Changing Practice in Gulf of Changing Practice in Gulf of Mexico Design and Operating Mexico Design and Operating

CriteriaCriteria

The Early DaysThe Early Days((sometimes it is better to be lucky than goodsometimes it is better to be lucky than good))

Gulf of Mexico platforms built around 1946 – 48 typically Gulf of Mexico platforms built around 1946 – 48 typically had deck heights 20 to 40 feet above mean sea levelhad deck heights 20 to 40 feet above mean sea level

Consultants’ evaluations:Consultants’ evaluations: ““in 100 feet of water waves will probably seldom, IF EVER, exceed in 100 feet of water waves will probably seldom, IF EVER, exceed

20 feet in height”20 feet in height” “ … “ … settled on a maximum wave height of about 25 feet and a settled on a maximum wave height of about 25 feet and a

recommended deck height of 32 feet” recommended deck height of 32 feet”

Consensus: maximum wave ~ 29 feet, occurring perhaps Consensus: maximum wave ~ 29 feet, occurring perhaps once every 40 to 50 years.once every 40 to 50 years.

Very loose “consensus” – no API guidance, little regulation.Very loose “consensus” – no API guidance, little regulation.

Luck Starts to Run OutLuck Starts to Run Out 1947 – 1952: series of relatively weak, small 1947 – 1952: series of relatively weak, small

hurricanes in the Gulfhurricanes in the Gulf

October 1949 – platform off Freeport damaged – October 1949 – platform off Freeport damaged – post-mortem suggested waves as high as 40 feet.post-mortem suggested waves as high as 40 feet.

Observed damage in others led to estimates of Observed damage in others led to estimates of 22-29 feet – calls into question both the upper 22-29 feet – calls into question both the upper limit and frequency of occurrence of high waves limit and frequency of occurrence of high waves in Gulfin Gulf

Leads to stronger designs for a few operatorsLeads to stronger designs for a few operators

Lulled to Sleep?Lulled to Sleep?All Hurricanes and Trop Storms in Gulf 1947 - 1955All Hurricanes and Trop Storms in Gulf 1947 - 1955

Luck Starts to Run OutLuck Starts to Run Out 1956 – Hurricane Flossie1956 – Hurricane Flossie

A Category 1 stormA Category 1 storm

50 men rode out the storm in the Gulf. One 50 men rode out the storm in the Gulf. One vessel lost its anchor and floated around during vessel lost its anchor and floated around during the storm in keeping with a philosophy of “taking the storm in keeping with a philosophy of “taking a calculated risk that they would be safe.” a calculated risk that they would be safe.”

Led to calls for complete evacuation in Led to calls for complete evacuation in hurricanes.hurricanes.

Luck Starts to Run OutLuck Starts to Run Out

1957 – Hurricane Audrey1957 – Hurricane Audrey

Forms in Gulf – now called “Sudden storms”Forms in Gulf – now called “Sudden storms”

One mobile drilling rig sank, with four tenders One mobile drilling rig sank, with four tenders suffering damage when pulled loose from their suffering damage when pulled loose from their mooring and running aground mooring and running aground

Industry record of no fatalities heldIndustry record of no fatalities held..

Industry Intensifies ActionIndustry Intensifies Action 1957 – Hurricanes Audrey and Bertha – three 1957 – Hurricanes Audrey and Bertha – three

significant storms in 2 years.significant storms in 2 years.

API forms “Advisory Committee on Fundamental API forms “Advisory Committee on Fundamental Research on Weather Forecasting.”Research on Weather Forecasting.”

Disbanded in 1962.Disbanded in 1962.

Why? Other issues and Gulf fairly quiet (Carla in Why? Other issues and Gulf fairly quiet (Carla in 1961 but it hits Texas) 1961 but it hits Texas)

Hmmmm?Hmmmm?All Hurricanes and Trop Storms in Gulf 1956 - 1963All Hurricanes and Trop Storms in Gulf 1956 - 1963

No ConsensusNo Consensus

Deck height practices:Deck height practices: Varied from the 1950 era standard of 28 – 32 Varied from the 1950 era standard of 28 – 32

feet above mean Gulf level to higher than 50 feet above mean Gulf level to higher than 50 feet.feet.

