Publications

Large Scale Modeling and Assessment of the Feasibility of CO₂ Storage Onshore Abu Dhabi

Published in Energy, 2019

Therefore, we present in this study the results of feasibility studies to determine the prospects of long term injection of CO₂ into the proposed aquifers. The aquifers assessed are the Simsima, Dammam, UER and Shuaiba formations. The assessment criteria employed include the estimation of storage capacities, prediction of plume migration, contribution of trapping mechanisms to storage and sensitivity analysis to different reservoir parameters. Geologic models of the aquifers have been created by combining information from wells, seismic, logs and numerical models have been made by upscaling the respective geologic models. The analytical estimates of storage capacities indicate capacities of 5 GT, 1.7 GT, 8 GT and 960 MT for the Simsima, Dammam, UER and Shuaiba aquifers respectively. Dissolution is the dominant trapping mechanism at early and late times via diffusion and convection respectively.

Recommended citation: Ajayi T., Awolayo, A.N., Gomes, J.S., Parra, H., and Hu, J. (2019). "Large Scale Modeling and Assessment of the Feasibility of CO₂ Storage Onshore Abu Dhabi." Energy. 185: 653 - 670. https://doi.org/10.1016/j.energy.2019.07.052

Numerical Modeling of Fluid-Rock Interactions During Low-Salinity-Brine-CO₂ Flooding in Carbonate Reservoirs

Published in Proceedings of the SPE Reservoir Simulation Conference, 2019

A reactive transport model, which uses surface complexation reactions (SCR) to describe the equilibrium between the rock surface sites and ion species in the brine solution coupled with transport equation, was developed to predict a set of low-salinity-brine-CO₂ flooding experiments conducted on carbonate rocks. While conducting batch simulations of the model, it was shown that the thermodynamic parameters reported in the literature for SCRs in a rock–brine system are not suited to natural carbonate rocks. The same thermodynamic parameters could not fit the model to experimental zeta potential data with pulverized and intact carbonate cores at varying potential determining ion concentrations. The model was further utilized to predict the effluent compositions of potential determining ions in single-phase flooding experiments on natural carbonate cores. The failure of thermodynamic parameters in the prediction of reactive transport single-phase experiments, implies that zeta potential is not enough to optimize such parameters for the reactive transport model.

Recommended citation: Awolayo, A.N., Sarma, H.K. and Nghiem L.X. (2019). "Numerical Modeling of Fluid-Rock Interactions During Low-Salinity-Brine-CO₂ Flooding in Carbonate Reservoirs." Proceedings of the 2019 SPE Reservoir Simulation Conference, April 10 - 11, Galveston, Texas, USA. https://doi.org/10.2118/193815-MS

Brine-Dependent Recovery Processes in Carbonate and Sandstone Petroleum Reservoirs: Review of Laboratory-Field Studies, Interfacial Mechanisms and Modeling Attempts

Published in Energies, 2018

This paper provides a comprehensive review on laboratory and field observations, descriptions of underlying mechanisms and their validity, the complexity of the oil-brine-rock interactions, modeling works, and comparison between sandstone and carbonate rocks.

Recommended citation: Awolayo, A.N., Sarma, H.K., and Nghiem L.X. (2018). "Brine-Dependent Recovery Processes in Carbonate and Sandstone Petroleum Reservoirs: Review of Laboratory-Field Studies, Interfacial Mechanisms and Modeling Attempts." Energies. 11(11): 3020. https://doi.org/10.3390/en11113020

Thermodynamic Modeling of Brine Dilution-Dependent Recovery in Carbonate Rocks with Different Mineralogical Content

Published in Energy & Fuels, 2018

In this study, we have formulated a theory for the anticipated chemical interactions between oil, brine, and rock, and linked the geochemical interactions to multi-component transport within the porous rock. In so doing, we investigated different hypotheses on the viable link between geochemical and wettability modifications. Our simulation results were able to capture the trend in the experimental oil recovery results, together with the effluent ions under varying mineralogical content. Based on our model, we infer that mineral alteration alone could not describe the observed behavior, and that one has also to consider the interplay between surface charge and mineral alteration.

