DRAFT Guideline for Structural Well Integrity

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Dec 6, 2012 ... [1] Hopper, C.T., “Vortex Induced Oscillations of Long Marine Drilling Risers”, ... API 17d / ISO 13628-4 – Specification for Subsea Wellhead and ...

Draft 2012-11-20

Guideline for Structural Well Integrity Status JIP and ongoing development work Lars Tore Haug 2012-12-06

DRAFT

Presentation Outline  Subsea wellhead system overview and industry experience - wellhead integrity, complexity - current industry approaches, main areas of uncertainty

 JIP – Structural integrity of drilling and well systems  JIP phase 2 plans

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 2

System Overview  MODU Motions  Riser Movements and BOP motion  Well Construction, - WH relative movement / non-pre-loaded, and pre-loaded designs

 Seabed Support  Environmental Conditions

 Stakeholders - Operator - Rig owner - Subsea manufacturer

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 3

Background – wellhead function Well Head  The function of the wellhead system. Conductor Housing

- wellhead including conductor constitutes a crucial structural element within the entire drilling and well system. - provides a safe well barrier during drilling of intermediate sections.

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 4

Background – Hotspots Typically the hotspots consists of:

18 ¾” Subsea wellhead

 Welds - On conductor and wellhead housings - Shown in the two red dots higher up

 Connectors - On conductor and wellhead housings - Shown in the two red dots lower down

 Base Material Transitions

30” conductor 20” casing 13 3/8” 9 5/8” Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved. 5

DRAFT

Background - incidents

Few incidents experienced or reported:  West of Shetland 1983: A fatigue failure of a high pressure wellhead housing due to VIV west of Shetland [1]  North Sea 2005. Abnormal BOP movements were explained by a parted conductor casing extension weld, caused by fatigue [2]

[1] Hopper, C.T., “Vortex Induced Oscillations of Long Marine Drilling Risers”, Proc. Deep Offshore Technology Conf., Malta, 1983. [2] Reinås, L., Sæther, M., Hørte, T., and Grytøyr, G., “Wellhead Fatigue Analysis Method,” Proc. of the International Offshore Mechanics and Arctic Engineering Conference Rotterdam, Netherlands, 2011. Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 6

Lack of standards for wellhead  There is no industry-wide standard or guideline available for subsea wellhead calculation. - API 6a / ISO 10423 – Specification for Wellhead and Christmas Tree Equipment (section 4.3.3.1):

“Fatigue analysis and localized bearing stress values are beyond the scope of this International Standard”

- API 17d / ISO 13628-4 – Specification for Subsea Wellhead and Christmas Tree Equipment: (section 5.1.2.1.1):

“The effects of external loads (i.e. bending moments, tension), ambient hydrostatic loads and fatigue shall be considered.”

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 7

Challenges – areas of uncertainty  Old subsea wells: Main driver for methodology developed in the Method Statement. - Issue in the North Sea: Template wells. Non-preloaded WH with 45° load shoulder (rocking WH). Shallow water, harsh conditions.

 Lack of design-, fabrication records and load history. - Change in industry required; new approach to handling contracts from early phase to finish; operators, drilling contractors, wellhead manufacturers.

 New subsea wells: Design basis, roles and boundary conditions - Challenging to quantify load early in the project.

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 8

Challenges in fatigue assessment  Critical hotspots are not accessible for inspection  Riser loads can be monitored, but there are still uncertainties on the resulting stresses in the hot-spots.  Strains or stresses in wellheads are not monitored

 The logging results of cement between the high pressure housing and the low pressure housing are uncertain and provide little guidance to the analyst. - For new wells : It is possible to log through the surface casing before installing intermediate casings, but there is a cost issue and uncertain results. Half a day of rig time.

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 9

Joint Industry Project (JIP), Phase 1 - 2010 to 2012  Triggered by industry needs - Challenges in documenting integrity margins for both static and dynamic loading

 Demand for guidelines related to loading and capacity of the well system - in particular with respect to fatigue

 Ensure a consistent approach for integrity of entire drilling and well systems

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 10

JIP Participants  Norwegian Oil and Gas Association (observer)

 Lundin

 Statoil (chair)

 Talisman

 BG Group  BP  Det Norske  Eni  ExxonMobil

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

 Marathon  Shell

 Total  Woodside  Nexen  GDF Suez  Chevron

DRAFT 11

Scope & Deliverables, Phase 1 Objective to address the well systems’ structural integrity as a complete system. Scope

Intermediate deliverables

Final deliverable

Act 1 - State of the Art Review Act 2 - Uniform Structural Design Philosophy Act 3 – Fatigue Design and Calculations Act 4 & 5 – Integrity and Information Management Act 6 – Well Foundation Act 7 – Work Group Contribution Act 8 – Ultimate & Accidental Limit State Design Act 9 – Fatigue Design, Alternative Analysis Method

