Bitumen-Water Interfacial Tension Modeling by Using Subtractive Clustering Method

H. Asaadian, H. Zanboori, B.S. Soulgani, (2018), Petroleum Science and Technology, Volume 36, 2018 - Issue 11. https://doi.org/10.1080/10916466.2018.1446170

Abstract: Calculation of interfacial tension during bitumen production is a crucial issue in heavy crude oil history. Upon variation in pressure, temperature and phases composition, interfacial tension between bitumen and water change. In this work a sophisticated method called subtractive clustering was utilized to predict dynamic interfacial tension between bitumen and water. The subtractive clustering method is composed of optimized fuzzy logic algorithm. A data bank which is collected from open-source literature, is used to create a reliable model. Then the prediction accuracy of the measured dynamic interfacial tension using subtractive clustering have been examined. Results state that the comparison of measured interfacial tension and predicted interfacial tension indicate acceptable accuracy of proposed model. Also more than 90 percent of data points have less than 3 percent absolute error.

Keywords: 
#Bitumen
#Fuzzy_modeling
#Interfacial_tension
#Subtractive_clustering
#Water-bitumen_emulsion

PST02.pdf (Download here)

An Experimental Study on Electrical Effect on Asphaltene Deposition

 H. Asaadian, B.S. Soulgani, A. Karimi, (2017), Petroleum Science and Technology, Volume 35, 2017 - Issue 24. https://doi.org/10.1080/10916466.2017.1397696

Abstract: Asphaltene generally existed in colloidal form in crudes and will precipitate in non-equilibrium conditions. Asphaltene instability may take place in the reservoir leading to permeability damage and contributing to flow restriction issues. It may also occur in production strings and surface facilities causing pipe blockage. Any change in oil composition or pressure and temperature at any stage of production will destabilize crude oil producing asphaltene precipitation. In this paper, the stability of target crude oil under the influence of a direct current and contacting with polar fluid, water, is investigated. The amount of the asphaltene deposit and its electrical charge at various operating conditions are investigated. The fact that deposits form on the anode surface proves that asphaltene particles possess a positive charge. The amounts of asphaltenes precipitation were increased considerably by increasing water as polar component.

Keywords: 
#Asphaltene;
 #Electrode_position; 
#Electrical_field; 
#Water; 
#Precipitation

PST01.pdf (Download here)

بررسی آزمایشگاهی تفکیک گر سایکلون استوانه ای گاز و مایع

حمیدرضا اسعدیان، بهرام سلطانی سولگانی، پژوهش نفت (۱۳۹۸)، صفحه ۱۱۲-۱۲۴، https://dx.doi.org/10.22078/pr.2019.3186.2466

چكيده: نســل جدیــدی از تفکیکگرهــا بــا عنــوان تفکیکگرهــای ســیکلون اســتوانهای گاز و مایــع توانســتهاند خــود را بــه عنــوان اخیــرا جایگزیـن مناسـبی بـرای تفکیکگرهـای معمـول جاذبـه محـور معرفـی کننـد. در ایـن پژوهـش تـاش شـده اسـت تـا تاثیـر ایجـاد تغییــرات فیزیکــی در اجــزای مختلــف ایــن تفکیکگــر بــر روی عملکــرد و دامنــه آن مــورد بررســی و تحقیــق واقــع شــود. از ایــن رو نتایــج ایــن تغییــرات بــر روی یــک نمونــه آزمایشــگاهی تفکیکگــر ســیکلون اســتوانهای گاز و مایــع کــه ســیال هــوا را از آب جـدا میکنـد، مشـاهده و گـزارش شـده اسـت. همچنیـن تاثیـر ایـن تغییـرات بـر روی نتایـج مـدل ریاضـی ثابـت شـده بـرای ایـن تفکیکگـر بررسـی شـده اسـت. ایـن تغییـرات فیزیکـی شـامل افزایـش طـول خروجـی هـای گاز و مایـع، کاهـش سـتون گازی، قطـر نــازل ورودی، قطــر بدنــه اصلــی و خروجیهــای گاز و مایــع اســت. نتایــج ایــن تحقیــق نشــان میدهنــد کــه کاهــش در قطــر نــازل ورودی باعـث بهبـود عملکـرد تفکیـک فازهـا دسـتگاه شـده اسـت. ایـن در حالـی اسـت کـه هرگونـه کاهـش قطـر بدنـه اصلـی و قطـر خروجیهـای گاز و مایـع تفکیکگـر جدایـش فازهـای سـیال چندفـازی را مشـکلتر کـرده اسـت. همچنیـن .تغییـر در طـول سـتون گازی تفکیکگــر تغییــری در عملکــرد دســتگاه نشــان نمیدهــد. هرگونــه افزایــش در طــول خروجــی دســتگاه باعــث بیشــتر شــدن .اثــر اصطــکاک و تضعیــف عملکــرد دســتگاه میشــود

