As hydrocarbon fields in production mature, the resultant increase in produced water poses a problem due to the ever-increasing costs associated with handling and separation. Current technology requires produced water to be brought back to a host platform or onshore from offshore reservoirs to address this issue of produced water separation and disposal. Significant interest within industry exists for Subsea Separation Technology, especially where current technology is challenged. The need for new or improved technologies is particularly salient when considering the topic of seabed discharge of produced water. Interest is further magnified in regions such as Trinidad and Tobago, where exploration activities in deepwater blocks have commenced and subsea processing could prove advantageous when compared to topsides.
This paper will discuss the need for development and testing of a subsea produced water treatment system for seabed discharge and the ongoing efforts involved in commercializing this technology. Various existing subsea separation systems will be presented, with reasons why each has failed to render a solution to the issue of disposal of the produced water to the sea. A discussion will be made to illustrate the new era of linear separators, spherical separators, and compact flotation devices that may bring about a technology breakthrough for allowing subsea separation and discharge of the environmentally clean produced water to be discharged at the seabed.
Oil-in-water sensors enabling continuous measurement of produced water discharged at the seabed will also be introduced to illustrate current technology developments. The sensors' design basis and criteria are compared to existing discharge limits in the U.S. Gulf of Mexico and Trinidad and Tobago to highlight the benefits of their use in these regions. In particular, four (4) sensor technologies subject to bench-scale testing in mid-2016 and their working principles are outlined.