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Papers by Geraldo A. R. Ramos

Angolan Mineral, Oil & Gas Journal, 2021

Hydrocarbon exploration in Angola commenced in 1910 with its first oil recovered in 1955. The pro... more Hydrocarbon exploration in Angola commenced in 1910 with its first oil recovered in 1955. The proven reserves in Angola are estimated to reach up to 13 billion barrels (2.1 billion m3). Most of the Angolan oil fields are mature or maturing and some are or may be abandoned due to unprofitable recovery limit beyond the conventional type of oil production. The oil recovery is mainly by primary and secondary recovery methods. Apart from the issue of maturity, there is increasing energy demand due to population growth and difficulties in discovering and developing new fields as alternatives to the current oil fields. For incremental and sustained production rate of these fields and in addition to instability of oil prices and concerns about future oil supply, Angola has started to work towards developing affordable and efficient technologies capable of recovering residual oil in reservoirs as well as extend the life of many current fields which can be achieved through the implementation ...

Angolan Industry and Chemical Engineering Journal, 2021

Apart from oil and natural gas conventional reservoirs scarcities, global warming is one of the e... more Apart from oil and natural gas conventional reservoirs scarcities, global warming is one of the environmental petroleum industry challenges in the short-medium-long term. This is related to the dramatic growth of greenhouse gases (GHGs) emission in which carbon dioxide (CO2) produced by the combustion of fossil fuels plays a significant role in atmosphere carbonization. Different technologies or systems for capturing CO2 are available such as pre-combustion systems, post-combustion systems, oxy-fuel combustion systems and capture from industrial process streams. However, decarbonization involves the removal of greenhouse gases emissions and storing them in geological formation or using them for other sectors of industries including oil production optimization. This process is known as carbon dioxide capture usage and storage (CCUS), a promising method to reduce CO2 emissions due to increasing energy demand and continued dependency on fossil fuel in the next decades while green energ...

An extensive investigation on the applicability of Polyvinyl Alcohol (PVA, a polymer) and its syn... more An extensive investigation on the applicability of Polyvinyl Alcohol (PVA, a polymer) and its synergy with Rhamonolipid (a surfactant active agent) and/or alkaline (NaOH) was carried out to evaluate and define the best fluid formulation for enhanced oil recovery (EOR) processes. First,the effect of molecular weight, concentration, and temperature of PVA solution on surface tension (ST), interfacial tension (IFT), shear viscosity and thermodynamic stability was established. Then, a systematic formulation of PVA combined with Rhamonolipid and NaOH in reconstructed brine from Angolan offshore field was developed. The IFT experiment were carried out on crude oil samples obtained from Block T of Angolan offshore field. The combined PVA-Rhamonolipid (SP) and NaOHRhamonolipid-PVA (ASP) in saline medium reduced the ST and IFT to values below 30 mN/m and 1mN/m respectively. This provides an opportunity to use this new synergistic formulation in EOR processes particularly in offshore Angolan ...

Journal of Oil, Gas and Petrochemical Sciences, 2017

An artificial intelligence technique based on five (5) layered feedforward backpropagation algori... more An artificial intelligence technique based on five (5) layered feedforward backpropagation algorithm is applied in this study for technical screening of enhanced oil recovery (EOR) methods. Explicit knowledge pattern associated with the field data are extracted by taking advantage of the robustness of fuzzy logic reasoning and learning capability of neural networks. Associated field data from successful EOR projects include parameters such as depth, porosity, permeability, viscosity, oil API and oil saturation. These parameters were used as input and predicted output in the training and validation processes, respectively. The developed model was then tested by using data set from Block T of the Angolan oilfield. Sensitivity analysis was performed between the Mandani and the Takagi Sugero (TSK) model approach incorporated in the algorithm. The results of the sensitivity analysis have shown the robustness of the ANFIS approach in comparison to other approaches for the prediction of suitable EOR technique. Five nonregression models (linear, potential, logarithm, power and polynomial) were applied to evaluate the accuracy of the model between the trained and the tested data set. The results of simulation show that hydrocarbon gas, polymer, combustion and CO 2 are the suitable EOR techniques and could be used for further experimental and numerical studies.

Angolan Mineral, Oil & Gas Journal, 2020

The neuro-fuzzy (NF) approach presented in this work is based on five (5) layered feedforward bac... more The neuro-fuzzy (NF) approach presented in this work is based on five (5) layered feedforward backpropagation algorithm applied for technical screening of enhanced oil recovery (EOR) methods. Associated reservoir rock-fluid oilfield data from successful EOR projects were used as input and predicted output in the training and validation processes, respectively. The developed model was then tested by using data set from Block B of an Angolan oilfield. The results of the sensitivity analysis between the Mamdani and the Takagi-Sugeno-Kang (TSK) approach incorporated in the algorithm has shown the robustness of the TSK ANFIS (Adaptive Neuro-Fuzzy Inference System) approach in comparison to the other approach for the prediction of a suitable EOR technique. The simulation test results showed that the model presented in this study can be used for technical selection of suitable EOR techniques. Within the area investigated (Block B, Angola) polymer, hydrocarbon gas, and combustion were ident...

