Detection of Leaks In Offshore PipelinesShane SiebenalerSouthwest Research Institute

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Joint Industry Program• Program commenced in early 2013• Focus on distributed sensors for offshore leak detection

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Project Drivers• Offshore leak detection needs:

• High reliability and sensitivity for small leaks• Continuous detection capability (time and space)• Ability to locate leaks• Performance over wide range of pipeline conditions

• Two candidate technologies identified:• Distributed temperature sensing (DTS)• Distributed acoustic sensing (DAS)

• Commercial technologies exist• Lack of available data for offshore applications

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Project Overview• Overall scope

• Study the leak behavior (thermal, acoustic) for various leaks• Perform testing of fiber-based systems

• Underlying motivation• Understand main drivers of leak propagation (e.g. fluid properties,

location, etc.)• Evaluate ability of systems to detect leaks (specific applications

may require further work)

• Overall objective• Determine, in controlled environment, if DTS and DAS can detect

small (<0.25”) leaks

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Project Progression

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Engage operators as to establish range of each parameter

Characterize acoustic and thermal profiles

Design and fabricate test bed(s)

Conduct large-scale testing of systems

Baseline Conditions• Line size: 0.51-0.76 m (20-30 in)• Water depth: 300 m (984 ft)• Internal pipeline pressure: 3.45-13.79 MPa (500-2,000

psi)• Oil: 20-30 °API• Minimum gas temperature: 278 K (40°F)• Minimum oil temperature: 305 K (90°F)• Nominal water temperature: 277 K (39°F)• Simulated leak size: ≤ 6.35 mm (0.25 in) diameter

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Characterization Work• Topics:

• Jet-to-plume transition lengths• Water entrainment• Temperature profiles• Plume migration (near-field)• Near-field acoustics

• Approaches:• Analytical modeling• Numerical modeling• Small-scale testing

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Two CasesLeak Into Water Leak Into Soil

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Small-Scale Testing

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Small-Scale Testing – cont’d

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Small-Scale Testing Cont’d

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Large-Scale Testing• Seven technology

providers• Three DAS• Four DTS

• Separate test beds for water and soil

• Test objective was event detection

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Water Testing

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Water Test Bed

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Equipment Installation

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Overall Layout

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Leak Location/Size Summary• 20”-diameter pipe• 14 different leak ports

• Size ranging from 1/32” to 3/16”• Some directly under cable, most

offset from cable• Three radial positions

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Cable Installation

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10-km and 25-km spools used upstream

Example Nitrogen Leak

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Soil Testing

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Soil Bed

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Testing In Soil• Leak sizes from 1/32” to 1/8”• Soil bed “reset” between each run

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Cable Arrangement

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10-km spools used upstream

Pipe Section

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Setup

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Project Status• Most testing is complete• Results from testing show promise in systems being

applicable to offshore pipelines• Large-scale testing results planned for publishing in 2015

• Looking towards expansion to future topics• Open to new operators joining the JIP• May tackle future projects as one-time activities as opposed to

continuation of single program

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Future Topics of Interest• Non-orifice leak geometries• Multiphase flow• Inflow• Cable installation

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Questions?Shane SiebenalerManager, Fluid DynamicsSouthwest Research Instituteshane.siebenaler@swri.org

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