Reduction of Residual Oil Content in Produced Water at Offshore Gas Production Platform P/6A

1990 ◽  
Author(s):  
F.J. op ten Noort ◽  
J.P. Etten ◽  
R.S. Donders

2021 ◽  
Author(s):  
Jawaher Almorihil ◽  
Aurélie Mouret ◽  
Isabelle Hénaut ◽  
Vincent Mirallès ◽  
Abdulkareem AlSofi

Abstract Gravity settling represents the main oil-water separation mechanism. Many separation plants rely only on gravity settling with the aid of demulsifiers (direct or reverse breakers) and other chemicals such as water clarifiers if they are required. Yet, other complementary separation methods exist including filtration, flotation, and centrifugation. In terms of results and more specifically with respect to the separated produced-water, the main threshold on its quality is the dispersed oil content. Even with zero discharge and reinjection into hydrocarbon formations, the presence of residual oil in the aqueous phase represents a concern. High oil content results into formation damage and losses in injectivity which necessitates formation stimulations and hence additional operational expenses. In this work, we investigated the effects of different separation techniques on separated water quality. In addition, we studied the impact of enhanced oil recovery (EOR) chemicals on the different separation techniques in terms of efficiency and water quality. Based on the results, we identified potential improvements to the existing separation process. We used synthetic well-characterized emulsions. The emulsions were prepared at the forecast water: oil ratio using dead crude oil and synthetic representative brines with or without the EOR chemicals. To clearly delineate and distinguish the effectiveness of different separation methods, we exacerbated the conditions by preparing very tight emulsions compared with what is observed on site. With that, we investigated three separation techniques: gravity settling, centrifugation, and filtration. First, we used Jar Tests to study gravity settling, then a benchtop centrifuge at two speeds to evaluate centrifugation potential. Finally, for filtration, we tested two options: membrane and deep-bed filtrations. Concerning the water quality, we performed solvent extraction followed by UV analyses to measure the residual oil content as well as light transmission measurements in order to compare the efficiency of different separation methods. The results of analyses suggest that gravity settling was not efficient in removing oil droplets from water. No separation occurred after 20 minutes in every tested condition. However, note that investigated conditions were severe, tighter emulsions are more difficult to separate compared to those currently observed in the actual separation plant. On the other hand, centrifugation significantly improved light transmission through the separated water. Accordingly, we can conclude that the water quality was largely improved by centrifugation even in the presence of EOR chemicals. In terms of filtration, very good water quality was obtained after membrane filtration. However, significant fouling was observed. In the presence of EOR chemicals, filtration lost its effectiveness due to the low interfacial tension with surfactants and water quality became poor. With deep-bed filtration, produced water quality remained good and fouling was no longer observed. However, the benefits from media filtration were annihilated by the presence of EOR chemicals. Based on these results and at least for our case study, we conclude that centrifugation and deep-bed filtration techniques can significantly improve quality of the separated and eventually reinjected water. In terms of the effects of EOR chemicals, the performance of centrifugation is reduced while filtrations are largely impaired by the presence of EOR chemicals. Thereby, integration of any of the two methods in the separation plant will lead to more efficient produced-water reinjection, eliminating formation damage and frequent stimulations. Yet, it is important to note that economics should be further assessed.



2021 ◽  
Author(s):  
Jawaher Almorihil ◽  
Aurélie Mouret ◽  
Isabelle Hénaut ◽  
Vincent Mirallés ◽  
Abdulkareem AlSofi

Abstract Gravity settling represents the main oil-water separation mechanism. Many separation plants rely only on gravity settling with the aid of demulsifiers (direct or reverse breakers) and others chemicals such as water clarifiers if they are required. Yet, other complementary separation methods exist including filtration, flotation, and centrifugation. In terms of results and more specifically with respect to the separated produced-water, the main threshold on its quality is the dispersed oil content. Even with zero discharge and reinjection into hydrocarbon formations, the presence of residual oil in the aqueous phase represents a concern. High oil content results into formation damage and losses in injectivity which necessitates formation stimulations and hence additional operational expenses. In this work, we investigated the effects of different separation techniques on separated water quality. Based on the results, we identified potential improvements to the existing separation process. We used synthetic well-characterized emulsions. The emulsions were prepared at the forecast water:oil ratio using dead crude oil and synthetic representative brine. To clearly delineate and distinguish the effectiveness of different separation methods, we exacerbated the conditions by preparing very tight emulsions compared with what is observed on site. With that, we investigated three separation techniques: gravity settling, centrifugation, and filtration. First, we used jar tests to study gravity settling, then a benchtop centrifuge at two speeds to evaluate centrifugation potential. Finally, for filtration, we tested two options: membrane and deep-bed filtrations. Concerning the water quality, we performed solvent extraction followed by UV analyses to measure the residual oil content as well as light transmission measurements in order to compare the efficiency of different separation methods. The results of analyses suggest that gravity settling was not efficient in removing oil droplets from water. No separation occurred after 20 minutes in every tested condition. However, note that investigated conditions were severe, tighter emulsions are more difficult to separate compared to those currently observed in the actual separation plant. On the other hand, centrifugation significantly improved light transmission through the separated water. Accordingly, we can conclude that the water quality was largely improved by centrifugation. In terms of filtration, very good water quality was obtained after membrane filtration. However, significant fouling was observed. With deep-bed filtration, produced water quality remained good and fouling was no longer observed. On the basis of those results, we conclude that for our case study, centrifugation and deep-bed filtration techniques can significantly improve quality of the separated and eventually reinjected water. Thereby, integration of any of the two methods in the separation plant will lead to more efficient produced-water reinjection, eliminating formation damage and frequent stimulations. Yet, it is important to note that economics should be further assessed.



