Alternative Innovative Operation Practices to Debottleneck Upstream Facilities Tight Emulsion and Water Cut Increase at Low to No Cost
Authors: Alshehri Ali Homoud , Soliman Mohamed Ahmad 
Published: April 2023

An assessment was conducted to showcase different innovative strategies and operating practices to tackle the increasing water cut and tight emulsion at one of the upstream Gas Oil Separation Plant (GOSP) at low to no cost. Also, this innovative strategy will reduce the crude carbon intensity and the operating margin.

The assessment is intended to evaluate the existing treatment process of formation water that is produced in GOSP. The current practice is to recycle the produced formation water from desalter plant to degassing tank. This practice causes the degassing tank to handle excessive formation water while the degassing tank is designed to separate the wet crude from the oil field into three phases that are oil, gas, and formation water. The assessment proved that the recycling of the formation water from dehydrator to degassing tanks is adversely impacting the plant operation in which there will be less time retention of inlet wet crude. Therefore, the outlet crude does not achieve the allowable time to get rid of the water droplet to be associated with the crude formation and cause impact on the degassing tank's downstream. In addition to that, recycling formation water will require more draw off pumps that are responsible to transfer the accumulated formation water in the degassing tank that results in an increase in the operation and capital cost to facilitate the new equipment. In addition, the assessment analyzed the sample of oil-in-water content samples that are taken from the discharge header of formation water from degassing tank and desalter plant. It shows high oil-in-water content at the discharge header of formation water from the degassing tank compared to the formation water header from desalter plant.

In addition, several proposal solutions were raised in which they support the process separation and improve the Gas Oil Separation Plant performance such as Fixed high operating temperature at Dehydrator of 150 F that lower the viscosity and enhance the separation compared to lower operating temperature at the Low Pressure Degassing Tank (LPDT) from 70 to 100 F. This increment of temperature will improve the oily water separation and reduce the emulsion that does begin to form inside the tank. Also, using the combined electrostatic and gravity separation in dehydrators is much better than gravity separation alone at LPDT. Moreover, optimum demulsifier dosage enhances oily water separation in the dehydrator at high temperature compared to low temperature at the LPDT. Water separation at the dehydrator can be further improved by the selection of a proper demulsifier that can improve the oily water separation while meeting the crude Basic Sediment & Water (BS&W) and salt content.

The assessment proposes to utilize the formation water line that is connecting the desalter plant with the utility plant in which the produced formation water can be transferred directly to the utility plant and avoid sending the huge quantity of the formation water back to the degassing tank. Finally, it is recommended to closely monitor the interface level of dehydrator and desalter vessels in the desalter plant to ensure the quality of produced formation water.