:کلیدواژه‌ها

Investigation of The Simultaneous Chemicals Influences to Promote Oil-in-Water Emulsions Stability During Enhanced Oil Recovery Applications

P. Ahmadi, H. Asaadian, S. Kord, A. Khadivi, (2018), Journal of Molecular Liquid,  Volume 275,  Pages 57-70. https://doi.org/10.1016/j.molliq.2018.11.004

Abstract: Emulsion application in Enhanced Oil Recovery (EOR) processes is a common and practical subject in petroleum industry. Considering the chemical usage limitations, quantitative understanding of the ability of chemicals to improve other chemical performance is very important. In the present article, the coincident impacts of nanoparticles, salts and surfactants on interfacial tension reduction as well as zeta potential for determining the best emulsion stability have been examined. Resultant findings have shown that cobalt oxide nanoparticle and aluminum ions lead to an improvement in emulsion stability than each individually. Resulted emulsion stability indexes for cobalt oxide nanoparticles and aluminum ions are 0.48 and 0.49 at 25 °C and 0.54 and 0.66 at 50 °C, respectively. Nonetheless, their simultaneous presence, i.e., dispersion of cobalt oxide optimum weight percent in crude oil and dissolving of optimum aluminum ions concentration in water, change the stability indexes to 0.64 and 0.75 at temperatures of 25 °C and 50 °C, respectively. Presence of dispersed silica nanoparticles with low weight percent resulted in stability indexes of 0.49 and 0.43 at temperatures of 25 °C and 50 °C, respectively, but at high concentration because of repulsive forces against the asphaltene molecules, emulsion stability drops eventually with indexes of 0.35 and 0.26 at temperatures of 25 °C and 50 °C, respectively. While presence of cationic surfactant in the phase that silica nanoparticle is dispersed in, rises emulsion stability and viscosity. In all cases, along with emulsion stability increasing, quantities of zeta potential became more negative. But results of silica nanoparticle show that descending negative zeta potential trend of media does not lead to stability necessarily. This paper, quantitatively demonstrated that the effect of chemical co-existence by stimulating the polar molecules of crude oil caused a significant difference in emulsion stability than using the chemicals individually.

A New Approach for Determination of Carbonate Rock Electrostatic Double Layer Variation Towards Wettability Alteration

P. Ahmadi, H. Asaadian, A. Khadivi, S. Kord, (2019), Journal of Molecular Liquids, Volume 275, Pages 682-698. https://doi.org/10.1016/j.molliq.2018.11.106

Abstract: Focus on the molecular scale of low salinity brine effects seems to be necessary to clarify the possible mechanisms of carbonate rock wettability alteration. This study aimed at investigating the effects of different operational parameters such as pH, salinity, and types of ions on wettability alteration (WA) during low salinity brine injection as a tertiary recovery process. In the present study, using the electrostatic double-layer concept and molecular behavior, along with a good view of the past studies, led to the justification of the obtained results. The studied reservoir is one of the Middle East carbonate reservoirs which is considered for low salinity brine injection plan. Although the concept of ζ potential is ill-defined in electrostatic or/and electrokinetic topics, nonetheless, to the extent possible, has been tried to use this concept to illustrate and justify underlying mechanisms during low salinity process beneficially.

