Technical Paper: Compact and Lightweight Equipment for Floating Production Systems

Society: OTC
Paper Number: 24727
Presentation Date: 2014
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Floating production facilities are very sensitive to equipment weight and footprint. New electrostatic technologies have enhanced the dehydration and desalting process for crude oils by improving treater hydraulics and increasing the electrostatic field strength of the treaters, enabling the use of compact and lighter equipment.

Floating production facilities also present special challenges for both the process and mechanical aspects of the crude oil train. Sea heave produces mechanical forces on the supports of the process equipment and fluid dynamic forces inside the treaters, necessitating special attention for the treater internals and instrumentation. In addition to the amplitude of the roll and pitch of the facility hull, the frequency of these movements is equally important.

Efficient vessel hydraulics are essential for achieving maximum dehydration performance and efficient utilization of the treater vessel volume. Not only is the oil distribution critical, oil collection is equally important for maintaining treater dehydration and desalting performance. A new distributor can increase the treater volumetric utilization from low 50% to 95%, enabling the use of smaller and lightweight treaters for crude oil dehydration and desalting.

Crude oil dehydration and desalting performance decreases as the crude oil conductivity increases, whether this is caused by an increase of polar organic components, heavy solids, or asphaltenes; the electrostatic field strength reduces significantly. One effective method for maintaining the electrostatic field strength is to use a high-frequency electrostatic field to quickly replenish the charge and reduce the decay caused by the crude oil conductivity. Modulating the voltage amplitude has also proven to be effective for increased dehydration performance.

Another treater improvement is the use of composite electrodes, which increases the water tolerance of the treater and also improves the treater dehydration performance.

This paper describes special design considerations for dehydration and desalting equipment for floating production facilities and how these treaters can be drastically reduced in size and weight while still maintaining the required process performance. We will also discuss special considerations for instrumentation, slosh suppression, and operating procedures. The paper also includes case histories with examples of compact equipment installed on floating production, storage, and offloading facilities (FPSOs); spars; tension-leg platforms (TLPs); and semisubmersibles.

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Crude Oil Dehydration and Desalting

NATCO DUAL POLARITY electrostatic treater
Cameron provides a range of electrostatic technologies to effectively remove unwanted salts and water from crude oil and thus combat fouling, corrosion, and loss of catalyst activity. Visit Dehydration and Desalting page on the Cameron website