ACOUSTIC CONTROL SYSTEM FOR BOP OPERATION
The Acoustic Control System – ACS500 is designed for acoustic control of Blow Out Preventer – BOP and subsea production units. The subsea unit may control up to 16 different functions.
KEY TECHNICAL INFORMATION
An advanced acoustic telemetry link, using either the latest technology, Direct Sequence Spread Spectrum, or upon request from operator : the traditionally used Frequency Shift Keying. This provides a reliable communication in noisy and reverberant offshore environment and maintains compatibility with new and existing topside control system.
ACOUSTIC CONTROL SYSTEM OPERATING DEPTHS
The ACS500 system is delivered as medium frequency (MF) system and can be delivered for water depths down to 4000 meters (13000 feet).
The ACS500 system is divided into two units :
1. Surface system (portable).
2. Subsea system.
Applications :
- Emergency BOP backup control system.
- Pipeline Valve Control.
- Workover system.
- Offshore loading.
- Other subsea control systems.
The surface system consists of :
One Acoustic Command Unit w/charger cable
The ACU is the main and certified interface for the Acoustic Control System. The unit is a part of the safety equipment on board an drilling rig or drillship. It is delivered in a splashproof portable case, with carrying handle and carrying strap. It has an internal rechargeable battery and a fully charged battery will provide more than 10 hours of operation. It is operated via the computer (touch screen/trackball).
One Dunking Transducer Unit
The dunking transducer unit is a cable drum with a 70 m cable and a dunking transducer. The dunking transducer unit can be carried by one person.
The following dunking transducers are available :
TDD 303 MF
– a 50 degree dunking transducer suitable for use in water depths down to 1500 m operations.
TDD 30V MF
– a 30 degree dunking transducer suitable for use in water depths down to 4000 m operations.
TDD 180 MF
– a 180 degree dunking transducer suitable for use in water depths down to 500 m operations.
The SCUs are mounted on the valve package and receive acoustic command signals from the ACU. The SCUs translate the signals into operational commands, then act on those commands sending control signals to solenoids which in turn opens or closes the hydraulic control valves on the valve package. A signal is then transmitted by the SCU to the ACU as a confirmation that the command has been executed. The control system can also read the status of the SCU, including various hydraulic control valves and sensor read backs.
The subsea system consists of :
Two subsea control units
• Now available with interseal test ports for seal testing.
Two subsea communication transducers
• With cables and subsea connectors.
Three possible interfaces with the valve package :
Two interface cables (nontestport system)
One cable from each SCU to the valve package.
Two interface jumper cables (non-testport system)
One cable from each SCU to a junction box with one interface cable to the valve package.
One y-split cable (testport systems)
Connecting both SCU’s to the valve package.
TECHNICAL SPECIFICATION
Environmental
• Operation temp:-5 to +55°C*
• Storage temp: -30 to +70°C
* Operational specification for on deck testing purposes: -20 to +55°C. ACU 30 must be in standby/power ON mode
before exposed to temperatures below -5°C.
Operating frequencies
• PSK : 23600 – 27600 Hz.
• FSK : 25000 – 26500 Hz in steps of 250 Hz.
Surface system
ACU
• Weight : Approximately 19.5 kg.
• Degree of protection : IP54.
Electronic details
• Input voltage : 100 to 240 VAC (47 – 63 Hz).
Battery
• Type: 7 Lead/acid cells, connected in series.
• Transmission power (max): 300 W.
• Continuous use : Approx.10 hrs.
Dunking Transducer Unit
• Length of cable : 70m.
Beam width
• TDD303 MF : approx. 50° at -3dB.
• TDD30V MF : approx. 30° at -3dB.
• TDD180 MF : approx. 180° at -3dB.
Subsea system
SCU
• Operating depth (max): 4000 m.
• Material : Super Duplex Steel.
Electronic details
• Operating voltage : 10 to18 VDC.
• Communication principle : Phase Shift Keying and Frequency Shift Keying
Wake-up.
• PSK : M53/M54.
• FSK : Channel 76: 24 and 23.5 Hz.
Channel 86: 24.5 and 23.5 Hz.
Transmission power.
• Max : 300 W.
Battery
• Weight : 5.9 kg
• Number of batteries : 1
• Cells per battery : 48
• Type of cells : Non-rechargeable, lithium.
• Battery output:14 VDC, single voltage.
• Total battery energy content, 14 V : 128 Ah.
• Battery life time : Calculations on request.
Remote Subsea Transducers
Material
• Super Duplex Steel
Operating frequency
• 21-31 kHz
Weight in air
• 20 kg
Weight in water
• 17 kg
Beam width
• TDR40V MF : approx. 50° at -3dB
• TDR30V MF : approx. 30° at -3dB
• TDR180 MF : approx. 180° at -3dB
Operating depth
• TDR40V MF : 1500 m
• TDR30V MF : 4000 m
• TDR180 MF : 500 m
Mounting bracket
• Material : AISI 316L Stainless Steel
• Weight : 22 kg
• Mounting holes : Compatible with ACS 400
SCU Junction box (option)
• Weight : 8.6 kg
Material :
• Unit : Bronze.
• Connectors : Titanium/Bronze.
Standards and Certificates
• DNV-OS-E101
• API 16D
• Type Approval by Det Norske Veritas when used with ACU30 as topside unit.
CUSTOMER BENEFITS.
- Acoustic BOP emergency control system which also includes monitoring features.
- Monitoring features for temperature and pressure etc. with acoustic sensor data communication.
- Acoustic control communication which support both digital wideband protocol based on Direct Sequence Spread Spectrum based on Phase shift keying – PSK, in addition to traditional frequency shift keying – FSK.
- Acoustic communication with high reliability in noisy and reverberant offshore environment.
- Dedicated address for each subsea controller unit.
- Two-way communication.
- Operator override of two-way communication.
- Off-line BOP status reading and command test.
- Dual transceivers in subsea unit.
- Dual transducers on subsea unit.
- Long range acoustic link option for production tree control.
- System self-test diagnostics.
- Portable control unit for over the side helicopter and life boat use.
- Possibility of Integration of the acoustic control system with an Hydroacoustic Position and Reference System, HiPAP and HPR, also makes the surface system redundant.
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