Resultant findings have shown that pH value directly affects carbonate rock powder ζ potential and determines the type of surrounding ions that form the Stern layer and ion distribution in diffuse layer as well. A close examination at two temperatures of 25 °C and 80 °C, showed that active ions in WA e.g. Ca2+ and Mg2+ and SO42− as an agent facilitator to access active ions to the rock powder surface, have profound impacts on the Stern layer. The obtained optimal ions concentrations, (i.e., 1000 ppm sulfate + 1000 ppm magnesium @ 80 °C) and (500 ppm calcium and 800 ppm sulfate @ 25 °C) have changed the ζ potential of oil-wet rock powder in Seawater form −23.6 mV to −6.71 mW and −8.7 mV respectively, using a new designed procedure. In the present study, influence of ion valence on the electrostatic double layer variation of an oil-wet rock powder has been led to directly link this alteration to the wettability state changes. Therefore, this approach could be very helpful to monitor the wettability state of the rock powder in molecular scale.

Experimental Investigation of Gas/Liquid Cylindrical Cyclone Separator

H. Asaadian, B.S. Soulgani, (2019), Petroleum Research, 29(105007), Pages 112-124. http://pr.ripi.ir/jufile?ar_sfile=21292. 

DOI: 10.22078/pr.2019.3186.2466

Keywords: #Cylindrical_gas_and_liquid_cyclone_separator; #Main_body; #Inlet_nozzle; #Gas_and_liquid_outlets; #Phase_separation_function

PR-2019_3189.pdf (Download here)

Ion-mediated desorption of asphaltene molecules from carbonate and sandstone structures

P. Ahmadi, M. Aghajanzadeh, H. Asaadian, A. Khadivi, & S. Kord, (2022). Materials Research Express, 9(6), 065101. https://iopscience.iop.org/article/10.1088/2053-1591/ac784f/meta#back-to-top-target

Abstract: As more and more oil recovery scenarios use seawater, the need to identify the possible mechanisms of wettability state changes in oil reservoirs has never been greater. By using molecular dynamics simulations, this study sheds light on the effect of ions common to seawater (Ca²⁺, K⁺, Mg²⁺, Na⁺, Cl⁻, HCO³⁻, SO₄²⁻) on the affinity between silica and carbonate as the traditional rock types and asphaltene molecules as an important contributing factor of reservoir oil wetness. In the case of carbonate and silica being the reservoir rock types, the measured parameters indicate good agreement with each other, meaning that (HCO₃⁻ & SO₄²⁻) and (Na⁺ & Cl⁻) ions reached maximum bonding energies of (25485, 25511, 4096, and −4093 eV, respectively). As with the surface charge density measurements, the results of the non-bonding energies between the individual atomic structures agree with those from the simulation cell. In the presence of a silica surface, the radial distribution function (RDF) results determine that the peak of the maximum value for the distribution of the ions is 4.2. However, these values range from 3 to 6.6, suggesting that different ions perform better under the influence of carbonate rock. As these ions are distributed in the simulation box along with the adsorption domain, the conditions for sequestering asphaltene from the rock surface are made ideal for dissolution and removal. At equal ion strength, measuring the distance between the center of mass of rocks and asphaltene structures reveals a maximum repulsion force of 22.1 Å and a maximum detachment force of 10.4 Å in the presence of SO₄²⁻ and Na⁺ ions on carbonate and silica surfaces.

