The Robust 24/7 Solution for Produced Water Monitoring & Management
The client was looking for a level transmitter replacement to restore their automated level control back online for their Hazardous Open Drain (HOD) Caisson. Rocsole analyzed the situation and successfully implemented their innovative electrical tomographic technology to help with the produced water monitoring.
Some facts for context
The client was a joint operating company entrusted with the exploration, development and production of natural gas resources located northwest of Sabah, Malaysia.
A consortium of local and international oil companies was involved here.
BASIS OF DESIGN
The facility is an offshore platform designed with the capacity to process up to:
- 825 MMSCFD of natural gas,
- 80,000 barrels of crude oil and
- 22,000 barrels of condensate
With the clients' serious commitment to water quality management, the discharge of fluids had been monitored closely to avoid any hydrocarbons discharged to the sea, especially liquids from produced water treatment.
In this case, the HOD (Hazardous Open Drain) Caisson collected drain fluids from various drain locations on the platform which includes hydrocarbon fluids along with water. Besides that, this Caisson also received condensate from water seal drums and oily produced water from other Caissons. If not managed correctly, then oily discharge to the sea might cause environmental hazard.
The client was looking for a solution with a reliable level transmitter to control the pumping of hydrocarbon fluids from the HOD Caisson on a regular basis to prevent:
- hydrocarbon carry-under to the sea with sheen formation as a result as well as
- unintentionally breaking the regulations to discharge limits of oil
- damage to the environment and wildlife.
A 24/7 Produced Water Monitoring and Management Solution
After a diligent review of the whole situation, Rocsole proposed a "Liquid In-Tank Inspection" (LITI) with a 3.5-meter sensor for this individual application.
The sensor is attached to a 14-meter connecting cable from the mounting flange to the sensor to monitor the oil-water interface at the depth of 14 to 16 meters from the top of the Caisson. Real-time imaging is included in the measurement system to visualize the situation of the liquids inside the Caisson.
The pump is now automatically controlled by the ROCSOLE LITI system.
Some interesting details
The signal is sent to the pump via the client DCS.
The connection between LITI and the client DCS is established using Modbus.
The starting of the pump will now initialize the withdrawal of hydrocarbon fluids from the Caisson. Of course, the pump needs to be stopped as soon as the hydrocarbon level is low to prevent water from ingress into the receiving separator.
This is now handled by the fully automatic 24/7 LITI system by Rocsole.
Produced Water Challenges in an Offshore Setting:
3 ways of overcoming them
The HOD Caisson is subjected to dynamic forces mainly from the wave movement so the LITI system inside the Caisson required higher mechanical integrity. Adapting the already highly reliable system to the circumstances in which it must perform, is part of its success - so the Rocsole expert team suggested the following customizations:
The Rocsole LITI therefore was enhanced: The LITI system was customized so that each section of the electrode in the sensor is mechanically interlocked to withstand greater external force.
To create a stronger and more secure connection, the cable between the sensor and the mounting flange was secured by implementing a titanium wire rope .
Last but not least, the whole LITI system was constructed using duplex material which is perfect for a marine environment.
The integration with the clients' DCS was completed easily. It was installed and commissioned remotely.
Reduced occupation hazard
So now the new Rocsole LITI system in the HOD Caisson reduces occupational hazards by reducing the exposure of H2S during manual sampling. The productivity increased to less or no manual sampling.
The Rocsole LITI complies to international certifications as well as client specific requirements.
No pollution anymore
Last but not least, the client still upholds their environment commitment with no hydrocarbon fluids discharged to sea.
The Robust Produced Water Management Solution by Rocsole
The Rocsole electrical tomography using both conductivity and permittivity is proved to be an impeccable solution for this HOD Caisson - especially after the slight customizations to make sure that the solution is sustainably reliable.
Even salinity changes and variations in chemical treatments in the water phase do not affect the 24/7 measurement reliability.
With the Rocsole LITI system, the Rocsole team again was able to help another client to “See Beyond”, fulfilling their commitment to: