Introduction to Metocean

Metocean Awareness Course

An Introduction

Dr Bev Mackenzie

CSci, CMarSci, MIMarEST

Senior Technical Manager

April 2014

Purpose of ‘Introductory Metocean

Session’

• A brief overview of the full 3 day course

• An introduction to Metocean:

– learn about some of the key activities, products and services

– decide on the merits of different length courses

What is Metocean?

• Most offshore/nearshore activities affected by weather and sea conditions (meteorology and

oceanography = ‘Metocean’)

• Effective use of Metocean expertise, information and support throughout life cycle of a

development can improve planning, reduce costs and contribute to enhanced safety.

• The need for Metocean expertise was recognised in the oil and gas sector in the 1970’s;

setting up of dedicated Metocean departments in the major oil companies

• Physical parameters, e.g. winds, waves, currents, water levels, temps etc.

• does not cover biological and chemical oceanography

• BUT Metocean expertise is spread thinly and most companies involved in offshore activities

do not have dedicated staff

– heavy reliance on contractors

– NEED FOR INDIVIDUALS TO UNDERSTAND THE PRINCIPLES

•

Key Metocean

Activities

• Operations & Data Acquisition

– in-situ measurements

– spatial data (modelling/satellites)

– weather & ocean forecasting

• Data Management

– data QC/Archive

• Analyses & Reports

– standards, policies, processes

– operational stats

– design criteria

– expert advice

Metocean Services and Products – ‘Exploration’ Phase

• Initial Metocean briefing note (prior to award of licence block or sea area)

• Preliminary Metocean report (after licence has been awarded) includes:

– known conditions, available data, data collection requirements

– initial conservative operational statistics and design criteria

• Data is acquired through:

– measurements: sensor type, duration etc.

– consideration of modelling/hindcasts

• Weather forecasts

• Data QC/archive consideration

Metocean Services and Products – ‘Production’ Phase

• Continued data collection and modelling

• Metocean design criteria reports - ‘feasibility’ of initial design followed by ‘Final’

• Metocean equipment/sensors for new structure

• Tow-out and installation

– operational statistics and design criteria

– real-time data and weather forecasts

• Daily operations

– real-time data and weather forecasts

– final operational statistics

• weather downtime for maintenance, vessel ops, planning etc

• Regular 3-5 yearly updates of operational statistics and design criteria

Ethos of IMarEST 3-day Metocean

AwarenessTarget Audience

The course is aimed at those who need a greater understanding of Metocean so that they can make

informed decisions

– Project Managers, Engineers, Drillers, new Metocean staff

Format

Course format is a mixture of short presentations by a range of expert speakers together with

exercises, interactive sessions and team-based case studies. Speakers are internationally

renowned Metocean experts from oil and gas companies, Metocean contractors and consultancies.

• Delegates receive a comprehensive course manual

• Prior Metocean knowledge is not essential

IMarEST 3 Day Metocean Course –

Key Sessions

• Offshore requirements for Metocean

• Metocean parameters and processes

• Data trends/Climate variability

• Data acquisition

• Metocean conditions around the world

• Weather forecasting

• Operational statistics

• Metocean design criteria

Importance of Getting Metocean ‘Right’

• Hurricane Katrina in the Gulf of Mexico

– equivalent to 50-100 year design criteria

– BUT criteria ‘too low’

– extensive damage: 47 platforms destroyed, 20 badly damaged

– insurance costs in the $billions

Importance of Getting ‘Metocean’ Right

• Pressure from end-users for a ’number’

• Lack of dialogue between information providers and end-users

– how many clients just accept whatever numbers are given

• Metocean expertise is not widespread so people don’t always use the best providers of

Metocean support

– know your contractors

• May lead to incorrect values with potential adverse consequences for safety and/or cost

– overly conservative design criteria = additional cost

– under-estimation of potential downtime = additional cost

Key Metocean Issues

• Terminology and expertise

• Data sources – what data is available?

– measured vs. model vs. satellite

– differences between sensors, differences between models

• Data amount/appropriateness – how much is needed? Impact of climate variability/trends

• Data QC/archive/management – looking after the data

• How to derive design criteria and understand their meaning (extreme value analysis and

probabilities)

• Operational statistics – what types?

• How to present data (and interpret it)

• Standards/key documents

• Offshore vs. nearshore

Metocean Expertise • Oil and Gas companies

– majors only

• Renewables companies

– not enough, particularly in offshore wind

• Metocean contractors

– Integrated, weather forecasters, studies, modellers

• Metocean consultants

– generally ‘one-man bands’ (analysts/studies/modellers)

• Institutes/Academia

• Government

• Knowledge of capabilities, expertise, who to contact/use is important

UK H&E OIS Note – Role of a Metocean Advisor

Actions

21 HSE wishes to encourage duty holders to

pay appropriate attention to metocean

issues, bearing in mind the relevant

legislation and guidelines referred to in this

document. By so doing they can reduce the

risk to personnel and infrastructure while

offsetting the relatively minor costs against

potentially significant financial benefits that

will accrue in the short to medium term.