Keywords: #Wettability_state; #Molecular_dynamic_simulation; #Asphaltene_precipitation; #Smart_water; #Bonding_and_non-bonding_energy; #Coulomb_interaction

MRE-2053-1591.pdf (Download here)

Prevention of Acid-induced Sludge Formation using an Environmentally– Friendly Bio-based Nonionic Surfactant

H. Asaadian, P. Ahmadi, M. Z. Khormizi, S. Mohammadi, B. S. Soulgani, S. Baghersaei, & B. Mokhtari, (2022), Journal of Petroleum Science and Engineering, 218, 111009. https://www.sciencedirect.com/science/article/pii/S0920410522008610

Abstract: Asphaltene molecules are one of the main sub-fractions of heavy crude oils. During matrix acidizing operation, these polar molecules are highly susceptible to interaction with acid and form a third phase called asphaltic sludge. Deposition of the formed sludge on the rock surface and plugging their pore throats alters the rock's wettability state and consequently its permeability. In the present study, the impact of acid and oil on the volume of the formed sludge as well as on the wettability of three rock types including sandstone, fractured, and vuggy carbonate rocks were experimentally explored. A new environmentally friendly biosurfactant which is extracted from Zizyphus Spina-christ (ZSCS) shrub leaves was used as an inhibitor to control the potential damage caused by wettability alteration and the following pore plugging. Two common commercial additives were also evaluated against the bio-surfactant performance that was used in this study. As a complementary step, molecular dynamic simulations were also conducted firstly to shed the light on the affinities between asphaltene and acid molecules and then check how the presence of ZSCS intervenes in the interaction between asphaltene molecules and rock surface. Our findings prove that using ZSCS provides optimal solutions concerning production issues (i.e. Prevention of acid-induced sludge formation), both economically and environmentally; economically as it simply costs less than other commonly used chemicals, and environmentally as it is extracted from nature.

JPSE-10_1016.pdf (Download here)

Drainage Potential Curves of Single Tapping Point for Bulk Oil–Water Separation in Pipe

H. Asaadian, S. Harstad, M. Stanko, (2022), Energies 15(19), 6911. https://doi.org/10.3390/en15196911

Abstract: In this study, experimental quantification of drainage potential curves for unspiked and spiked Exxsol D60 was performed and compared against simplified numerical model results. This potential relates to the flow rate of tapped water from the bottom of the pipe to the water cut of the tapped stream. To mimic the separation characteristics of a real crude-water mixture, Exxsol D60 was spiked with small amounts of crude oil. A pipe separator with two parallel branches and one tapping point was used to measure drainage potential experimentally. There was a slight decrease in separation performance for the spiked Exxsol D60 in general when compared with the unspiked oil’s drainage potential curves. However, for low inlet water cuts, the performance of the former was significantly worse than the latter. There was, in general, a fair agreement between experimental and numerical drainage potential curves. The flow patterns of the oil–water mixture approaching the tapping point are the major determining factors of drainage potential curves. The results of this work could be employed to predict the performance and design of bulk oil–water pipe separators that have one or multiple tapping points.

Keywords: #single_tapping_point; #drainage_potential_curve; #parallel_pipe_bulk_oil–water_separator; #spiked_and_unspiked_oil

Energies-15-06911.pdf (Download here)

Experimental quantification of the performance of a horizontal multi-pipe bulk separator of water and oil with crude spiking

H. Asaadian, M. Stanko, (2023), Journal of Petroleum Exploration and Production Technology, 13(11), 2283-2302. https://link.springer.com/article/10.1007/s13202-023-01672-9

Abstract: Subsea water separation with pipe separators is crucial for ensuring efficient and environmentally responsible extraction of oil and gas from the seabed. In this study, in a process called as "crude oil spiking", two concentrations of crude oil (e.g., 185 and 400 ppm) are added to Exxsol D60 to mimic the separation characteristics of real crude oil mixtures in a multi-parallel pipe separator. The pipe separator performance for water-oil bulk separation such as separation efficiency, water cut ratio, the flow pattern at the separator inlet, and the thickness and evolution of the fluid layers in the separator is evaluated and compared to the values when operating with unspiked Exxsol D60.

