TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractQuantifying oil-water or emulsion separation has always been difficult. This is due, in part, to the numerous factors controlling oil-water separation. This paper describes a new method developed at Saudi Aramco for the quantification of oil-water separation process. It is designated as ESI or Emulsion Separation Index and it was developed to measure emulsion stability. This index has been used to select and screen demulsifiers and to quantify the effect of various factors that affect oil-water separation including temperature, shear, asphaltene content, watercut, demulsifier dosage and mixing different crudes. Its use has eliminated some of the 'art-work' associated with demulsifier selection and diagnosing emulsion treatment problems. This paper also describes three field case studies where the ESI was used to select the best demulsifier, diagnose, and ultimately solve emulsion related problems during oil production. The first field study is from the largest onshore oil field in the world. The emulsions from this field were being stabilized by inorganic scales and organic asphaltenes. The paper describes how the ESI was used to diagnose and resolve the problem. The second field study is from the second largest offshore field in the world. Here extremely tight emulsions were forming and plugging the separation equipment offshore. These emulsions contained 70-90% water and were very viscous. Their deposition in the separation equipment was resolved by using recommended demulsifiers and performing ESI tests in the field. The demulsifier dosage was also optimized using these tests. The third field case study is from another large offshore field that produces from seven different reservoirs. The properties of the crudes from the seven reservoirs vary significantly. These properties provide an interesting case of operational problems in oil-water separation including increased incidents of arcing/shorting in the separator, tripping of equipment and increased demulsifier consumption. The factors affecting oil-water separation were quantified using ESI. The results show a strong correlation of asphaltene content in the crude oil with ESI or emulsion tightness. Recommendations were made for reducing and optimizing demulsifier dosage by adding chemical additives. Many lessons learnt in these field studies are applicable to any crude oil treating facilities.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractQuantifying oil-water or emulsion separation has always been difficult. This is due, in part, to the numerous factors controlling oil-water separation. This paper describes a new method developed at Saudi Aramco for the quantification of oil-water separation process. It is designated as ESI or Emulsion Separation Index and it was developed to measure emulsion stability. This index has been used to select and screen demulsifiers and to quantify the effect of various factors that affect oil-water separation including temperature, shear, asphaltene content, watercut, demulsifier dosage and mixing different crudes. Its use has eliminated some of the 'art-work' associated with demulsifier selection and diagnosing emulsion treatment problems. This paper also describes three field case studies where the ESI was used to select the best demulsifier, diagnose, and ultimately solve emulsion related problems during oil production. The first field study is from the largest onshore oil field in the world. The emulsions from this field were being stabilized by inorganic scales and organic asphaltenes. The paper describes how the ESI was used to diagnose and resolve the problem. The second field study is from the second largest offshore field in the world. Here extremely tight emulsions were forming and plugging the separation equipment offshore. These emulsions contained 70-90% water and were very viscous. Their deposition in the separation equipment was resolved by using recommended demulsifiers and performing ESI tests in the field. The demulsifier dosage was also optimized using these tests. The third field case study is from another large offshore field that produces from seven different reservoirs. The properties of the crudes from the seven reservoirs vary significantly. These properties provide an interesting case of operational problems in oil-water separation including increased incidents of arcing/shorting in the separator, tripping of equipment and increased demulsifier consumption. The factors affecting oil-water separation were quantified using ESI. The results show a strong correlation of asphaltene content in the crude oil with ESI or emulsion tightness. Recommendations were made for reducing and optimizing demulsifier dosage by adding chemical additives. Many lessons learnt in these field studies are applicable to any crude oil treating facilities.
