MATTHEWS~DANIEL

MINIMIZING RISKS FOR JACKMINIMIZING RISKS FOR JACK--UP RIGS UP RIGS

WHENWHENWHENWHEN

PRELOADING ON LOCATIONPRELOADING ON LOCATIONPRELOADING ON LOCATIONPRELOADING ON LOCATION

Presented by:

S. Douglas DevoyMatthewsDanielatt e s a e

Houston, Texas

MATTHEWS~DANIEL

PRELOADING HAS PROVEN TO POSE THE PRELOADING HAS PROVEN TO POSE THE

JACK-UP RIGS SUSTAIN PUNCH-THROUGHS IN ALL AREAS OF THE WORLD

GREATEST RISK DURING THE FINAL GREATEST RISK DURING THE FINAL STAGES OF THE RIG MOVE!STAGES OF THE RIG MOVE!

MATTHEWS~DANIEL

Definition of Preloading of JackDefinition of Preloading of Jack--Up RigUp Rig

Preloading consists of taking largePreloading consists of taking largePreloading consists of taking large Preloading consists of taking large volumes of salt water into designated volumes of salt water into designated preload tanks greatly increasing thepreload tanks greatly increasing thepreload tanks, greatly increasing the preload tanks, greatly increasing the

overall weight of the rig. overall weight of the rig.

MATTHEWS~DANIEL

Definition of Preloading of JackDefinition of Preloading of Jack--Up RigUp Rig

This additional weight results in theThis additional weight results in theThis additional weight results in the This additional weight results in the spud cans penetrating deeper into the spud cans penetrating deeper into the soil profile in order to reach soils withsoil profile in order to reach soils withsoil profile in order to reach soils with soil profile in order to reach soils with adequate strength to support the rig.adequate strength to support the rig.

MATTHEWS~DANIEL

Rig Preloading on LocationRig Preloading on Location

MATTHEWS~DANIEL

Risk Mitigation Measures For PreloadingRisk Mitigation Measures For Preloading

Location ApprovalLocation Approval

Detailed Geotechnical Analysis /Detailed Geotechnical Analysis /yyPunchPunch--Through StudyThrough Study

Recommendations for Preloading Air GapRecommendations for Preloading Air Gap

Recommendations for Close Monitoring of Leg Recommendations for Close Monitoring of Leg Loads and PenetrationsLoads and Penetrations

Recommendation for Action if Penetrations are Recommendation for Action if Penetrations are Different than PredictedDifferent than Predicted

MATTHEWS~DANIEL

Preloading Risk Level AssessmentPreloading Risk Level AssessmentR d ti f Ai G D i P l diR d ti f Ai G D i P l diRecommendation for Air Gap During PreloadingRecommendation for Air Gap During Preloading

Normal CautionNormal Caution Normal to Maximum 3 5’Normal CautionNormal Caution Maximum Air Gap Maximum 3-5’

Special Caution Minimal Air Gap Maximum 0-2’

N t t E d 0’ tExtreme Caution 0’ Air Gap or Draft Not to Exceed 0’ to Draft

MATTHEWS~DANIEL

Rig Arrives on LocationInitial Penetrations Taken5’ Air Gap5’ Air Gap

Li it d S il I f tiLimited Soils Information . . .Generic Location Approval . . .

No Preloading Program. . .

MATTHEWS~DANIEL

Maximum preload water onboardEven penetrations on all 3 legsAll useful work completed for this stageAll useful work completed for this stage

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Dump preload water Rig jacked back to 5’ air gapPrepare for next preload cyclePrepare for next preload cycle

UNIT RE-ELEVATED

MATTHEWS~DANIEL

Near end of preloading cycleLegs at even penetrationRig at 5’ air gapRig at 5 air gap