Crude oil spiking significantly reduces the efficiency of the pipe separator and reduces the water cut ratio for oil continuous regimes (low water cuts) up to 49%. Water continuous regimes with water fractions 90% have the highest efficiency values, thus, these are not affected significantly by crude oil spiking. With crude spiking, the flow regime dispersion of oil in water and water in oil (Dw/o+Do/w) occupies more area in the flow pattern map than unspiked Exxsol D60. It was observed through visual inspection that crude oil spiking induces a thicker and more stable emulsion in higher flow rates (e.g., 700 L/min). Therefore, the spiked mixture needs more time to separate. The findings of this study can help in a better understanding of the applicability of pipe separators and the usage of spiked oils to extrapolate experimental results to real field conditions.

Keywords: #Multi-parallel_pipe_separator (MPPS); #Crude_oil_spiking; #Separation_efficiency; #Water_cut_ratio; #Flow_pattern; #Fluid_layer_thickness

Experimental characterization and evaluation of crude spiking influence on oil/water dispersed flow in pipe

H. Asaadian, M. Stanko, (2023), Molecules, 28(17), 6363. https://doi.org/10.3390/molecules28176363

Abstract: This research focuses on the effect of adding various (small) amounts of crude oil to mineral oil (Exxsol D60) on the resulting characteristics of oil-saltwater dispersions and emulsions. Experiments were conducted using bottle tests and a small flow loop setup with a 2-meter horizontal pipe section to investigate rheology properties, droplet size distribution, separation time and interfacial tension. The results show that mixtures of oil spiked with crude and salt-water with water fractions of 25% and 50% require more time to separate and for the interface to form and stabilize than mixtures of un-spiked oil and saltwater. For example, for spiking concentrations of 200 to 800 ppm in 25% water fraction samples, separation time increases from 51 seconds to 2 minutes and 21 seconds. When the water fraction was 75 percent, however, the separation time was not noticeably affected by crude spiking. It was found that the Pal & Rhodes emulsion viscosity model was the most suitable to predict the viscosity of the resulting emulsions. Adding crude spiking increases emulsion viscosity at high mixture velocities and decreases interfacial tension from 30.8 to 27.6 mN/m (800 ppm spiking). Finally, the droplet size distributions of the designed dispersed pipe flow were compared to a real crude saltwater emulsion system.

Design Methodology for Multi-parallel Pipe Separator (MPPS)

H. Asaadian, M. Stanko, COMING SOON!

Abstract: The growing amount of water produced together with deep-sea petroleum resources often bottlenecks the capacity of topside water treatment systems, leading to the need for subsea separation. The Multiple Parallel Pipe Separator (MPPS) is a design for bulk oil-water separation that utilizes multiple horizontal pipe segments connected in parallel. Drainage of water is performed through tapping points on the pipe’s bottom. Pipe segments can be added in series (stacked) if needed. To address the knowledge gaps, this study presents a comprehensive design methodology for the MPPS.

The methodology employs different types of models: flow pattern, drainage potential curves, and oil-water dispersion in pipe. The flow pattern model is used to determine the number of branches and pipe diameter to ensure segregated flow patterns. The batch dispersion-separation model is used to predict the thickness of the water oil and dispersion layers approaching the tapping point. The drainage potential model is used to determine tapping point separation performance and the number of required tapping points.  All models are validated with experimental data available from experimental campaigns.

Several design cases that include different flow conditions are discussed.  The results indicate that when the flow is oil-continuous (e.g., with a WC_inlet of 30%) and the mixture velocity is high, the droplet coalescence is limited, and the thickness of the emulsion layer does not change significantly. However, if the number of parallel branches is increased, the mixture velocity decreases, and the residence time becomes longer, facilitating the separation of the phases. Furthermore, incorporating pipe segments in series and extracting different amounts of water from each stack, enhances water separation efficiency.

