GB2504685A

GB2504685A - Environmental survey apparatus incorporating a buoy and mooring mounted sensors

Info

Publication number: GB2504685A
Application number: GB201213895A
Authority: GB
Inventors: David Rigg; Luke Murray
Original assignee: NORTH SEA SERVICES Ltd
Current assignee: NORTH SEA SERVICES Ltd
Priority date: 2012-08-05
Filing date: 2012-08-05
Publication date: 2014-02-12
Also published as: GB201213895D0; GB201402895D0; GB2509256B; WO2014023925A1; GB2509256A

Abstract

A survey apparatus 17 comprises a buoy 1 tethered to a mooring 3 on the sea bed by an umbilical 2. A power system (Fig-2, 7) is contained within the buoy. The umbilical comprises a structural member and electrical cabling, wherein the structural member forms the tether connecting the buoy to the mooring (Fig-3, 14) and the cabling (Fig-3, 16) provides communication and power to bottom mounted sensors (Fig-3, 13). A radio transmitter (Fig-2, 12) allows communication of collected data to a receiver located onshore. It may be that the floating arrangement for the buoy may comprise a mono-hull or a catamaran or a small water-plane area twin hull. There may be an onboard generation unit harnessing the power of the sun, tidal currents or waves to recharge on board energy storage. Further sensors may be used for collecting environmental data. The radio transmitter may provide real time communication of data collected to a receiver and may also provide remote control of the survey apparatus from shore.

Description

Ii R&d o the nvenUon The present invention relates generally to a system facilitating subsea environmental survey in extreme conditions such as high tidal flow and large waves.

1.2 Backç'round & the nvenUon As the growing marine energy industry starts to take shape there is an increasing requirement to be able to deploy sensors to capture detailed environmental information for extended periods of time.

Developers need accurate data describing, but not limited to, flow velocities, turbulence, flow velocity variation with depth, and wave height. Turbulence and wave parameters for a given site are particularly important because these effects can have a detrimental impact upon the fatigue life of structures and therefore they must be adequately designed for.

The highly dynamic nature of most marine energy sites makes it particularly difficult to take precise measurements. It also makes the deployment and recovery of survey instrumentation hazardous.

Without live feedback of the data being collected and no indication of the correct deployment of the sensor, many sensors are being deployed in these environments unsuccessfully. The failure to capture the required data is only discovered after retrieval of the sensor and post analysis of the data.

This results in large delays and significant wasted cost.

Without long term precise measurement of key environmental parameters for a given site, designers are forced to account for uncertainty in environmental conditions by applying safety factors to their designs. This drives up the size and costs of structures to be deployed in these environments.

1' 2 the nvenuon It is an object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages, or to provide a useful alternative.

1 4 of the rwnton In a first aspect, the present invention provides a survey apparatus adapted to collecting environmental data in harsh environmental conditions, the apparatus comprising: a purpose built buoy designed for operation in extreme wave and tidal flow conditions; a power system contained with the buoy to provide continuous power to navigational aids, environmental sensors and telemetry to collect data for extended periods of time without intervention; a radio transmitter to allow collected data to be sent to a receiver station positioned onshore; an umbilical providing the tether connecting the buoy to a mooring and to provide a means of providing power to, and receiving transmission of data from, bottom mounted sensors deployed on the mooring; and a mooring that keeps station in the extreme conditions preventing the buoy from moving from its intended location; a subsea platform for the secure and stable mounting of various telemetry and sensors.

In a preferred embodiment, the purpose built buoy will be comprised of a monohull floating arrangement. Alternatively, the buoy is comprised of a catamaran or small-waterplane-area twin hull arrangement.

Preferably, the buoy is sized to contain sufficient on board power in the form or energy storage such as batteries to power all navigational aids, environmental sensors and radio transmission to allow the survey to be performed without intervention for a period of up to several months.

Optionally, the buoy will contain on board power generation to enable recharging of the energy storage system contained within the buoy to facilitate longer deployments without intervention.

In a preferred embodiment, the umbilical will be made from structural outer members sized to resist the substantial forces required to tether the buoy to the mooring. These outer structural members will be connected to the attachment point on the buoy and likewise to the mooring point on the bottom mounted mooring. Further preferably, the umbilical will provide a sufficient number of inner cable cores to provide power to the sensors mounted below the water on the mooring base from the on board power system located in the buoy, whilst also transmitting data collected from the sensors on the mooring to the buoy.

