Mars is an offshore drilling and production platform operating in the deepwater region of the Mississippi Canyon area in the Gulf of Mexico. It started production in 1996 with a design basis of 140,000 BOPD. In 2003 at the start of the work reported here, Mars was producing an average of 200,000 barrels of oil per day. While the platform had undergone a number of expansions, many process units, including the Bulk Oil Treater were operating above the design capacity. Due to the high throughput and therefore short residence times, the platform was experiencing oil dehydration problems, and a high rate of demulsifier was required to meet the oil discharge dehydration target of 1.0 % BS&W.

The original Mars electrostatic treater was a conventional design involving a serpentine perforated pipe distributor, steel electrostatic rods, conventional AC electrostatic treating technology and a perforated pipe collection header. During the hurricane Katrina shutdown (late 2005/early 2006), the Mars Bulk Oil Treater was upgraded to composite grids, Dual Frequency AC/DC electrostatic treating technology and a Hi-Flo pipe/deflector spreader. After the upgrade, a significant savings in demulsifier cost was realized. This paper discusses how the new electrostatic treating technology was used to reduce treating chemical cost and improve throughput. Additionally, comparison of different crude dehydration technologies is discussed.