A Theoretical and Experimental Investigation of Continuous Oil-water Gravity Separation, 

Abstract: In this study, a mathematical model for three-phase separators is developed. The model consists of the inlet-section and the separation-section, separated by a perforated calming baffle. In the inlet section, two dispersion layers undergo droplet size evolution due to turbulent breakage and coalescence, described by a spatially homogeneous PBE. In the separation-section, the two flowing dispersion layers are interacting at an interface. The model incorporates droplet gravity-driven transport, binary and interfacial coalescence employing a film drainage model, and an effective diffusion term to account for the formation of the dense-packed layer ensuring a physical volume fraction range of 0-1. Steady-state and transient numerical solvers are developed to solve the resulting advection-diffusion equations. Additionally, a series of experiments were conducted using a pipe separator to investigate the impact of volume fraction and flow rate on the separation efficiency. The model results are compared with the experimental data which shows promise.

Carbonate Acidizing Optimization in Iranian Oil Field

H. Asaadian, B.S. Soulgani, 78th EAGE Annual Conference and Exhibition, Vienna, Austria, 8 June 2016. https://doi.org/10.3997/2214-4609.201601623

Summary: The main point in matrix acidizing treatment optimization is to reduce the skin factor in every single stage of injection and finally reaching the minimum value. If the skin effect owning to damage is quantified, then the treatment must reduce the total skin effect by that amount. Further, to be cost-effective, the injected volume and the pumping time should be minimized. The goal of this study is to evaluate various acidizing treatments for three wells placed in south east of Iran.

Th_SP1_12.pdf (Download here)

Experimental Study on Acidizing Fluid Viscosity Variation  During Carbonate Stimulation

H. Asaadian, B.S. Soulgani, A. Sahnalizadeh, 79th EAGE Annual Conference and Exhibition, Paris, France, 12 June 2017. https://doi.org/10.3997/2214-4609.201701485

Summary: During an acidizing treatment execution, success depends on correct prediction of reactive fluids behavior under stimulation condition. Determining the variation of acid viscosity and having it under control through the whole process of reaction can aid in improving the effective acid penetration radius, accessibility of acid to the pore space and an appropriate cleaning in back-flow stage. The goal of this work is to investigate the effect of acids with different concentrations on viscosity of the acidizing fluid which is used in acidizing process for carbonate rocks during the process. Finally, we want to determine a correlation between acid concentration and viscosity of the ultimate solution.

Th_SP2_15.pdf (Download here)

Water-Cut Metering by Flow Electrical Resistivity Measurement Method

H. Asaadian, B.S. Soulgani, R. Najafi, 80th EAGE Annual Conference and Exhibition, Copenhagen, Denmark, 11 June 2018. https://doi.org/10.3997/2214-4609.201801747

Summary: Accuracy of well-performance data increases the chance of success in field management. Similarly, water-cut monitoring helps to control the well during the drilling and production stages. This paper it was tried to design an experimental setup and particular tests. Then based on the gathered data, the effect of flow water-cut changes in the test pipe on the flow electrical resistivity value between two electrodes that are placed in the pipe is investigated. The higher the water cut was, the less flow resistivity was measured. The rate of mixture resistivity decreasing is higher in lower water cuts (between 8 to 50%). Also, two matched equations are gained to predict the water cut for known flow electrical resistivity in two different ranges of water cut.

Th_SP2_14.pdf (Download here)

On The Effect of Salinity, Asphaltenes and Resins on Interfacial Tension: Application to Low Salinity Water Injection

R. Moghadasi, S. Kord, J. Moghadasi, H. Asaadian, 80th EAGE Annual Conference and Exhibition, Copenhagen, Denmark, 11 June 2018. https://doi.org/10.3997/2214-4609.201801712

Summary: In this study, it has been tried to investigate the effects of asphaltenes, resins and NaCl salinity on IFT value between oil/water. Most importantly, it was revealed that low salinity water injection could only be effective for IFT reduction within a specific range. Therefore, it is recommended to optimize water salinity instead of just decreasing it. It was shown that Asphaltenes could reduce IFT value, but their effects are dependent on Resins.