As watercuts increase, tight emulsions formed in the produced fluids from some wells in Saudi Arabian oilfields are causing problems at an increasing number of wet crude handling facilities. The processing of these fluids impacts operations in three major areas:–Inability to produce some wells, particularly during cooler weather.–Plant upsets due to grid trips and accumulation of sludge in vessels.–Increased chemical demulsifier demands. The overall effect is an increase in treatment costs and loss of revenue. In January 1995 a multi-disciplined emulsion study team was formed. As part of this study the Laboratory implemented the following stepwise investigation strategy:Develop an Index to compare emulsions for tightness.Perform tests for the physical and chemical characterization of the emulsions.Develop a model to correlate emulsion tightness with analytical data.Based on the above findings make recommendations for improved emulsion treatment. The paper discusses the development of an Emulsion Separation Index (ESI) through investigation of the effect of mechanical chokes on emulsion stability. Details of other tests - including droplet size, viscosity, TGA, organic and inorganic solids content, composition and particle size distribution are reported and related to emulsion stability. The emulsion formation mechanism developed from the above data is described. A model of organic and inorganic solids precipitation caused by shear and pressure drops during production is developed with reference to the literature. The paper concludes by using the model to make recommendations for solutions to the problems and for field trials and further laboratory work. Introduction Crude Production. Saudi Aramco is responsible for maintaining oil production throughout Saudi Arabia. Oil produced varies from Arab Heavy (API 27) through to Arab Super Light (API 51). This paper deals with emulsions encountered during the production of Arab Light (AL - API 31–33) The wet crude is processed through Wet Crude Handling Facilities (WCHF's) where demulsifier chemicals are added at the Production Header. The Company produces AL through around 20 WCHF's of up to 330MBD capacity. Since there are no fired heaters, problems with tight emulsions are typically encountered during the cooler months when demulsifier requirements increase from <5ppm in Summer to 10–20ppm in Winter. Compared to many parts of the world, peak demulsifier demands of 20ppm may seem to be a minor inconvenience. However, in view of the millions of barrels of AL produced, the potential for savings by reducing chemical use is considerable. Impact of Emulsion Problems. As the oilfields mature and watercuts become higher, oil/water emulsions are causing operational problems at an increasing number of (WCHFs). Processing of tight emulsions impacts operations in the following areas:–Inability to produce some wells, particularly in cooler weather. This results not only in loss of revenue, but also has a negative impact on long term Reservoir Management. - Upsets in WCHFs due to grid trips in vessels.–Accumulation of sludge in vessels, increasing downtime and decreasing residence times.–Increased demulsifier usage (and hence chemical costs) by a factor of five to ten times. The overall effect is a significant increase in treatment costs and loss of revenue. P. 675^
Tight emulsions, formed during the production of Arabian Light crude oil, were causing problems at an increasing number of wet crude handling facilities. The processing of these fluids impacted operations in three major areas: Inability to produce some wells, particularly during cooler weather. Plant upsets due to grid trips and accumulation of sludge in vessels. Increased demulsifier usage. The overall effect was a loss of revenue and increase in treatment costs. In January 1995 a multi-disciplined team of scientists and engineers was formed to characterize the emulsions and make recommendations for improved emulsion treatment. Studies showed that solids, which include scale particles, are precipitated from produced fluids during production. These solids were shown to be largely responsible for the formation of stable emulsions in our systems. A very successful scale squeeze program was already in place to mitigate carbonate scaling - with squeeze lifetimes of over ten years. Based on the link between scale and tight emulsions, this program was accelerated and scale treatments were performed on emulsion ‘problem’ wells to suppress solids formation and therefore reduce/ eliminate emulsion problems. The paper describes the emulsion model developed. The mechanism of organic and inorganic solids precipitation during production is presented and the effect of pressure drops caused by mechanical ‘chokes’ used for well restriction is demonstrated. Scale inhibitor squeeze and encapsulated inhibitor treatments are discussed with reference to case histories. The effectiveness of scale inhibitor in reducing emulsion tightness is demonstrated using laboratory data. The paper concludes by summarizing the success of this treatment strategy in terms of economics, reduction of chemical demulsifier use and elimination of downtime due to emulsion problems
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.