Imperial College London

Dr Benaiah Anabaraonye

Faculty of EngineeringDepartment of Chemical Engineering

Academic Visitor







ACE ExtensionSouth Kensington Campus





Publication Type

12 results found

Mokhtari R, Anabaraonye BU, Afrough A, Mohammadkhani S, Feilberg KLet al., 2022, Experimental investigation of low salinity water-flooding in tight chalk oil reservoirs, Journal of Petroleum Science and Engineering, Vol: 208, ISSN: 0920-4105

Chalk reservoirs, due to their high storage capacity and very low permeability, are one of the most interesting cases for reservoir engineering research on carbonates. They exhibit complex fluid-rock interactions because of their chemically active porous media. This study investigates the effect of brine composition, injection scenario, and temperature on oil recovery by low salinity water-flooding in chalk core samples from a Danish North Sea reservoir. The mechanisms governing oil-brine-rock interactions were also explored. Actual reservoir chalk core samples, without any open fractures, were selected using computed tomography analyses. These cores were saturated with representative fluids (crude oil and synthetic formation brine) and aged at reservoir conditions for approximately three weeks. The role of brine chemistry has been investigated through effluent analysis by ion chromatography, and results indicate that low salinity diluted seawater promotes rock-surface reactions if left to incubate for at least 48 h. Rock dissolution, observed through the monitoring of effluent ions, increased both with increase in temperature and decrease in brine salinity. The recovery curves show that formation water and diluted seawater produce significantly more oil (of the order of 10 % more) at the secondary stage compared to seawater. Additionally, there is also some indication of an effect of low salinity brine at the tertiary stage. These experiments were performed on reservoir materials and corresponding crude oil samples and provide new data on the low salinity flooding potential for chalk, and provide further evidence for the applicability of the low salinity effect in carbonates.

Journal article

Anabaraonye BU, Bentzon JR, Khaliqdad I, Feilberg KL, Andersen SI, Walther JHet al., 2021, The influence of turbulent transport in reactive processes: A combined numerical and experimental investigation in a Taylor-Couette reactor, Chemical Engineering Journal, Vol: 421, ISSN: 1385-8947

Turbulent reactive flows are ubiquitous in industrial processes. Decoupling transport effects from intrinsic chemical reactions requires an in-depth understanding of fluid flow physics; computational fluid dynamics (CFD) methods have been widely used for this purpose. Most CFD simulations of reactive liquid-phase flows, where the Schmidt numbers are large, rely on isotropic eddy viscosity models. However, the assumption of turbulent isotropy in most stirred reactors and wall-bounded flows is fundamentally incorrect and leads to erroneous results. Here, we apply a systematic CFD approach to simulate liquid-phase diffusive and convective transport phenomena that occur in a Taylor-Couette (TC) reactor. We resolve the turbulent flow by extracting statistics from large eddy simulation which is used to tune the anisotropic Reynolds stress model. In addition, we conducted a series of turbulent precipitation and mixing studies in a TC reactor that was designed and fabricated in-house. The numerical model is successfully validated against a published torque correlation and it is found to accurately describe the advection and diffusion of chemical species. The validated model is then used to demonstrate key flow properties in the reactor. We define new local turbulent Peclét numbers to characterize the relative increase in diffusivity from turbulent advection and observe a 29% increase in the turbulent contribution as Reynolds number is doubled. Both reactive simulations and experiments show an increase in overall reaction rates with increased turbulence. The results from reactive simulations provide a deeper understanding of flow-kinetics interactions at turbulent conditions.

Journal article

Mohammadkhani S, Anabaraonye BU, Afrough A, Mokhtari R, Feilberg KLet al., 2021, Crude oil–brine–rock interactions in tight chalk reservoirs: An experimental study, Energies, Vol: 14

We present a systematic study of crude oil–brine–rock interactions in tight chalk cores at reservoir conditions. Flooding experiments are performed on outcrops (Stevns Klint) as well as on reservoir core plugs from Dan field, the Ekofisk and Tor formations. These studies are carried out in core plugs with reduced pore volumes, i.e., short core samples and aged with a dynamic ageing method. The method was evaluated by three different oil compositions. A series of synthetic multi-component brines and designed fluid injection scenarios are investigated; injection flow rates are optimized to ensure that a capillary-dominant regime is maintained. Changes in brine compositions and fluid distribution in the core plugs are characterized using ion chromatography and X-ray com-puted tomography, respectively. First, we show that polar components in the oil phase play a major role in wettability alteration during ageing; this controls the oil production behavior. We also show that, compared to seawater, both formation water and ten-times-diluted seawater are better candi-dates for enhanced oil recovery in the Dan field. Finally, we show that the modified flow zone indi-cator, a measure of rock quality, is likely the main variable responsible for the higher oil recoveries observed in Tor core samples.

