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
Introduction to fiber optic measurements The fibre is the sensor A pulse of light is sent down the fiber T 1 T 2 Backscattered light is measured at the detector (reflection) T 3 Only one pulse in the fiber at the time T 4 The two-way travel-time of the light gives the depth of the measurement T 1000 T 1001 T1003 T 1004 DTS: Distributed Temperature Sensing DAS: Distributed Acoustic Sensing
Survey the entire wellbore in real time
Applications for fiber optic technology Leak Detection Flow allocation Overburden integrity Fracturing / Stimulation Restrictions in wellbore Flow pattern diagnostic Flow behind casing Microseismic Gas Lift Optimization VSP Real time flow and production understanding
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 Dielectric CCL GR Pressure Temperature Caliper ρ V w, V s Depth vs completion Depth vs formation P T I.D.
DTS & DAS as PLT replacement?? Distributed measurements PLT Quantity Gas Low GOR Oil High GOR Oil Spinner ν C SoS C SoS (Challenging) C SoS P<P bubble Gradio ρ PVT C SoS density C SoS density Dielectric V w, V s - - - 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? C SoS = Speed of Sound from DAS Array Processing
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 0 Band 7
Improve understanding of flow patterns - Better understanding of dynamics in the well - Production data improvements - Improves expensive simulation models
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Stability during production slugging DAS Signal to Noise ratio Cyclic production Unstable production interval
Flow pattern slugging conditions Gas bubbling through liquid TIME
Production quantification? Effect in the 4 Hz band before and after water breakthrough Before After 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!