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Contenu archivé le 2022-12-27

UNDERWATER DRILL FOR LARGE CAPACITY PILES

Objectif

This project intends to study and build a subsea drilling machine for the excavation of very large capacity anchoring piles in medium to hard soil. This drill will be operated from a standard drilling ship in several hundred metres water depth (3 000 feet maximum). The main advantage of this down hole tool is that no torque is transmitted from surface, limiting string failures as encountered in big hole rotary drilling.
Description of the Rectangular Marine Hydrofraise.
For these studies, we have based the concept on the following fundamentals :
- implementation of simple solutions.
- provisioning of usual components aboard the drill ship.
These fundamentals have led us to an easy and simple conception based on the use of seawater as power fluid.
The primary energy is converted with a turbine driving an underwater hydraulic power pack, the whole being mounted inside the A frame.
Description of the Circular Marine Hydrofraise
The Circular Marine Hydrofraise has to answer two operational criteria compared to rectangular marine Hydrofraise :
- soil stability meanwhile drilling,
- compatibility with the present concept for offshore foundation.
These two constraints have led us to design the Circular Marine Hydrofraise on the following principles :
- Pile drilling protected with a casing on the whole height of the shaft. This casing is the definitive casing which is installed into the borehole in oneoperation prior to the cementation. This technique is based on the pile driving principle.
- Undereaming to help casing lowering. The motors and the mills are mounted on an opening system to allow few centimers over drilling around the casing.
The technical file has been completed. However every contact made with main contractors and oil companies to analyse their interest in developing the tool with us has been negative. The main reasons are :
- the time which would be required to build and test the equipment up to an operational level, which may be estimated as 3 years.
- the uncertainty about the market, which does not allow to analyse the potential recovery on such an investment over the next 10 years.
- the reluctance of clients to use new equipments. An example is the tender sent by an oil company recently which prohibits the use of non standard drilling tools and impose conventional rotary rig even though fist there is none available to-day for the diameter required, and second the work is to take place in more than three years.
Considering the reductance of clients of users to share the investment with us, and our impossiblity to invest alone, we have decided not to proceed with the construction of the portotype even though the construction file is finalised.
This equipment is based on the HYDROFRAISE a hydraulically driven drilling tool developed by SOLMARINE's mother Company SOLETANCHE to excavate trenches and reinforced piles for Civil Works. The subsea drill consists of :
- a 150 to 200 kN guiding frame held by a string set to the drilling ship.
- 2 parallel cutter wheels, rotating on horizontal axes in opposite directions, set at bottom of frame.
- a pump set above the wheels to remove cuttings.
- a jack to monitor weight or speed during drilling.
- a casing equipped with reentry funnel is pulled with the drilling tool to cover overburden layers.
- a 400 HP power pack supplied hydraulic power from the surface through hydraulic lines.
- deflection is monitored by an inclinometer and maintained below 0.3%.
This machine will be able to drill rectangular shafts (2.40 m x 1.00 m section) down to 100 metres in soil with a simple compressive strength up to 100 MPa.

Appel à propositions

Data not available

Régime de financement

DEM - Demonstration contracts

Coordinateur

BELGIAN OFFSHORE SERVICES NV
Contribution de l’UE
Aucune donnée
Adresse
SCHERMERSTRAAT 46
2000 Antwerpen
Belgique

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Coût total
Aucune donnée