Journal article

Gray F, Anabaraonye BU, Crawshaw JP, Boek ESet al., 2021, ( )Pore-scale dissolution mechanisms in calcite-CO2-brine systems: The impact of non-linear reaction kinetics and coupled ion transport, GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 305, Pages: 323-338, ISSN: 0016-7037

Journal article

Anabaraonye BU, Crawshaw JP, Trusler JPM, 2019, Brine chemistry effects in calcite dissolution kinetics at reservoir conditions, Chemical Geology, Vol: 509, Pages: 92-102, ISSN: 0009-2541

Understanding the chemical interactions between CO 2 -saturated brine systems and reservoir rocks is essential for predicting the fate of CO 2 following injection into a geological reservoir. In this work, the dissolution rates of calcite (CaCO 3 ) in CO 2 -saturated brines were measured at temperatures between 325 K and 373 K and at pressures up to 10 MPa. The experiments were performed in batch reactors implementing the rotating disk technique in order to eliminate the influence of fluid-surface mass transport resistance and obtain surface reaction rates. Three aqueous brine systems were investigated in this study: NaCl at a molality m = 2.5 mol·kg −1 , NaHCO 3 with m ranging from (0.005 to 1) mol·kg −1 and a multicomponent Na-Mg-K-Cl-SO 4 -HCO 3 brine system with an ionic strength of 1.8 mol·kg −1 . Measured dissolution rates were compared with predictions from previously published models. Activity calculations were performed according to the Pitzer model as implemented in the PHREEQC geochemical simulator. Calcite dissolution rates in NaCl and the multicomponent brine system showed minor increases when compared to the (CO 2 + H 2 O) system at identical conditions, despite the lower concentration of dissolved CO 2 . These trends are consistent with the expected minor decreases in solution pH. In NaHCO 3 systems, consistent with increase in solution pH, significant decreases in dissolution rates were observed. In addition, these systems significantly deviated from model predictions at higher salt molalities. Vertical scanning interferometry (VSI) was used to examine the mineral surfaces before and after dissolution experiments to provide qualitative information on saturation states and dissolution mechanism.

Journal article

Singh K, Anabaraonye BU, Blunt MJ, Crawshaw Jet al., 2018, Partial dissolution of carbonate rock grains during reactive CO<inf>2</inf>-saturated brine injection under reservoir conditions, Advances in Water Resources, Vol: 122, Pages: 27-36, ISSN: 0309-1708

One of the major concerns of carbon capture and storage (CCS) projects is the prediction of the long-term storage security of injected CO2. When injected underground in saline aquifers or depleted oil and gas fields, CO2mixes with the resident brine to form carbonic acid. The carbonic acid can react with the host carbonate rock, and alter the rock structure and flow properties. In this study, we have used X-ray micro-tomography and focused ion beam scanning electron microscopy (FIB-SEM) techniques to investigate the dissolution behavior in wettability-altered carbonate rocks at the nm- to µm-scale, to investigate CO2storage in depleted oil fields that have oil-wet or mixed-wet conditions. Our novel procedure of injecting oil after reactive transport has revealed previously unidentified (ghost) regions of partially-dissolved rock grains that were difficult to identify in X-ray tomographic images after dissolution from single fluid phase experiments. We show that these ghost regions have a significantly higher porosity and pore sizes that are an order of magnitude larger than that of unreacted grains. The average thickness of the ghost regions as well as the overall rock dissolution decreases with increasing distance from the injection point. During dissolution micro-porous rock retains much of its original fabric. This suggests that considering the solid part of these ghost regions as macro (bulk) pore space can result in the overestimation of porosity and permeability predicted from segmented X-ray tomographic images, or indeed from reactive transport models that assume a uniform, sharp reaction front at the grain surface.