Energy & Fuels, 2020

An extensive investigation on the applicability of Polyvinyl Alcohol (PVA, a polymer) and its syn... more An extensive investigation on the applicability of Polyvinyl Alcohol (PVA, a polymer) and its synergy with Rhamonolipid (a surfactant active agent) and/or alkaline (NaOH) was carried out to evaluate and define the best fluid formulation for enhanced oil recovery (EOR) processes. First,the effect of molecular weight, concentration, and temperature of PVA solution on surface tension (ST), interfacial tension (IFT), shear viscosity and thermodynamic stability was established. Then, a systematic formulation of PVA combined with Rhamonolipid and NaOH in reconstructed brine from Angolan offshore field was developed. The IFT experiment were carried out on crude oil samples obtained from Block T of Angolan offshore field. The combined PVA-Rhamonolipid (SP) and NaOH-Rhamonolipid-PVA (ASP) in saline medium reduced the ST and IFT to values below 30 mN/m and 1mN/m respectively. This provides an opportunity to use this new synergistic formulation in EOR processes particularly in offshore Angolan oilfields.

Energies, 2017

In this work, a neuro-fuzzy (NF) simulation study was conducted in order to screen candidate rese... more In this work, a neuro-fuzzy (NF) simulation study was conducted in order to screen candidate reservoirs for enhanced oil recovery (EOR) projects in Angolan oilfields. First, a knowledge pattern is extracted by combining both the searching potential of fuzzy-logic (FL) and the learning capability of neural network (NN) to make a priori decisions. The extracted knowledge pattern is validated against rock and fluid data trained from successful EOR projects around the world. Then, data from Block K offshore Angolan oilfields are then mined and analysed using box-plot technique for the investigation of the degree of suitability for EOR projects. The trained and validated model is then tested on the Angolan field data (Block K) where EOR application is yet to be fully established. The results from the NF simulation technique applied in this investigation show that polymer, hydrocarbon gas, and combustion are the suitable EOR techniques.

Angolan Mineral, Oil & Gas Journal, 2021

Hydrocarbon exploration in Angola commenced in 1910 with its first oil recovered in 1955. The pro... more Hydrocarbon exploration in Angola commenced in 1910 with its first oil recovered in 1955. The proven reserves in Angola are estimated to reach up to 13 billion barrels (2.1 billion m3). Most of the Angolan oil fields are mature or maturing and some are or may be abandoned due to unprofitable recovery limit beyond the conventional type of oil production. The oil recovery is mainly by primary and secondary recovery methods. Apart from the issue of maturity, there is increasing energy demand due to population growth and difficulties in discovering and developing new fields as alternatives to the current oil fields. For incremental and sustained production rate of these fields and in addition to instability of oil prices and concerns about future oil supply, Angola has started to work towards developing affordable and efficient technologies capable of recovering residual oil in reservoirs as well as extend the life of many current fields which can be achieved through the implementation ...

Angolan Industry and Chemical Engineering Journal, 2021

Apart from oil and natural gas conventional reservoirs scarcities, global warming is one of the e... more Apart from oil and natural gas conventional reservoirs scarcities, global warming is one of the environmental petroleum industry challenges in the short-medium-long term. This is related to the dramatic growth of greenhouse gases (GHGs) emission in which carbon dioxide (CO2) produced by the combustion of fossil fuels plays a significant role in atmosphere carbonization. Different technologies or systems for capturing CO2 are available such as pre-combustion systems, post-combustion systems, oxy-fuel combustion systems and capture from industrial process streams. However, decarbonization involves the removal of greenhouse gases emissions and storing them in geological formation or using them for other sectors of industries including oil production optimization. This process is known as carbon dioxide capture usage and storage (CCUS), a promising method to reduce CO2 emissions due to increasing energy demand and continued dependency on fossil fuel in the next decades while green energ...

