Isah Mohammed

Investigation of Surface Charge at the Mineral/Brine Interface: Implications for Wettability Alteration

Frontiers in Materials, 2022

The reservoir rock is made up of different minerals which contribute to the overall formation wet... more The reservoir rock is made up of different minerals which contribute to the overall formation wettability. These minerals in their natural state differ in chemistry and structure and thus behave differently in an environment of varying composition and salinity. These have direct implications for enhanced oil recovery due to water flooding, or wettability alteration due to long-term exposure to brine. With the reservoir rock being a complex system of multiple minerals, the control of wettability alterations becomes difficult to manage. One of the dominant mechanisms responsible for wettability alteration is the mineral surface charge, which is dependent on pH, and fluid composition (salt type and salinity). For the first time, the surface charge development of barite, dolomite, and feldspar minerals in their native reservoir environments (accounting for the formation brine complexity) is presented. Also, the effect of oilfield operations (induced pH change) on minerals’ surface charge development is studied. This was achieved by using the zeta potential measurements. The zeta potential results show that barite and dolomite minerals possess positively charge surfaces in formation water and seawater, with feldspar having a near-zero surface charge. Furthermore, the surface charge development is controlled by the H+/OH− (pH), electrical double-layer effect, as well as ion adsorption on the mineral’s surfaces. These findings provide key insights into the role of fluid environment (pH, composition) and oilfield operations on mineral surface charge development. In addition, the results show that careful tuning of pH with seawater injection could serve as an operational strategy to control the mineral surface charge. This is important as negatively charged surfaces negate wettability alteration due to polar crude oil components. Also, the design of an ion-engineered fluid to control the surface charge of minerals was implemented, and the results show that reduction in the Ca2+ concentration holds the key to the surface charge modifications. Surface charge modifications as evidenced in this study play a critical role in the control of wettability alteration to enhance production.

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Effects of the Reservoir Environment and Oilfield Operations on the Iron Mineral Surface Charge Development: An Insight into Their Role in Wettability Alteration

Energy & Fuels, 2022

Effect of Native Reservoir State and Oilfield Operations on Clay Mineral Surface Chemistry

Molecules, 2022

An understanding of clay mineral surface chemistry is becoming critical as deeper levels of contr... more An understanding of clay mineral surface chemistry is becoming critical as deeper levels of control of reservoir rock wettability via fluid–solid interactions are sought. Reservoir rock is composed of many minerals that contact the crude oil and control the wetting state of the rock. Clay minerals are one of the minerals present in reservoir rock, with a high surface area and cation exchange capacity. This is a first-of-its-kind study that presents zeta potential measurements and insights into the surface charge development process of clay minerals (chlorite, illite, kaolinite, and montmorillonite) in a native reservoir environment. Presented in this study as well is the effect of fluid salinity, composition, and oilfield operations on clay mineral surface charge development. Experimental results show that the surface charge of clay minerals is controlled by electrostatic and electrophilic interactions as well as the electrical double layer. Results from this study showed that clay ...

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Impact of Asphaltene Precipitation and Deposition on Wettability and Permeability

ACS Omega, 2021

Asphaltene precipitation and deposition have been a formation damage problem for decades, with th... more Asphaltene precipitation and deposition have been a formation damage problem for decades, with the most devastating effects being wettability alteration and permeability impairment. To this effect, a critical look into the laboratory studies and models developed to quantify/predict permeability and wettability alterations are reviewed, stating their assumptions and limitations. For wettability alterations, the mechanism is predominantly surface adsorption, which is controlled by the asphaltene contacting minerals as they control the surface chemistry, charge, and electrochemical interactions. The most promising wettability alteration evaluation techniques are nuclear magnetic resonance, ζ potential, and the use of high-resolution microscopy. The integration of such techniques, which is still missing, would reinforce the understanding of asphaltene interaction with rock minerals (especially clays), which holds the key to developing a strategy for modeling wettability alteration. With regard to permeability impairment, surface deposition, pore plugging, and fine migration have been identified as the dominant mechanisms with several models reporting the simultaneous existence of multiple mechanisms. Existing experimental findings showed that asphaltene deposition is non-uniform due to mineral distribution which further complicates the modeling process. It also remains a challenge to separate changes due to adsorption (wettability changes) from those due to pore size reduction (permeability impairment).