2016 ◽  
Vol 10 (4) ◽  
pp. 437-444 ◽  
Author(s):  
Ilma Cirne ◽  
◽  
Jaime Boaventura ◽  
Yuri Guedes ◽  
Elizabete Lucas ◽  
...  

Infrared spectrometry and spectrofluorimetry methods were correlated in the measurement of oil concentration in produced water. Furthermore, we compared colorimetry and gravimetry techniques. Adsorption experiments were performed in synthetic oily wastewaters by polymer compounds based on poly(hydroxyethyl acrylamide and polypropylene. The residual oil content was used in the techniques correlation.



SPE Journal ◽  
2020 ◽  
Vol 25 (05) ◽  
pp. 2482-2495
Author(s):  
Jared Theurer ◽  
Oluwatobi Ajagbe ◽  
Jhouly Osorio ◽  
Rida Elgaddafi ◽  
Ramadan Ahmed ◽  
...  

Summary Recent studies have shown encouraging results using amine-coated magnetite (Fe3O4) nanoparticles to remove residual oil from produced water using a magnetic field. However, the manufacturing of magnetite nanoparticles requires an expensive coating operation, which limits the application of this technology in large-scale treatment operations. The goal of this study is to develop a simple, efficient, and economically feasible method for removing oil from produced water using nanoparticles. Iron oxide nanoparticles are biocompatible and even safely used in medical applications. This study focuses on the removal of residual oil from produced water using uncoated, recyclable, and less expensive maghemite (γ-Fe2O3) nanoparticles. These particles have shown the potential for removing oil layers from the surface of water. However, they have not been tested for their capability of removing emulsified and dissolved oil from produced water. In this study, commercial and synthesized maghemite nanoparticles were used. The maghemite nanoparticles were synthesized using the coprecipitation process. Laboratory-synthesized produced water samples with high oil concentration (1,000 ppm) were prepared by mixing medium oil with brine [1,180 ppm sodium chloride (NaCl) solution]. The nanoparticles were dispersed in 3% NaCl brine (w/w) at varying concentrations (0.31 to 5 mg/cm3) to form different nanosuspensions. Subsequently, the nanosuspensions were mixed with synthesized produced water for 10 minutes. When a magnetic field was applied to the mixture, a clear separation of the nanoparticles was observed within seconds. Residual oil in the samples was measured using nondispersive infrared spectroscopy. Oil content analysis confirmed the successful (99.9%) removal of oil from laboratory-synthesized water samples. For the real produced water samples, results showed a reduction of oil content to an undetectable level (i.e., less than 0.1 ppm). The ease of nanoparticle collection and washing after subsequent water treatments further demonstrates the feasibility of magnetic nanoparticle (MNP)-based separations for large-scale use in produced water treatment operations. The unique finding of this study is the elimination of one additional step of synthesizing (amine coating) MNPs. Direct use of uncoated maghemite nanoparticles with high oil removal efficiency can reduce produced water treatment costs and promote this technology as an economically feasible option within the industry.



2011 ◽  
Vol 62 (10) ◽  
pp. 2095-2105 ◽  
Author(s):  
C. William Yeung ◽  
Brent A. Law ◽  
Tim G. Milligan ◽  
Kenneth Lee ◽  
Lyle G. Whyte ◽  
...  




2000 ◽  
Vol 41 (10-11) ◽  
pp. 117-123 ◽  
Author(s):  
C. Visvanathan ◽  
P. Svenstrup ◽  
P. Ariyamethee

This paper presents a case study of a natural gas production site covering various technical issues related to selection of an appropriate Reverse Osmosis (RO) system. The long-term field experience indicates the necessity of the selection of appropriate pretreatment systems for fouling-free RO operational conditions. The produced water has a variety of impurities such as oil and grease, process chemicals used for corrosion and scaling control, and dehydration of natural gas, etc. This situation leads to a complicated and extremely difficult task for a membrane specialist to design RO systems, especially the pre-treatment section. Here as part of the pretreatment selection, two types of UF membrane modules viz. spiral wound and hollow fibre, with MWCO of 8000 and 50,000 Dalton respectively, were tested in parallel with NF membranes of the spiral wound type with MWCO 200 Dalton. The UF permeate is used as feed for RO compatibility testing. Both configurations of UF failed to be compatible, due to irreversible fouling of the RO membrane. The NF membrane, however, showed interesting results, due to membrane stability in terms of cleaning and fouling. The NF plant with 50% capacity gave a recovery of 75% and the RO plant gave a recovery of 60% versus the expected 92–95%. The long-term tests have indicated that the reminder of the membranes could be installed to achieve full capacity of the plant. This study also demonstrates the importance of selection of proper pre-treatment set-up for the RO system design.



2021 ◽  
pp. 90-104
Author(s):  
L. V. Taranova ◽  
A. G. Mozyrev ◽  
V. G. Gabdrakipova ◽  
A. M. Glazunov

The article deals with the issues of improving the quality of highly watered well production fluid processing using chemical demulsifier reactants at crude oil processing facilities; the analysis of the use of the reactants at the Samotlor field has been made. The article presents the results of the study of the effectiveness of the "Hercules 2202 grade A" and "SNPH-4460-2" demulsifiers in comparison with the indicators of oil and bottom water processing achieved in the presence of the reactants used at existing facilities; their optimal consumption has been determined. The study has shown that the selected demulsifiers provide the required quality of the oil and water under processing at the considered oil processing facilities and can be used along with the basic reactants for these facilities. On the basis of total indicators, the best results have been achieved using "Hercules 2202 grade A" with the improved indicators of water cut and residual oil content in water by 33.9 % and 2.8 % while reducing the reactant consumption by 9.7 % compared to the basic demulsifier.



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