Variance‐based sensitivity analysis can provide a comprehensive understanding of the input factor... more Variance‐based sensitivity analysis can provide a comprehensive understanding of the input factors that drive model behavior, complementing more traditional system dynamics methods with quantitative metrics. This paper presents the methodology of a variance‐based sensitivity analysis of the Biomass Scenario Learning Model, a published STELLA model of interactions among investment, production, and learning in an emerging competitive industry. We document the methodology requirements, interpretations, and constraints, and compute estimated sensitivity indices and their uncertainties. We show that application of variance‐based sensitivity analysis to the model allows us to test for non‐additivity, identify influential and interactive variables, and confirm model formulation. To enable use of this type of sensitivity analysis in other system dynamics models, we provide this study's R code, annotated to facilitate adaptation to other studies. A related paper describes application of ...
Combinatory flooding techniques evolved over the years to mitigate various limitations associated... more Combinatory flooding techniques evolved over the years to mitigate various limitations associated with unitary flooding techniques and to enhance their performance as well. This study investigates the potential of a combination of 1-hexadecyl-3-methyl imidazolium bromide (C16mimBr) and monoethanolamine (ETA) as an alkali–surfactant (AS) formulation for enhanced oil recovery. The study is conducted comparative to a conventional combination of cetyltrimethylammonium bromide (CTAB) and sodium metaborate (NaBO2). The study confirmed that C16mimBr and CTAB have similar aggregation behaviors and surface activities. The ETA–C16mimBr system proved to be compatible with brine containing an appreciable concentration of divalent cations. Studies on interfacial properties showed that the ETA–C16mimBr system exhibited an improved IFT reduction capability better than the NaBO2–CTAB system, attaining an ultra-low IFT of 7.6 × 10−3 mN/m. The IFT reduction performance of the ETA–C16mimBr system was ...
Journal of Petroleum Exploration and Production Technology, 2022
Amino acid-based surfactants (AASs) and other novel surfactants have recently gained attention to... more Amino acid-based surfactants (AASs) and other novel surfactants have recently gained attention to provide a favorable environmental image (“green”) in surfactant application. Yet their potential in enhancing oil recovery is not well investigated. Only a few works have been reported on their potential enhanced oil recovery (EOR) application with less satisfactory results. Here in, sodium cocoyl alaninate (SCA), an acylated amino acid with excellent properties that facilitate its application in other fields, is investigated for its EOR potential. Its effectiveness in lowering the interfacial tension and the emulsifying crude oil–brine mixture were studied. The ability to alter rock surface wettability and its adsorption behavior on the sand surface were studied as well. Then, its oil recovery potential was confirmed through a core displacement experiment. All studies were performed in comparison with conventionally deployed sodium dodecyl sulfate (SDS). The critical micelle concentrat...
Sand management is essential for enhancing the production in oil and gas reservoirs. The critical... more Sand management is essential for enhancing the production in oil and gas reservoirs. The critical total drawdown (CTD) is used as a reliable indicator of the onset of sand production; hence, its accurate prediction is very important. There are many published CTD prediction correlations in literature. However, the accuracy of most of these models is questionable. Therefore, further improvement in CTD prediction is needed for more effective and successful sand control. This article presents a robust and accurate fuzzy logic (FL) model for predicting the CTD. Literature on 23 wells of the North Adriatic Sea was used to develop the model. The used data were split into 70% training sets and 30% testing sets. Trend analysis was conducted to verify that the developed model follows the correct physical behavior trends of the input parameters. Some statistical analyses were performed to check the model’s reliability and accuracy as compared to the published correlations. The results demonstr...
The objective of this study was to investigate the effect of polymer (GLP-100) and surfactant (MF... more The objective of this study was to investigate the effect of polymer (GLP-100) and surfactant (MFOMAX) towards the efficiency of oil removal in a flotation column by using the Response Surface Methodology (RSM). Various concentrations of surfactant (250, 372 and 500 ppm) and polymer (450, 670, and 900 ppm) produced water were prepared. Dulang crude oil was used in the experiments. Flotation operating parameters such as gas flow rate (1–3 L/min) and duration of flotation (2–10 min) were also investigated. The efficiency of oil removal was calculated based on the difference between the initial concentration of oil and the final concentration of oil after the flotation process. From the ANOVA analysis, it was found that the gas flow rate, surfactant concentration, and polymer concentration contributed significantly to the efficiency of oil removal. Extra experiments were conducted to verify the developed equation at a randomly selected point using 450 ppm of polymer concentration, 250 ...