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Experimental and numerical studies on production scheme to improve energy efficiency of bitumen production through insitu oil-in-water (O/W) emulsion

Energy, 2021

Emulsification involving dispersion of bitumen droplets in a continuous aqueous phase (as oil-in-... more Emulsification involving dispersion of bitumen droplets in a continuous aqueous phase (as oil-in-water (O/W) emulsion), is an efficient method of reducing the viscosity. The objective of this research is to harness the potential of insitu emulsification for production of bitumen to improve energy efficiency. Thus, O/W emulsion was prepared using poly vinyl alcohol (PVA) surfactant (with NaOH and ethanol additivities) at different ratios of bitumen: PVA solution viz. 70:30 (RX1), 55:45 (RX2), 40:60 (RX3). The data was incorporated in computational fluid dynamics (CFD) analysis to obtain emulsification reaction parameters at different temperatures (30e150 C). Subsequently, numerical simulation considering insitu formation of O/W emulsion was performed at different injection temperatures (50, 100, and 150 C). The results were compared with those of conventional steam injection at 215 C. Significant viscosity reduction of bitumen was obtained from emulsification experiments. From numerical simulation, the proposed method resulted in higher oil: steam ratio (OSR) compared with steam injection method. Ultimately, with reference to steam injection (thermal efficiency, DE eff ¼ 0.02 m 3 /GJ; net bitumen production ¼ 692 m 3), the most promising operation is the production from RX3, at 150 C, with thermal efficiency, DE eff ¼ 0.04 m 3 /GJ, and 649 m 3 net bitumen production.

Surface Charge Investigation of Reservoir Rock Minerals

Energy & Fuels, 2021

The reservoir rock is made up of different minerals and its surface chemistry is influenced by th... more

$Research paper thumbnail of A review of pressure transient analysis in reservoirs with natural fractures, vugs and/or caves$

A review of pressure transient analysis in reservoirs with natural fractures, vugs and/or caves

Petroleum Science, 2020

A review of the pressure transient analysis of flow in reservoirs having natural fractures, vugs ... more A review of the pressure transient analysis of flow in reservoirs having natural fractures, vugs and/or caves is presented to provide an insight into how much knowledge has been acquired about this phenomenon and to highlight the gaps still open for further research. A comparison-based approach is adopted which involved the review of works by several authors and identifying the limiting assumptions, model restrictions and applicability. Pressure transient analysis provides information to aid the identification of important features of reservoirs. It also provides an explanation to complex reservoir pressure-dependent variations which have led to improved understanding and optimization of the reservoir dynamics. Pressure transient analysis techniques, however, have limitations as not all its models find application in naturally fractured and vuggy reservoirs as the flow dynamics differ considerably. Pollard’s model presented in 1953 provided the foundation for existing pressure trans...

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A Surface Charge Approach to Investigating the Influence of Oil Contacting Clay Minerals on Wettability Alteration

ACS Omega, 2021

Reservoir rock wettability has been linked to the adsorption of crude fractions on the rock, with... more Reservoir rock wettability has been linked to the adsorption of crude fractions on the rock, with much attention often paid to the bulk mineralogy rather than contacting minerals. Crude oil is contacted by different minerals that contribute to rock wettability. The clay mineral effect on wettability alterations is examined using the mineral surface charge. Also, the pH change effect due to well operations was investigated. Clay mineral surface charge was examined using zeta potential computed from the particle electrophoretic mobility. Clay minerals considered in this study include kaolinite, montmorillonite, illite, and chlorite. Results reveal that the clay mineral charge development is controlled by adsorption of ionic species and double layer collapse. Also, clay mineral surface charge considered in this study shows that their surfaces become more conducive for the adsorption of hydrocarbon components due to the presence of salts. The salt effect is greater in the following order: NaHCO 3 < Na 2 SO 4 < NaCl < MgCl 2 < CaCl 2. Furthermore, different well operations induce pH environments that change the clay mineral surface charge. This change results in adsorption prone surfaces and with reservoir rock made up of different minerals, and the effect of contacting minerals is critical as shown in our findings. This is due to the contacting mineral control wettability rather than the bulk mineralogy.