MATTHEWS~DANIEL

MATTHEWS~DANIEL

CASE STUDYCASE STUDYCASE STUDYCASE STUDY

Jack Up Rig PunchJack Up Rig Punch--Through Through

Middle EastMiddle East

MATTHEWS~DANIEL

Information Developed Prior to Rig MoveInformation Developed Prior to Rig MoveMWS Location ApprovalMWS Location ApprovalMWS Location ApprovalMWS Location Approval

Detailed Soils Analysis conducted by Detailed Soils Analysis conducted by y yy y

Geotechnical ExpertGeotechnical Expert

PunchPunch--Through PredictedThrough Predicted

Preload in Water RecommendedPreload in Water Recommended

MATTHEWS~DANIEL

Rig Move Plan Agreed Prior to SitingRig Move Plan Agreed Prior to Siting(Two(Two Stage Preloading)Stage Preloading)(Two(Two--Stage Preloading)Stage Preloading)

1.1. Preload in Water to 100%Preload in Water to 100%

2.2. Followed by Preload at Minimal Air Gap to 100%Followed by Preload at Minimal Air Gap to 100%

MATTHEWS~DANIEL

FindingsFindings

Leg Penetration Curve showed ‘punchLeg Penetration Curve showed ‘punch--through’through’g pg p gg

Initial penetrations were different than predictedInitial penetrations were different than predicted

(5’ ti i t d 9(5’ ti i t d 9 14’)14’)(5’ vs. anticipated 9(5’ vs. anticipated 9--14’)14’)

First stage of preload conducted at draft with no First stage of preload conducted at draft with no

settlement of legssettlement of legs

Rig raised to 5’ air gap in final stages of preloadRig raised to 5’ air gap in final stages of preload Rig raised to 5 air gap in final stages of preloadRig raised to 5 air gap in final stages of preload

Port leg punchPort leg punch--through occurred at 91% preload through occurred at 91% preload

MATTHEWS~DANIEL

Failure in SystemFailure in System

Agreed Rig Move ProceduresAgreed Rig Move ProceduresAgreed Rig Move Procedures Agreed Rig Move Procedures

Superseded by Rig MoverSuperseded by Rig Mover

Preloading Conducted at 5’ Air GapPreloading Conducted at 5’ Air Gapg pg p

MATTHEWS~DANIEL

Communication is very important between allCommunication is very important between allLessons LearnedLessons Learned

Communication is very important between all Communication is very important between all parties engaged in preloading operation.parties engaged in preloading operation.

It is important to keep accurate measurements It is important to keep accurate measurements of leg loads and penetrations.of leg loads and penetrations.of leg loads and penetrations. of leg loads and penetrations.

When the soils do not behave as Leg When the soils do not behave as Leg CC CCPenetration Curve predicts, Penetration Curve predicts, EXTREME EXTREME Caution Caution

is advised. Lower air gap = less damage.is advised. Lower air gap = less damage.

MATTHEWS~DANIEL

Accurate Accurate Measurement Measurement of Spud Can of Spud Can

L d dL d dLoad and Load and PenetrationPenetration

MATTHEWS~DANIEL

Case StudyCase Study

Estimated Estimated P hP hPunch Punch

Through Through

5’ Ai G5’ Ai G5’ Air Gap5’ Air Gap

MATTHEWS~DANIEL

R d ti t R d Ri k D i P l diR d ti t R d Ri k D i P l diRecommendations to Reduce Risk During PreloadingRecommendations to Reduce Risk During Preloading

Utilize JRC Scope of Work for Rig Moves Utilize JRC Scope of Work for Rig Moves

MWS to issue Location Approval with Geotechnical InputMWS to issue Location Approval with Geotechnical InputMWS to issue Location Approval with Geotechnical InputMWS to issue Location Approval with Geotechnical Input

PunchPunch--Through Risk and Recommended Through Risk and Recommended Preloading Air Gap to be in MWS ApprovalPreloading Air Gap to be in MWS ApprovalPreloading Air Gap to be in MWS ApprovalPreloading Air Gap to be in MWS Approval