IOP Conference Series: Earth and Environmental Science, 2019
Low salinity water flooding is one of the emerging enhanced oil recovery technologies as it has b... more Low salinity water flooding is one of the emerging enhanced oil recovery technologies as it has been proven economical and environmentally friendly. However, the recovery mechanism of low salinity water (LSW) is still under debatable due to the complex effect of low salinity water and its ionic compositions. Therefore, this study aims to discover the optimum seawater dilution salinity and influence of single and binary ionic compounds low salinity water on wettability alteration of carbonate core slices at optimum salinity. To achieve that, a modified Design of Experiments (DOE) has been implemented. Contact angle measurement was carried out to characterize the wettability of core slices at 0 hour, after 24 hours and after 48 hours. The results revealed that dilution of seawater reduced the contact angle of carbonate core slices towards more water wet until the optimum salinity of 1750ppm. Further dilution to 700ppm only shown a slight impact in shifting the wettability of the carbo...
To date, several methods have been designed and implemented either individually or as combination... more To date, several methods have been designed and implemented either individually or as combination to increase oil recovery. The combined methods also called hybrid Enhanced Oil Recovery (EOR) pose great challenges in the oil and gas industry. This is also confirmed from the Industry Technology Facilitator (ITF)'s Gulf Cooperation Council (GCC) Technology roadmap that pinpointed hybrid EOR as the top challenge. This work investigates the potential of a new hybrid EOR method termed Low Salinity Water Assisted Foam flooding (LSWAF). Typically, it consists of injecting Low Salinity Water (LSW) followed by an alternated injection of a Surfactant Aqueous Solution (SAS) and CO2 gas. The selection of LSW was based on its ability to produce significant changes of rock wettability. While the SAS was made, so that it results in a considerable reduction of IFT and produce foam that will remain considerably stable in the presence of oil under reservoir conditions. The selection of the best LSW and SAS followed a screening phase whereby formulations of different ion compositions and salinities were prepared and their performances were compared against each other. Tests were carried out by using two types of light crude oil with different Total Acid Number and Base Number, namely Crude oil A and B. In terms of changes in wettability, for both crude oils A and B, the experimental results revealed that much changes were experienced by the LSW of KCl composition followed by that of NaCl, then CaCl2, MgCl2, Mix composition, and finally the formation water (FW) that presented negligible changes. The changes with crude oil B were greater than crude oil A. However, for crude oil A and B, the core flooding experiments showed that the highest residual oil recovery was achieved by the LSWAF of KCl composition (87.45% of OOIP) compared to the MgCl2 and FW.
Journal of Petroleum Exploration and Production Technology
One of the most effective enhanced oil recovery techniques is carbon dioxide (CO2) flooding. It i... more One of the most effective enhanced oil recovery techniques is carbon dioxide (CO2) flooding. It is because of its high oil recovery rate and associated advantage on the environment. CO2 flooding has been broadly used and commercially proven. Depending on the reservoir and operational conditions, it can be implemented either in immiscible or miscible modes. Determining the injection mode depends on the minimum miscibility pressure (MMP). The conventional ways of determining the MMP (slim-tube experiments, supercritical extractor, etc.) are costly and time-consuming. A simulation approach has been deployed to determine the MMP of a synthetic reservoir model using a one-dimension compositional slim-tube model in ECLIPSE300. The MMP was also determined using the group method of data handling (GMDH) and other existing correlations. The MMP determined by slim-tube simulation was ~ 4176 psia. Comparing the MMPs of the correlations to the slim-tube simulation, the correlation by Maklavani e...
This contribution introduces a new hybrid enhanced oil recovery (EOR) method which combines smart... more This contribution introduces a new hybrid enhanced oil recovery (EOR) method which combines smart water-assisted foam (SWAF) flooding, known as the SWAF process. The concept of applying SWAF flooding in carbonate reservoirs is a novel approach previously unexplored in the literature. The synergy effect of the SWAF technique has the potential to mitigate a number of limitations related to individual (i.e., conventional water injection and foam flooding) methods encountered in carbonates. In general, carbonate rocks are characterized by a mixed-wet to oil-wet wettability state, which contributes to poor oil recovery. Hence, the smart water solution has been designed to produce a dual-improvement effect of altering carbonate rock wettability towards more water-wet, which preconditions the reservoir and augments the stability of the foam lamellae, which has for some conditions more favorable relative permeability behavior. Then the smart water solution is combined with surfactant (surfa...
