Abstract
Mars is an offshore drilling and production platform operating in the deepwaterregion of the Mississippi Canyon area in the Gulf of Mexico. It startedproduction in 1996 with a design basis of 140,000 BOPD. In 2003 at the start ofthe work reported here, Mars was producing an average of 200,000 barrels of oilper day. While the platform had undergone a number of expansions, many processunits, including the Bulk Oil Treater were operating above the design capacity.Due to the high throughput and therefore short residence times, the platformwas experiencing oil dehydration problems, and a high rate of demulsifier wasrequired to meet the oil discharge dehydration target of 1.0 % BS&W.
The original Mars electrostatic treater was a conventional design involving aserpentine perforated pipe distributor, steel electrostatic rods, conventionalAC electrostatic treating technology and a perforated pipe collection header.During the hurricane Katrina shutdown (late 2005/early 2006), the Mars Bulk OilTreater was upgraded to composite grids, Dual Frequency® AC/DC electrostatictreating technology and a Hi-FloTM pipe / deflector spreader. After theupgrade, a significant savings in demulsifier cost was realized. This paperdiscusses how the new electrostatic treating technology was used to reducetreating chemical cost and improve throughput. Additionally, comparison ofdifferent crude dehydration technologies is discussed.
Introduction
When a field reaches its maximum production rates, mechanical separationcapacity is often exceeded. For deepwater platforms, separation residence timeis typically short due to the high cost of space and weight. Topsidesseparation problems can be costly, particularly when production must bedeferred to meet oil or water quality specifications (BS&W and oil in waterconcentration).
The work reported here was carried out in 2003 through early 2006. It wascarried out in two phases. In 2003 and early 2004, the platform was operatingat historically high production rates. Oil production averaged 200,000 BPD.Dehydration problems were addressed by adding more heat, improving the chemicalapplication, and improving the operating procedures. In addition, the option toupgrade the Bulk Oil Treater vessel internals was evaluated during this timeperiod. This was the first phase of the work during which the platform wasoperating at high production rates.