Not coincidently, those using higher values Not coincidently, those using higher values were companies directly impacted by storms were companies directly impacted by storms either in terms of property or direct threat to either in terms of property or direct threat to employees.employees.

Higher meant safer and more expensive – Higher meant safer and more expensive – “each company placed a bet on the right “each company placed a bet on the right combination of safety and cost”. combination of safety and cost”.

(Primitive cost-benefit analysis) (Primitive cost-benefit analysis)

Luck Starts to Run Out Luck Starts to Run Out All Hurricanes and Trop Storms in Gulf 1964 - 1973All Hurricanes and Trop Storms in Gulf 1964 - 1973

Luck Run Outs 1964 - 1969Luck Run Outs 1964 - 1969 1964: Hurricane Hilda – Category 41964: Hurricane Hilda – Category 4

1965: Hurricane Betsy1965: Hurricane Betsyhttp://en.wikipedia.org/wiki/Hurricane_Hilda

http://en.wikipedia.org/wiki/Hurricane_Betsy

Luck Runs Out 1964 - 1969Luck Runs Out 1964 - 1969 1964: Hurricane Hilda – Category 41964: Hurricane Hilda – Category 4

Hilda was the most damaging tropical cyclone to Hilda was the most damaging tropical cyclone to the offshore oil industry, at the time of its impact. the offshore oil industry, at the time of its impact.

More than US$100 million in losses.More than US$100 million in losses.

13 oil platforms were destroyed13 oil platforms were destroyed

5 more damaged beyond repair5 more damaged beyond repair[[

Luck Runs Out 1964 - 1969Luck Runs Out 1964 - 1969

1965: Hurricane Betsy – strong Category 3 1965: Hurricane Betsy – strong Category 3 at landfallat landfall

Eight offshore oil platforms were destroyed Eight offshore oil platforms were destroyed during Betsy, with others experiencing during Betsy, with others experiencing damage. damage.

The oil rig Maverick disappeared during The oil rig Maverick disappeared during the cyclone the cyclone

Industry ActionIndustry Action

1966: API Committee on Standardization 1966: API Committee on Standardization of Offshore Structures created.of Offshore Structures created.

Focus to create better design standards Focus to create better design standards through cooperative efforts. through cooperative efforts.

Basic research and measurement of wind, Basic research and measurement of wind, waves, and soils continueswaves, and soils continues. .

Includes the Ocean Data Gathering Program Includes the Ocean Data Gathering Program (ODGP) – 6 platforms instrumented in Gulf (ODGP) – 6 platforms instrumented in Gulf from 1968 through 1971 from 1968 through 1971

Some “Good Luck”, Some BadSome “Good Luck”, Some Bad

1969: Hurricane Camille1969: Hurricane Camille

ODGP measured a wave between 70 and 75 feet high!!!

http://en.wikipedia.org/wiki/HurricaneCamille

Some “Good Luck”, Some BadSome “Good Luck”, Some Bad

1969: Hurricane Camille1969: Hurricane Camille

ODGP measured a wave between 70 and 75 feet high!!!

Used to calibrate hindcast models in Gulf for decades.

Metocean criteria developed using those hindcasts as database of storms in Gulf.

API Standards and Design WavesAPI Standards and Design Waves First API offshore standard (RP2A) issued in First API offshore standard (RP2A) issued in

19691969

No design wave information until 7No design wave information until 7thth edition edition in 1976.in 1976.• Recommends use of “the 100-year wave”Recommends use of “the 100-year wave”

To this point the owner chose the return To this point the owner chose the return period and the use of both 25 and 100 year period and the use of both 25 and 100 year values was common.values was common.

• 1% risk of exceedance annually = 100 yr1% risk of exceedance annually = 100 yr• 4% risk of exceedance annually = 25 yr4% risk of exceedance annually = 25 yr

API Standards and Design WavesAPI Standards and Design Waves

20th edition (1993) includes a new wave 20th edition (1993) includes a new wave force calculation “recipe” that force calculation “recipe” that substantially changes that of the 19substantially changes that of the 19thth edition (1991)edition (1991)

Design (“100-year”) wave conditions Design (“100-year”) wave conditions changed as wellchanged as well

WOW!WOW!