The aging of the existing reservoirs makes the hydrocarbon extraction shift toward newer reserves... more The aging of the existing reservoirs makes the hydrocarbon extraction shift toward newer reserves, and harsh conditioned carbonates, which possess high temperature and high salinity (HTHS). Conventional polymer-flooding fails in these HTHS carbonates, due to precipitation, viscosity loss, and polymer adsorption. Therefore, to counteract these challenges, novel polymer-based cEOR alternatives employ optimized polymers, polymer–surfactant, and alkali–surfactant–polymer solutions along with hybrid methods, which have shown a potential to target the residual or remaining oils in carbonates. Consequently, we investigate novel polymers, viz., ATBS, Scleroglucan, NVP-based polymers, and hydrophobic associative polymers, along with bio-polymers. These selected polymers have shown low shear sensitivity, low adsorption, and robust thermal/salinity tolerance. Additionally, adding an alkali-surfactant to polymer solution produces a synergy effect of improved mobility control, wettability altera...
Drilling rate of penetration (ROP) is a crucial factor in optimizing drilling cost. This is mainl... more Drilling rate of penetration (ROP) is a crucial factor in optimizing drilling cost. This is mainly due to the excessive cost of the drilling equipment and rig rental, where the longer the drilling activity would reflect a higher expenditure. If the drilling rate of penetration can be predicted accurately, we would be able to avoid unnecessary spending. Hence, this can lead to minimizing the drilling cost significantly. In this paper, an Adaptive Neuro-Fuzzy Inference System (ANFIS) model is generated using MATLAB environment. A total number of 504 data sets from a Sudanese oilfield is used to develop a welltrained and tested ANFIS model for ROP prediction. The parameters included in the model generation are: depth, bit size, mud weight, rotary speed and weight on bit. Training options were set to give the best predicted ROP against the real data. This model is proven to give a high performance with an error as low as 1.47% and correlation coefficient of 98%. With this model, the est...
Variance‐based sensitivity analysis can provide a comprehensive understanding of the input factor... more Variance‐based sensitivity analysis can provide a comprehensive understanding of the input factors that drive model behavior, complementing more traditional system dynamics methods with quantitative metrics. This paper presents the methodology of a variance‐based sensitivity analysis of the Biomass Scenario Learning Model, a published STELLA model of interactions among investment, production, and learning in an emerging competitive industry. We document the methodology requirements, interpretations, and constraints, and compute estimated sensitivity indices and their uncertainties. We show that application of variance‐based sensitivity analysis to the model allows us to test for non‐additivity, identify influential and interactive variables, and confirm model formulation. To enable use of this type of sensitivity analysis in other system dynamics models, we provide this study's R code, annotated to facilitate adaptation to other studies. A related paper describes application of ...
Combinatory flooding techniques evolved over the years to mitigate various limitations associated... more Combinatory flooding techniques evolved over the years to mitigate various limitations associated with unitary flooding techniques and to enhance their performance as well. This study investigates the potential of a combination of 1-hexadecyl-3-methyl imidazolium bromide (C16mimBr) and monoethanolamine (ETA) as an alkali–surfactant (AS) formulation for enhanced oil recovery. The study is conducted comparative to a conventional combination of cetyltrimethylammonium bromide (CTAB) and sodium metaborate (NaBO2). The study confirmed that C16mimBr and CTAB have similar aggregation behaviors and surface activities. The ETA–C16mimBr system proved to be compatible with brine containing an appreciable concentration of divalent cations. Studies on interfacial properties showed that the ETA–C16mimBr system exhibited an improved IFT reduction capability better than the NaBO2–CTAB system, attaining an ultra-low IFT of 7.6 × 10−3 mN/m. The IFT reduction performance of the ETA–C16mimBr system was ...
