rig move risk assessment
Post on 16-Apr-2015
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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
MATTHEWS~DANIEL
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
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