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Guidance Notes on Subsea Pipeline Route DeterminationGUIDANCE NOTES ONSUBSEA PIPELINE ROUTE DETERMINATIONAUGUST 2016American Bureau of ShippingIncorporated by Act of Legislature ofthe State of New York 1862 2016. American Bureau of Shipping. All rights reserved.ABS Plaza16855 Northchase DriveHouston, TX 77060 USA

ForewordForewordThe ABS Classification of a subsea pipeline system requires review of data and analysis results concerningconditions along the selected route of the pipeline. Prior to the final selection of the route and detailed designof the pipeline system, different routes will be considered and assessed. A method for route determinationis presented in these Guidance Notes where candidate routes are selected and assessed. The method relieson the use of available Geographic Information System (GIS) technology and risk assessment techniques.An example of the method’s application is provided.The ABS Guide for Building and Classing Subsea Pipeline Systems is the controlling standard for the ABSClassification of such a system. The process of pipeline route determination is not in the scope of ABS’Classification of a pipeline system. However, the contents of these Guidance Notes provide a suggestedapproach to this topic that should be beneficial to readers.It is acknowledged that methods of survey data collection and interpretation, data assessment and routingtechniques, and risk assessment are constantly evolving. Improvements in these subjects are encouraged,and the publication of these Guidance Notes is not to inhibit the use of applicable, proven technology.These Guidance Notes become effective on the first day of the month of publication.Users are advised to check periodically on the ABS website www.eagle.org to verify that this version ofthese Guidance Notes is the most current.We welcome your feedback. Comments or suggestions can be sent electronically by email to [email protected] of UseThe information presented herein is intended solely to assist the reader in the methodologies and/or techniquesdiscussed. These Guidance Notes do not and cannot replace the analysis and/or advice of a qualifiedprofessional. It is the responsibility of the reader to perform their own assessment and obtain professionaladvice. Information contained herein is considered to be pertinent at the time of publication, but may beinvalidated as a result of subsequent legislations, regulations, standards, methods, and/or more updatedinformation and the reader assumes full responsibility for compliance. This publication may not be copiedor redistributed in part or in whole without prior written consent from ABS.iiABS GUIDANCE NOTES ON SUBSEA PIPELINE ROUTE DETERMINATION . 2016

Table of ContentsGUIDANCE NOTES ONSUBSEA PIPELINE ROUTE DETERMINATIONCONTENTSSECTION 1Criteria for Pipeline Route Determination . 11Introduction . 13571.1Purpose and Scope . 11.3Pipeline Route Selection Criteria and Determination Flowchart . 11.5Required Documentation . 21.7Pipeline System Design Guides and Standards . 3Data Acquisition and Site Characterization . 33.1Regional Geophysical Surveys. 43.3Metocean Data . 73.5Coring and In Situ Testing . 83.7Other Kinds of Surveys. 9Hazard Identification . 105.1Geohazards . 105.3Manmade Hazards . 215.5Effect of Geohazards on Pipelines and General Responses . 21Other Routing Considerations . 227.1Ecological and Environmental Constraints . 227.3Cultural Constraints . 237.5Pipeline Curvature Constraint . 237.7Project-Specific Constraints . 237.9Onshore Routing . 23TABLE 1Geophysical Survey Types . 5TABLE 2Potential Pipeline Geohazards and Manmade Hazards andResponse to Their Effect . 22FIGURE 1Pipeline Route Determination Flowchart . 2FIGURE 2Geophysical Survey Data Resolution Comparison . 6FIGURE 3AUV SBP, 3-D Seismic, and 2-D UHR Data ResolutionComparison . 7FIGURE 4Geohazard Examples . 11FIGURE 5Example Geometric Geohazards . 11FIGURE 6Mass Transport Deposits . 13FIGURE 7Sediment Transport Pathways . 14FIGURE 8Erosion and Deposition . 15FIGURE 9Tectonic Effects. 16ABS GUIDANCE NOTES ON SUBSEA PIPELINE ROUTE DETERMINATION . 2016iii

