GB2491650A

GB2491650A - Penetrometer drive mechanism

Info

Publication number: GB2491650A
Application number: GB1109820.9A
Authority: GB
Inventors: Peter Gerard Allan
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-06-11
Filing date: 2011-06-11
Publication date: 2012-12-12
Anticipated expiration: 2031-06-11
Also published as: GB2491650B; GB201109820D0

Abstract

A cone penetrometer (CPT) drive mechanism comprises driven wheels 1 & 2 which are directly driven from a motor driven shaft 5 and idler wheels 3 & 4 which are not directly driven by the motor but are driven via the driven wheels. The idler wheels are kept in place by a pressure spring system 6 9. A penetrometer rod 12 is thus clamped between the 4 wheels and is driven by the rotation of the wheels. This mechanism can be attached to a subsea remotely operated vehicle (ROV) and used to test the seabed. The mechanism may be stackable to increase the thrust applied to the penetrometer rod.

Description

TITLE: geoROV A subsea remotely operated vehicle (ROV) mountable cone penetration (CPT) tool; hereafter referred to as geoROV.

This invention relates to a CPT tool that can be attached to a standard subsea workclass ROV to be used in the investigation of the geotechnical properties of seabed soil.

When a structure (e.g. pipeline or foundation) is to be constructed on the seafloor one of the main geotechnical parameters that is paramount to the success of the engineering design is the in-situ soil strength. To ascertain the in-situ soil strength a CPT test is carried out. A CPT test is performed using a cylindrical penetrometer with a conical tip (cone) penetrating into the soil at a constant rate. During the penetration, the forces on the cone tip and the friction sleeve are measured and transferred electronically to a data logger. The data is then processed and a profile of the seabed with geotechnical properties is developed. The majority of seabed CPT tools are large stand alone devices that require mobilisation from a survey vessel using a heavy lift crane or A-frame.

To support the ever expanding need for seabed geotechnical properties, both in the oil and gas industry and renewable energy sector, geoROV has been developed. The invention is an ROV mountable CPT tool. An ROV is a vehicle used in the offshore industry which is operated remotely from a survey vessel and can dive to depths in excess of 2000m. Once mounted on the ROy, geoROV connects to the power supply on the ROV for the data logging electronics and surface umbilical for instantaneous data transfer, and to the hydraulics to power the motor. geoROV uses a unique method of driving the cone into the seabed, which is further described below with the aid of illustrations.

Due to the unique drive method consisting of a single driven shaft, geoROV is able to be a compact and lightweight CPT tool that can be mounted quickly onto any workclass ROV for rapid deployment and seabed testing. Due to its compact size it can also be shipped almost anywhere in the world quickly. The extensive user manual allows easy installation and operation.

geoROV is also a cost effective method of carrying out a CPT test as no high lift crane is required. Once attached to the ROV the tool can remain in place for any length of time and does not require to be recovered' from the seabed independently, as with a standalone CPT tool. The personnel required to operate geoROV are the ROV controllers, therefore no further specialists are required for the deployment or operation of the tool, although geoROV experts are available on 24hr contact.

The invention will now be described by way of example and will make reference to the accompanying drawings, in which: Figure 1: This is a section isometric view of geoROV detailing the various parts that are going to be further discussed, including the parallel 4 wheel combi-drive' and the pressure spring mechanism' for the idler wheels.

Figure 2: This shows the parallel 4 wheel combi drive' without the casing and with the CPT rod section for further clarification.

Figure 3: This is a section elevation view showing the directional movements of the parallel 4 wheel corn bi-drive', the pressure spring mechanism' and the general function of geoROV Referring to Figure 1, items 1 to 4 make up the parallel 4 wheel combi drive'. Items I and 2 are the driven wheels, so called as they run directly off the drive shaft from the motor; items 3 and 4 are the idler wheels, so called as they are not directly driven off the motor, but from the driven wheels. The drive shaft from the motor is labelled item 5. The pressure spring mechanism' are labelled 6 to 9 and items 10 and 11 are the idler wheel plates; these hold the idler wheels in place. Item 12 is a section of CPT rod.

Figure 2 shows a second image of the parallel 4 wheel combi drive' with CPT rod in place.

The drive and idler wheels, items 1 to 4, are each made up of two sections, one part is the cog section, and the other is the wheel section that holds and applies friction to the rods.

Referring to Figure 3, the working mechanism will now be explained, the numbering system is as Figure 1. On the surface the required length of push rods rod (12) with cone are inserted into geoROV. This is done by first loosening the bolts housing the pressure spring mechanism' (6 to 9), once the rods are through, the bolts are tightened and the pressure spring mechanism' clamps the idler wheels against the rods, thus clamping the rods between both the idler wheels and the driven wheels. To push the cone into the seabed the drive cog on the drive shaft (5) is rotated, this directly rotates the driven wheels (1,2) which in turn instantly rotate the idler wheels (3,4). As these are clamped to the rod via the pressure spring mechanism' the friction drives the rods into the seabed. To extract the rods from the seabed the direction of rotation of the drive motor is reversed, on Figure 3 positive signifies downward motion into the seabed and negative signifies upward motion, or extraction.

geoROV can be attached to most workclass ROVs and can be easily integrated into the hydraulic systems and electronics.

Claims

Claims 1. Parallel 4 wheel combi drive'. This is a unique drive method in which all four wheels are driven from one single drive shaft.
2. Pressure spring mechanism'. This clamps the parallel 4 wheel combi drive' (as specified in claim 1) to the rod and provides the friction to grip and drive the rods.The mechanism includes the idler well plates which house the idler wheels.
3. A further unique design feature of geoROV is the fact that the units are stackable', i.e. one unit can be placed on top of another to increase the thrust force.