Gas oil separation plant systems and methods for rag layer treatment

Abstract

Systems and methods for treating a rag layer in a gas oil separation plant. The method includes withdrawing the rag layer from a vessel proximate an oil water interface; conveying the rag layer to a separation device, the separation device operable to effect electrostatic coalescence on the rag layer to separate oil and water; and recycling separated oil from the separation device back to the gas oil separation plant process.

That claimed is: 
     
         1 . A method for treating a rag layer in a gas oil separation plant process, the method comprising the steps of:
 withdrawing the rag layer from a vessel proximate an oil water interface;   conveying the rag layer to a separation device, the separation device operable to effect electrostatic coalescence on the rag layer to separate oil and water; and   recycling separated oil from the separation device back to the gas oil separation plant process.   
     
     
         2 . The method according to  claim 1 , where the step of withdrawing the rag layer from the vessel occurs in a vessel selected from the group consisting of: a low pressure production trap; a dehydrator; and a desalter. 
     
     
         3 . The method according to  claim 1 , where the separation device is selected from the group consisting of: a three-phase separation device equipped with fully insulated electrostatic electrodes and a spool of pipe equipped with fully insulated electrostatic electrodes. 
     
     
         4 . The method according to  claim 1 , where the step of withdrawing the rag layer from the vessel proximate an oil water interface includes withdrawing the rag layer from the vessel proximate an oily water interface skimmer. 
     
     
         5 . The method according to  claim 1 , where the step of conveying the rag layer to a separation device includes the step of conveying the rag layer through a restricted orifice. 
     
     
         6 . The method according to  claim 5 , where the step of withdrawing is continuous during operation of the gas oil separation plant process. 
     
     
         7 . The method according to  claim 1 , where the step of withdrawing is controlled in part by a level indicator and controller in communication with the vessel and in communication with a control valve, the control valve in fluid communication with the vessel. 
     
     
         8 . The method according to  claim 1 , further comprising the step of discontinuing conveying the rag layer to the separation device when the separation device detects about 100% water being withdrawn from the vessel. 
     
     
         9 . The method according to  claim 1 , further comprising the step of increasing the pressure of the rag layer prior to the conveying step. 
     
     
         10 . The method according to  claim 9 , where the step of increasing the pressure includes the use of at least one of a turbocharger and a pump. 
     
     
         11 . A system for treating a rag layer in a gas oil separation plant process, the system comprising:
 an outlet stream to withdraw the rag layer from a first vessel proximate an oil water interface;   a separation device, the separation device in fluid communication with the outlet stream and operable to effect electrostatic coalescence on the rag layer to separate oil and water; and   a recycle line to recycle separated oil from the separation device back to a second vessel of the gas oil separation plant process, where the outlet stream further comprises a restricted orifice operable to reduce a water level in the first vessel to below an oily water interface skimmer such that the oil water interface is proximate the oily water interface skimmer, and   where the system is operable to withdraw the rag layer in part based on a pressure differential between a pressure in the first vessel and a pressure in the second vessel, the pressure in the first vessel being greater than the pressure in the second vessel.   
     
     
         12 . The system according to  claim 11 , where the outlet stream effects continuous withdrawal from the vessel to the restricted orifice during the operation of the gas oil separation plant process.