Design of Offshore Pipelines_Shore Approach

DESIGN OF OFFSHORE PIPELINES  Shore Approach Design 

Presentation Reference Number Here

Typical Offshore Field Development 

Shore Crossing 

Why Are Shore Approaches Challenging?  • Environmental Conditions Most Severe  • Often Complex Geology  • Environmental Value Highest  • Greatest Exposure to the Public  • Survey, Construction and Inspection Access Difficult  • In Most Cases No Reference Available  • Common Failure Location 

Shore Approach Design  • Site Data Collection  • Pipeline Shore Approach Routing Selection  • Landfall Site Selection  • Construction Method Definition  • Pipeline Mechanical Design (Installation & Operation)  • Pipeline Hydrodynamic Stability Design (Inst. & Op.)  • Shoreline Environment Protection Design 

Site Data Collection  • Topographic and Bathymetric Surveys  • Geophysical and Geotechnical Surveys and Studies  • Metocean Data Collection Surveys and Studies  • Weather Data Collection Surveys and Studies  • Seismic Data Collection Surveys and Studies  • Environmental Surveys and Studies (Flora & Fauna)  • Cultural and Heritage Surveys and Studies  • Land and Water Use (Ports, Shipping, Tourism, Etc) 

Site Visit 

Site Visit 

Acquisition of Seabed Data  • Bathymetry data  • Top 3-5m of Seabed  • Composition (Soil/Rock)  • Engineering Properties 

Acquisition Method  • Geophysical Surveys (Seismic) • Geotechnical Surveys 

Lead Line 

Multi Beam Echo Sounder (MBE) 

LIDAR (Light Detection and Ranging) 

Water Depth Contour Lines 

Geophysical Survey Systems  • Side Scan Sonar  • Shallow Seismic Reflection (Sub Bottom Profiler) • Seismic Refraction  • Electric Resistivity 

Side Scan Sonar 

Side Scan Sonar 

Seismic Refraction/Refle Refraction/Reflection  ction 

Geotechnical Techniques  • Cone Penetration Tests

Vibr broo Co Cori ring ng • Vi • Drop Core/Piston Core  • Rotary Coring 

 Laboratory

Testing

Near Ne arsh shor ore e Co Core re Sa Samp mpli ling  ng 

Nearshore Core Sampling 

Jack-Up Barge 

Scenic Coastline 

Populated Area / Coastal Erosion 

Coastal Erosion 

Severe Wave Climate 

Perfect Beach? 

Turtle Tracks 

High Strength Igneous Rock 

EXISTING PIPELINES

EXISTING SHIPPING CHANNELS

EXISTING DUMPING GROUND

Pipeline Mechanical Design  • Onshore (AS 2885) and Offshore (OS F101)

Standards  • Wall Thickness, Corrosion Protection, Abrasion

Protection  • Mechanical Protection (Human Activity, Shipping

Traffic, Fishing, Dredging)

Hydrodynamic Stability Design  • Shoaling / Breaking Waves  • Weight Coating Design (Balance btw Ease of

Installation and Need for Stability)  • Design to Account for Scour and Liquefaction

Phenomena 

Hydrodynamic Stability Design 

Shoreline Environment Protection  • Avoid Accelerated Erosion  • Flora & Fauna Protection  • Heritage Protection  • Continuous Dialogue with Stakeholders 

Dune Erosion 

Shore Approach Construction  • Open-Cut and Cover  • Horizontal Directional Drilling  • Tunnelling 

Open-Cut and Cover  • Pre-Lay Trenching  • Pipeline Installation  • Trench Backfill 

Open-Cut and Cover 

Open-Cut and Cover 

Backhoe Dredge 

Backhoe Dredge 

Cutter Suction Dredge

Cutter Ladder

Cutter Head

Spuds

Cutter Suction Dredge 

Trailer Suction Hopper Dredge 

Trailer Suction Hopper Dredge 

Drag Head (TSHD) 

Onshore Excavation 

Shore Pull 

Tow-Out 

Open-Cut and Cover  • Conventional Method  • All Ground Conditions  • Requires Friendly Seastate  • Relatively High Environmental and Social

Impact 

Horizontal Directional Drilling  (HDD) 

HDD 

HDD Rig 

HDD Spread 

HDD  • High Risk (if not well designed, prepared

and managed)  • Relatively Low Environmental and Social

Impact  • Up to 2 - 2.5 km length in Favourable

Site Conditions 

Tunnelling  • Vertical Shaft or Launching Pit

Construction  • Exit Point Preparation  • Tunnelling  • Pipeline Installation 

Tunnelling 

Tunnelling 

Tunnel Launching Shaft 

Tunnelling  • High Risk (if not well designed, prepared

and managed)  • Relatively Low Environmental and Social

Impact  • Up to several kms in Favourable Site

Conditions, however, diameter increases with tunnel length