Journal of Petroleum Exploration and Production Technology, 2022
Amino acid-based surfactants (AASs) and other novel surfactants have recently gained attention to... more Amino acid-based surfactants (AASs) and other novel surfactants have recently gained attention to provide a favorable environmental image (“green”) in surfactant application. Yet their potential in enhancing oil recovery is not well investigated. Only a few works have been reported on their potential enhanced oil recovery (EOR) application with less satisfactory results. Here in, sodium cocoyl alaninate (SCA), an acylated amino acid with excellent properties that facilitate its application in other fields, is investigated for its EOR potential. Its effectiveness in lowering the interfacial tension and the emulsifying crude oil–brine mixture were studied. The ability to alter rock surface wettability and its adsorption behavior on the sand surface were studied as well. Then, its oil recovery potential was confirmed through a core displacement experiment. All studies were performed in comparison with conventionally deployed sodium dodecyl sulfate (SDS). The critical micelle concentrat...
Sand management is essential for enhancing the production in oil and gas reservoirs. The critical... more Sand management is essential for enhancing the production in oil and gas reservoirs. The critical total drawdown (CTD) is used as a reliable indicator of the onset of sand production; hence, its accurate prediction is very important. There are many published CTD prediction correlations in literature. However, the accuracy of most of these models is questionable. Therefore, further improvement in CTD prediction is needed for more effective and successful sand control. This article presents a robust and accurate fuzzy logic (FL) model for predicting the CTD. Literature on 23 wells of the North Adriatic Sea was used to develop the model. The used data were split into 70% training sets and 30% testing sets. Trend analysis was conducted to verify that the developed model follows the correct physical behavior trends of the input parameters. Some statistical analyses were performed to check the model’s reliability and accuracy as compared to the published correlations. The results demonstr...
The objective of this study was to investigate the effect of polymer (GLP-100) and surfactant (MF... more The objective of this study was to investigate the effect of polymer (GLP-100) and surfactant (MFOMAX) towards the efficiency of oil removal in a flotation column by using the Response Surface Methodology (RSM). Various concentrations of surfactant (250, 372 and 500 ppm) and polymer (450, 670, and 900 ppm) produced water were prepared. Dulang crude oil was used in the experiments. Flotation operating parameters such as gas flow rate (1–3 L/min) and duration of flotation (2–10 min) were also investigated. The efficiency of oil removal was calculated based on the difference between the initial concentration of oil and the final concentration of oil after the flotation process. From the ANOVA analysis, it was found that the gas flow rate, surfactant concentration, and polymer concentration contributed significantly to the efficiency of oil removal. Extra experiments were conducted to verify the developed equation at a randomly selected point using 450 ppm of polymer concentration, 250 ...
IOP Conference Series: Earth and Environmental Science, 2019
Low salinity water flooding is one of the emerging enhanced oil recovery technologies as it has b... more Low salinity water flooding is one of the emerging enhanced oil recovery technologies as it has been proven economical and environmentally friendly. However, the recovery mechanism of low salinity water (LSW) is still under debatable due to the complex effect of low salinity water and its ionic compositions. Therefore, this study aims to discover the optimum seawater dilution salinity and influence of single and binary ionic compounds low salinity water on wettability alteration of carbonate core slices at optimum salinity. To achieve that, a modified Design of Experiments (DOE) has been implemented. Contact angle measurement was carried out to characterize the wettability of core slices at 0 hour, after 24 hours and after 48 hours. The results revealed that dilution of seawater reduced the contact angle of carbonate core slices towards more water wet until the optimum salinity of 1750ppm. Further dilution to 700ppm only shown a slight impact in shifting the wettability of the carbo...
To date, several methods have been designed and implemented either individually or as combination... more To date, several methods have been designed and implemented either individually or as combination to increase oil recovery. The combined methods also called hybrid Enhanced Oil Recovery (EOR) pose great challenges in the oil and gas industry. This is also confirmed from the Industry Technology Facilitator (ITF)'s Gulf Cooperation Council (GCC) Technology roadmap that pinpointed hybrid EOR as the top challenge. This work investigates the potential of a new hybrid EOR method termed Low Salinity Water Assisted Foam flooding (LSWAF). Typically, it consists of injecting Low Salinity Water (LSW) followed by an alternated injection of a Surfactant Aqueous Solution (SAS) and CO2 gas. The selection of LSW was based on its ability to produce significant changes of rock wettability. While the SAS was made, so that it results in a considerable reduction of IFT and produce foam that will remain considerably stable in the presence of oil under reservoir conditions. The selection of the best LSW and SAS followed a screening phase whereby formulations of different ion compositions and salinities were prepared and their performances were compared against each other. Tests were carried out by using two types of light crude oil with different Total Acid Number and Base Number, namely Crude oil A and B. In terms of changes in wettability, for both crude oils A and B, the experimental results revealed that much changes were experienced by the LSW of KCl composition followed by that of NaCl, then CaCl2, MgCl2, Mix composition, and finally the formation water (FW) that presented negligible changes. The changes with crude oil B were greater than crude oil A. However, for crude oil A and B, the core flooding experiments showed that the highest residual oil recovery was achieved by the LSWAF of KCl composition (87.45% of OOIP) compared to the MgCl2 and FW.