SECTION 2FIGURE 10Faults .17FIGURE 11Expulsion Features .18FIGURE 12Volcanic Activity .19FIGURE 13Sea Ice .20FIGURE 14Anthropogenic-Generated Slope Failure .21Methods for Route Determination . 241Route Determination Options.2431.1Required Input . 241.3Required Software . 24Geocost: Geohazard, Cultural, and Ecological Classification .253.157SECTION 3Composite Geocost Map . 26Route Selection .285.1Manual Route Selection . 285.3Least-geocost Path Optimization . 285.5Stochastic Simulation for Sensitivity Analysis . 29Route Evaluation .31TABLE 1Descriptions for Geocosts .25TABLE 2Examples of Typical Geocosts for Subsea Geohazards .26TABLE 3Ranges of Sample Points Recommended for StochasticSimulation of Cost Surface Uncertainties .30FIGURE 1Composite Geocost Map Premise .27FIGURE 2Composite Geocost Map .27FIGURE 3Least-Geocost Path Pipeline Routing .29FIGURE 4Stochastic Simulations .30Risk Assessment . 321Principles.321.1Hazard Identification . 331.3Risk Matrix . 341.5Site or Component Specific Risk Analysis . 36TABLE 1Example Risk Matrix .35TABLE 2Example Risk Levels for Health and Safety, Environmental,Social, and Financial Consequences .36FIGURE 1Risk Assessment Flowchart .33APPENDIX 1 Acronyms and Abbreviations . 37ivABS GUIDANCE NOTES ON SUBSEA PIPELINE ROUTE DETERMINATION . 2016

APPENDIX 2 Case Study. 38Step 1 Collect and evaluate available geological, geophysical,geotechnical, and metocean data . 39Step 2 Collect, evaluate, classify, and weight geohazard, cultural,environmental, and geotechnical constraints. 40Step 3 Create a geocost composite map and perform manual routing,least-geocost routing, or stochastic simulations and select theroute. . 44Step 4 Perform an evaluation of the routing results . 46Step 5 Risk Assessment . 47Step 6 Route Selection . 48Step 7 Recommendations . 50TABLE 1Geocosts for Geohazards, Manmade Hazards, andEnvironmental Constraints . 43TABLE 2Geocost Comparison . 47TABLE 3Risk Assessment Levels . 47TABLE 4Risk Assessment Matrix . 48TABLE 5Geohazard Risk Values for Areas 1 through 5 . 49FIGURE 1Pipeline Route Determination Flowchart . 38FIGURE 2Study Area and Manifold Termini. 39FIGURE 3Available Data . 40FIGURE 4Geometric Hazards . 41FIGURE 5Geohazards, Manmade Hazards, and EnvironmentalConstraints . 42FIGURE 6Allocation of Geocosts to Seafloor Slope, Roughness, andGeologic Hazards. 43FIGURE 7Geocost Composite Map . 45FIGURE 8Manual Route and Least-Geocost Route . 46FIGURE 9Risk Assessment Areas along Least-Geocost Route . 49ABS GUIDANCE NOTES ON SUBSEA PIPELINE ROUTE DETERMINATION . 2016v

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Section 1: Criteria for Pipeline Route DeterminationSECTION11Criteria for Pipeline Route DeterminationIntroductionThese Guidance Notes are developed to support the selection of subsea pipeline routes by systematicallyevaluating geological, geotechnical, ecological, and cultural factors that determine pipeline route suitabilityand assessing the risks of pipeline route selection.The procedures to determine a pipeline route in these Guidance Notes are built upon the important conceptusing a geocost map, which is established on a project basis to reflect the quantified geo riskscorresponding to geometric and geologic hazards. Favorite route can be determined by selecting a pathwhich causes the least accumulated geocost.1.1Purpose and ScopeThe purpose of these Guidance Notes is to assist in pipeline route determination by recognizing andcategorizing potential geological hazards (geohazards) as well as constraints ranging from cultural,ecological, pipeline, and/or project specific constraints. Consideration of such geohazards and constraints willhelp to reduce, control, or avoid potential engineering, construction, and operational problems.These Guidance Notes are applicable to the offshore pipelines that are defined in ABS Guide for Buildingand Classing Subsea Pipeline Systems. The pipelines can be trenched, buried, as-laid, or even anchored.The objectives of these Guidance Notes are to:1.3 Specify appropriate data to be collected and interpreted as part of a phased approach for selection ofpotential pipeline corridors or routes. Provide a representative but not exhaustive list of potential geohazards, ecological, cultural, andeconomic constraints, and possible effects on pipeline development and related infrastructure. Describe options for pipeline route selection and evaluation of route alternatives. Establish a general risk assessment procedure that can be used as a guide for specific projects.Pipeline Route Selection Criteria and Determination FlowchartThe favorable pipeline route is the shortest path that minimizes the summation score of geocost between twotermini. But the design working space for the route determination is bounded by applicable constraints thatrestrict the pipeline from passing through.Pipeline route determination flowchart, Section 1, Figure 1, illustrates a systematic approach of selectingpipeline route. This systematic approach consists of a series of steps that are grouped into three sections withinthese Guidance Notes.In the beginning, geo data collection and route constraint recognition are performed to collect informationwithin the project working area. The general required information such as geophysical data, geotechnicalinvestigations, and geological studies are stated in Subsection 1/3. Geohazard constraints are discussed inSubsection 1/5. Cultural, environmental, and geotechnical routing constraints are covered in Subsection 1/7.Following that, geohazard classification and weighting procedure are conducted which are described inSubsection 2/3 and the development of the geocost map is stated in 2/3.1. Route determination methods(manual, least geocost, stochastic) are then discussed in Subsection 2/5 followed by route evaluation given inSubsection 2/7.Finally, risk assessment and route acceptance are performed in accordance with Subsection 3/1.ABS GUIDANCE NOTES ON SUBSEA PIPELINE ROUTE DETERMINATION . 20161

