challenges on hdd pipeline shore approach - dnv gl on hdd... · challenges on hdd pipeline shore...
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DNV GL © 2014 02 November 2016 SAFER, SMARTER, GREENERDNV GL © 2014
02 November 2016
Luis D'Angelo - Danilo Machado
OIL & GAS
Challenges on HDD Pipeline Shore Approach
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DNV GL New Recommended Practice
DNV GL © 2014 02 November 2016
Agenda
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• Objectives• Why to use HDD in Shore Approach? • HDD Process• HDD Advantages• HDD Technical Complexities • Site Investigation to address Geotechnical Plan• Recommendations for the Drill Path• Product Pipe String Design• Corrosion Protection• Additional Recommendations• How & why DNVGL can help your company?
DNV GL © 2014 02 November 2016
Objectives
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JIP participants: Petrobras, Subsea7, Sinopec, Brasfix, Intech, Laney, Megadrill, Polidrill, Superpesa, MGI, MEARS, Herrenknecht
• Ensure the site investigation, HDD
engineering, planning and execution of the
crossings in accordance with requirements
and best practices;
• Reflect consensus on the HDD industry
practices and a reference for Designers,
Companies, Contractors and Operators;
• Serve as a technical reference document in
contractual matters between involved parts;
DNV GL © 2014 02 November 2016
• High dynamic and interaction
between waves, currents and
sediment transportation.
• Site investigation, installation
design and operation difficulties in
the surf zone.
• Pipeline on-bottom stability
throughout the design life (concrete
coating).
• Environmental challenges and
regulations, buried pipeline, etc.
Why to use HDD in Shore Approach?
Severe environmental conditions.
DNV GL © 2014 02 November 2016
1- Drilling a small-diameter pilot
hole along a designed path.
HDD Process
3- Pull back the pipeline
into the enlarged hole.
2- Enlarging (reaming)
the pilot hole to a
diameter that will
support the pipeline.
includes
several reaming
stages and
swabbing
DNV GL © 2014 02 November 2016
HDD Advantages
• Surface preservation.
• No shore excavation.
• No cofferdam requirement.
• Secure depth of cover.
• Minimal site preparation
and reinstatement.
• No disturbance to shoreline flora
and fauna.
• Short construction duration.
• Environmentally friendly.
• Cost effective.
DNV GL © 2014 02 November 2016
HDD Technical Complexities
HDD may be complex than typical surface to surface method.
• Define drill path length according rig tools and drill
pipes technology.
• Acquire appropriate geotechnical information
(subsurface soil and ocean floor sediments).
• Steering system ability to readily access the exit
point, minimizes elevation differences.
• Keep the borehole stability and drilling fluid
management appropriated.
• Use adequate product pipe installation strategies
and buoyancy control.
• Consider the tidal and storm influences.
DNV GL © 2014 02 November 2016
Site Investigation to address Geotechnical Plan
Acquired Data:
• Physical characteristics: (particle size distribution, plasticity, specific
weight, water content, pH.)
• Mechanical characteristics: (strength deformation properties,
abrasiveness and hardness)
Geotechnical Characterization:
• Estimate efforts for the methods, costs, and
feasibility of a project.
• Guide drilling work and actual conditions.
• Establish methods, requirements and the
information that should be available for each
crossing design.
DNV GL © 2014 02 November 2016
Recommendations for the Drill Path
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Entry and Exit Points:• Drilling rig positioned at
entry point. • Pipeline is pulled into exit
point and back to entry point.
Entry and Exit Angles:• Entry angles generally designed between 8° and 20°. • Drill rigs typically manufactured to operate at 10° to 15°. • Exit angles designed to provide ease in break over support of the pull
section. • Exit angles generally range from: ≤ 2° for D > 24in
≤ 4° for D ≤ 24in
Design Radius of Curvature• Minimum design radius for HDD paths is 1,200 times the nominal
diameter (D).• Some projects requires a combination in two planes (Rcombined).
DNV GL © 2014 02 November 2016
Product Pipe String Design
Design, construction and installation:
• Define the drill path to place the pipeline within stable ground
and isolated from obstacle’s active conditions.
Design Code: Ensure quality of the pipeline design, construction and
installation (ex: DNV OS F101).
• Guarantee the Pipe string to
withstand all loads (installation
phases and operating loads) and
no overstress.
• Ensure corrosion protection (entire
pipeline design life).
DNV GL © 2014 02 November 2016
HDD Corrosion Protection
• Pipeline coating and CP will not influence the feasibility of a
crossing.
• Operational risk should be addressed to avoid the pipeline
coating damage.
• Protective coatings are susceptible to damaging during
pullback operation by the forces involved and contact with
soils, rocks and other debris.
• The pipeline will not be readily accessible to future coating
repairs.
• Mitigation: good design and execution of borehole as well as
correct specification and use of the external coating.
DNV GL © 2014 02 November 2016
Additional Recommendations
• Verify pipeline on-bottom stability
prior to pull back operation.
• Verify and mitigate free-span issues at
borehole exit point.
• Proper handling of pipeline – buoyance
control, etc.
• Perform pipeline hydrotest prior and
after pull back (minimum 4 hours
holding period).
• Final pressure system test.
DNV GL © 2014 02 November 2016
How & Why DNV GL can help your company?
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• Knowledge of pipeline design codes, safety philosophy, limit state design and the relevant failure modes.
• Understanding of the HDD design phases, challenging, knowledge of the construction techniques and best practices.
• Experience on different HDD projects worldwide helping the industry on the pipeline design verification ensuring the proper pipeline design and integrity assurance.
DNV GL RP is a public document and will be released early 2017.