We_SP2_07.pdf (Download here)

Experimental Investigation Over Effect of Geometrical Changes on Gas/Liquid Cylindrical Cyclone (GLCC) Separator

H. Asaadian, B.S. Soulgani, S. Rezaei Gomari, B.S. Soltani, The Abu-Dhabi International Petroleum Exhibition and Conference (ADIPEC), Abu Dhabi, UAE, 12-15 November 2018. https://doi.org/10.2118/193029-MS

Abstract: Study of any changes in liquid and gas outlets length and their effect on Gas/liquid Cylindrical Cyclone (GLCC) separator performance.
• Study of any changes in gas body column length and its effect on GLCC separator performance.
• Study of any changes in body column and inlet diameter and their effect on GLCC separator performance.
• Study of any changes in liquid and gas outlet diameter and its effect on GLCC separator performance.
An experimental GLCC separator is designed and built in the laboratory to determine its domain. The best operational domain is where the equilibrium liquid level is placed below the inlet and between 1 L/D and 3 L/D of the separator column. If it passes the inlet it causes the liquid to carry over and if it settles below the 3 L/D it will create gas carry under in the separation. Thus the equilibrium liquid level was measured for different ranges of liquid and gas flow rates. In this work, the gas superficial velocity was set for 1, 100, and 200 ft. per second, and for each gas superficial velocity, the liquid superficial velocity was changed between 1 to 11 feet per second. After that, any part of this test separator was changed and its effect on the separator operational domain was observed. These changes are a 0.5-inch reduction in inlet diameter size, 0.2-inch reduction in liquid outlet diameter size, 0.2-inch reduction in gas outlet diameter size, 0.4 ft. reduction in gas column length, 1-inch reduction in column diameter size, and 4.6 ft. increment in outlet length.
Results show:
• Reduction in inlet diameter helps the GLCC separator performance. It allows more gas and liquid flow rates to enter the separator for total separation by improving the centrifugal effect on liquid and gas phases.
• Reduction in liquid outlet diameter has a negative effect in the GLCC flowrates domain but this reduction can be used to control the equilibrium liquid level by a gate valve in the liquid outlet leg.
• Also any reduction in gas outlet diameter has a negative effect on GLCC performance. But in specific situations controlling the amount of accumulated gas in GLCC can avoid liquid carryover in the system.
• Reduction in gas column length shows no effect on the separator flowrates domain.
• Increasing the length of outlet legs increases the friction force and limited the separator performance.
• Reduction in separator body diameter raises the chance of liquid carry over and gas carry under and has a negative effect on flowrates domain.

These understandings from GLCC performance guide to reach the best separator design in the field. Proper designing makes the separator performance domain wider whereas it creates separators more compact and minimizes the cost of construction accordingly.  

Artificial-Lift Method Screening For One of The Southwestern Iranian Oil Fields Based on Fuzzy Logic Approach

H. Asaadian, M. Nazari Sarem, 82nd EAGE Annual Conference and Exhibition, Amsterdam, The Netherlands, 9 December 2020. https://doi.org/10.3997/2214-4609.202010242

Summary: Hydrocarbon reservoirs reach a stage during their lifetime when the reservoir pressure is not sufficient to generate the expected production value of fluids. Artificial lift is one of the common methods to compensate for this problem and increase production. In fact, artificial lift is a method of increasing the longevity of the oil well. Artificial lift as one of the IOR methods reduces the minimum pressure at the bottom of the well to produce and thereby increases the volume of the production fluid from the reservoir. The proper selection of artificial lift methods for the long-term profitability of productive wells is very important. In fact, poor selection can reduce production and increase operational costs. The selection of suitable methods of artificial lift is dependent on the effective parameters in reservoir production, well constraints, fluid properties, and operational conditions.

