depth Encoder

PGR Scintillation Gamma Ray

Notebook PC

Ultrawire Tool bus Telemetry PDC Dual X-Y Caliper (Bowspring for Open Hole)

SRO PL Acquisition System Short Compact String Using Notebook PC

ILS In-Line Spinner

DBT Diverter Basket Flowmeter

FDR Radioactive Fluid Density

PRC Roller Centraliser

CTF Combined Capacitance Fast Response Temperature and Spinner rotation pickup.

FDD dP Fluid Density

PSC Springbow Centraliser (Open Hole Completions)

The Magnificent 7: Pressure CCL Gamma Ray Temperature - Fluid Movement Fluid Capacitance - Fluid ID Density - Fluid ID Flowmeter - Total Flow Others: Centralisers X-Y Caliper Gas Holdup In Line Spinner Capacitance Array Tool etc

Interchangeable CFB Continuous Fullbore Flowmeters

CFS Continuous Roller Bearing Spinner Flowmeter

CFJ Continuous JewelledBearing Spinner Flowmeter

PRODUCTION LOGGING FOR F.ENG.'S

Theory of operation and use of tools Pressure:

CCL

Temperature

Quartz Crystal

-The crystal has a natural oscillation. As pressure increases the oscillation decreases. As temperature increases the oscillation increases. We measure the pressure frequency and crystal temperature to correct the pressure reading.

-Changes in metal volume move the lines of magnetic flux within a coil. This generates a voltage.

-Changes in temperature alter the resistance of a Platinum wire. Consequently There is a varying voltage Differential across the probe With temperature change. PRODUCTION LOGGING FOR F.ENG.'S

Detector

High Voltage Power Supply

Gamma Ray Tool

Photo Multiplier Tube Sodium Iodide Crystal Hydrocarbons and Water have different dielectric constants. The speed the capacitor charges up gives us a: High Frequencies in oil / gas Low frequency in water

Capacitance Water Holdup

Capacitor Plates

Fluid Path PRODUCTION LOGGING FOR F.ENG.'S

Detector

High Voltage Power Supply

Radio Active Density

Photo Multiplier Tube Sodium Iodide Crystal Fluid Flow Path

Americium Radioactive Source

Gamma Ray Path

Differential Pressure Density (FDD) In Gas:

In Water:

Differential Pressure is HIGH

Differential Pressure is LOW

2ft GAS Wellbore

2ft Silicon Oil

Inside Tool

2ft WATER

DP Sensor

Wellbore

PRODUCTION LOGGING FOR F.ENG.'S

2ft Silicon Oil

Inside Tool

Flowmeters: (The King of the PL tools). All are spinner type. The faster the spinner rotates, the faster the flowrate. Tools are chosen to match the completion Multiple Zone Completions Swab Valve

Wing Valve

Dual String

Single String

WELLHEAD Crown Valve

20” Casing

13 3/8” Casing

Tubing Hanger Safety Valve

Tubing In 9 5/8” Casing 4.5-5.5” In 7” Casing 3.5”

Long String SSD’s may be opened and closed by tools run on wireline Sliding Side Door (Sleeve Valve)

Cement

Short String Tubing In 9 5/8” Casing 2.875” In 7” Casing 2.375”

Zone A

Tubing

Nipple for Plug

Zone B

9 5/8” Casing Perforations

SSD for Circulation

Packer End Of Tubing

Log in tubing with continuous spinners. Log in casing with fullbore spinners.

Reservoir A

Zone C Zone D

Reservoir B

In this case we use a CFB

Dual strings allow production from zones at very different pressures

In this case we use a CFB and ILS SIZE matters! PRODUCTION LOGGING FOR F.ENG.'S

Dual Completions offer more flexibility such as injecting down one string and producing the other but tubing size is limited.

Production Logging Quantitative Analysis Step 1: Determine Total Flowrate

Spinner Crossplot

In-Situ Calibration at different line speeds. Gives response slope and Intercept (threshold).

12 10

y = 0.0603x - 0.3674

Spinner RPS

8 6

Spinner RPS

4 2

Dow nw ard

0 -200

-150

-100

-50

-2 -4

Upw ard

0

50

100

150

Line Speed / Fluid Vel

200

Linear (Upw ard) Linear (Dow nw ard)

-6

1000 BPD is: 9.6 ft/min in 9 5/8” Casing 18.6 ft/min in 7” Casing 79.8 ft/min in 3 1/2” Tubing

y = 0.0547x + 0.0229 -8 -10

Line Speed

Fluid Velocity = (RPS/Slope + Threshold) - Line Speed Measure Fluid Velocity is corrected to average velocity allowing for spinner size in relation to wellbore and also for the flow regime.