1992 saw Hurricane Andrew1992 saw Hurricane Andrew

http://en.wikipedia.org/wiki/Hurricane_Andrew

What Hath Andrew Wrought?What Hath Andrew Wrought?

Category 4 storm in GulfCategory 4 storm in Gulf MMS estimates 700 structures took MMS estimates 700 structures took

“significant” hit“significant” hit 22 older platforms destroyed22 older platforms destroyed 65 others with significant damage65 others with significant damage Majority had been designed to 25 year Majority had been designed to 25 year

values and 35 to 40 foot decksvalues and 35 to 40 foot decks Newer platforms that were designed with Newer platforms that were designed with

decks to pass up to 72 foot waves had decks to pass up to 72 foot waves had only minor damageonly minor damage

Effect of Andrew and New API Effect of Andrew and New API Force RecipeForce Recipe

Gave a boost of energy to an API Gave a boost of energy to an API committee looking at assessment of committee looking at assessment of existing platformsexisting platforms

Task group decided that the new criteria Task group decided that the new criteria should be relaxed for existing platforms should be relaxed for existing platforms and consideration be given to and consideration be given to CONSEQUENCE OF FAILURECONSEQUENCE OF FAILURE

Willing to take higher risks with older assets in part Willing to take higher risks with older assets in part because cost to modify/replace are too highbecause cost to modify/replace are too high

Effect of Andrew and New API Effect of Andrew and New API Force RecipeForce Recipe

Three categories with different metocean criteriaThree categories with different metocean criteria::

L-1 (high consequence / manned-evacuated or unmannedL-1 (high consequence / manned-evacuated or unmanned• Full-population of hurricanes, 1% annual exceedance probabilityFull-population of hurricanes, 1% annual exceedance probability

L-2 (low consequence / manned-evacuated)L-2 (low consequence / manned-evacuated)• Sudden hurricane and winter storm populationSudden hurricane and winter storm population

L-3 (low sequence / unmanned, or minimum consequenceL-3 (low sequence / unmanned, or minimum consequence• Winter storm populationWinter storm population

Included deck height criteriaIncluded deck height criteria

Consequence-based Criteria for Consequence-based Criteria for New-Build PlatformsNew-Build Platforms

CBC for assessing existing platforms in CBC for assessing existing platforms in place in 1996 (issued as a supplement to place in 1996 (issued as a supplement to the 20the 20thth edition of RP2A. edition of RP2A.

Sets stage for introducing this concept for Sets stage for introducing this concept for new-buildnew-build

L1 L1 L2L2 L3 L3

Table 1 – Risks Considered for Table 1 – Risks Considered for

Consequence-Based Criteria for the Consequence-Based Criteria for the

Gulf of MexicoGulf of Mexico

LEVEL 1LEVEL 1 LIFE SAFETYLIFE SAFETYCONSEQUENCES CONSEQUENCES

OF FAILUREOF FAILURE

11 Manned, non-Manned, non-evacuatedevacuated

HIGHHIGH

22 Manned, Manned, evacuatedevacuated

MEDIUMMEDIUM

33 UnmannedUnmanned LOWLOW

Lulled to Sleep Again?Lulled to Sleep Again?All Hurricanes and Trop Storms in Gulf 1993 - 2000All Hurricanes and Trop Storms in Gulf 1993 - 2000

What’s Happening Out There?What’s Happening Out There?All Hurricanes and Trop Storms in Gulf 2001 - 2005All Hurricanes and Trop Storms in Gulf 2001 - 2005

Impact of Ivan, Katrina, and RitaImpact of Ivan, Katrina, and Rita

Impact of Ivan, Katrina, and RitaImpact of Ivan, Katrina, and Rita

2005 Atlantic Season: most active in 2005 Atlantic Season: most active in recorded historyrecorded history

28 named storms, 15 hurricanes, 7 major 28 named storms, 15 hurricanes, 7 major hurricanes, and four category 5 hurricanes hurricanes, and four category 5 hurricanes ((per NOAA NHCper NOAA NHC) )

Worst season previously: 1933 with 21 Worst season previously: 1933 with 21 named storms, 10 hurricanes, and 5 major named storms, 10 hurricanes, and 5 major hurricanes hurricanes