In a preferred embodiment the mooring intended to be deployed on the seabed will provide mounting locations for environmental sensors to be mounted in their optimal mounting orientations.

I.. Dcrkm o'ffle Drwnqs A preferred embodiment of the invention will now be described by way of specific example with reference to the accompanying drawings, in which: Fig. 1 depicts a survey system intended for collecting environmental data in extreme conditions; Fig. 2 depicts a mono hull floating buoy design; Fig. 3 depicts a plan view of the mooring which is mounted on the seabed.

( Ds htkm cf th PrSerr.d Embdrnrt Fig.1 depicts survey apparatus 17 adapted to collecting environmental data in harsh environmental conditions. The purpose built buoy 1 is shaped so that is designed to perform well in extreme wave and tidal flow conditions. The buoy 1 is specifically designed to reduce drag acting on the structure and to be stable during high wave events.

The umbilical 2 provides the tether connecting the buoy ito a mooring 3 and to provide a means of providing power to, and receiving transmission of data from, bottom mounted sensors 13 deployed on the mooring 3.

The mooring 3 keeps station in the extreme conditions which prevents the buoy 1 from moving from its intended location. It does this by having sufficient mass to resist the drag acting on the buoy 1 as well as the mooring 3 itself. The mooring 3 like the buoy 1, is specifically designed for reduced drag.

Depicted in Fig. 2 is a monohull floating buoy 4, on which is housed a navigation mast 5 and a navigation aid 6 in the form of a light. The navigation aid 6 is powered via cables S from an energy storage device 7 which is mounted within the sealed chamber formed within the hull of the buoy 4. In addition to this a radio transmitter 12 is powered from the same energy storage device 7 to allow transmission of all collected data from on board sensors ii and bottom mounted sensors 13 to a shore based receiving station.

The floating buoy 4 has a sealed inner chamber. Cables from the umbilical 2 can be passed through the wall of the buoy 4 without water ingress using the cable penetrator 10 that is provided in close proximity to the umbilical attachment point 9.

The energy storage device 7 that is housed within the buoy 4 is sized to provide continuous power to all navigational aids6, on board sensors 11, bottom mounted sensors 13 and radio telemetry 12 for extended periods of time without intervention.

Referring to Fig. 3, the mooring unit 14 is shown in plan elevation and has a shape that is favourable for reduced drag. A mooring attachment point 15 is provided to connect to one end of the umbilical 2 whilst the other end is connected to the buoy I itself. Mounting points are provided so that sea bed mounted sensors 13 may be installed in their optimal arrangement on the seafloor after deployment of the mooring unit 14. The necessary cables 16 are broken out from the umbilical 2 and connect to the sensors 13 to provide power to these devices subsea and to allow transmission of data to the buoy 4. iJ

Claims

1. a survey apparatus adapted to collecting environmental data in harsh environmental conditions, the apparatus comprising: a purpose built buoy designed for operation in extreme wave and tidal flow conditions; a power system contained within the buoy to provide continuous power to navigational aids, environmental sensors and telemetry to collect data for extended periods of time without intervention; a radio transmitter to allow collected data to be sent to a receiver station positioned onshore; an umbilical providing the tether connecting the buoy to a mooring and to provide a means of providing power to, and receiving transmission of data from, bottom mounted sensors deployed on the mooring; and a mooring that keeps station in the extreme conditions preventing the buoy from moving from its intended location.

2. The survey apparatus highlighted in 1, wherein the buoy is a monohull floating arrangement.

3. The survey apparatus highlighted in 1, wherein the buoy is a catamaran or small-waterplane-area twin hull floating arrangement.

4. The survey system of any one of the preceding claims, further comprising an on board generation unit harnessing the power of the sun, tidal currents or wave to recharge the on board energy storage system in an effort to extend the intervention free operation of the system.

5. The survey system of any one of the preceding claims, further comprising sensors used for the collection of environmental data.

6. The survey system of claim 5, wherein the sensors are located on the sea floor on the mooring unit with data being transmitted to the buoy by means of the umbilical.

7. The survey system of any of the preceding claims, further comprising a radio transmitter to provide real time communication of data collected to a shore based receiver station and to provide remote control of the survey system from shore.