Single Phase (Oil, Gas or Water) Barrels/Day = Average Velocity (ft/min) x 1.4 x ID”^2 PRODUCTION LOGGING FOR F.ENG.'S

Step 2: Calculate the fraction of each phase in the wellbore (holdup) - 2 Phase flow. From DENSITY

Oil Density

Heavy Holdup = Density Measured - Density Light Density Heavy - Density Light

1.2 Log Density, g/cc

Water Density

DENSITY vs HOLDUP

1.1 1 0.9

Light Holdup = 1 - Heavy Holdup

0.8 0.7 0

0.5

1

Water Holdup, fraction

From CAPACITANCE

Water Holdup is a direct measurement.

Water Freq.

Oil Freq.

Fractional Response

Fractional Response CWH vs Water Holdup

Due to non linearity and other effects Density is usually more reliable.

1 0.8 0.6 0.4 0.2 0 0

0.2

0.4

0.6

0.8

Water Holdup, fraction

1

PRODUCTION LOGGING FOR F.ENG.'S

Step 2a: Calculate the fraction of each phase in the wellbore (holdup) - 3 Phase flow.

A)

Determine Water Holdup from Capacitance Tool

B)

Knowing water holdup and water density use the DENSITY data to determine oil and gas holdups

Water Holdup – directly from CWH tool. Oil holdup, Yo = ((dens meas - dens gas) + Yw (dens gas - dens water))

(dens oil - dens gas) Gas holdup, Yg = 1 - Yw - Yo PRODUCTION LOGGING FOR F.ENG.'S

Step 3: Determine the slip velocity Slip velocity is the difference in velocity between one phase and another. The light phase travels up the well faster than the heavy phase. This is one of the great unknowns – many different correlations are available.

Light Phase Slip Velocity ft/min

Slip Velocity vs Holdup 80.00 60.00 40.00 20.00 0.00 0.00

Oil 0.8 g/cc Oil 0.7 g/cc Gas 0.50

1.00

Water Holdup (Fraction) PRODUCTION LOGGING FOR F.ENG.'S

Step 4: Calculate the superficial fluid velocity of each phase. If NO slip: Superficial Velocity = Total Velocity x holdup For example if flow was 100 ft/min and water holdup was 0.5 Water flow would be 50 ft/min and oil flow 50 ft/min.

Oil is travelling up at slip velocity

Problem is that THERE IS slip! Oil Superficial Velocity = (Oil holdup x Total Velocity) + Extra Oil flow due to slip Water Superficial Velocity = (Water holdup x Total Velocity) - Extra Oil flow due to slip

Water is falling back down around oil bubbles

Qheavy ft/min = (Yh x Qtotal ft/min) – (Yh x (Yl x Vslip light ft/min)) Qlight ft/min = Qtotal ft/min – Qheavy ft/min Step 5: Convert to Downhole Volumetric Flowrate Downhole volumetric rate, BPD = Superficial Velocity, ft/min x 1.4 x ID”^2 Step 6: Convert to Surface Volumetric Flowrates SURFACE volumetric rate = Downhole / Correction Factor to Surface Conditions (FVF) PRODUCTION LOGGING FOR F.ENG.'S

Production Profiling: Decision made from log data An example interpretation of a production well log Injection Well

Production Well This production well was producing at 76% water cut. The client presumed that the bottom zone had watered out and wanted to plug off the zone.

Proposed location of bridge plug Before performing the job one of the engineers proposed a PLT job to check. PRODUCTION LOGGING FOR F.ENG.'S

The Production Log and Interpretation Method

Using the calibration crossplot the Spinner data gives us total flowrate

When we know the downhole density of oil and water we can use density data to give us the downhole water holdup. DENSITY vs HOLDUP

Log Density, g/cc

1.2 1.1 1 0.9 0.8 0.7

We could also have used Capacitance for holdup. PRODUCTION LOGGING FOR F.ENG.'S

0

0.5 Water Holdup, fraction

1

The Interpreted Data

High Gamma Ray indicates RA scale which is associated with water production. Lends confidence to the analysis.

WATER IS COMING FROM ALL THE ZONES.