Impact of Ivan, Katrina, and RitaImpact of Ivan, Katrina, and Rita

2004-2005 was worst two year period (23 2004-2005 was worst two year period (23 hurricanes) since 1886-1887 (21 total)hurricanes) since 1886-1887 (21 total)

Lots of damage to platforms and mobile Lots of damage to platforms and mobile rigs (114 platforms destroyed in Katrina rigs (114 platforms destroyed in Katrina and Rita)and Rita)

Lots of infrastructure damage (pipelines) Lots of infrastructure damage (pipelines) leading to loss of oil and gas productionleading to loss of oil and gas production

MODU Failures – Floating (Semi) and JackupMODU Failures – Floating (Semi) and Jackup

      Total FailureTotal Failure Partial FailurePartial Failure

Ivan: Sept. '04, Cat 4Ivan: Sept. '04, Cat 4SemiSemi 44 11

JackupJackup 11 11

Katrina: Aug. '05, Cat 5Katrina: Aug. '05, Cat 5SemiSemi 44 33

JackupJackup 22 00

Rita: Sept. '05, Cat 4Rita: Sept. '05, Cat 4SemiSemi 77 44

JackupJackup 77 11

Ivan, Katrina, and Rita

API Metocean ReactionAPI Metocean Reaction

Study of Ivan led to conclusion it was a Study of Ivan led to conclusion it was a rare event statistically but no need for rare event statistically but no need for significant criteria revision (OTC Paper significant criteria revision (OTC Paper 17740)17740)

Recommendation was to simply include Recommendation was to simply include Ivan in any extremal analysis Ivan in any extremal analysis

Maximum Hs (m):Maximum Hs (m): IvanIvan 16.016.0 KatrinaKatrina 16.916.9 RitaRita 11.511.5

API Criteria before these storms? Hmax = 21.5 m

Hs ≈ 12.6 m

Industry and API Metocean ReactionIndustry and API Metocean Reaction

The rapid-fire occurrence of three huge storms in The rapid-fire occurrence of three huge storms in two years led to significant revisions in part due two years led to significant revisions in part due to a mooring risk JIP led by ABS which required to a mooring risk JIP led by ABS which required the best possible metocean data the best possible metocean data

Several key findings:Several key findings:• Loop current and or Loop eddies provided get source of Loop current and or Loop eddies provided get source of

energy for all three of these stormsenergy for all three of these storms• Dividing the Gulf into four regions was deemed Dividing the Gulf into four regions was deemed

appropriateappropriate• Use of the full 1990 – present hurricane database was Use of the full 1990 – present hurricane database was

not appropriate not appropriate

Loop Current - Source of Deep Warm Water

Stages develop on time scale of months = persistent warm water conditions

De

pth

be

low

Oc

ea

n s

urf

ac

e,

m

-400

-300

-200

-100

0

10° 20° 30° 40°Temperature, deg C

Loop and

EddyAreas

Other Areas

Storm Tracks over LoopStorm Tracks over Loop

http://www.esl.lsu.edu/quicklinks/publications/images/PreStorms.gif

Reprinted courtesy of Colorado Center for Aerodynamics Research

API Metocean Criteria Changes API Metocean Criteria Changes after Ivan, Katrina, and Rita after Ivan, Katrina, and Rita

Gulf divided into 4 regions.Gulf divided into 4 regions.

Frequent Loop

“Eddy Graveyard”

Random Eddies

Occasional Loop

Bias in Storms Prior to 1950Bias in Storms Prior to 1950

Measurements were sparse, often only at Measurements were sparse, often only at land stations. What went on in the Gulf land stations. What went on in the Gulf was speculative.was speculative.

In a 2006 paper (OTC 18418), Cooper and In a 2006 paper (OTC 18418), Cooper and Stear concluded that there was a negative Stear concluded that there was a negative bias in the 1900 to 1949 storms as bias in the 1900 to 1949 storms as characterized by the National Hurricane characterized by the National Hurricane Center. Center.