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Impact of Iron Minerals in Promoting Wettability Alterations in Reservoir Formations

ACS Omega, 2021

Asphaltene adsorption and deposition onto rock surfaces are predominantly the cause of wettabilit... more Asphaltene adsorption and deposition onto rock surfaces are predominantly the cause of wettability and permeability alterations which result in well productivity losses. These alterations can be induced by rock−fluid interactions which are affected by well operations such as acidizing, stimulation, gas injections, and so forth. Iron minerals are found abundantly in sandstone reservoir formations and pose a problem by precipitation and adsorption of polar crude components. This is due to rock−fluid interactions, which are dependent on reservoir pH; thus, this research work studied the surface charge development of pyrite, magnetite, and hematite. To ascertain conditions that will result in iron mineral precipitation and adsorption of asphaltene on iron mineral surfaces, zeta potential measurement was carried out. This is to determine the charge and colloidal stability of the iron mineral samples across wide pH values. Experimental results show that the charge development of iron minerals is controlled by mineral dissolution, the formation of complexes, adsorption of ions on the mineral surface, and the collapse of the double layer. The findings provide insights into the implications of iron mineral contacting crude oil in reservoir formations and how they contribute to wettability alterations due to different well operations.

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A review on polymer, gas, surfactant and nanoparticle adsorption modeling in porous media

Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles, 2020

Adsorption is a rock surface phenomenon and has increasingly become popular, especially in partic... more Adsorption is a rock surface phenomenon and has increasingly become popular, especially in particle-transport applications across many fields. This has drawn a remarkable number of publications from the industry and academia in the last decade, with many review articles focused on adsorption of polymers, surfactants, gas, and nanoparticles in porous media with main applications in Enhanced Oil Recovery (EOR). The discussions involved both experimental and modeling approaches to understanding and efficiently mimicking the particle transport in a bid to solve pertinent problems associated with particle retention on surfaces. The governing mechanisms of adsorption and desorption constitute an area under active research as many models have been proposed but the physics has not been fully honored. Thus, there is a need for continuous research effort in this field. Although adsorption/desorption process is a physical phenomenon and a reversible process resulting from inter-molecular and t...

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A New Mathematical Workflow to Predict Permeability Variation using Flowing Gas Material Balance

Offshore Technology Conference Asia, 2020

In the dynamic approach, production data including the flowing wellhead or bottomhole pressures a... more In the dynamic approach, production data including the flowing wellhead or bottomhole pressures are used to conduct the material balance analysis to determine the gas in place at any time during the life of well. However, the procedure did not extend to identify the well health issues such as permeability variation. The objective of this research is to develop a simplified mathematical workflow to identify and verify permeability variation using flowing gas material balance. In this approach, a new form of flowing gas material balance equation is derived by adding permeability variation term. In this new mathematical workflow, linear and exponential curve fitting tools along with the flowing material balance analysis are used to predict well expected behavior. The prediction is then compared with initial well production behavior. The deviation of the prediction and the expected production behavior formed the basis of permeability variation. The component of the model is tested with ...