22 This note has provided an example of

good practice as to how these requirements

may be met through the role of a Metocean

Advisor. It will form the basis for part of the

inspection interventions carried out by HSE

inspectors.

Topics

Metocean process

Competency

Duties

Metocean Design Criteria & Operational Statistics

• 2 key sets of information required

– operational statistics ('typical', 'average' or 'normal' conditions)

– design criteria (extreme or 'survival' conditions)

• Deriving operational statistics is relatively straightforward; deriving design criteria is one of the most

challenging activities for Metocean engineers

• Important to appreciate we are analysing historical data

– operational statistics are summaries of past data ('facts')

– design criteria are derived from extrapolation of past data ('fiction')

• Significant difference between values for operational statistics (typical conditions) and design criteria

(extreme conditions)

Metocean Design Criteria 1• A need to ensure that installations are optimally designed (balancing safety and cost issues)

– avoid under-design (impact on people, equipment & asset)

– avoid over-design (increased cost)

• Not designing for the worst foreseeable condition, rather a statistical or probability-based approach

– a 100 year return period value tends to be the default requirement

– the value that will be exceeded once on average during 100 years

– a 1% probability of being exceeded in any one year (10-2

)

• In order to derive meaningful design criteria, we need

– knowledge of the area or location, legislation and standards

– quality long term database(s) and appropriate analytical tools

– consideration of climate variability

– dialogue between the Metocean engineer and end-user

Metocean Design Criteria 2• ‘End-users generally want a number’, e.g. the 100 year Hs

• BUT as part of the process of deriving the criteria, a wide range of extreme values can be generated.

Due to:

– data amount / availability / representativeness / quality

– different data types (measured vs. hindcast vs. satellite)

– different sensor types (buoys vs. radar)

– how data is extrapolated (EVA)

– people: ‘give the same dataset to 5 people and you can get 5 different answers’

• The challenge is to distil the diversity of extreme values into final design criteria and presentations

– a ‘journey’ from extreme values to design criteria

– needs expertise and experience as well as statistical knowledge

– engineering judgement plays a key role

Operational Statistics• Weather-related downtime can significantly affect cost and schedule

• Appropriate statistics from long datasets can assist with

– safety, planning and execution of activities e.g. maintenance

– selection of suitable vessels

– estimating budgets

• Examples of what is needed

– how often is the Hs >2m in April?

– how many weather windows of Hs<2m for 3 days in September?

– how long will an activity take to complete if I start 1 May?

– what are dominant wind directions?

• Types of presentations and analyses

– min/mean/max tables

– percentage exceedance/percentiles

– persistence/duration stats and weather windows analysis

– wind roses

Climate Variability

Natural Variability• Solar, earth's orbit, volcanoes

• Ocean heat cycles, eg

– El Nino/La Nina

– AMO (Atlantic Multi-decadal Oscillation)

– NAO (North Atlantic Oscillation)

High NAO index

More westerlies

More storms

Milder, wetter

Low NAO index

Less westerlies

Less storms

Colder

Metocean Standards

• ISO 19901-1 – Metocean Design and Operating Considerations

• Norsok N-002 – Collection of Metocean Data

• HSE RR392 – Wave Mapping in UK Waters

• OGP 447 – HSE Guidelines for Metocean and Arctic Surveys

• DNV OS J101 – Design of Offshore Wind Turbines

• Need to be careful using OTR 2001/010 Environmental Considerations

Example of an Integrated Approach for Metocean

Data

collection

Post-

storm

reports

Monthly

data QC

Daily checks

Of data

Forecast

verification

reports

Maintenance

reports

Gov't &

Institutes

Third party

transmission

access

Offshore

maintenance

visits

Metocean

database

Annual

data

reports

Pre-Storm

warningMet

Office

Data server

Metocean

library

UsersSurvey

Contractor

Weather

Forecast

Contractor

Independent

Data QC

Contractor

Weather

Forecasts

website

Data

website

Users

Survey

& Data QC

contractors

Metocean

statistics

websites

Initial

pre QC

data

Studies

Contractor

Design

Criteria &

Ops Stats

Users

Booking a Course

Courses are available internationally. For more details on the course, please get in touch:

We can also offer bespoke Metocean training for organisations who would like a tailored Metocean

course programme.

ContactE: stephen.bodie@imarest.org

T: +44 (0)20 7382 2652