Recommended citation: Awolayo, A.N., Sarma, H.K., and Nghiem L.X. (2018). "Thermodynamic Modeling of Brine Dilution-Dependent Recovery in Carbonate Rocks with Different Mineralogical Content." Energy & Fuels. 32(9): 8921 – 8943. https://doi.org/10.1021/acs.energyfuels.8b01080

Modeling the Characteristic Interplay between Potential Determining Ions during Brine-Dependent Recovery Process in Carbonate Rocks

Published in Fuel, 2018

Brine-dependent recovery processes in carbonate reservoirs have been receiving much attention for the past two decades, and wettability alteration has been identified among the dominant process mechanisms. Most studies suggest that the wettability alteration in carbonate rocks is caused by desorption of oil acid groups from rock surfaces by the adsorbed sulfate, with concomitant co-adsorption of the divalent cations. Although such symbiotic interaction between active ions (Ca²⁺, Mg²⁺, and SO₄^2-) and the rock surface has been established, their systematic interplay under different conditions remains to be better explored and understood. In this study, we propose a reactive transport model that considers various reaction sets to investigate the affinity of these active ions toward the rock surface. The important thermodynamic properties were obtained by using the model to interpret single-phase experiments.

Recommended citation: Awolayo, A.N., Sarma, H.K., and Nghiem L.X. (2018). "Modeling the Characteristic Interplay between Potential Determining Ions during Brine-Dependent Recovery Process in Carbonate Rocks." Fuel. 224: 701 - 717. https://doi.org/10.1016/j.fuel.2018.03.070

An Analytical Solution to Interpret Active Ion Transport during Chemically-Tuned Waterflooding Process in High-Temperature Carbonate Rocks

Published in The Canadian Journal of Chemical Engineering, 2018

Recent studies on carbonate reservoirs suggest that modifying the injected brine chemistry leads to a competition amongst ions at the rock surface sites, causing alteration in the rock wettability. As such, the potential increase in oil recovery heavily relies on the relationship between the ion transport and chemical reaction. In this work, we highlighted the three processes that govern this relationship as advection by fluid transport, hydrodynamic dispersion resulting in spreading, and sorption of the ions to the rock. An analytical solution to the mathematical equations describing solute reactive transport was derived based on the advection-reaction-dispersion equation (ARDE). Our model was first used to replicate produced ion histories from single phase experiments to emphasize the impact of the active ions on rock surface sites. We then studied the movement of the active ions by predicting the breakthrough composition of different ions during oil-brine displacement experiments and evaluated the impact of the transport and reaction parameters on the wettability change.

Recommended citation: Awolayo, A.N. and Sarma, H.K. (2018). "An Analytical Solution to Interpret Active Ion Transport during Chemically-Tuned Waterflooding Process in High-Temperature Carbonate Rocks." The Canadian Journal of Chemical Engineering. 97(1): 310 - 322. https://doi.org/10.1002/cjce.23183

A Geochemical Model for Investigation of Wettability Alteration during Brine-Dependent Flooding in Carbonate Reservoirs

Published in Proceedings of the Abu Dhabi International Petroleum Exhibition & Conference, 2017

The impact of brine salinity and compositions on improving brine-dependent recovery processes has been an active research area over the past two decades. Various studies have demonstrated an improvement in oil recovery, attributed predominantly to the ability of the brine to alter rock’s wettability towards water-wetness. The proposed hypothesis is that the wettability of carbonate rocks is altered due to desorption of oil carboxylic groups from rock surfaces by the adsorbed sulfate, while the divalent cations are co-adsorbed. We developed a reactive transport model to test this hypothesis and considered wettability alteration through geochemical interactions among brine, oil and rock surface. In this model, we used various reaction pathways to account for the competition between oil acid-groups and active ionson the rock surface. The equations developed from various reactions are coupled with multiphase flow equations to control flow functions that ultimately determine the oil recovery. The model we developed was used to investigate the effects of ionic variations during carbonate coreflooding experiments. Thereafter, we extended DLVO (Derjaguin, Landau, Verwey and Overbeek) theory of surface forces to explain the molecular interactions between rock−brine−oil system by generating interfacial disjoining pressure and interaction energy.