Asphaltene precipitation and deposition: A critical review

Journal of Petroleum Science and Engineering, 2020

Abstract Asphaltene deposition in the reservoirs, tubbing, and surface facilities causes serious ... more Abstract Asphaltene deposition in the reservoirs, tubbing, and surface facilities causes serious flow assurance problems with significant economic implications. Asphaltene flow assurance challenge results from pressure depletion, fluid compositional change, and electrostatic interactions between the rock-fluid system resulting in deposition inside the reservoir and alteration of petrophysical properties such as permeability and wettability. Ultimately, these damages affect production and economically impact business decisions. Several preventive and corrective approaches have been presented with the focus of mitigating asphaltene flow assurance problems. Accordingly, many experimental findings and models have been proposed over the years, with each assuming different precipitation and depositional mechanisms. Thus, begs the question of which model best describes the asphaltene depositional problem and what unique attributes give it the advantage. Furthermore, what prevention strategy can be applied economically at the field scale? This and many other questions are the pivots upon which this paper rest, with the sole purpose of giving researchers a clear view of what is been known and what areas are open for further research. Comparative and critique-based approaches have been adopted in this review, with the intent of providing a holistic view of the asphaltene problem by analyzing the existing approaches adopted by several researchers and field applicability of their findings. Thus, this paper investigates the asphaltene problem from its chemistry and molecular level to field-scale implications thus giving a holistic view of the problem.

Study of the impact of injection parameters on the performance of miscible sour gas injection for enhanced oil recovery

Journal of Petroleum Exploration and Production Technology, 2019

Sour gas reservoirs have faced critics for environmental concerns and hazards, necessitating a no... more Sour gas reservoirs have faced critics for environmental concerns and hazards, necessitating a novel outlook to how the produced sour gases could be either utilized or carefully disposed. Over the years of research and practice, several methods of sour gas processing and utilization have been developed, from the solid storage of sulfur to reinjecting the sour gas into producing or depleted light oil reservoir for miscible flooding enhanced oil recovery. This paper seeks to investigate the impact of injection parameters on the performance of sour gas injection for enhance oil recovery. In designing a miscible gas flooding project, empirical correlations are used and the key parameter which impacts the phase behavior is identified to be the minimum miscibility pressure (MMP). A compositional simulator was utilized in this research work to study the effect of injection parameters such as minimum miscibility pressure, acid gas concentration, injection pressure and injection rate on the ...

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Probabilistic approach for shale volume estimation in Bornu Basin of Nigeria

Journal of Petroleum and Gas Engineering, 2019

The gamma ray log has over the years provided the conventional means for shale volume (Vsh) estim... more The gamma ray log has over the years provided the conventional means for shale volume (Vsh) estimation. Knowledge of Vsh is used in the prediction of petrophysical parameters like effective porosity and water saturation, which are the input parameters for the calculation of oil in place. Currently, many studies have been conducted on the Bornu Basin of Nigeria, to access its hydrocarbon potential. Unfortunately, the practice of using best gamma ray log value for the computation of gamma ray index, I GR , and subsequently Vsh estimation incorporates huge uncertainty in the estimated volumes. Uncertainty is best captured when estimates are represented in a possible range rather than single value measurements. To the best of our knowledge, this is the first time shale volume has been estimated from the gamma ray log using sampling techniques. The gamma ray log data of the two upper shaly intervals of the NGAMMAEAST_1 well, which penetrates the Gombe formation of the basin, were utilized for this study. The gamma ray log response of the zone of interest is the uncertain parameter in Vsh estimation. A histogram plot of the uncertain log data was used to assume the probability distribution of the data. In the MATLAB platform, Standard Monte Carlo (MC) and Latin Hypercube sampling techniques were used to model the uncertain log response using random numbers. Possible input log data generated from the distribution of the uncertain log data were used in the linear and non-linear models for shale volume estimation to run a series of simulations to determine the possible range of estimates with their probabilities. The Latin hypercube method has shown to be a quick and accurate alternative method to the standard MC method. The approach presented here sets a guideline for the implementation of a probabilistic approach for the volume of shale estimation.