We_E104_12A.pdf (Download Here)

A Novel Population Balance Model For Subsea Multi-Parallel Pipes Separator

M. Assar, H. Asaadian, M. Stanko, B. A. Grimes, UTC 2022, Bergen, Norway, 14 June 2022.

Abstract: The management of ever-increasing produced water is a critical issue for mature oil fields. Subsea oil-water separation using multi-parallel pipes is one viable solution to address this problem as it can reduce the load on topside facilities and gathering networks, allowing for increased production. This study develops a mathematical model for the separation process along the pipe separator. Theoretically, the process consists of binary coalescence between droplets, hindered settling of the droplets, and interfacial coalescence at the oil/water interface. Population balance modeling is an indispensable part of the model to consider polydispersity in the system. In addition to the terminal velocity of the droplets, a vertical dispersion term is considered, representing the volume fraction hindrance effect. Additionally, the maximum volume fraction of the dense-packed layer is included in this term which can incorporate the physical restriction of the max volume fraction at the dense-packed layer. A parallel film drainage model is adopted for binary and interfacial coalescences, with the collision frequency calculated according to the terminal velocity difference between the droplets. The solution technique consists of an element-based orthogonal collocation technique for the discretization of the polydispersity, a finite volume technique for vertical direction discretization, and a semi-implicit ode solver for time integration. Several experiments were performed using a lab-scale multi-parallel pipes separator to study the effect of different volume fractions and flow rates. Accordingly, the model parameters were tuned, which shows a good match. The developed model can be readily used in designing the subsea separators by linking the characterization information obtained from the experiments to large-scale industrial designs. The model provides promise for performing scale-ups as well as improvements to the existing designs.

A_NOVEL_POPULATION_BALANCE_MODEL.pdf (Download Here)

An Experimental Study on the Effect of Gas on the Performance of a Multi-parallel Pipe Oil-Water Separator (MPPS)

H. Asaadian, M. Stanko, Gas & Oil Technology Showcase and Conference, Dubai, UAE, March 2023. https://doi.org/10.2118/214062-MS

Abstract: This work presents a comprehensive experimental study on the effect of gas on the performance of oil-water bulk separation in a multi-parallel pipe separator (MPPS). Several flowrates of gas, up to 10% volume fraction were tested and values of separation efficiency and water cut ratio were estimated from measurements. Also, the three-phase flow pattern upstream the separator inlet is reported.

Exxsol D60 spiked with 700 ppm of crude oil, 3.4 wt% NaCl saltwater, and air were used in steady-state and transient tests on a transparent 6.1 m long, 15.24 cm diameter, separator prototype. Preliminary values of separation efficiency and water cut ratio were measured over a variety of total flow rates (300 to 700 L/min), water cuts (WC, 30%, 50%, 70%, and 90%), and water extraction rates (ER, 50% to 90% the rate of inlet water). It is observed that the gas phase accumulates at higher sections of the separator (i.e. at the inlet section after the splitting and at the exit section where water rich fluid is tapped from the bottom of the pipe). It seems the reduction in separation performance is due to turbulence caused by the gas and reduced cross section for the oil-water mixture to flow. The higher the gas flow rate, the lower the separation efficiency and water cut ratio. The presence of gas impacts more flow conditions with low water cuts including 30 and 50%. The presence of gas has less negative impact on separator performance when the liquid flow rate is high. Results show even small amounts of gas entering the separator have a significant detrimental effect on oil-water separation. Pipe oil-water separators have several advantages over heavy gravity vessels, including cost, compactness, ease of deployment and enable energy saving by separating close to the source. However, this study shows that the presence of gas can impact dramatically their performance. Thus, the performance of upstream gas separation must be studied closely.