Overview No contract type can protect you from a Contractors - - PowerPoint PPT Presentation

SLIDE 1

SLIDE 2

Overview

• No contract type can protect you from a Contractor’s underperformance

that results in claims and delays

• Contractor’s issues with underperformance become a Client’s headache
• Robust production estimates provide the best insurance against slipping

budgets and schedules

SLIDE 3

Hig igh-Level In Introductio ion to Production Lim imiti ting Factors

• Cutting or jetting
• Pick-up
• Pumping
• Operator or control system

Identify Bottleneck(s) Establish Consequences/ Estimates Manage/Develop Alternatives Prevent/Analyse and Select

Conducting Bottleneck Assessments

in iJ redging

Solutions adding value

Identifying bottlenecks is critical toj mproving and monitoring productivity

SLIDE 4

In Introduction to Dredge Performance Monit itoring

• Why use performance monitoring?

 Optimise production  Review permit compliancy  Administer contract  Conduct engineering or scientific analyses

• Monitoring system in a nutshell:

 Calibrated sensors  Manipulate data, if required  Verify data integrity  Visualise data

Vessel Speed Monitoring

7,612,500 7,612,000 7,611,500 7,611,000 7,610,SOO 7,610,000 7,609,500 7,609,000 7,608,500 7,608,000 7,607,500

7,607,000- 7,605,000 7,604,500 7,604,000 7,603,500 7,603,000

7,602,500 7,602,000 - 7,601,500 7,601,000 7,600,500 7,600,000 7,599,500

Track Plot

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• Track Plot
• Contour Plot

Evidence based decision making rationalises relationship between Client and Contractor

SLIDE 5

Dis isappointing Dis ischarge Producti tion

• Dredging professionals can accurately estimate suction and discharge

production with specialised tools such as Pumps ‘n Pipeline (PnP)

• Define pumps and pipelines before committing or
• mobilising. Required data includes:

 Pump engine characteristics  Pump characteristics  Pipeline configuration

• Provide enough definition on mixture properties

from geotechnical data. Required data includes:

 Particle size distribution  Shell content  In-situ, lump and solid density  Yield stress

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Pump Regression Curves

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Pump Range Diagram no-.u

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SLIDE 6

Pumping Productio ion Lim imitations in in One Graph

• Operating areas:

 Green is “possible”  Orange is “challenging”  Red is “impossible”

• Pump Production

Limitations:

 Pickup mixture density  Pump’s limiting vacuum  Engine’s characteristics  Mixture’s critical velocity

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Production Limitations (PrQ-Diagram)

Flowrate (Q) [USG/min) 40,000 60,000

80,000 100,000 120,000

4 6 Flowrate (Q) [m3 /sec)

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SLIDE 7

• Hydraulically transporting clay balls is a major risk as its potential impact
• n discharge production is disastrous, if not expected
• Clay balls are likely to remain intact when:



Clay content > 50%



Undrained shear strength > 25 kPa



Situ density > 1,500 kg/m3



Liquid limit > 25% < 125%



Plasticity Index > 25%

Clay Balls

Ris isks of No Cla lay Ball l Degradatio ion

Slurrified

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Discharge P roduction Limitation (Prl d-Diagram)

Discharge Pipeline Length (Ld} [ft] l .600 +----~~

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Discharge Production Limitation (P rld-Diagram)

Discharge Pipeline Length (Ldl [ft] 2,500 5,000 7,500 10,000 12,500 15,000 17,500 1,600+----~---~---~---~-------~---~--~ 1,400 1.200

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• 1,000

2,000 3,000 4,000 5,000 Discharge Pipeline Length (ldl [m] 2,000 1,750 1,500 ~ 1,250 {

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750 J 250

More physical modelling anp detailed field observations are required

SLIDE 8

Underestimating Cutting Production in in Hard Rock

• Large Contractors have gained invaluable expertise on cutting hard rock
• Cutting hard rock is less known by remainder of dredging industry
• The risk from the

potential presence of rock is often underestimated

• r even ignored
• The cutting of hard rock

can be limited by:

 Cutter Power  Side Winches  Spud Hold Force  Ladder Weight

in iJ

redging

Solutions adding value

Cutter head aver-cutting SMPa rack. Arrows shaw teeth and resultant farces.

SLIDE 9

• The cutting forces on each tooth allow calculation of the resultant force,

a principle on which the Subsea Rock Cutting (SRC) estimation tool is based

• The resultant force is

counteracted by the cutting installation

Underestimating Cutting Production in in Hard Rock (2 (2)

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Utilisation of Installat ion

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cutter UC

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600 400 200 14

SLIDE 10

Underestimating Jett tting Producti tion

• By resolving the jet trajectories
• ne can accurately estimate

jetting production in sandy and clayey soils

• Jetting production is low

in less permeable sand (10-5 m/s)

• Jetting is energy inefficient in

medium to hard clay and often a schedule risk

J et Configuration

• f Drag Head

A small up front investment in jet modelling may result in a

sizeable saving during execution

SLIDE 11

Underperformance

• Soil and weather are the biggest risk factors, but what are the true

causes of delays and cost overruns?

• Detailed performance monitoring has shown that the following causes

are just as relevant as unsuitable soil and weather conditions:

 Lack of instructions on requirements  Wrong work methodology  Operator error

• Gather evidence on daily performance from:

 Sensor reading log files (ASCII data file)  Progress surveys (xyz files)

~

surveys (xyz

SLIDE 12

Conclusions

• Production estimates are key to Budgets and Schedules

 High-definition production estimates reduce risk of delays & cost overruns  Estimates should be produced by both Clients and Contractors  Advanced tools for pumping, cutting and jetting are

available that produce robust and reliable estimates

• Performance Monitoring

 Almost all dredges have onboard systems from

which you can acquire data files

 Performance monitoring is best carried out

by both Clients and Contractors

 Daily equipment performance monitoring safeguards

reputations as well as budgets and schedules