Bias in Storms Prior to 1950Bias in Storms Prior to 1950Start=1900, End=1949, Min CPI (mb)=63

40 60 80 100 120 140 160

CPI (mb)

400

200

0D

ista

nce

fro

m S

ho

re (

km)

1900/09/061915/09/301916/08/191919/09/121932/08/141933/09/04

Start=1955, End=2005, Min CPI (mb)=63

40 60 80 100 120 140 160

CPI (mb)

400

200

0

Dis

tan

ce f

rom

Sh

ore

(km

)

1961/09/101964/10/021965/09/091969/08/171970/08/021974/09/091979/09/121980/08/101982/09/101992/08/251995/10/101999/08/222004/09/152005/07/092005/08/272005/09/22

Plots:Plots:6 pre-’50; 16 post-’50 storms6 pre-’50; 16 post-’50 stormsPre-’50, 70% of storms show no drop as they near coastPre-’50, 70% of storms show no drop as they near coastPost-’55, 12% show no dropPost-’55, 12% show no drop

Suggest: pre-’50 applied coastal data offshore resulting in Suggest: pre-’50 applied coastal data offshore resulting in low biaslow bias

Other factors support conclusion:Other factors support conclusion:NOAA generally does not use pre-’50NOAA generally does not use pre-’508 of top 10 winds occurred post-’508 of top 10 winds occurred post-’507 of top 10 waves occurred post-’507 of top 10 waves occurred post-’50

Plots provided by Chevron Energy Technology Company

Hurricane Reconnaissance Hurricane Reconnaissance

Became common after WWII

Industry ResponseIndustry Response

Interim Guidance for Design of Offshore Structures for Hurricane ConditionsAPI BULLETIN 2INT–DGFirst Edition, May 2007

Interim Guidance for Assessment of Existing Offshore Structures for Hurricane ConditionsAPI BULLETIN 2INT–EXFirst Edition, May 2007

Interim Guidance on Hurricane Conditions in the Gulf of MexicoAPI BULLETIN 2INT–METFirst Edition, May 2007

API RPs 2I, 2SM, and 2SK were API RPs 2I, 2SM, and 2SK were all updatedall updated

MODU Mooring JIP (budget MODU Mooring JIP (budget approx. $2.2m)approx. $2.2m)

Measured Data is FoundationalMeasured Data is Foundational Hindcasts are used to generate Hindcasts are used to generate

criteria BUT these are calibrated criteria BUT these are calibrated against dataagainst data

Excellent network of data buoy in Gulf and along coast

Future HurricanesFuture Hurricanes

More/less?More/less? Stronger?Stronger? Similar tracks?Similar tracks? Was the 2004-2005 season a Was the 2004-2005 season a

precursor of things to come?precursor of things to come?

Future HurricanesFuture Hurricanes Atlantic Hurricane Variability Over Time: 1886 – 2004Atlantic Hurricane Variability Over Time: 1886 – 2004

Multi-decadal variabilityMulti-decadal variability El NinoEl Nino

Yellow = named storms, Green = hurricanes, Red = Category 3 and above

Future HurricanesFuture Hurricanes Was the 2004-2005 season a precursor of things Was the 2004-2005 season a precursor of things

to come? Was it all that unusual?to come? Was it all that unusual?

How confident can we be in the historical record?How confident can we be in the historical record?• Prior to about 1950 – no air reconnaissancePrior to about 1950 – no air reconnaissance• Satellites much laterSatellites much later

Future HurricanesFuture Hurricanes

Key factors: warm water and wind shear Key factors: warm water and wind shear generally considered most importantgenerally considered most important

Area of much current research AND Area of much current research AND considerable controversyconsiderable controversy

““Experts” do not agree Experts” do not agree

Models do not agreeModels do not agree

Two interpretations of SST data lead to VASTLY Two interpretations of SST data lead to VASTLY different future Atlantic activitydifferent future Atlantic activity

Science 31 October 2008:Vol. 322. no. 5902, pp. 687 - 689DOI: 10.1126/science.1164396CLIMATE CHANGE:Whither Hurricane Activity?Gabriel A. Vecchi,1 Kyle L. Swanson,2 Brian J. Soden3

extrapolated into the 21st century using absolute SSTs calculated

from global climate model projections suggest that it is the SST in the tropical Atlantic main development region relative to the tropical mean SST that controls fluctuations in Atlantic hurricane activity

Future Hurricanes and APIFuture Hurricanes and API As opposed to the general historical pattern of As opposed to the general historical pattern of

API, being API, being REACTIVEREACTIVE, there is a shift to being , there is a shift to being more more PROACTIVEPROACTIVE