Recommended citation: Awolayo, A.N., Sarma, H.K., Nghiem L.X. and Gorucu, S.E. (2017). "A Geochemical Model for Investigation of Wettability Alteration during Brine-Dependent Flooding in Carbonate Reservoirs." Proceedings of the 2017 Abu Dhabi International Petroleum Exhibition & Conference (ADIPEC 2017), November 13 - 16, UAE. https://doi.org/10.2118/182912-MS

Uncertainty Analysis of Smart Waterflood Recovery Performance in Clastic Reservoirs

Published in Advances in Petroleum Exploration and Development, 2017

In recent years, numerous laboratory studies have documented the benefits of smart waterflooding as an emerging enhanced oil recovery (EOR) process, along with a few successful field applications, notably clastic reservoirs. In most cases, there are undeniable inconsistencies between lab and field results. This process has led to unpredictable outcomes and misleading prediction of smart waterflooding projects. Hence, this work is conducted to evaluate uncertainties in smart waterflooding from laboratory to field-scale. An one-dimensional (1-D) reactive transport model was developed and validated with flooding experiments. Validation shows that combinations of various matching parameters can be used to interpret the experiment. Different realizations lead to different results when extended to 3-D heterogeneous model. The sensitivity of parameters like grid size and heterogeneity in full-field model majorly influences smart waterflooding performance, which is responsible for the inconsistencies. Therefore, these parameters should be considered in field-scale simulation to fully demonstrate the potential of smart waterflooding.

Recommended citation: Kadeethum, T., Awolayo, A.N., Sarma, H.K., Maini, B., and Jaruwattanasakul, C. (2017). "Uncertainty Analysis of Smart Waterflood Recovery Performance in Clastic Reservoirs." Advances in Petroleum Exploration and Development. 14(1): 18 - 42. https://doi.org/10.3968/9683

Geochemical Modeling of the Interplay Between Potential Determining Ions During Brine-Dependent Recovery in Carbonate Rocks

Published in Proceedings of the SPE Annual Technical Conference and Exhibition, 2017

Brine-dependent oil recovery in carbonate rocks has developed into an active area of research in the past two decades. It is well documented in the literature that wettability of carbonate rocks is altered due to desorption of oil acid groups from rock surfaces by the adsorbed sulfate, while the divalent cations co-adsorbed to maintain the surface charge balance as well as to reverse the oil-surface charge. Though the symbiotic interaction between active ions (Ca²⁺, Mg²⁺, and SO₄^2-) and the rock surface has been established but how they systematically interplay at different conditions have not been well explored and available data seems inconsistent. In the present work, we develop a reactive transport model that includes various reaction sets like aqueous reactions, mineral reactions in terms of precipitation and dissolution, and surface sorption reactions in terms of adsorption and ion exchange to investigate and discuss the affinity of these active ions toward the rock surface.

Recommended citation: Awolayo, A.N. (2017). "Geochemical Modeling of the Interplay Between Potential Determining Ions During Brine-Dependent Recovery in Carbonate Rocks." Proceedings of the 2017 SPE Annual Technical Conference and Exhibition, October 9-11, San Antonio, Texas, USA. https://doi.org/10.2118/189280-STU

A Comprehensive Geochemical-based Approach at Modeling and Interpreting Brine Dilution in Carbonate Reservoirs

Published in Proceedings of the SPE Reservoir Simulation Conference, 2017

It has been amply proven through laboratory studies, affirmed by a few field trials, that dilution of brine injected has a potent impact on improving oil recovery in carbonate reservoirs. However, debate still exists as to the mechanisms responsible for such impact. The widely acknowledged underlying mechanism is the wettability alteration, achieved through a combination of lower ionic strength, multi-ion exchange, surface charge and mineral alteration. Therefore, the motive behind this study is to develop a model that can further support and interpret the brine dilution approach in the framework of carbonate reservoirs. In this paper, we formulated a theory for the observed behavior that coupled equations of multi-component transport and geochemical reactions. The geochemical system considered a choice of significant ions and minerals, relevant to the published experiments. Mechanisms included in the model were dispersion/diffusion, instantaneous equilibrium reactions in terms of intra-aqueous and sorption reactions, and non-equilibrium rate controlled kinetic reactions-mineral alteration. The equivalent modification in wettability was represented by interpolating through a set of flow functions, particularly the relative permeability characteristics.

