Seabed installation apparatus
A seabed installation apparatus comprising a soil penetration means (2), a deployment line (4) from which the soil penetration means is suspended, a mooring line (6) attached to the soil penetration means, the mooring line being releasably secured to the deployment line. The mooring line (6) is shorter than the deployment line (4). The deployment line (4) supplies power to the soil penetration means (2) and is releasably attached to the soil penetration means. The mooring line (6) is releasably secured to the deployment line substantially along the length of the mooring line. The soil penetration means includes an auger and fins capable of resisting torque generated by the action of the soil penetration means. Measurement and control means capable of assessing the pressure characteristics of the soil penetration means and altering the action of the soil penetration means in response to the penetration characteristics are included.
The present invention relates to a seabed installation apparatus and methods for its deployment from a vessel.
The installation may be used for any purpose requiring the installation below the sea bed for example a mooring anchor for ships or other sea going vessels or alternatively it may be used for a means of locating probes or sensors at required depths in the sea bed. Other uses will be apparent to skilled persons.
For example when laying anchors for a rig in the conventional manner, a supply vessel tows the anchor, chains, and sometimes a polyester mooring line as far out from the rig as possible. The anchor is then dropped, and when it has reached the seabed the rig uses winches to pull upon the anchor by the mooring line. Hopefully the anchor gets a grip and buries itself in the seabed under the weight of the chain and aided by the angles of the anchor's blades, however this process can be very laborious and time consuming. Two opposing mooring lines have to be deployed before they can be tensioned and tested. If one anchor has failed to become embedded, it must be retrieved and re-laid. It can take a rig sometimes seven days or longer to achieve a secure mooring position.
A common known way of analysing the structure of formation structures below the seabed is to deploy one or more lines of sensors from a ship. The sensor lines or ‘streamers’ trail behind the ship, and receive sound waves produced by a source transmitted and then reflected or emitted from the seabed, so that deductions of the structure and composition of the formation structure may be made. It is often desirable to cover a wide area in a single pass, so the lines have to be spread of the greatest width possible. One way of doing this is to attach a common rigid bar, perpendicular to the sensor lines, to the trailing end of the streamers, and keep the spacing of the streamers as wide as possible at the stem of the ship. A large ship is necessary both to keep the lines widely spaced, and to accommodate the equipment associated with doing this.
It is difficult to reproduce results obtained by towing such streamers, since the position of the sensors trailing behind the ship is uncertain and cannot be precisely repeated. This is especially inconvenient when it is wished to monitor some aspect of a particular region of the seabed over time.
As a result, arrays of cables are now installed onto the seabed. A number of lines of cables containing sensors are deployed from the stern of a ship as previously, and allowed to settle upon the seabed. These parallel lines of cables are connected at one end to a common perpendicular cable which includes a pick up point.
The seabed array is deployed in a similar way to the towed array, and again requires a large ship and much equipment to space the lines of sensors.
The invention also relates to an apparatus and method for deploying probes and sampling devices. Presently such probes are deployed using so called push sampling techniques which require a dedicated or pre-existing casing into which a sampling device or probe is introduced. These sampling probes are then advanced into the casing to sample and test the formation at the lower end of the casing. Additional lengths of casing are required to reach lower depths in the formation. Drilling will usually be required before the casing can be installed. A derrick is required to deploy the casing lengths, and to deploy the sampling apparatus and its packing to the casing wall.
It is an object of the invention to provide an improved apparatus and method for the deployment of probes and sampling devices and improved sampling devices therefore.
An object of the present invention to provide a form of seabed array and method of deployment of the same which is more efficient and convenient than the prior art methods.
A further object of the present invention is to provide a means for quickly and easily securing an anchor for a mooring line upon the seabed, with less chance that the anchor point will not be properly embedded.
A further object of the present invention is to provide a means of applying further operations to the anchor upon the seabed in order to ensure that it is more reliably secured.
According to the present invention there is provided a seabed installation apparatus comprising
a soil penetration means
a deployment line from which the soil penetration means is suspended
a mooring line attached to the soil penetration means the mooring line being releasably secured to the deployment line.
Preferably the mooring line is shorter than the deployment line. Preferably the deployment line supplies power to the soil penetration means. The deployment line is preferably releasably attached to the soil penetration means.