Section1Criteria for Pipeline Route DeterminationFIGURE 1Pipeline Route Determination Flowchart1.52Required DocumentationRecommended procedures for subsea pipeline route determination are based primarily on the followingkinds of data and documents in order to demonstrate that the route selected meets all pertinent acceptancecriteria: Data required to assess seabed conditions where a pipeline will be installed: 2-D or 3-D seismic, multibeambathymetry, multibeam backscatter, side scan sonar, geotechnical or geological cores, pipeline termini,manifold locations, existing infrastructure, envrionmentally sensitive areas, pipe geometry and properties,loads and load matrix (pressure and temperature at installation, testing, and operation conditions). Specialist reports on geophysical surveys Specialist reports on geotechnical or geological cores Specialist reports on soil sampling/testing and pipe-soil interaction, including sea-bed and near subsurface soil conditions as well as pipe-soil interaction. Special study reports (if applicable) to identify parameters and/or actions that require specialconsideration and/or monitoring during soil sampling/testing, material testing, fabrication, installation,post installation survey and and operation.ABS GUIDANCE NOTES ON SUBSEA PIPELINE ROUTE DETERMINATION . 2016

Section1Criteria for Pipeline Route DeterminationThe data and documents listed above are those required for route determination. In the case of routes that havebeen determined, a route determination report describing the procedures used and a risk assessment reportare also expected.1.73Pipeline System Design Guides and StandardsFor subsea pipeline engineering standards and codes focusing on engineering design, material selection,installation, inspection, and soil site investigation, references can be made to the following: ABS Guide for Building and Classing Subsea Pipeline Systems (Pipeline Guide) ABS Rules for Building and Classing Offshore Installations API RP 1111 API RP 2RD API 5L ASME B31.4 ASME B31.8Data Acquisition and Site CharacterizationThis Subsection describes methods used to collect the data necessary to evaluate potential pipeline routesand discusses aspects pertinent to subsea pipeline route selection. 1/3.1 discusses regional geophysical surveysrequired for optimal assessment of seafloor and shallow subsurface geological conditions. 1/3.3 addressesthe importance of collecting relevant metocean data for assessment of conditions prior to pipeline selection.1/3.5 emphasizes the importance of collecting geological and geotechnical core samples to obtain designlevel information once a preliminary pipeline route or corridor has been determined.Pipeline route selection as outlined in Section 1, Figure 1 is an iterative process in which the quality of theinformation collected is refined as the cycle is repeated. For example, during the first iteration a provisionalroute might be determined on the basis of a desktop study and existing regional geophysical data with littleroute-specific geotechnical information. Such a provisional route, or more likely a corridor several kilometerswide, can then be used to target collection of more detailed geophysical and geotechnical information tofurther refine the route until uncertainty and risk are reduced to an acceptable level.A desktop study is an initial step that can define the regional geologic setting within the area of a potentialpipeline route, using existing information. The desktop study should involve an understanding of the regionalgeology from published studies, nearby locations, and analogous sites. Integration of all available data isimportant at this point. The information that is considered in a desktop study can include public domainbathymetric (water depth) maps (e.g., GEBCO – General Bathymetric Chart of the Oceans, Admiralty eNautical Publications) produced using different methods, scientific publications, or regional informationsuch as 2-D or 3-D seismic reflection data used to guide petroleum exploration and development.Regional geophysical surveys are a convenient starting point for route selection because, having been collectedto support oil and gas exploration, they are typically available early in the process. They can therefore beused to support determination of one or more preliminary route corridors along which additional geophysical,geotechnical, and geological information can be collected and used to refine the route. One disadvantage ofregional geophysical data is that they may be available over the reservoir or field development area butperhaps not along the full length of any export route corridors. Additional data may be required in order toproperly evaluate export route corridors or other areas of concern such as the source areas of long-runoutslope failures (e.g., debris flows) that may affect pipeline operation.Additional high-resolution geophysical surveys, geotechnical in-situ testing and sampling, and geohazard coresare required for optimal assessment of seaf