Recommended citation: Awolayo, A.N., Sarma, H.K. and Nghiem L.X. (2017). "A Comprehensive Geochemical-based Approach at Modeling and Interpreting Brine Dilution in Carbonate Reservoirs." Proceedings of the 2017 SPE Reservoir Simulation Conference, February 20 - 22, Montgomery, Texas, USA. https://doi.org/10.2118/182626-MS

A Cohesive Approach in Estimating Water Saturation in a Low-Resistivity Pay Carbonate Reservoirs

Published in Journal of Petroleum Exploration & Production Technology, 2017

Carbonate reservoir characterization and fluid quantification seem more challenging than those of sandstone reservoirs. The intricacy in the estimation of accurate hydrocarbon saturation is owed to their complex and heterogeneous pore structures, and mineralogy. Traditionally, resistivity-based logs are used to identify pay intervals based on the resistivity contrast between reservoir fluids. However, few pay intervals show reservoir fluids of similar resistivity which weaken reliance on the hydrocarbon saturation quantified from logs taken from such intervals. The potential of such intervals is sometimes neglected. In this case, the studied reservoir showed low resistivity. High water saturation was estimated, while downhole fluid analysis identified mobile oil, and the formation produced dry or nearly dry oil. Because of the complexity of Lowresitivity pay (LRP) reservoirs, its cause should be determined a prior to applying a solution. Several reasons were identified to be responsible for this phenomenon from the integration of thin section, nuclear magnetic resonance (NMR) and mercury injection capillary pressure (MICP) data—among which were the presence of microporosity, fractures, paramagnetic minerals, and deep conductive borehole mud invasion. In this paper, we integrated various information coming from geology (e.g., thin section, X-ray diffraction (XRD)), formation pressure and well production tests, NMR, MICP, and Dean–Stark data. We discussed the observed variations in quantifying water saturation in LRP interval and their related discrepancies.

Recommended citation: Awolayo, A.N. Salahuddin, A.A., Uchida, M., Ashqar, A. and Olayiwola, S.O. (2017). "A cohesive approach at estimating water saturation in a low-resistivity pay carbonate reservoir and its validation." Journal of Petroleum Exploration & Production Technology. 7(3): 637 – 657. https://doi.org/10.1007/s13202-017-0318-2

Evaluating Low-Resistivity Pay Carbonate Reservoir: Model to Implementation

Published in Proceedings of the Abu Dhabi International Petroleum Exhibition & Conference, 2016

Early identification of low resistivity pay (LRP) reservoir is vital in assessing its prospect and capability. Productive reservoirs may exhibit low resistivity and consequently, their potential is simply overlooked. Remapping these intervals can have significant production and reserve implications. Traditionally, resistivity logs are used to identify pay intervals due to the resistivity contrast between oil and formation water. However, when pay intervals exhibit low resistivity, such logs return low confidence in defining hydrocarbon potential. Due to the complexity of low resistivity pay (LRP), its cause and proper mitigation should be determined prior to applying a solution. Researchers have identified several reasons responsible for this occurrence; among which are the presence of heterogeneous pore structures specifically micro-porosity, fractures, paramagnetic minerals, and deep conductive mud invasion. Almost all preceding publications assume a technique will work but not the other. However, this is the first time, to our knowledge; an integrated approach is used to develop LRP assessment workflow. We have integrated the information coming from geology (e.g., thin-section, XRD), formation pressure and well tests, NMR, MICP, and dean stark data.

