Abdelaziz Omari - Academia.edu (original) (raw)

Papers by Abdelaziz Omari

All Days, Apr 11, 2016

Foam injection has been proven to be an efficient technique for EOR applications, stimulation ope... more Foam injection has been proven to be an efficient technique for EOR applications, stimulation operations and profile control. However, foam is known to have low stability and poor oil tolerance but adding polymer is reported to be an efficient way to improve such foam stability. An extensive study has been undertaken with different surfactants (foaming agents) and polymers to screen out the surfactant/polymer combinations providing the highest foam stability. We performed a systematic study consisting of static tests (foamability, stability) from which we selected two surfactants (nonionic and anionic) and two polymers (nonionic and associative polymer) expected to highly improve foam performances. Core-flood experiments were performed in high-permeability sandpacks in successive sequences starting with foam propagation, followed by a water flow and then an oil backflow. The Resistance Factor (RF) has been measured for each flow sequence. Based on our experiments, polymer-enhanced foams is shown to be a promising way for profile control during waterflood and recommendation of use of an associative polymer instead of a classical nonionic polymer is discussed.

Journal of Contaminant Hydrology, Mar 1, 2021

Foam can be used to achieve environmental remediation in case of contamination caused by light no... more Foam can be used to achieve environmental remediation in case of contamination caused by light non aqueous phase spills. However, when it comes in contact with oily pollutants, foam becomes weaker and its life time is greatly reduced. Such weakening can be dampened by using silica particles -together with saponin surfactant- which were shown to reinforce foam in bulk and 1D sandpack experiments. Here is addressed both foam propagation in a 2D porous media when buoyancy and gravity interfere, and foam behaviour when in contact with floating oil. Therefore, macroscopic foam displacement, and specific liquid and gas phases behaviours were studied in a 2D-tank. A piston-like displacement was observed during foam propagation in the absence of oil, while foam liquid phase was influenced by gravity and did not propagate homogeneously on entire tank height. In the presence of oil, foam was partly destroyed, which increased the local permeability of gas and created new preferential paths for gas flow. This effect was partially avoided via a surfactant concentration increase, but solid colloidal particles turned out to be a more efficient stabilizing agent, by significantly increasing foam strength and its oil-tolerance.

All Days, Feb 5, 2003

Two microgel samples were prepared by crosslinking an acrylamide-based terpolymer solution with a... more Two microgel samples were prepared by crosslinking an acrylamide-based terpolymer solution with a non-toxic zirconium crosslinker under controlled shear flow. The characteristics of these two microgel samples were determined by using different laboratory techniques in order to evaluate their performances for water shutoff or profile control operations. The microgel size was measured by Photon Correlation Spectroscopy (PCS) in dilute regime and at small scattering vector. As predicted by our theoretical model, microgel size decreases as the -1/3 power of applied shear rate. The size of these microgels is almost independent of pH, salinity and temperature in the domain investigated. Their mechanical and thermal stability is also satisfactory. In addition, such microgels can be easily injected into porous media without any sign of plugging. All these results suggest that these microgels should be good candidates for water shutoff and profile control operations. However, a further investigation is required to optimize their preparation to obtain the desired properties for a given application.

Summary One of the major issues of polymer flooding in EOR is the loss of polymer material during... more Summary One of the major issues of polymer flooding in EOR is the loss of polymer material during injection due to retention/adsorption and even the formation damage because of other mechanical phenomena. So, operating companies usually look for minimizing this polymer loss. To understand the retention of polymers in reservoir rocks, we carried out several core flood experimental studies by investigating the influence of rock nature and permeability (high and intermediate permeability considering Bentheimer and Berea sandstones), polymer molecular weight (low and high), and concentration of polymer solutions (from dilute to semi-dilute). Under monophasic conditions and high permeability, we show that the polymer retention if corrected for inaccessible pore volume (IPV) depends on polymer concentration regime: retention increases rapidly with polymer concentration (Cp), in the dilute regime and increases then very weakly in the semi-dilute regime. Moreover, the use of low polymer weight results in a high material loss, and in case of high molecular weight and low permeability, plugging is evidenced. Besides, diphasic tertiary experiments were performed under water-wet and intermediate wet conditions. The first set of experiments was performed on the native water-wet Bentehimer porous medium. The second set of experiments was performed by altering first the wettability of the same porous media, by submitting them to ageing in presence of crude oil. Our results mainly show that the polymer retention decreases when the oil is present in the porous system due to additional inaccessible pore volume as the added volume is now occupied by residual oil. However, the retention is even smaller in intermediate wet porous media because the pore surface is partially filled by oil. A phenomenological explanation is proposed that supports such observed behaviors.