OIL IS COMING FROM THE ZONE BELOW WHERE WE WANTED TO SET THE BRIDGE PLUG PRODUCTION LOGGING FOR F.ENG.'S

The Results of the Interpretation The total water cut is 76% of which: Zone 1

Zone 1: 89% Water Cut

Zone 2: 72% Water Cut Zone 2 Zone 3

Zone 3: 68% Water Cut Zone 4: 77% Water Cut

Zone 4

All the zones have high water cut.

If the client had set the bridge plug: A lot of money would have been spent and 515 BOPD of production from Zone 4 would have been left in the ground. There would be no gain: The well would remain at 76% water cut (total of zones 1 to 3) and because the water cut is the same the BHP, hence flowrate would say the same. PRODUCTION LOGGING FOR F.ENG.'S

Where Next ?: This Horizontal Well Production Log was recorded using memory PL tools on coiled tubing. Why is it so good? Because it is 99% water! The CWH tool shows hydrocarbons only at the highest point of the well. The rest of the production is water.

Depth: 1300m TVD

1325m TVD

Horizontal Well Trajectory PRODUCTION LOGGING FOR F.ENG.'S

After 8,000,000 bbls oil production this is the new oil / water contact.

This is what multi-phase logs run using conventional Centre Sampling tools look like! WATER Freq. GAS Freq.

THERE MUST BE A BETTER WAY! PRODUCTION LOGGING FOR F.ENG.'S

Geometry of CAT Sensors

GAS

OIL

WATER Simultaneous measurement of sensors close to the casing circumference provides a cross-section in partially segregated multi-phase flows. PRODUCTION LOGGING FOR F.ENG.'S

Flow profile from Capacitance Array Tool

Gas has entered the well

Stream of oil passing by at the top PRODUCTION LOGGING FOR F.ENG.'S

Bubbles of oil passing through trough

CATview Imaging Software - side view Water = Blue, Oil = Red, Gas = Yellow

PRODUCTION LOGGING FOR F.ENG.'S

Planning a PLT job 1-WELL INFORMATION Complete Well bore diagram showing ID's and depths of all down hole hardware. Complete proposed logging program. Shut-in Wellhead Pressure. Flowing Wellhead Pressure. (For each flow rate) Expected Flowrates to be used during logging program. Expected fluid phases. Well Deviation. Pressure Build up/Draw down required. Production rates of Gas/Oil/Water. Sand production. Concentrations of H2S/CO2 present. (Needed for inhibitor considerations and choice of O Ring and cable head boot material). Natural or artificial lift. Type of lift system. (Gaslift, Submersible pump). Special requirements for lift system. ("Y" tool for logging below a submersible pump; Gas lift Side Pocket Mandrels (SPM)). Need "Y" tool plug and hammer. Details of SPM. (Special full bore flowmeter cage required?)

PRODUCTION LOGGING FOR F.ENG.'S

Production Casing data. •Outside Diameter. •Weight/Foot. •Total Depth and date of last T.D. check. •Outside Diameter of tool used to check T.D. •Type of depth measurement, wireline or logging. •Perforated intervals. •Type of charges/carrier used for perforating. •Position of any squeezed perforations. •Gravel pack. Production Tubing data •Tubing end. •Outside Diameter. •Weight/Foot. •Diameter of the smallest restriction in the well. •Position of other down hole hardware. •ID/OD of protection/separation sleeve. (Protects the seat when DHSV is removed) Wellhead Connection. •Swab Valve present on tree. (A swab valve is required to shut in the well above the •flowline and permit installation of pressure equipment •without disturbance of the normal well flow.) •Flange or Threaded. (Size and Thread type). •Measurement Reference. Rotary Table (RT) to Tubing Hanger (TH) measurement. PRODUCTION LOGGING FOR F.ENG.'S

PRODUCTION LOGGING FOR F.ENG.'S

3.PL Job Planning Establish with the client the objectives of the job. Is there a logging program?

Write the logging program to meet the objectives

No

Yes

Does the program meet the objectives

No

Yes

Does the well have a history of problems or a hostile environment?

Discuss with the client and plan accordingly.

Yes

No

Estimate the downhole flowrate and flow regime and select which tools to use

Limit Flowrate Perform Tool Lift Estimation No

Yes

Flow too high? No

Can we add weight? Yes

Start Logging Job No

Is well stable and ready to be logged?

Wait for well to be stable

Yes

Perform Logging Job PRODUCTION LOGGING FOR F.ENG.'S

Setup Encoder on Wireline / CTU unit

Edit toolstring configuration Edit Calibration Files Edit Log Presentation Files Create Warrior Database

Edit Depth Menu

Check tools are working properly.

