Produced Water Quality: Uncovering the Effects of Centrifugation for Water and Chemical Floods Using a Dispersion Analyzer

2021 ◽  
Author(s):  
Jawaher Almorihil ◽  
Ahmed Alsmaeil ◽  
Ziyad Kaidar ◽  
Abdulkareem AlSofi
Keyword(s):  
Water Quality ◽  
Produced Water ◽  
Separation Efficiency ◽  
Light Transmission ◽  
Lower Efficiency ◽  
Gravity Settling ◽  
Processing Plants ◽  
Different Temperatures ◽  
Emulsion Separation

Abstract A second stage of gravity settling with the addition of demulsifiers or clarifiers is commonly used in processing plants to further treat the separated produced water. In previous work, we demonstrated gravity settling lower efficiency in removing oil carryover from produced water compared to other processing techniques. Both centrifugation and filtration were found to significantly improve the separated water quality. In this work, we focus on centrifugation and further evaluate its efficiency in improving the quality of separated water for both water and chemical floods, specifically surfactant/polymer (SP) flooding. Samples were firstly prepared to imitate the separation plant projected feed and operations. Synthetic representative brines were prepared and used with dead crude oil to prepare the oil/water emulsions. Emulsion separation was conducted at different temperatures, as well as different concentrations of SP, and the demulsifier. The kinetics and efficiency of separation were thoroughly studied over two stages of separation: primary gravity settling and secondary centrifugation. We performed gravitational separation using bottle tests in order to firstly obtain the separated produced water for use in secondary water treatment studies and to secondly further investigate gravity settling kinetics and efficiency. Water quality, in terms of oil content, was then assessed through solvent extraction and UV analyses. Samples of the produced water separated by the primary gravity settling were then exposed to secondary centrifugation. Centrifugation was performed at different rotational speeds using a dispersion analyzer. Light transmission evolution in space and time was used to study kinetics, efficiency and mechanisms of secondary centrifugation. The results reconfirmed that a single-stage gravity settling is not sufficient to reduce oil carryover to acceptable levels for disposal and re-injection into oilfields. Secondary centrifugation yielded clear and significant improvement in water quality even in the presence of EOR chemicals. With centrifugation, the separation efficiency was a function of the rotational speed. Higher rotational speeds resulted in higher creaming velocities and faster separation. In addition, creaming velocities indicated that higher temperatures yield favorable effects on oil droplets migration and separation rates. This is possibly due to the lower density and larger bouncy at higher temperatures. Based on these results, we conclude that secondary centrifugation is very efficient and effective in improving the quality of separated water. In terms of the effects of investigated EOR formulations, SP addition caused minor but manageable reduction in separated water quality at a level that would not harm conventional disposal practices.

Produced Water Quality: The Effects of Different Separation Methods for Water and Chemical Floods

2021 ◽  
Author(s):  
Jawaher Almorihil ◽  
Aurélie Mouret ◽  
Isabelle Hénaut ◽  
Vincent Mirallès ◽  
Abdulkareem AlSofi
Keyword(s):  
Water Quality ◽  
Oil Content ◽  
Produced Water ◽  
Light Transmission ◽  
Formation Damage ◽  
Residual Oil ◽  
Separation Plant ◽  
Deep Bed Filtration ◽  
Separation Techniques ◽  
Gravity Settling

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.

Produced Water Quality: the Effects of Different Separation Methods

2021 ◽  
Author(s):  
Jawaher Almorihil ◽  
Aurélie Mouret ◽  
Isabelle Hénaut ◽  
Vincent Mirallés ◽  
Abdulkareem AlSofi
Keyword(s):  
Water Quality ◽  
Oil Content ◽  
Produced Water ◽  
Light Transmission ◽  
Formation Damage ◽  
Residual Oil ◽  
Separation Plant ◽  
Deep Bed Filtration ◽  
Separation Techniques ◽  
Gravity Settling

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.

scholarly journals Water Quality Index of Suceava River in Suceava City Metropolitan Area

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2111 ◽  
Author(s):  
Andrei-Emil Briciu ◽  
Adrian Graur ◽  
Dinu Iulian Oprea
Keyword(s):  
Water Quality ◽  
Water Quality Index ◽  
Quality Index ◽  
Produced Water ◽  
Human Life ◽  
Specific Conductivity ◽  
Temporal Frequency ◽  
Treatment Plant ◽  
Water Contaminants

The water quality of rivers worldwide is of persistent interest due to its impact on human life. Five streamwater quality parameters of Suceava River were monitored in 2019 upstream and downstream of Suceava city, Romania: dissolved oxygen, specific conductivity, pH, oxidation-reduction potential, and temperature. Data was recorded at a high temporal frequency, every hour, and produced Water Quality Index (WQI) time series of similar resolution. Our additive WQI has variants with particular advantages. Water quality of Suceava city exhibits a diurnal cycle. Upstream, WQI values indicate a quasi-permanent good water quality; downstream, the water quality oscillates around the average WQI value because of the various sources of water contaminants, especially the wastewaters from the wastewater treatment plant. Parameters from this point source of pollution are taken into account to explain the decaying streamwater quality towards the end of 2019. WQI is useful for detecting time intervals when water self-purification events have a high chance of occurrence.

Effects of Kaolin Processing Plants on the Water Quality of Streams in Brazil

2002 ◽  
Vol 82 (3-4) ◽  
pp. 139-158 ◽  
Author(s):  
C.P. JordÃo ◽  
M.G. Pereira ◽  
J.L. Pereira
Keyword(s):  
Water Quality ◽  
Processing Plants

Spatial and Temporal variation analysis of water quality of Hemavathi River, Karnataka, India

2018 ◽  
Vol 6 (9) ◽  
pp. 196
Author(s):  
Santhosh K. M ◽  
S. Prashanth
Keyword(s):  
Water Quality ◽  
Agricultural Runoff ◽  
Spatial And Temporal Variation ◽  
Final Conclusion ◽  
Variation Analysis ◽  
Pollution Load ◽  
Quality Of Water ◽  
Pollution Loading ◽  
Origin Point

Urban development, agricultural runoff and industrialization have contributed pollution loading on the environment.  In this study Hemavathi river water from a stretch from its origin point to its sangama was studied for pollution load by determining parameters of water quality like pH, Alkalinity,  Ca, Mg, Nitrate, TDS, BOD, COD , and the results were compared with WHO and BIS standards to draw final conclusion on the quality of water.

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