An experimental study of polymer flooding is here presented focusing on the influence of initial ... more An experimental study of polymer flooding is here presented focusing on the influence of initial core wettability and flood maturity (volume of water injected before polymer injection) on final oil recovery. Experiments were carried out using homogeneous Bentheimer sandstones of similar properties. The cores were oil flooded using mineral oil for water wet conditions, and with crude oil (after an ageing period) for intermediate wet conditions keeping constant in all experiments the viscosity ratio between oil and polymer solution. Polymer, which is a partially hydrolysed polyacrylamide (HPAM) was used at a concentration of 2500ppm in a moderate salinity brine. The polymer solution was injected in the core at different maturity times (0PV, Breakthrough, 1PV, 1.75PV, 2.5PV, 4PV and 6.5PV). Coreflood results show that the maturity of polymer injection plays an important role on final oil recovery regardless wettability. The 0PV maturity (secondary polymer flooding) leads to the best sweep efficiency while final oil production decreases when the polymer flood maturity is high (late polymer injection after waterflooding). A difference of 15% in recovery is observed between secondary polymer flooding and late maturity (6.5 PV). Concerning the effect of wettability, the recovery factor obtained with water wet cores is always lower (from 10% to 20% depending on maturity) than the values obtained with intermediate wet cores, raising the importance of correctly restoring core wettability to obtain representative values of polymer incremental recovery. The influence of wettability can be explained by the oil phase distribution at the pore scale. Considering that the waterflooding period leads to different values of the oil saturation at which polymer flooding starts, we measured the core dispersivity using a tracer method at different states. The two-phase dispersivity decreases when water saturation increases which is favourable for polymer sweep. This study shows that in addition to wettability, maturity of polymer flooding plays a dominant role in oil displacement efficiency. Final recovery is correlated to the dispersion value at which polymer flooding starts. The highest oil recovery is obtained when the polymer is injected early.

Proceedings, Apr 24, 2017

The presence of polymer molecules in an altered wettability core and its possible interactions wi... more The presence of polymer molecules in an altered wettability core and its possible interactions with the solid phase is the subject of this study. Experiments were carried out in Bentheimer sandstone which wettability is altered by an ageing process. The wettability index after ageing (WI = 0.075) shows an intermediate wettability. After ageing we carried out spontaneous imbibition tests by putting in contact the core with brine or polymer solution (HPAM, C = 2500ppm) or in a sequence (first with brine and then with the polymer solution) For each experiment we measure the volume of oil recovered by spontaneous imbibition, this oil volume gives us an evaluation of the core wettability, the higher the recovered oil volume, the more water wet is the core. The experimental data show that final oil production by spontaneous imbibition is higher when the core was kept for a long time in contact with polymer solution rather than with brine. Moreover if the core is put in contact with polymer after having been immerged in brine, we notice a significant increment of produced oil. All these results confirm that the polymer has an interaction with the solid phase and makes the core more water wet.

Spe Journal, Dec 31, 2018

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de

The objective of this study is to simulate the transport and deposition of colloidal particles at... more The objective of this study is to simulate the transport and deposition of colloidal particles at the pore scale by means of computational fluid dynamics simulations (CFD). This consists in the three-dimensional numerical modeling of the process of transport and deposition of colloidal particles in a porous medium idealized as a bundle of capillaries of circular cross section. The velocity field obtained by solving the Stokes and continuity equations is superimposed to particles diffusion and particles are let to adsorb when they closely approach the solid wall. Once a particle is adsorbed the flow velocity field is updated before a new particle is injected. Our results show that both adsorption probability and surface coverage are decreasing functions of the particle’s Peclet number. At low Peclet number values when diffusion is dominant the surface coverage is shown to approach the Random Sequential Adsorption value while it drops noticeably for high Peclet number values. Obtained...

