Fibre optic interventions enable intelligent

decision making in any well

Frode Hveding

VP Reservoir

Agenda

• Introduction to fiber optic measurements

• Applications for fiber optic technology

• Analysis of the data – how?

• Flow visualization

• Real time decisions

• What’s coming – future of fiber optics

T1

T2

T3 T4

T1000 T1001

T1003 T1004

Introduction to fiber optic measurements

The fibre is the sensor

• A pulse of light is sent down

the fiber

• Backscattered light is

measured at the detector

(reflection)

• The two-way travel-time of the

light gives the depth of the

measurement

Only one pulse in the fiber at the time

DTS: Distributed Temperature Sensing

DAS: Distributed Acoustic Sensing

Survey the entire wellbore in real time

Applications for fiber optic technology

Leak Detection

Restrictions in wellbore

Overburden integrity

Flow behind casing

Gas Lift Optimization

Fracturing / Stimulation

Flow pattern diagnostic

Microseismic

Real time flow and production understanding

VSP

Flow allocation

Flow allocation analysis of Distributed Temperature

Flow allocation analysis of Distributed Temperature

Analysis of Distributed Temperature

• Advantage:

– Software exist on the market to analysis DTS

– Comparable to traditional PLT in favourable conditions

• Challenges:

– Accurate geothermal measurement

– Challenging if horizontal wellbore with same geothermal gradient

– Requires stable conditions

• Stable shut-in before

• Stable production / injection

• Stable shut-in after

• Do we ever have a stable situation?

• Is analysing a PLT log challenging some times? Why?

• How will you quantify production if slugging conditions?

Differences in DTS & DAS

• DAS

– Real time effects – what is happening now

– «Shallow» depth of investigation (could be kilometers if

earthquakes...)

• DTS

– Affected by wellbore history for injectors

– Looks deeper into the formation

• Will it be able to replace PLT?? Do more than PLT??

– DTS will show the overall trend and provide quantitative answers

– DAS will need more work and focus in the industry in order to obtain

quantitative measurements – can it be done?

• Production / injection rates

• Multiphase flow

• Flow pattern

• +++

DTS & DAS as PLT replacement??

PLT Quantity Gas Low GOR Oil High GOR Oil

Spinner ν

Gradio ρ

Dielectric Vw, Vs

CCL Depth vs

completion

GR Depth vs

formation

Pressure P

Temperature T

Caliper I.D.

DTS & DAS as PLT replacement??

PLT Quantity Gas Low GOR Oil High GOR Oil

Spinner ν ∆CSoS ∆CSoS

(Challenging)

∆CSoS

P<Pbubble

Gradio ρ PVT CSoS density CSoS density

Dielectric Vw, Vs - - -

CCL Depth vs

completion

Fiber optic

CCL

Fiber optic

CCL

Fiber optic

CCL

GR Depth vs

formation

- - -

Pressure P Gauge or DPS Gauge or DPS Gauge or DPS

Temperature T DTS DTS DTS

Caliper I.D. Ultrasonic? Ultrasonic? Ultrasonic?

CSoS = Speed of Sound from DAS Array Processing

Distributed measurements

Flow regime detection

• Why?

– Multiphase production log interpretation requires a known flow regime.

– Flow regime is the cased hole analog of lithology

– Help in interpreting the signals, evaluate the flow rates per phase

basis and reduce post processing load

• SPE paper 59067 – Neural Net identification of flow regime

with band spectra of flow-generated sound

– Concludes that the neural net can classify flow regimes correctly in

85-90% of all cases using hydrophones from noise logging tools

– Limitations?

• Point measurement

• Can this be transferred over the distributed way of thinking?

From signal to noise to multiple frequency bands

• Each band represents one frequency range

• Covers frequencies from 1 Hz to 10 kHz (or higher)

• Each band from same time interval

• Acoustic information from different frequencies

Band 0-36 Band 7

Band 0

Improve understanding of flow patterns

- Better understanding of dynamics in the well

- Production data improvements

- Improves expensive simulation models

Tune into your favorite song.....

Stability during production – slugging

Cyclic production

DAS – Signal to Noise ratio

Unstable production interval

Flow pattern – slugging conditions

Gas bubbling through liquid

TIME

Production – quantification?

Before After

Effect in the 4 Hz band before

and after water breakthrough

Higher energy in the low Hertz

domain showing water breakthrough

from nearby injector

How to standardize DTS & DAS formats?

• Several DAS & DTS box providers with different format on

the data

• DTS is small datasets (100’s MB)

• DAS is «Big Data» (>1 TB’s)

• Challenge: The industry needs to agree on a common

format for DAS data handling

• Suggest HDF5 as the standard format for handling DAS

– Open Source format (hdfview.org)

– Easy to work with

– Easy to write processing software around it

– Can easily export/import data

– Ready to use immediately

– Used by NASA for handling large quantity of data

What is coming next

• Quantitative DAS measurement

– Real time flow allocation

– Real time flow regime detection along entire wellbore

simultaneously

– Real time leak detection (Tubing, A, B, C annulus) with phase and

quantity

• Combined software

– Manage large amount of data

• Are we going to store everything or just a fraction?

– Fast processing methods

– Integrated solutions with universal database structure for easy

handling

Thank You!