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Energy Integration of Kero Hydrotreating Unit, A Case Study of Nigerian Refinery

Journal of Chemical Engineering & Process Technology, 2018

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Effect of Native Reservoir State and Oilfield Operations on Clay Mineral Surface Chemistry

Molecules, 2022

An understanding of clay mineral surface chemistry is becoming critical as deeper levels of contr... more An understanding of clay mineral surface chemistry is becoming critical as deeper levels of control of reservoir rock wettability via fluid–solid interactions are sought. Reservoir rock is composed of many minerals that contact the crude oil and control the wetting state of the rock. Clay minerals are one of the minerals present in reservoir rock, with a high surface area and cation exchange capacity. This is a first-of-its-kind study that presents zeta potential measurements and insights into the surface charge development process of clay minerals (chlorite, illite, kaolinite, and montmorillonite) in a native reservoir environment. Presented in this study as well is the effect of fluid salinity, composition, and oilfield operations on clay mineral surface charge development. Experimental results show that the surface charge of clay minerals is controlled by electrostatic and electrophilic interactions as well as the electrical double layer. Results from this study showed that clay minerals are negatively charged in formation brines as well as in deionized water, except in the case of chlorite, which is positively charged in formation water. In addition, a negative surface charge results from oilfield operations, except for operations at a high alkaline pH range of 10–13. Furthermore, a reduction in the concentrations of Na, Mg, Ca, and bicarbonate ions does not reverse the surface charge of the clay minerals; however, an increase in sulfate ion concentration does. Established in this study as well, is a good correlation between the zeta potential value of the clay minerals and contact angle, as an increase in fluid salinity results in a reduction of the negative charge magnitude and an increase in contact angle from 63 to 102 degree in the case of chlorite. Lastly, findings from this study provide vital information that would enhance the understanding of the role of clay minerals in the improvement of oil recovery.

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Feature Ranking and Modeling of Mineral Effects on Reservoir Rock Surface Chemistry Using Smart Algorithms

ACS Omega

Reservoir rock minerals and their surface charge development have been the subject of several stu... more Reservoir rock minerals and their surface charge development have been the subject of several studies with a consensus reached on their contribution to the control of reservoir rock surface interactions. However, the question of what factors control the surface charge of minerals and to what extent do these factors affect the surface charge remains unanswered. Also, with several factors identified in our earlier studies, the question of the order of effect on the mineral surface charge was unclear. To quantify the mineral surface charge, zeta potential measurements and Deryaguin−Landau−Verwey−Overbeek (DLVO) theories, as well as surface complexation models, are used. However, these methods can only predict a single mineral surface charge and cannot approximate the reservoir rock surface. This is because the reservoir rock is composed of many minerals in varying proportions. To address these drawbacks, for the first time, we present the implementation of machine learning models to predict reservoir minerals' surface charge. Four different models namely the Adaptive Boosting Regressor, Random Forest Regressor, Support Vector Regressor, and the Gradient Boosting tree were implemented for this purpose with all the model predictions over 95% accuracy. Also, feature ranking of the factors that control the mineral surface charge was carried out with the most dominant factors being the mineral type, salt type, and pH of the environment. Findings reveal an opportunity for accurate prediction of reservoir rock surface charge given the enormous amount of data available.

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Effects of the Reservoir Environment and Oilfield Operations on the Iron Mineral Surface Charge Development: An Insight into Their Role in Wettability Alteration

