Constraining Geohazards to the Past: Impact Assessment of Submarine Mass Movements on Seabed Developments

Thomas, Stephen J.; Hooper, James R.; Clare, Michael

doi:10.1007/978-90-481-3071-9_32

Cited by 22 publications

(21 citation statements)

References 30 publications

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“…Haneberg et al, 2013;Balogun et al, 2013;Chandio et al, 2012;Bagli et al, 2011;Yildirim and Yomralioglu, 2011;Byron, 2010;Price, 2010;Choi et al, 2009;Yildirim et al, 2007;Moghaddam and Delavar, 2007;Nonis et al, 2007;Iqbal et al, 2006;Atkinson et al, 2005;Luettinger and Clark, 2005;Saha et al, 2005;Yu et al, 2003;Thomaidis, 2000;Feldman et al, 1995). Haneberg et al, 2013;Balogun et al, 2013;Chandio et al, 2012;Bagli et al, 2011;Yildirim and Yomralioglu, 2011;Byron, 2010;Price, 2010;Choi et al, 2009;Yildirim et al, 2007;Moghaddam and Delavar, 2007;Nonis et al, 2007;Iqbal et al, 2006;Atkinson et al, 2005;Luettinger and Clark, 2005;Saha et al, 2005;Yu et al, 2003;Thomaidis, 2000;Feldman et al, 1995).…”

Section: Least-cost Path Optimizationunclassified

A Sensible Approach to Subsea Pipeline Route Determination – Moving from Hand-Drawn Routes to Geologically-Constrained, Least-Cost Optimized Paths

Devine

Haneberg

Lee³

et al. 2016

Day 2 Tue, May 03, 2016

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Pipeline routes have traditionally been selected in the early stages of prospect development, using low-resolution datasets, with minimal consideration for seafloor and shallow subsurface geological conditions, and rudimentary rules about seafloor gradients and pipeline curvature. We describe advantages of a modern GIS-based approach using least-cost path optimization over a composite geocost surface, which provides a structured framework for quantifiable decision-making, incorporates formal risk assessment as part of the route acceptance process, and forms the basis for a forthcoming industry guidance document. The workflow that we propose comprises: 1) geophysical data acquisition, geotechnical investigations, and geological studies during the initial stages of development to evaluate potential pipeline routes; 2) systematic evaluation of geological, geotechnical, ecological, and cultural factors that determine pipeline route suitability; 3) the classification and weighting of all identified geohazards and constraints to develop a geocost composite map; 4) determination of an optimal route using least-cost path optimization within a geographic information system; 5) risk assessment of the least-cost route; and, finally, 6) route acceptance. The classification and weighting of component hazard maps, as well as the risk assessment, are best performed collaboratively by a multi-disciplinary team that includes expertise in marine engineering geology, geotechnical engineering, pipeline engineering, marine ecology and archaeology, and health, safety, and environmental personnel. We will demonstrate a step-by-step application of the method, which has already been used for pipeline route determination on geologically challenging deepwater projects. If geohazards are not identified in early stages and used to guide route selection, changes to the original pipeline route or mitigation -either of which could affect schedules and budgets -may be necessary. This method is relatively new to subsea pipeline route determination, however, it offers important advantages over previous methods and can be applied starting in the earliest conceptual phases of field development, iterating if necessary, as new information becomes available.

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Section: Least-cost Path Optimizationunclassified

A Sensible Approach to Subsea Pipeline Route Determination – Moving from Hand-Drawn Routes to Geologically-Constrained, Least-Cost Optimized Paths

Devine

Haneberg

Lee³

et al. 2016

Day 2 Tue, May 03, 2016

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“…From this model, it is possible to conduct an inventory of geohazards, to estimate their conditioning factors and their potential occurrence (Thomas et al, 2010). This model will be a representation of the spatial distribution of geological, geotechnical and geohazard conditions within the area of interest.…”

Section: Understanding the Geological Processmentioning

confidence: 99%

Gap analysis for the development of a Geohazard Monitoring and Warning System

Cauquil

2014

Day 4 Thu, May 08, 2014

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The classical approach to cope with geohazards is to conduct a "baseline" geohazard assessment recognizing the threat (shallow gas, shallow water flow, gas hydrate, unconsolidated / over consolidated sediments, slope instabilities, over steepening seafloor (fault through, pockmarks…), active faults, mud volcanoes, seabed fluid escapes, chemosynthetic communities…) and to avoid it by moving the facility outside the impact area of the given geohazard. Avoidance is the safest and most satisfactory long-term solution to cope with geohazards. However, as E&P activity is moving to more complex and deeper geo-environmental contexts, recent projects have shown that it may not be possible to avoid the geohazard and its impact area. In this case, mitigation measures as reducing risk through engineering work may be implemented so that the risk is reduced to an acceptable level. In addition to the "baseline" approach, it may be necessary to evaluate the impact of a given geohazard that may evolve during the field life time (20–25 years). This new concern introduces the notion of time that is rather difficult to address for geological processes. For example, an area may be recognized as a sliding prone area and appropriate mitigation in terms of foundation design may be proposed during the engineering study, but the long term behavior of the sliding area must be properly evaluated and monitored for forecasting during the field lifetime. Similarly, seabed conditions and foundation bearing capacity may be subject to modifications during the life time of a field due to E&P itself, as subsidence due to reservoir depletion or overpressure due to gas/water/cutting reinjection.

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“…(3) what are the triggering mechanisms; (4) what is the area of influence; (5) what is the nature and magnitude of the impact; and (6) can previous failures be re-activated (Locat and Lee, 2002;Thomas et al, 2010b). While not a detailed or comprehensive study, this section will outline some of the key tools used in the assessment of submarine geohazards.…”

Section: Hazard Assessmentmentioning

confidence: 99%