WELL-SENSE. June 2021

Well-SENSE FiberLine Intervention

Disposable Fibre Optic Intervention System for: Well Integrity Leak Detection, Pre-Abandonment Leak Detection Barrier Placement Verification

A new line in intervention

FiberLine Intervention (“FLI”)
Well surveillance and diagnostics at the speed of light

What is FLI

- A compact plug and play intervention system
- Laying bare optical fibre deployed from surface to total depth
- Combining either or both DTS and DAS – distributed temperature & acoustic sensing
- And single-point electronic sensors
- In real-time, delivering high-quality data

DTS Data Interrogation

DTS logs the data to an array table - CSV, DLIS, LAS etc.

- For each sample it records:
    
  Time stamp (every 1 second to multi-hour user defined)
  Temperature at every measurement point (gauge length user defined)
  Stokes and Anti-Stokes at each measurement point
  Loss Events (optical loss along the length of fibre)

- Interpretation Software solutions:

  Can be imported into all commercial interpretation packages (Kappa, Plato etc.)
  Thermal modelling can be applied to data sets
  Data can be visualised in many ways
  Absolute temperature, Delta temperature between points, Waterfall chart (heat map)
  Used to determine fluid interface, cooling effects, flow characteristics, natural gradients, leaks

DAS Data Interrogation

When deployed in tubing a single DAS measurement can convey different information in different frequency bands:

- Low frequencies: 0-20hz (0-4hz = Strain Events)
   Thermal disturbances
   Fluid interfaces
   Seismic (and micro-seismic)

- Medium frequencies: 2—100hz
   Flow past obstacles
   Behind tubing flow

- High Frequencies >100hz
   Gas leaks
   GLV flow
   Tubing leaks

As you move away from the sound source, higher frequencies are attenuated quicker than lower frequencies. High frequency acoustic may only be detected some Centimetres from a sound source but low frequencies may travel for many metres. We use this to determine the point of flow origin.

FLI Single Point Measurements

- Single-point electronic sensor
- Pressure gradient measurement during RIH, and BHP
- Real-time, along fibre measurements
- Sensors can be included in the lower housing of a standard FLI Tool

When to use FLI: well lifecycle applications

Drilling

- Cement Assurance
- P/T Gradient
- Bottom Hole P/T
- Temperature
- Gradient/Profile
- Vertical Seismic
- Profile (VSP)
- Micro-seismic
- Monitoring
- Cross-well Strain

Completion

- Assess Completion Effectiveness
- Micro-seismic Monitoring
- Cross-well Strain

Production

- P/T Gradient
- Bottom hole P/T
- Temperature
- Gradient/Profile
- Acoustic Gradient/Profile
- Leak Detection
- Vertical Seismic Profile

Key Applications

Late Life

- P/T Gradient
- Bottom Hole P/T
- Temperature Gradient/Profile
- Injectivity Logging – Warm Back
- Acoustic Gradient/Profile
- Leak Detection

P&A

- Leak detection
- Cement Assurance/ Cement Plug Evaluation
- Pre Abandonment Thermal Profiling

Real Life Examples of Data Capture with FLI Cement Plug Verification & Pre Abandonment Leak Detection

FLI Leak Detection

- Date: 18/07/2020
- Application: DAS and DTS Leak Detection
- Well Status: Plugged
- Location: UK North Sea

FLI Objectives:

- Deploy tool into wellbore through the suspension flange
- Determine origin of sustained tubing pressure (GAS) cement plug passing OR compromised 9-5/8” Casing
- Remote monitoring of data acquisition – operational efficiency

Run In Hole Capture DAS and DTS

Cement Plug Leak Stimulation: First Bleed Down

Indication of Fluid movement from below the FLI originating from the Cement Plug.

Fluid movement observed to be repeatable, with multiple charge and discharge on A annulus

Cement Plug Leak Stimulation Summary

FLI was successfully landed out on the existing cement plug @ 4,935ft
A base line survey was logged before opening the A Ann to drain
Data was captured over 3 bleed down and charge cycles. Sufficient data was captured to identify leak location onsite
The data pointed to the cement plug passing. The cement plug was subsequently drilled out and replaced

FLI Leak Detection

- Date: 22/07/2020
- Application: DAS and DTS Leak Detection
- Well Status: Pre-Abandonment
- Location: UK North Sea

FLI Objectives:

- Deploy into completion tubing in between wireline operations for plug change out.
- Determine depth(s) at which gas is leaking into B-Annulus
- Remote monitoring of data acquisition

Barrier Placement Verification: Leak Stimulation First Pass

Barrier Placement Verification: First Pass Detail

Barrier Placement Verification Summary

- FLI was successfully deployed to target depth of 8,857ft and a base line survey was logged before opening the; Ann to drain through a ¼” line
- On opening the valve to drain, obvious and immediate acoustic event originating at a depth of 7,960ft observed
- The flow is observed to move upwards from this point to 7- 5/8” liner top, and downwards to a depth of 8,200ft which correlated to the top of milled window in the 9-5/8” casing
- No indication present of leak(s) originating above this area

Why FLI?

- Fit for purpose real-time intervention utilizing bare fiber
- Portable plug and play intervention system
- Rapid mobilization; minimal personal & logistics
- Cost effective / small footprint (1x FLI engineer)
- Low risk / health and safety priority
- Effective on and offshore
- Applicable in various applications
- No spool or fibre at surface (housed in tool / pays out on descent)
- Quality data

Or don’t FLI…

- Increased safety risk
- Increased POB
- Increased footprint
- Increase in timing / delay exposure
- Increased cost
- Data quality?

Thank You – Questions?