Journal article

Gray F, Anabaraonye B, Shah S, Boek E, Crawshaw Jet al., 2018, Chemical mechanisms of dissolution of calcite by HCl in porous media: simulations and experiment, Advances in Water Resources, Vol: 121, Pages: 369-387, ISSN: 0309-1708

We use a pore-scale dissolution model to simulate the dissolution of calcite by HCl in two different systems and compare with experiment. The model couples flow and transport with chemical reactions at the mineral surface and in the fluid bulk. Firstly, we inject HCl through a single channel drilled through a solid calcite core as a simple validation case, and as a model system with which to elucidate the chemical mechanisms of the dissolution process. The overall dissolution rate is compared to a corresponding experiment. Close agreement with experimental and simulated dissolution rates is found, which also serves to validate the model. We also define a new form of effective Damkohler number which can be obtained from simulated chemical distributions, and show how this gives a more precise measure of the balance of transport and reaction. Secondly, we inject HCl into a Ketton carbonate rock core at high flow rate, which leads to wormhole formation, and compare to experiment. The simulation matches the experimental mass dissolution rate extracted from the micro-CT images, and predicts the resulting morphological changes reasonably well. The permeability change though is greater in the experiment than in the simulation, and this is shown to be due to more elongated wormhole formation in experiment. Possible reasons for this are discussed, including uncertainties in diffusion coefficients, and calcite density variations and micro-porosity in the Ketton grains. The distribution of chemical species from the simulation then permits a detailed understanding of the rate-controlling mechanisms at work, including the relative importance of the H+–calcite and H2CO3–calcite dissolution pathways.

Journal article

Inguva P, Teck A, Anabaraonye B, Chen W, Shah U, Lee-Lane D, Brechtelsbauer Cet al., 2018, Advancing experiential learning through participatory design, Education for Chemical Engineers, Vol: 25, Pages: 16-21, ISSN: 1749-7728

Participatory design (PD) as a module development tool offers significant potential to enhance experiential learning courses such as laboratory modules. Involvement of students and other stakeholders results in pre-delivery feedback on module design, implementation strategy, and teaching material. In this study, PD was employed for design and development of a systems control and reaction engineering laboratory project. The nature of stakeholder interaction at various levels was analysed and specific examples for how such an approach improved the development process is presented. Current students provided feedback on how the module was perceived by their peers and participated in developing solutions to make the learning process more inclusive. Senior students and graduate teaching assistants (GTAs) were able to contribute at a higher technical design level. Students were intellectually stimulated by the module design, enhancing the overall teaching and learning process.

Journal article

Peng C, Anabaraonye BU, Crawshaw JP, Maitland GC, Trusler JPet al., 2016, Kinetics of carbonate mineral dissolution in CO2-acidified brines at storage reservoir conditions., Faraday Discussions, Vol: 192, Pages: 545-560, ISSN: 1364-5498

We report experimental measurements of the dissolution rate of several carbonate minerals in CO2-saturated water or brine at temperatures between 323 K and 373 K and at pressures up to 15 MPa. The dissolution kinetics of pure calcite were studied in CO2-saturated NaCl brines with molalities of up to 5 mol kg(-1). The results of these experiments were found to depend only weakly on the brine molality and to conform reasonably well with a kinetic model involving two parallel first-order reactions: one involving reactions with protons and the other involving reaction with carbonic acid. The dissolution rates of dolomite and magnesite were studied in both aqueous HCl solution and in CO2-saturated water. For these minerals, the dissolution rates could be explained by a simpler kinetic model involving only direct reaction between protons and the mineral surface. Finally, the rates of dissolution of two carbonate-reservoir analogue minerals (Ketton limestone and North-Sea chalk) in CO2-saturated water were found to follow the same kinetics as found for pure calcite. Vertical scanning interferometry was used to study the surface morphology of unreacted and reacted samples. The results of the present study may find application in reactive-flow simulations of CO2-injection into carbonate-mineral saline aquifers.

Journal article

Kabalan M, Anabaraonye B, 2014, Solar Photovoltaic versus Micro -Hydroelectricity: A Framework for Assessing the Sustainability of Community-run Rural Electrification Projects, 4th annual IEEE Global Humanitarian Technology Conference (GHTC), Publisher: IEEE, Pages: 6-13, ISSN: 2377-6919

Conference paper

Crawshaw J, Gray F, Anabaraonye B, Shah Set al., Pore-Scale Observations of Reactive Transport During CO2 Storage in Carbonate Rocks by Experiment and Direct Numerical Simulation

Journal article

Anabaraonye B, Crawshaw J, Trusler JPM, Dissolution Kinetics of Carbonate Minerals in Co2-Acidified Brines: The Impacts of Brine Chemistry and Surface Contaminants

Journal article

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