Recommended citation: Ashqar, A., Uchida, M., Salahuddin, A.A., Olayiwola, S.O. and Awolayo, A.N. (2016). "Evaluating Low-Resistivity Pay Carbonate Reservoir: Model to Implementation." Proceedings of the 2016 Abu Dhabi International Petroleum Exhibition & Conference (ADIPEC 2016), November 7 - 10, UAE. https://doi.org/10.2118/182912-MS

Impact of Multi-ion Interactions on Oil Mobilization by Smart Waterflooding in Carbonate Reservoirs

Published in Journal of Petroleum & Environmental Biotechnology, 2016

The injected brine composition has been observed to have intense effect on efficiency of waterflooding in carbonate reservoirs. This process is known as smart waterflooding and has proved to be an effective process in improving oil recovery. Different approaches have been tested in carbonate reservoirs due to the complexity of the process. Based on these approaches, different mechanisms have been proposed with some level of uncertainties. This has led to several arguments on the chemical mechanisms responsible for such feat achieved. One of the approaches is discussed in this paper, however with much interpretation considering all factors influencing the oil-brine-rock interactions. Therefore, this paper presents the influence of multi-ion interactions during smart water flood on carbonates.

Recommended citation: Awolayo, A.N., Sarma, H.K., and AlSumaiti, A.M. (2015). "Impact of Multi-ion Interactions on Oil Mobilization by Smart Waterflooding in Carbonate Reservoirs." Journal of Petroleum & Environmental Biotechnology. 7(3): 278. https://doi.org/10.4172/2157-7463.1000278

An Experimental Investigation into the Impact of Sulfate ion in Smart Water to Improve Oil Recovery in Carbonate Reservoirs

Published in Transport in Porous Media, 2015

Carbonate reservoirs are considered to be in the range of mixed to oil wetting state. Their present wetting state seems unfavorable to recover more oil via conventional waterflooding especially as the water cut increases with huge residual oil saturation. In recent years, studies have shown that tuning the injected brine chemistry can help decrease the oil-wetness, resulting in additional oil recovery and reduction in residual oil saturation. Thus, rock wettability is being dictated by the surface chemistry associated with the water-film stability between crude oil and the rock surface. This study presents series of experiments conducted on Middle Eastern carbonate core plugs at high pressure and high temperature in order to determine the impact of sulfate ions in smart brine on oil recovery.

Recommended citation: Awolayo, A.N., Sarma, H.K., and AlSumaiti, A.M. (2015). "An Experimental Investigation into the Impact of Sulfate ion in Smart Water to Improve Oil Recovery in Carbonate Reservoirs." Transport in Porous Media. 111(3): 649 - 668. https://doi.org/10.1007/s11242-015-0616-4

Improvement of the Compositional Model to Represent a Complex Fluid System of a U.A.E. Carbonate Reservoir

Published in Proceedings of the Abu Dhabi International Petroleum Exhibition & Conference, 2015

The studied field is located in Abu Dhabi and has been identified as faulted anticlines structure with associated local fractures. The reservoir is characterized by lateral and vertical variations in reservoir rock and fluid properties ranging from a gas condensate at the top of the structure to undersaturated black oil down the reservoir. A substantial compositional gradient has been identified from over 50 fluid samples taken at different depths over the thick fluid column of about 1500 feet. The field is presently under miscible hydrocarbon WAG (HC-WAG) injection, water injection and future consideration for CO2-WAG injection. The field has been characterized using an Equation of State (EOS) model and compositional mapping with areal changes of saturation pressure. Therefore, the aim of this study is to improve the compositional model that can replicate the areal and vertical variation in the fluid thermodynamic.

Recommended citation: Khan, A.K., Uchida, M., Awolayo, A.N., Olayiwola, S.O. and Khaled E.A. (2015). "Improvement of the Compositional Model to Represent a Complex Fluid System of a U.A.E. Carbonate Reservoir." Proceedings of the 2015 Abu Dhabi International Petroleum Exhibition & Conference (ADIPEC 2015), November 9 - 12, UAE. https://doi.org/10.2118/177693-MS

Evaluation of Water Saturation in a Low-Resistivity Pay Carbonate Reservoir Onshore Abu Dhabi: An Integrated Approach

Published in Proceedings of the Abu Dhabi International Petroleum Exhibition & Conference, 2015

Characterization and fluid quantification of Carbonate reservoirs looks more challenging than those of sandstone reservoirs. The determination of accurate hydrocarbon saturation is more tasking due to their complex and heterogeneous pore structures, and mineralogy. Traditionally, resistivity logs are used to identify pay intervals due to the resistivity contrast between oil and water. However, when pay intervals exhibit low resistivity, such logs exhibit low confidence in the precise determination of the hydrocarbon saturation. Few Middle-Eastern reservoirs are categorized as low resistivity pay, where resistivity based log analysis results in high water saturation. However, downhole fluid analysis identifies mobile oil, and the formation flows dry or nearly dry oil during production tests. This makes resistivity based saturation computation questionable.