Funding a synthetic hurricane study at a cost Funding a synthetic hurricane study at a cost significantly larger than “normal” API-funded significantly larger than “normal” API-funded research to develop a long term (100000 yrs) research to develop a long term (100000 yrs) synthetic data base of hurricanes in the Gulfsynthetic data base of hurricanes in the Gulf

Supportive of National Center for Atmospheric Supportive of National Center for Atmospheric Research (NCAR) modelling work on how climate Research (NCAR) modelling work on how climate change is likely to influence hurricane activity change is likely to influence hurricane activity through 2055 through RPSEA with Industry reps through 2055 through RPSEA with Industry reps on steering committee, members’ time, etc. on steering committee, members’ time, etc.

Future Hurricanes and APIFuture Hurricanes and API

No criteria changes to account for any No criteria changes to account for any future climate scenario being applied in future climate scenario being applied in part due to uncertaintiespart due to uncertainties

May be applied when the results of the May be applied when the results of the sponsored research efforts are finished sponsored research efforts are finished

QUESTIONS ?QUESTIONS ?

BACKUPBACKUP

TABLE 2 – LIFE SAFETYTABLE 2 – LIFE SAFETY

LEVELLEVEL MANNING MANNING CONDITIONSCONDITIONS

EXPOSURE TO PERSONNELEXPOSURE TO PERSONNEL

11 Manned, non- Manned, non- evacuatedevacuated

Platform continuously mannedPlatform continuously manned Evacuation prior to design event is not intended or is Evacuation prior to design event is not intended or is not feasiblenot feasible Personnel exposed to severe hurricanes Personnel exposed to severe hurricanes

22 Manned, Manned, evacuatedevacuated

Platform normally mannedPlatform normally manned Evacuation prior to design event is planned and feasibleEvacuation prior to design event is planned and feasible Largest events that personnel are exposed to are a Largest events that personnel are exposed to are a “sudden” hurricane or a winter storm“sudden” hurricane or a winter storm

33 UnmannedUnmanned Platform normally unmanned except for day trips to Platform normally unmanned except for day trips to perform short field operationsperform short field operations May have emergency shelter but no permanent quartersMay have emergency shelter but no permanent quarters Personnel exposed to worst event that can occur during Personnel exposed to worst event that can occur during the day the day

Occasional manning for short durationsOccasional manning for short durations Short maintenance, construction, workover, or drillingShort maintenance, construction, workover, or drilling Scheduled to minimize potential hurricane exposure Scheduled to minimize potential hurricane exposure

TABLE 3 – CONSEQUENCE OF FAILURETABLE 3 – CONSEQUENCE OF FAILURE

PLATFORM PLATFORM CATEGORYCATEGORY

CONSEQUENCE CONSEQUENCE OF FAILUREOF FAILURE

PLATFORM CHARACTERISTICSPLATFORM CHARACTERISTICS

11 HighHigh Platform with major drilling, production, pipeline Platform with major drilling, production, pipeline processing, or storage facilitiesprocessing, or storage facilities Other platforms with high consequences of failureOther platforms with high consequences of failure Wells not shut-in during design event Wells not shut-in during design event Potential for well flow in the event of platform failurePotential for well flow in the event of platform failure All platforms in depths greater than 400 feetAll platforms in depths greater than 400 feet

22 MediumMedium Platform with drilling or production pipeline facilities Platform with drilling or production pipeline facilities with medium consequences of failurewith medium consequences of failure Wells shut-in during design eventWells shut-in during design event Wells protected by SSSV’s Wells protected by SSSV’s Oil storage limited to process inventory and “surge” Oil storage limited to process inventory and “surge” tanks for pipeline transferstanks for pipeline transfers

33 LowLow Small well protectors and caissons with small Small well protectors and caissons with small consequences of failureconsequences of failure No more than 5 completions on or connected to No more than 5 completions on or connected to platform platform Wells shut-in during design eventWells shut-in during design event Wells protected by SSSV’sWells protected by SSSV’s No more than 2 pieces of production equipmentNo more than 2 pieces of production equipment Oil storage limited to process inventory Oil storage limited to process inventory Maximum water depths of 100 feetMaximum water depths of 100 feet