An extensive investigation on the applicability of Polyvinyl Alcohol (PVA, a polymer) and its syn... more An extensive investigation on the applicability of Polyvinyl Alcohol (PVA, a polymer) and its synergy with Rhamonolipid (a surfactant active agent) and/or alkaline (NaOH) was carried out to evaluate and define the best fluid formulation for enhanced oil recovery (EOR) processes. First,the effect of molecular weight, concentration, and temperature of PVA solution on surface tension (ST), interfacial tension (IFT), shear viscosity and thermodynamic stability was established. Then, a systematic formulation of PVA combined with Rhamonolipid and NaOH in reconstructed brine from Angolan offshore field was developed. The IFT experiment were carried out on crude oil samples obtained from Block T of Angolan offshore field. The combined PVA-Rhamonolipid (SP) and NaOHRhamonolipid-PVA (ASP) in saline medium reduced the ST and IFT to values below 30 mN/m and 1mN/m respectively. This provides an opportunity to use this new synergistic formulation in EOR processes particularly in offshore Angolan ...

Journal of Oil, Gas and Petrochemical Sciences, 2017

An artificial intelligence technique based on five (5) layered feedforward backpropagation algori... more An artificial intelligence technique based on five (5) layered feedforward backpropagation algorithm is applied in this study for technical screening of enhanced oil recovery (EOR) methods. Explicit knowledge pattern associated with the field data are extracted by taking advantage of the robustness of fuzzy logic reasoning and learning capability of neural networks. Associated field data from successful EOR projects include parameters such as depth, porosity, permeability, viscosity, oil API and oil saturation. These parameters were used as input and predicted output in the training and validation processes, respectively. The developed model was then tested by using data set from Block T of the Angolan oilfield. Sensitivity analysis was performed between the Mandani and the Takagi Sugero (TSK) model approach incorporated in the algorithm. The results of the sensitivity analysis have shown the robustness of the ANFIS approach in comparison to other approaches for the prediction of suitable EOR technique. Five nonregression models (linear, potential, logarithm, power and polynomial) were applied to evaluate the accuracy of the model between the trained and the tested data set. The results of simulation show that hydrocarbon gas, polymer, combustion and CO 2 are the suitable EOR techniques and could be used for further experimental and numerical studies.

Angolan Mineral, Oil & Gas Journal, 2020

The neuro-fuzzy (NF) approach presented in this work is based on five (5) layered feedforward bac... more The neuro-fuzzy (NF) approach presented in this work is based on five (5) layered feedforward backpropagation algorithm applied for technical screening of enhanced oil recovery (EOR) methods. Associated reservoir rock-fluid oilfield data from successful EOR projects were used as input and predicted output in the training and validation processes, respectively. The developed model was then tested by using data set from Block B of an Angolan oilfield. The results of the sensitivity analysis between the Mamdani and the Takagi-Sugeno-Kang (TSK) approach incorporated in the algorithm has shown the robustness of the TSK ANFIS (Adaptive Neuro-Fuzzy Inference System) approach in comparison to the other approach for the prediction of a suitable EOR technique. The simulation test results showed that the model presented in this study can be used for technical selection of suitable EOR techniques. Within the area investigated (Block B, Angola) polymer, hydrocarbon gas, and combustion were ident...

Energy & Fuels, 2020

An extensive investigation on the applicability of Polyvinyl Alcohol (PVA, a polymer) and its syn... more An extensive investigation on the applicability of Polyvinyl Alcohol (PVA, a polymer) and its synergy with Rhamonolipid (a surfactant active agent) and/or alkaline (NaOH) was carried out to evaluate and define the best fluid formulation for enhanced oil recovery (EOR) processes. First,the effect of molecular weight, concentration, and temperature of PVA solution on surface tension (ST), interfacial tension (IFT), shear viscosity and thermodynamic stability was established. Then, a systematic formulation of PVA combined with Rhamonolipid and NaOH in reconstructed brine from Angolan offshore field was developed. The IFT experiment were carried out on crude oil samples obtained from Block T of Angolan offshore field. The combined PVA-Rhamonolipid (SP) and NaOH-Rhamonolipid-PVA (ASP) in saline medium reduced the ST and IFT to values below 30 mN/m and 1mN/m respectively. This provides an opportunity to use this new synergistic formulation in EOR processes particularly in offshore Angolan oilfields.

Energies, 2017

In this work, a neuro-fuzzy (NF) simulation study was conducted in order to screen candidate rese... more In this work, a neuro-fuzzy (NF) simulation study was conducted in order to screen candidate reservoirs for enhanced oil recovery (EOR) projects in Angolan oilfields. First, a knowledge pattern is extracted by combining both the searching potential of fuzzy-logic (FL) and the learning capability of neural network (NN) to make a priori decisions. The extracted knowledge pattern is validated against rock and fluid data trained from successful EOR projects around the world. Then, data from Block K offshore Angolan oilfields are then mined and analysed using box-plot technique for the investigation of the degree of suitability for EOR projects. The trained and validated model is then tested on the Angolan field data (Block K) where EOR application is yet to be fully established. The results from the NF simulation technique applied in this investigation show that polymer, hydrocarbon gas, and combustion are the suitable EOR techniques.