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.

DNV GL © 2014 02 November 2016

SAFER, SMARTER, GREENER

www.dnvgl.com

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Luis.dangelo@dnvgl.com