Make Pre-job Calibrations and check calculated output

Test depth measurement. Edit setup if necessary Set Zero and start recording data

Rig Up Tools

4. Warrior SRO PLT flow chart

Run In Hole Depth correlate tools

Perform Production Logging Job Make Post-job Calibrations and check calculated output

Refine Depth correlation of each pass and logging stations

Export on-depth LAS data for interpretation and client and for Sondex crossplots

Make headers, crossplots etc. for API strip log. Print Log

PRODUCTION LOGGING FOR F.ENG.'S

Memory PL Acquisition

MPL Depth and Time Drive .LAS Files

Use Service Builder to generate toolstring

Surface Readout Acquisition

Log toolstring diagram to Warrior Database

Edit Warrior Import Filter Files

Warrior Import

Edited Presentation Files .PRS using

Data in Warrior Database

Depth Correlate and Shift Curves

Format Editor

Data Recalculation SRO data only

Export depth correlated LAS files using LAS Writer

5.Warrior Log Printing Flowchart

Additional ASCII Files (logging station statistics, log tail, other info etc)

Merge Log passes using Automerge

Add: Annotations,Log Banners,Well Sketch

Make Spinner Crossplots printout as .PRN files

Edit Header

Plot Job Editor to build the sequence of logs PLOT THE LOG

PRODUCTION LOGGING FOR F.ENG.'S

What can go wrong ??

The order of seriousness as to what can go wrong is:

A. The tools may be lost in hole. B. The tools may fail. C. The client may not get the data he needs.

PRODUCTION LOGGING FOR F.ENG.'S

A) The tools may be lost in hole. What can you do to minimise the risk of losing your tools?

• • • • • • • • • • • •

Check well history Your wire line equipment; up-to-the job?! Pre –job toolbox meeting. Well trajectory and max. tool straight length. Maximum restriction. Tool lift estimation. Job supervision against unwise suggestions. Tool catchers & tool traps beside the hydraulic relief valve. Avoid right angle tips in your downhole string. Radioactive tools should placed above weak points in your PLT string. Avoid running in hole during a sluggy flowing condition. X-mass valves should be operated under your supervision.

Discuss: What do you do if the tools are stuck in hole? What do you do if the tools are dropped or lost in hole? PRODUCTION LOGGING FOR F.ENG.'S

B) The tools may fail . What can you do to avoid tool failure:

•Check max. downhole temperature & pressure. •Lower running speeds to avoid tool jerking. •Have a backup string on site. •If running memory tools, check battery specifications and calculate the estimated power consumption under downhole conditions (not on surface..!!) •If running MPL avoid quick bleeding your lubricator after coming out of hole. •Check and replace O’rings to suit your application and to adhere to any possible CO2 & H2S existence. •During surface check; the tool’s raw data (Sensor raw reading)should be monitored before checking the calibrated output in “Outputs” window. •Operation with GLM’s existence: •Use Bow-Spring Full bore-mechanical-spinner sections. •Use the right size to avoid blades extraction while running thru a GLM. •Increase the tool length between full-gauge ancillaries to be more than the GLM length. •If there’s junk in the well, consider running a continuous spinner. Discuss: Specific precautions pertaining to individual tools PRODUCTION LOGGING FOR F.ENG.'S

C) The client may not get the data he needs. •See what if the client required data is attainable by your PLT job. For example: He may need to log fluid contacts behind casing or to flowprofile multiple zones producing thru SSD.

•If you are running MPL job & the Slick line cannot attain a steady speed;the spinner data shall be invalid.Then consider conducting lots of stations,say on a 5 ft intervals. Run the correct tools •Choose the right spinner mecahinical sections to suit your application and consider having an inline spinner as a backup. •To get good CCL’s use knuckle joints or modify your tools order to be able to de-centralise your CCL as much as you can. •Allow for well stabilisation. •Allow for delays.(i.e. While running MPL,put in mind stabilisation periods in fast and slow sampling rates of your tools. Present the log clearly Discuss: Log Quality Assurance. PRODUCTION LOGGING FOR F.ENG.'S

Finally.. We came to the end of our session…. Before say ‘Good Bye’ we are having a small test….

To tackle your minds and open some channels,in the way you think about Production Logging…

Hope to see you again in a more advanced PL course… Farewell..!! PRODUCTION LOGGING FOR F.ENG.'S