Iron minerals are hydrophobic minerals predominately found in sandstone formations with their rol... more Iron minerals are hydrophobic minerals predominately found in sandstone formations with their role in wettability alteration not fully understood. With the reservoir rock being a complex system of multiple minerals, the control of wettability alterations becomes difficult to manage due to the different surface chemistry of constituent minerals. This study presents for the first time the surface charge development of pyrite, magnetite, and hematite minerals in native reservoir environments and the effect of oilfield operations such as acidizing, water injection, polymerization, surfactant flooding, and alkaline flooding on iron minerals, surface charge development. This was achieved using zeta potential measurement, which depicts the type of surface charge and infers the propensity of precipitation. The experimental results show that pyrite, magnetite, and hematite behave similarly under reservoir conditions with all the minerals being positively charged although pyrite and hematite are negatively charged in seawater (SW). Results also show that the surface charge development is controlled by the electrical double-layer effect and ion adsorption on the mineral surfaces. These findings provide key insights into the role of iron minerals in wettability alteration as they provide surfaces that serve as a precursor for polar crude component adsorption. Also, the design of an ion-engineered fluid to control the surface charge of iron minerals was implemented, and the results showed that they behave differently. Furthermore, the effect of low-salinity water on the mineral surface charge was examined. The findings revealed that low-salinity water can produce a negatively charged surface, however, cannot mitigate the iron mineral precipitation challenge as the observed zeta potential values are near zero. Finally, slug and continuous injection of the ethylenediaminetetraacetic acid chelating agent was implemented as an iron mineral precipitation control strategy, with the continuous injection observed to significantly improve the colloidal stability of the iron minerals in the reservoir native state and after SW injection.

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Experimental and numerical studies on production scheme to improve energy efficiency of bitumen production through insitu oilin-water (O/W) emulsion

Energy, 2021

Emulsification involving dispersion of bitumen droplets in a continuous aqueous phase (as oil-in-... more Emulsification involving dispersion of bitumen droplets in a continuous aqueous phase (as oil-in-water (O/W) emulsion), is an efficient method of reducing the viscosity. The objective of this research is to harness the potential of insitu emulsification for production of bitumen to improve energy efficiency. Thus, O/W emulsion was prepared using poly vinyl alcohol (PVA) surfactant (with NaOH and ethanol additivities) at different ratios of bitumen: PVA solution viz. 70:30 (RX1), 55:45 (RX2), 40:60 (RX3). The data was incorporated in computational fluid dynamics (CFD) analysis to obtain emulsification reaction parameters at different temperatures (30e150 C). Subsequently, numerical simulation considering insitu formation of O/W emulsion was performed at different injection temperatures (50, 100, and 150 C). The results were compared with those of conventional steam injection at 215 C. Significant viscosity reduction of bitumen was obtained from emulsification experiments. From numerical simulation, the proposed method resulted in higher oil: steam ratio (OSR) compared with steam injection method. Ultimately, with reference to steam injection (thermal efficiency, DE eff ¼ 0.02 m 3 /GJ; net bitumen production ¼ 692 m 3), the most promising operation is the production from RX3, at 150 C, with thermal efficiency, DE eff ¼ 0.04 m 3 /GJ, and 649 m 3 net bitumen production.

Impact of Asphaltene Precipitation and Deposition on Wettability and Permeability

ACS Omega, 2021

Asphaltene precipitation and deposition have been a formation damage problem for decades, with th... more Asphaltene precipitation and deposition have been a formation damage problem for decades, with the most devastating effects being wettability alteration and permeability impairment. To this effect, a critical look into the laboratory studies and models developed to quantify/predict permeability and wettability alterations are reviewed, stating their assumptions and limitations. For wettability alterations, the mechanism is predominantly surface adsorption, which is controlled by the asphaltene contacting minerals as they control the surface chemistry, charge, and electrochemical interactions. The most promising wettability alteration evaluation techniques are nuclear magnetic resonance, ζ potential, and the use of high-resolution microscopy. The integration of such techniques, which is still missing, would reinforce the understanding of asphaltene interaction with rock minerals (especially clays), which holds the key to developing a strategy for modeling wettability alteration. With regard to permeability impairment, surface deposition, pore plugging, and fine migration have been identified as the dominant mechanisms with several models reporting the simultaneous existence of multiple mechanisms. Existing experimental findings showed that asphaltene deposition is non-uniform due to mineral distribution which further complicates the modeling process. It also remains a challenge to separate changes due to adsorption (wettability changes) from those due to pore size reduction (permeability impairment).

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