Module 6 2012

Oil & Gas introduction Course for Non-Engineers SEC

1

Module 6Dredging


2

1. Capital Dredging vs Maintenance Dredging

Dredging is the under water removal of soil and subsequent transportation to another place, either for deepening or for profitable use

Drivers: Swift population towards coastal areas, Economic growth, World population growth.

DEFINITION:

CAPITAL MAINTENANCE

New IslandsNew Ports

Remove silt/sand from to keep existing water ways to the required depth


3

2. Draught

Water depth in the Port or Shipping channel required

Desired depth in Vietnam -12/14m

Tide Vungtau = 3 m Cai Mep/Thi Vai -10 to -13m; TOA/Van Oord 2010

100.000 DWT = 8.000 TEU = approx. 16 m80.000 DWT = 6.000 TEU = approx. 14 m60.000 DWT = 4.000 TEU = approx. 12 m

Soai Rap river / Hiep Phuoc -12? Currently -5/6


4

3. Soil conditions

Type of soil and the condition it is in

- Sand (Loose or Compacted)- Silt- Clay (Soft or Stiff)- Gravel- Rock- Coral

Round

Sharp

Silt

Gravel

Modern Soil


5

4. Reclamation

Creating Land in the Sea by dumping sand

Maasvlakte 2 Netherlands

Project Vungtau

WHY?

Hai phong


6

5. Soil improvement

Improve the bearing capacity from reclaimed land

Kansai Airport sinks 50 cm per year

Methods:- Compaction- Wick/Vertical drains- Vibro floatation- Soil mixing

Consolidation


7

6. Beach Nourishment

Replenish sand removed by currents

Break water


8

7. Dredging Contractor

THE BIG 4:- Boskalis (Netherlands)- Van Oord (Netherlands)- Jan de Nul (Belgium)- Dredging International (Belgium)

Together hold 60% of the world Dredging market.

VINAWACO

Why they are BIG?:- Buy best equipment (IHC)- In house training school- Large versatile fleet- OPEX over CAPEX

Company to carry out the Dredging work

Link with Offshore?


9

8. TSHD

Trailing Suction Hopper Dredger

Long Chau 1969

Trailing is to moving in one direction with something resting on the ground.

Hopper is area to contain the dredged material.

Suction stand for the pump action, vacuuming the seabed.

Hopper capacity can vary from 1.500 m3 up to 34.000 m3.

How long to fill up?Slurrification


10

9. Cutter Dredger

A stationary dredger that can mechanically excavate the seabed

SlurryApplication?


11

10. Beaver DredgerSmaller cutter dredger by IHC

Application?

Vietnam owns 9 IHC Beaver Dredgers and about 10 more from other manufacturers

Vietnam has 3 Hopper Dredgers operational between 1.500 m3 and 4.000 m3.


12

11. Dipper Dredger

A stationary dredger that uses a bucket to excavate the seabed

Vietnam: Clamshell or Grab Dredging


13

12. Excavator

Dredging using an excavator on a pontoon

Application?


14

13. Split Hopper

Barge to transport dredged material that can dump quickly by splitting the hull


15

14. Multi CatWork boat to assist a cutter dredger with different tasks

- Personnel transfer- Change cutter head or teeth- Hook-up of floating pipe line- Towing Dredger to site

MOVIES


16

15. ProductionHow much dry material is dredged per second

m = Density Mixturew = Density Water g = Density In situ

Critical velocity 3 m/s


17

16. Suction/Drag head

Suction mouth that is trailing on the seabed at the end of the suction tube


18

17. Cutter teeth

Rock / Coral

Sand / Gravel

Clay / Silt


19

18. Impeller / Pump Housing

Double walled pump


20

19. Discharge pressurePressure at the pressure side of the dredge pump

Pressure

Pressure

Cavitation


21

20. Rain bowingEmptying the hopper by re-slurrifying the sand and spraying it from the bow

How Far?


22

21. Floating PipelinePipe line to transport mixture from the dredger to the dump site


23

22. Booster StationInstallation in the pipeline to bring the pressure back up

Booster

Dumpsite

6 km6 km


24

23. Bottom DoorsUnloading the hopper by dumping through bottom doors

Bottom door


25

24. Barge LoadingPump the mixture in a barge that is moored next to the Hopper or Cutter

The Dredging Cycle

Documents

Module 6 2012