TR1 – Structural Integrity Philosophy of Well System TR2 – Capacity Design and Analysis of Well Systems TR3 – Fatigue Design and Analysis of Well Systems TR4 – Integrity and Information Management for Well Systems

Act 10 – Houston Work Group Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 12

DNV Guideline

TR 1 TR 2 TR 3

Part 1 – Safety Philosophy

TR 4

 Overall structural integrity philosophy - Based on overall safety principles as outlined in existing DNV Offshore Standards - Adopting a safety class methodology (low, medium, high)

 Roles and responsibilities - Roles and responsibilities should be defined in early phase - Normally operator’s responsibility to define overall safety performance - Closely related to information and integrity management

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 13

TR 1

Part 2 – Structural Strength design and analysis  Main objective to establish a uniform method for assessing strength capacity of well systems.  Currently there are multiple methods presented in a range of international codes and standards.  The method will provide:

General ISO 13628-1 NORSOK D-001 NORSOK D-010 NORSOK U-001 OLF Guideline 070 PSA Norway DNV-OS-C101

TR 2 TR 3 TR 4

Drilling Equip. API 7K API RP 64 API 4F API 8C DNV-OS-E101

BOP ISO 13628-7 NORSOK D-001 NORSOK D-010 API Spec 6A API Spec 16A API RP 16E API RP 53 API 16d API Spec 16C

Riser/Umbilicals ISO 13628-2 ISO 13628-3 ISO 13628-5 ISO 13628-7 API RP 16Q API Spec 16R DNV-OSS-302 DNV-OS-F201 DNV-RP-F206 ISO 13624-2

- A bridge between established standards - A consistent safety level for overall system

Control Systems ISO 13628-6 API Spec 16D

To be handled in JIP phase 2

Wellhead/XT: API 6a API 17d ISO 10423 ISO 13628-4

Well Foundation API RP 2A

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 14

Casing Tubing, Downhole ISO 11960 API 5ct(2)(3) API 14a(b)(h)(j) ISO 10426-1 (cement)

TR 1 TR 2 TR 3

Part 3 – Fatigue analysis

TR 4

Describing important issues related to local and global analysis including:  Mechanical behavior of wellheads  BOP dynamics  Tensioning systems  Flex joints  Soil

Main challenge:  Sensitive to input parameters  Hydrodynamic properties of BOP and riser uncertain  Different analysis methodologies give incomparable results Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 15

TR 1

Part 4 - Information Management  Information management  Input information for analyses  Information flow  Structural well integrity process description

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 16

TR 2 TR 3 TR 4

Adequacy of analysis Previous calculation methods:  Insufficient fundamental description of the mechanical problem  raised doubt, could be too simplified or wrong

Guideline focus on calculation methods:  Addresses complex mechanical behavior  opens for alternative methods, ref benchmark study

 Recognizes following as key topics for future consideration - insufficient understanding of effect of important parameters - absence of properly calibrated wellhead strain/stress monitoring results

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 17

Benchmark Study  2H Offshore, Stress Engineering Services and Statoil are performing analyses of a test case  Purpose : - Assess and compare various methodologies for WH fatigue analyses

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 18

New JIP phase 2, propose launch 2013 - Objective  Further develop and revise/improve fatigue calculation methodology; - Increased accuracy, increased flexibility (different approaches), benefit of monitoring

 Systematic approach to analysis of ultimate and accidental load and capacity of the wellhead system.

Improved fatigue calculation methodology

Structural strength calculation methodology

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 19

JIP phase 2 - Scope 1. Fatigue Analysis Methodology  Bench marking of fatigue analysis methods, case studies  Monitoring, guidance on implementation  Improvement, of fatigue methodology (fracture mech., strain life, global analysis ..)  Structural Reliability Analysis, Fatigue  Vortex Induced Vibrations (VIV)

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 20

Riser load time series

JIP phase 2 - Scope 2. Structural strength; ( i.e. pressure, load, ultimate, extreme, accidental)  Identify industry best practices, identify risk and limitations and interfaces in present codes  Provide a Guideline to: - Numerical validation and handling of interfaces from a systems perspective.. - How to use existing codes for subsea applications - Guideline for common understanding of operating envelopes of equipment

 Supplement to ISO/API codes

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 21

Summary  The industry has not agreed on a unified approach to how to address the challenges. Different methods exists.  JIP phase 2 is planned with kick off in January 2013  The Guideline is still “work in progress” and has not yet been approved for industry release by the Steering Committee.

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 22

Safeguarding life, property and the environment www.dnv.com

Guideline for Structural Well Integrity 2012-12-06 © Det Norske Veritas AS. All rights reserved.

DRAFT 23