Compact and Light Weight Equipment for Floating Production Systems

摘要

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,allowing the use of compact and lighter equipment. The floating production facilities also present special challenges considering process aspects for the crude oil train as well as mechanical aspects.The effects of sea heave produces mechanical forces on the supports of the process equipment and also fluid dynamic forces inside the treaters which require 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 has an equally important role. Efficient vessel hydraulics is essential for achieving maximum dehydration performance and efficient utilization of the treater vessel volume.Not only is the oil distribution critical but oil collection is equally important to maintaining treater dehydration and desalting performance.A new distributor can increase the treater volumetric utilization from low 50%to 95%allowing for the use of smaller and light weight treaters for crude oil dehydration and desalting. The crude oil dehydration and desalting performance also 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 can be reduced significantly.One effective method for maintaining the electrostatic field strength is to utilize high frequency electrostatic field to quickly replenish the applied voltage 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 stories with examples of compact equipment installed on FPSOs,SPARs,TLPs and semi submersibles.