Journal of Petroleum Science and Engineering, 2018

Polymer addition to surfactant is known to enhance foam flood in porous media, however, the choic... more Polymer addition to surfactant is known to enhance foam flood in porous media, however, the choice of polymer type and its possible interactions with the surfactant is still a research concern. The objective of this paper is to compare the effect of different polymer types on foam generation and propagation in porous media. Two types of polymer, nonionic and associative, were used alone or with surfactant to evaluate their ability to generate and propagate a Polymer Enhanced Foam (PEF) in porous media. Foaming performance is evaluated by measuring the pressure drop during foam displacement and compared to the one phase gas flow through the Resistance Factor (RF gas). It appears clearly that if the RF gas is very low when injecting gas alone or along with PAM, its value increases significantly when gas is co-injected with surfactant solution alone but this increase is more marked when surfactant is mixed with polymer. PEF behavior depends strongly on polymer type, we show that amphiphilic polymer leads to stronger resistance than PAM due to interactions with surfactant, To interpret our experimental data, we present a pore scale scenario that sketches lamellae behavior and the interactions between surfactant and polymer that illustrates the core scale data.

All Days, 2005

The performances of new microgels specifically designed for water shutoff and conformance control... more The performances of new microgels specifically designed for water shutoff and conformance control were extensively investigated at laboratory scale. These microgels are preformed, stable, fully water soluble, size controlled with a narrow size distribution, and non-toxic. They reduce water permeability by forming adsorbed layers soft enough to be very easily collapsed by oil-water capillary pressure, so that oil permeability is not significantly affected. Since the manufacturing process of these new microgels make possible to vary chemical composition, size and crosslink density, they can be designed as desired to meet the requirements of a given field application. The laboratory results reported in this paper concerns mainly three microgel samples having significantly different crosslink densities. We describe the relevant laboratory methods used to determine main microgel characteristics. The microgels have remarkable mechanical, chemical and thermal stability. Their behavior in p...

The Canadian Journal of Chemical Engineering, 2015

Notre travail présente une étude expérimentale du dépôt de particules colloïdales dans un milieu ... more Notre travail présente une étude expérimentale du dépôt de particules colloïdales dans un milieu poreux consolidé, homogène et initialement saturé en eau. La phase fluide injectée dans le milieu poreux est une suspension de particules de latex dont la dimension est connue. L'influence de la force ionique de la suspension colloïdale et du débit d'injection sur le dépôt de particules est étudiée. On observe que le recouvrement de surface (u) croît avec la force ionique alors que le recouvrement de surface (u) décroît quand le nombre de Péclet augmente. Des mesures locales, par atténuation d'un rayonnement g, mettent en évidence la réduction de porosité due au dépôt de particules. La réduction de la perméabilité, mesurée en fin d'expérience.

The Journal of Physical Chemistry B, 2003

The reinforcement of regulations concerning environment protection in most countries is a strong ... more The reinforcement of regulations concerning environment protection in most countries is a strong incentive to use "green" cross-linkers for sol-gel processes. Among them, water soluble zirconium complexes seem attractive for various applications in the surface coatings , oil production, sol stabilization, and agriculture industries. Moreover, recent works demonstrated that a zirconium lactate-polyacrylate solution leads to the formation of size controlled microgels under shear flow. The speciation of zirconium, both in aqueous solutions (zirconium lactate) and in polymer gels (a terpolymer of acrylamide), was determined by combining X-ray absorption spectroscopy (XAS) and quantum mechanical calculations using density functional theory. XAS experiments were performed at the Zr-K-edge at the European Synchrotron Radiation Facility by using fluorescence detection in order to get results down to very low concentrations (37 ppm). The X-ray absorption near edge structure (XANES) results show that Zr is mainly surrounded by eight oxygens in the first coordination sphere, forming a dodecahedron. The analysis of extended X-ray absorption fine structure (EXAFS) spectra combined with quantum mechanical calculations results indicates that, in the concentrated zirconium lactate solutions (53300 ppm), which was found to be stable over years, the zirconium complexes are dimers ((Zr) 2 (lactate) 6) surrounded by six bidentate lactate ligands. As zirconium lactate concentration is decreased, the dimers condense first in cyclic tetramers (Zr 4 (lactate) X) and then in larger oligomers by tetramer association. In polyacrylamide microgels ([Zr]) 74 and 148 ppm) the Zr species remains dimers when gelation is completed at pH) 6, whereas tetramers are also observed at pH) 7. The XAS spectra were characterized by a very high signal-to-noise ratio, making possible to observe the gelation, i.e., the exchange of lactate by acrylate ligands.