A Seabed Installation apparatus and method of deployment embodying the invention will now be described, with reference to the drawings, of which;
FIGS. 1 to 8 relate to the apparatus being used for the deployment of an anchor which would typically be used for mooring vessels and other marine structures, but it will be appreciated that the apparatus could correspondingly be applied to other seabed located devices such as sensing means for investigating the propertied of the sea bed.
During sailing and while being handled at the dock the equipment occupies a secure standard container dimensions.
Referring to
The entire system is then lowered using the wire rope. The wire rope may either contain electrical power cables or it may have a hydraulic line attached for powering an auger fitted to the bottom of the anchor. Since the wire rope 4 is heave compensated, the anchor moves smoothly to the seabed independently of the heave of the vessel. In
Referring to
Referring particularly to
When the anchor deployment apparatus 2 has reached the desired position the flukes 12 are activated and initially extended by the arms 16, as shown in
The auger 14 diameter is slightly larger than the outer diameter (OD) of the undeployed flukes 12 of the anchor. The discharge from the auger is fed up inside the undeployed flukes 12 and exhausted above the anchor. If a hydraulic motor is used to power the auger the fluid outlet of the water driven hydraulic motor is directed into the auger exhaust flow to assist in the movement of the waste material and reduce the skin friction
Once the set position has been reached, the wire rope 4 can be released from the anchor 2 and forerunner 6. The release point can be at the anchor 2 if it is a disposable anchor, or it can be disconnected at the forerunner connection point above the mudline, for later reconnection. This provides the opportunity to at a later date reconnect to the anchor and power it to retract the flukes 12 and be recovered.
As shown in
In the embodiments so far described the soil penetration means remains in the seabed to form the anchor. The soil penetration means could equally be withdrawn after forming a hole, and a dedicated anchor inserted into this hole. Similarly although the embodiment described is for a disposable anchor, when the mooring apparatus is no longer needed in a particular spot, it may be retrieved to be reused. The auger may be driven by the motor to penetrate further so induces the flukes to close enabling the auger to drive the anchor apparatus back up.
The advantages of using the electrically driven. auger of this invention will also appreciate the additional benefits it provides. These are the real time monitoring of the azimuth and inclination, monitoring of the current demand to give a measurement of the torque required by the user, and bi-directional rotation of the auger to, for example, enable it to deploy the flukes. The apparatus can also be fitted with a battery and a transponder to provide long term feedback of the journey of the apparatus and it may also be fitted with accelerometers of seismic measurements.
Referring to
Referring to
Referring to
Referring to
Many variations will be apparent to those skilled in the art, such as including other well known methods of attaching an anchor or sensing apparatus in the seabed, for instance the anchor may be a suction pile, or the anchor may be driven into the seabed using a charge. Naturally, features disclosed in respect of one embodiment may be transferable to the other embodiments.
Although the mooring apparatus is primarily intended for the securement of floating rigs, it can be used whenever anchor points upon the seabed are required. It may also be incorporated into other underwater apparatus.
Claims
1. A seabed installation apparatus comprising
- a soil penetration means
- a deployment line from which the soil penetration means is suspended
- a mooring line attached to the soil penetration means
- the mooring line being releasably secured to the deployment line.
2. An apparatus according to claim 1 wherein the mooring line is shorter than the deployment line.
3. An apparatus according to claim 1 the deployment line supplies power to the soil penetration means.
4. An apparatus according to claim 1 wherein the deployment line is releasably attached to the soil penetration means.
5. An apparatus according to claim 1 wherein the mooring line is releasably secured to the deployment line substantially along the length of the mooring line.
6. An apparatus according to claim 3 wherein the deployment line supplies electric power to the soil penetration means.
7. An apparatus according to claim 3 wherein the deployment line supplies hydraulic power to the soil penetration means.
8. An apparatus according to claim 1 wherein the soil penetration means includes an auger.
9. An apparatus according to claim 1 wherein the apparatus includes fins capable of resisting torque generated by the action of the soil penetration means.
10. An apparatus according to claim 1 wherein there is included measurement and control means capable of assessing the penetration characteristics of the soil penetration means and altering the action of the soil penetration means in response to the penetration characteristics.
11. An apparatus according to claim 10 wherein the current supplied to the soil penetration means is measured.
12. An apparatus according to claim 1 wherein the soil penetration means includes securement elements having a changeable profile, when considered in the direction of the mooring line.
Type: Application
Filed: Jul 23, 2003
Publication Date: Jun 8, 2006
Inventor: Philip Head (Berks)
Application Number: 10/523,137
International Classification: E21B 7/12 (20060101);