Journal of Petroleum Exploration and Production Technology
One of the most effective enhanced oil recovery techniques is carbon dioxide (CO2) flooding. It i... more One of the most effective enhanced oil recovery techniques is carbon dioxide (CO2) flooding. It is because of its high oil recovery rate and associated advantage on the environment. CO2 flooding has been broadly used and commercially proven. Depending on the reservoir and operational conditions, it can be implemented either in immiscible or miscible modes. Determining the injection mode depends on the minimum miscibility pressure (MMP). The conventional ways of determining the MMP (slim-tube experiments, supercritical extractor, etc.) are costly and time-consuming. A simulation approach has been deployed to determine the MMP of a synthetic reservoir model using a one-dimension compositional slim-tube model in ECLIPSE300. The MMP was also determined using the group method of data handling (GMDH) and other existing correlations. The MMP determined by slim-tube simulation was ~ 4176 psia. Comparing the MMPs of the correlations to the slim-tube simulation, the correlation by Maklavani e...
This contribution introduces a new hybrid enhanced oil recovery (EOR) method which combines smart... more This contribution introduces a new hybrid enhanced oil recovery (EOR) method which combines smart water-assisted foam (SWAF) flooding, known as the SWAF process. The concept of applying SWAF flooding in carbonate reservoirs is a novel approach previously unexplored in the literature. The synergy effect of the SWAF technique has the potential to mitigate a number of limitations related to individual (i.e., conventional water injection and foam flooding) methods encountered in carbonates. In general, carbonate rocks are characterized by a mixed-wet to oil-wet wettability state, which contributes to poor oil recovery. Hence, the smart water solution has been designed to produce a dual-improvement effect of altering carbonate rock wettability towards more water-wet, which preconditions the reservoir and augments the stability of the foam lamellae, which has for some conditions more favorable relative permeability behavior. Then the smart water solution is combined with surfactant (surfa...
The aging of the existing reservoirs makes the hydrocarbon extraction shift toward newer reserves... more The aging of the existing reservoirs makes the hydrocarbon extraction shift toward newer reserves, and harsh conditioned carbonates, which possess high temperature and high salinity (HTHS). Conventional polymer-flooding fails in these HTHS carbonates, due to precipitation, viscosity loss, and polymer adsorption. Therefore, to counteract these challenges, novel polymer-based cEOR alternatives employ optimized polymers, polymer–surfactant, and alkali–surfactant–polymer solutions along with hybrid methods, which have shown a potential to target the residual or remaining oils in carbonates. Consequently, we investigate novel polymers, viz., ATBS, Scleroglucan, NVP-based polymers, and hydrophobic associative polymers, along with bio-polymers. These selected polymers have shown low shear sensitivity, low adsorption, and robust thermal/salinity tolerance. Additionally, adding an alkali-surfactant to polymer solution produces a synergy effect of improved mobility control, wettability altera...
Drilling rate of penetration (ROP) is a crucial factor in optimizing drilling cost. This is mainl... more Drilling rate of penetration (ROP) is a crucial factor in optimizing drilling cost. This is mainly due to the excessive cost of the drilling equipment and rig rental, where the longer the drilling activity would reflect a higher expenditure. If the drilling rate of penetration can be predicted accurately, we would be able to avoid unnecessary spending. Hence, this can lead to minimizing the drilling cost significantly. In this paper, an Adaptive Neuro-Fuzzy Inference System (ANFIS) model is generated using MATLAB environment. A total number of 504 data sets from a Sudanese oilfield is used to develop a welltrained and tested ANFIS model for ROP prediction. The parameters included in the model generation are: depth, bit size, mud weight, rotary speed and weight on bit. Training options were set to give the best predicted ROP against the real data. This model is proven to give a high performance with an error as low as 1.47% and correlation coefficient of 98%. With this model, the est...
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Papers by Mohammed Ayoub