Comptes Rendus Mécanique, 2009

Présenté par Michel Combarnous Résumé Cette Note se situe dans le cadre des études concernant le ... more Présenté par Michel Combarnous Résumé Cette Note se situe dans le cadre des études concernant le transport de colloïdes en milieux poreux, sujet qui concerne de nombreux domaines d'application tels que la contamination des eaux souterraines, le génie pétrolier ou le génie civil. Une étude expérimentale du dépôt de particules de Latex de polystyrène dans un milieu poreux artificiel consolidé est présentée. L'influence de la force ionique de la suspension colloïdale et du débit d'injection sur le dépôt de particules est étudiée. On observe que, au-delà d'une valeur critique, l'efficacité du collecteur (surface solide sur laquelle se déposent les particules) croît avec la force ionique alors que l'efficacité du collecteur décroît quand le débit d'injection augmente. Des mesures locales, par atténuation d'un rayonnement γ mettent en évidence la réduction de porosité due au dépôt de particules. Les épaisseurs de couches déposées, mesurées en fin d'expérience, correspondent à des structures de monocouches de particules déposées. Pour citer cet article : A.

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2013

Transport of a solid colloidal particle was simulated at the pore scale in presence of surface ro... more Transport of a solid colloidal particle was simulated at the pore scale in presence of surface roughness and particle/pore physicochemical interaction by adopting a "one fluid" approach. A code developed in our laboratory was used to solve equations of motion, while implementing additional modules in order to take into account lubrication and physicochemical forces. Particles were recognized through a phase indicator function and the particle/fluid interface position at each instant was obtained by solving a transport equation. Roughnesses of different shapes were considered and the magnitude of the particle/pore physicochemical interaction was monitored through the change of the ionic strength of the suspending fluid. We first show that if pore surface is smooth no retention of the transported particle occurs whether the particle/pore surface is attractive or repulsive. However for shape roughnesses of "peak" or "valley", particles may be retained inside pores or not depending on the considered ionic strength. In absence of particle retention, the residence time (the time needed for a particle to travel a characteristic pore distance) is finite and was found to be an increasing function of ionic strength for every considered roughness at fixed hydrodynamic conditions.

Etude du phenomene de depletion pres de la paroi pour des solutions de polymeres (polyacrylamide,... more Etude du phenomene de depletion pres de la paroi pour des solutions de polymeres (polyacrylamide, xanthane) ebn ecoulement dans des milieux poreux de taille comparable a celle des macromolecules. L'etude montre que l'epaisseur de la couche de depletion est une caracteristique intraseque du polymere

papers dealing with laboratory experiments or field operations confirm that, in some circumstance... more papers dealing with laboratory experiments or field operations confirm that, in some circumstances, low salinity waterflooding improves oil recovery. However, the basic mechanisms explaining the oil recovery improvement are not clearly established. The literature points out several hypotheses, among them is the role of clay particles detachment and migration. Experiments using an intermediate-wet clayey sandstone were first performed showing an oil recovery increment when the salinity of the injected brine was reduced. Following this trail, in a second set of batch experiments we investigated the role of microparticles on the formation and stability of brine/oil emulsions when the salinity is changed. For that, we used calibrated negatively charged polystyrene latex particles and several oils (mineral, crude and a blend of the two). Emulsion samples were observed using an optical microscope to determine their typical droplet size and the water/oil interface structure. The macroscopi...