Recommended citation: Uchida, M., Salahuddin, A.A., Awolayo, A.N., Olayiwola, S.O. and Khaled E.A. (2015). "Evaluation of Water Saturation in a Low-Resistivity Pay Carbonate Reservoir Onshore Abu Dhabi: An Integrated Approach." Proceedings of the 2015 Abu Dhabi International Petroleum Exhibition & Conference (ADIPEC 2015), November 9 - 12, UAE. https://doi.org/10.2118/177709-MS

An Experimental Study of Smart Waterflooding on Fractured Carbonate Reservoirs

Published in Proceedings of the ASME 33rd International Conference on Ocean, Offshore and Arctic Engineering, 2014

Wetting state in many fractured carbonate reservoirs exists between mixed-wet to oil-wet. Interaction of negatively charged carboxylic molecules in the crude oil with the rock surface, and high capillary pressure encountered during oil migration into the reservoir rock frequently render the rock oil-wet. Similarly, the existence of fractures solitarily governs the fluid flow dynamics in the porous media. Therefore, oil recovery from oil-wet fractured reservoirs is extremely tasking due to complex mechanisms involved in interactions between the double porosity system and the reservoir fluids.

Recommended citation: Awolayo, A.N., AlSumaiti, A.M., and Sarma, H.K. (2014). "An Experimental Study of Smart Waterflooding on Fractured Carbonate Reservoirs." Proceedings of the ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering, pp. V005T11A024, June 8 – 13, San Francisco, California, USA. https://doi.org/10.1115/OMAE2014-24597

Impact of Ionic Exchanges between Active and Non-Active Ions on Displacement Efficiency in Smart Waterflood Application in Carbonate Reservoirs

Published in Proceedings of the 76th EAGE Annual Conference and Exhibition, 2014

Smart waterflooding in carbonate reservoirs could be an effective IOR process to improve oil recovery through alteration of rock wettability. This paper presents the impact of ionic exchange between the active and non-active ions in smart water on carbonate sample. Coreflooding experiment was conducted by sequential injection of formation brine and smart brines and the effluent ionic composition was analyzed to verify the activity of these ions on improving recovery. In addition, zeta potential and contact angle measurement were conducted to examine the wettability alteration process and correlated to coreflood results.

Recommended citation: Awolayo, A.N., Sarma, H.K., and AlSumaiti, A.M. (2014). "Impact of Ionic Exchanges between Active and Non-Active Ions on Displacement Efficiency in Smart Waterflood Application in Carbonate Reservoirs." Proceedings of the 76th EAGE Annual Conference and Exhibition, June 16, Amsterdam, Netherland. https://doi.org/10.3997/2214-4609.20141011

A Laboratory Study of Ionic Effect of Smart Water for Enhancing Oil Recovery in Carbonate Reservoirs

Published in Proceedings of the SPE EOR Conference at Oil and Gas West Asia, 2014

Enhanced oil recovery by smart waterflooding represents a cheap, implementable and attractive emerging oil recovery technology. For sandstone reservoirs, smart waterflooding has shown incremental oil recovery in most laboratory and field tests while some promising experimental data have been presented from carbonates. It seems more difficult to assume a favourable performance for a reservoir a priori while dismissing the other, so more data and better understanding of the underlying mechanism in carbonates are needed.

Recommended citation: Awolayo, A.N., Sarma, H.K., and AlSumaiti, A.M. (2014). "A Laboratory Study of Ionic Effect of Smart Water for Enhancing Oil Recovery in Carbonate Reservoirs." Proceedings of the SPE EOR Conference at Oil and Gas West Asia, Muscat, Oman. https://doi.org/10.2118/169662-MS

Dapo Awolayo

Publications