Guidelines the DNV way

Transcription

1 Guidelines the DNV way for safe service elastomers in oil & gas Jon Huse

2 Guidelines the DNV way for safe service elastomers Content: What is a DNV-guideline? Examples of DNV-guidelines - Qualification of soft seals - Arctic materials - Performance assessment of soft seals 2

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4 Blow Out Preventer 4

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6 Guidelines 6

7 What is a DNV-Guideline? Developed through Joint Industry Projects (JIP) Based on industry needs In collaboration with industry Need for standardisation Guideline => Recommended Practice (RP) Where to find: or google dnv codes 7

8 Guideline for qualification of soft seals 8

9 Soft seals in the oilfield Introduction Elastomer and polymer materials are critical parts of equipment used to explore, produce and process oil and gas onshore, offshore and subsea These applications are challenging for elastomer and polymer materials New exploration is in deeper waters, reservoirs at higher temperatures and pressures, and in addition older fields are expected to last longer between equipment overhauls Typical oilfield challenges may include: Temperatures from - 30 o C to o C, vacuum to 1000 bar, ph 2 to 14, H 2 S, CO 2, sulphur, amines, caustic, acids, treatment chemicals Mechanical abuse is common and high pressures can cause rapid gas decompression There is no universal elastomer to deal with all these conditions Solution to selecting the right elastomer is through understanding the oilfield and the capabilities/limitations of available elastomers 9

10 Challenges with elastomers and polymers Leaks are one of the main reasons for downtime of equipment Elastomer or polymer seals are considered to be a major contributor to all leaks Long term effects on elastomers and polymers are not well known The industry offers limited standards to qualify new materials or sealing components 10

11 JIP - Guideline for qualification of soft seals - Partners Bel Valves FMC Technologies Petrobras Seadrill Seawell Oil Tools Statoil 11

12 Technology Qualification DNV s definition of Technology Qualification: The process of providing the evidence that the technology will function reliably within specific limits 12

13 Qualification of soft seals based on technology qualification Define accurately the design specification and qualification basis - Seal geometry - Seal material (elastomer properties) - Service conditions (including high pressure/high temperature (HPHT), chemical environment, cyclic service conditions) - Failure modes for the soft seal - Design life Establish if the technology is new and in need of full qualification Establish relevant acceptance criteria before any testing Test sealing system using relevant test methodology that mimick actual service conditions 13

14 Technology Qualification of soft seal systems Overview FE-analysis 14

15 Guideline for qualification of soft seals includes also: Recommendations on screening and qualification testing - Material testing - Seal design testing How to handle field experience Failure mechanisms Material selection and applications Reference to relevant standards for screening and qualification testing Special conditions Recommendation on FEA Change management Production QA/QC Guideline is available upon request. 15

16 Arctic Materials Guideline 16

17 Arctic Materials Guideline Result of KMB lead by SINTEF with partners. Objective: To establish criteria and solutions for safe and cost-effective application of materials for hydrocarbon exploration and production in arctic regions

18 Arctic Materials - Partners Aker Bredero Shaw DNV Eni GE Oil and gas NTNU SINTEF Statoil Technip Total Trelleborg Offshore JFE Steel Corp, Japan Nippon Steel, Japan Scana Bruck Forgings Norwegian Research Council 18

19 Arctic Materials Guideline - objective Provide recommendations for a systematic approach to material selection and qualification for applications in arctic. 1. General 2. Steel section 3. Polymer section 19

20 What is Arctic? 20

21 Oilfield Elastomer Applications Seals topside and subsea Thermal insulation risers, pipes and subsea equipment Corrosion protection risers and pipes Passive fire protection Flexible joints Elastomeric bearings Hoses, pipes, cables, bellows, gaskets 21

22 Elastomers in arctic considerations Low temperature physical properties Glass transition Low temperature crystallization Impact resistance Thermal contraction Temperature variations and cyclic loads Temperature gradients and structural loads Low temperature adhesion Ice accretion Ice abrasion 22

23 Arctic Materials Guideline Basis in existing codes for each application: - Thermal insulation (e.g ISO/DIS 12736) - Seals (e.g ISO 10423, NORSOK M710) - Liners and sheaths - Passive Fire protection - Other elastomer applications - Corrosion protective coatings (e.g NORSOK M-501, NACE SP0108) - Composite applications (e.g DNV-OS-C501) Codes are compared against the specific considerations relevant for arctic conditions and recommendations are given. Although the codes often do not exclude the use of the code in arctic they are written based on the experience from more benign climates and have also only been used in benign climates. Recommendations based on test results generated in project. Results TBA. 23

24 Performance Assessment of Soft Seals 24 Oceaneering

25 Performance Assessment of Soft Seals - Background Subsea equipment is build for long no-touch times, but even so the equipment is pulled for refurbishment at intervals During refurbishment all exposed seals are routinely changed Replaced seals are routinely thrown away Currently no routines for evaluation of replaced seals No feedback loop to ensure that information about the state of the replaced seals ever reaches the product owners Current practice does not exploit any of the learnings possible when replacing soft seals during refurbishment Important knowledge and experience from refurbishments is lost due to lack of routines in collecting this information 25

26 Documented field experience how to obtain that? Evaluation of seals during refurbishment would create essential documentation of field experience (both positive and negative) Soft seals are qualified using a limited number of international standards, mostly written to cover production fluid exposure. Other media exposure environments are not well covered by international standards. We know a lot how seals perform in the lab, but less about service performance Seals may look bad and have swelled severely, but still function. This is not captured. 26

27 Guideline: Performance Assessment of Soft Seals Industry need: A DNV-RP on performance assessment of soft seals for subsea production and process systems and associated tools which will provide standardized documentation of field experience that is currently not available. Testing of replaced soft seals will document state of seal after actual service Standardized test protocol will ensure all replaced seals will obtain documented field experience Documented field experience will provide added confidence in sealing solutions Documented field experience will increase quality and reduce leakage in sealing systems Testing of replaced seals will provide the link between laboratory testing and actual use in service Basis for development of analytical tools, especially with regards to lifetime predictions 27

28 JIP - Performance assessment of soft seals Q Q Objective is to establish test methodology for refurbishments: - How to perform assessment in workshop and in lab - What to examine for and test - What service conditions and seal performance data to capture - How to correlate with qualification data Methodology will be tried out on participant s equipment: - Christmas tree under refurbishment - Downhole equipment TBD 28

29 JIP - Performance assessment of soft seals - participants - Aker - BP - Eni - James Walker - Statoil - 29

30 Safeguarding life, property and the environment Thank you! 30