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Well surveillance by continuous temperature profiling using DTS kit by Wim der Kinderen Consultant Production Technologist Shell UK Exploration and Production.

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Presentation on theme: "Well surveillance by continuous temperature profiling using DTS kit by Wim der Kinderen Consultant Production Technologist Shell UK Exploration and Production."— Presentation transcript:

1 Well surveillance by continuous temperature profiling using DTS kit by Wim der Kinderen Consultant Production Technologist Shell UK Exploration and Production Aberdeen API/ASME Gas Lift Workshop, Houston, February 2001

2 Distributed Temperature System (DTS) How does it work? –Sensor is standard optical fibre –Fibre is pumped into well through control line post completion or hardwired using fibre optic braided cable –Measures temperature along the length of fibre (1 m resolution) History –>100 Oil well industry installations (e.g. Aera-steam flood) –BPA Wytch Farm successes KA-7, M12, M17 Value Drivers –Gas lift optimisation, tubing integrity, reservoir inflow data –Reliability of system potentially higher than standard PDGs

3 The physics behind DTS Distributed temperature is measured by sending a pulse of laser light down the optical fibre. Molecular vibration, which is directly related to temperature, creates weak reflected signals. The reflected signal is detected in the surface read-out unit and converted to values of temperature at 1 metre intervals along the fibre and well. Multi-mode fibre is 50µm diameter with a 125µm doped silicon cladding, within a wear resistant acrylate coating. Time =ƒ(depth) Anti-Stokes vs. Stokes amplitude = ƒ(temp)

4 Water Pump Casing Optic fibre deployment Accuracy & resolution up to 0.1°C Datapoint every metre Up to 10,000 datapoints Operates -40°C to + 300°C Up to 10 wells per surface unit Real Time Data Management System (RTMS) Fibre reel Sensa ® Signal Conditioner Packer Adaptor Flange Xmas Tree DTS specs:

5 TA27 DTS installation, April platform well - initial GL producer, later water injector - encapsulated dual 1/4sensor tube clamped to tubing, down to packer - datasets (T versus depth) collected every 20 minutes and sent to shore - latest 10 datasets accessible on the web - temperatures at 10 selected depths recorded in PI data historian

6 ahd (m) T (C) t 1 = 14:16 h - kick-off started

7 Observations: Bunch of wells coming together beneath the platform: –earth heated up by producing wells Lift gas: –100+ °C at wellhead –cooled by seawater Sensor tubes are plastic encapsulated: –insulated from the tubing –effectively T annulus is measured Above lift point: –T tubing > T annulus > T formation Below lift point: –T tubing T annulus

8 t1t1 t2t2 t3t3 t4t4 t5t5 t6t6 Annulus pressure and wellhead temperature trends during unloading

9 t 2 = 17:16 h - top ULV open t 3 = 18:01 h - 2nd ULV and orifice pass gas t 4 = 18:46 h - ULVs closed, inflow started t 5 = 21:46 h - ULVs re-open at higher gas rate t 6 = 23:01 h - ULVs closed, tubing warming upt 6 = 23:01 h - estimated tubing temperature ahd (m) T (C)

10 Combine gas lift surveillance and reservoir inflow monitoring DTS across reservoir sections inside/outside casing Develop real-time thermal profiling analyses tools Develop sub-sea Xmas tree wet mateable connector (on-going) Develop downhole liner top wet mateable connector Develop long distance DTS capability via umbilicals Whats planned next?

11 Subsea Deployment Optical Wet-Mate Connector SDU Subsea DTS pod Main Umbilical SCM Well Jumper Upper Completion Lower Completion Subsea Distribution Wellhead & Tubing Hanger Pod Jumper UTDA Data Comms. DTS POD DTS Processor Wet-Mate Connector for Tree/TH Optical Wet Connect OK 2001

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