Publications
295 results found
Lew JH, Hue KY, Matar O, et al., 2024, Atomic force microscopy and molecular dynamic simulation of adsorption of polyacrylamide with different chemistries onto calcium carbonate, Polymers, Vol: 16, ISSN: 2073-4360
This study investigates the interaction of polyacrylamide (PAM) of different functional groups (sulfonate vs. carboxylate) and charge density (30% hydrolysed vs. 10% hydrolysed) with calcium carbonate (CaCO3) via atomic force microscopy (AFM) and partly via molecular dynamic (MD) simulations. The PAM used were F3330 (30% hydrolysed), AN125 (25% sulfonated), and AN910 (% hydrolysed). A total of 100 ppm of PAMs was prepared in 0.1% NaCl, 3% NaCl, and 4.36% NaNO3 to be employed in AFM experiments, while oligomeric models (30 repeating units) of hydrolysed polyacrylamide (HPAM), sulfonated polyacrylamide (SPAM), and neutral PAM (NPAM) were studied on a model calcite surface on MD simulations. AFM analysis indicated that F3330 has a higher average adhesion and interaction energy with CaCO3 than AN125 due to the bulky sulfonate side group of AN125 interfering with SPAM adsorption. Steric repulsion of both PAMs was similar due to their comparable molecular weights and densities of the charged group. In contrast, AN910 showed lower average adhesion and interaction energy, along with slightly longer steric repulsion with calcite than F3330, suggesting AN910 adopts more loops and tails than the slightly flatter F3330 configuration. An increase in salt concentration from 0.1% to 3% NaCl saw a reduction in adhesion and interaction energy for F3330 and AN125 due to charge screening, while AN910 saw an increase, and these values increased further at 4.36% NaNO3. MD simulations revealed that the salt ions in the system formed salt bridges between PAM and calcite, indicating that the adhesion and interaction energy observed from AFM are likely to be the net balance between PAM charged group screening and salt bridging by the salt ions present. Salt ions with larger bare radii and smaller hydrated radii were shown to form stronger salt bridges.
Lew JH, Matar O, Muller E, et al., 2023, Atomic Force Microscopy of hydrolysed polyacrylamide adsorption onto calcium carbonate, Polymers, Vol: 15, ISSN: 2073-4360
In this work, the interaction of hydrolysed polyacrylamide (HPAM) of two molecular weights (F3330, 11–13 MDa; F3530, 15–17 MDa) with calcium carbonate (CaCO3) was studied via atomic force microscopy (AFM). In the absence of polymers at 1.7 mM and 1 M NaCl, good agreement with DLVO theory was observed. At 1.7 mM NaCl, repulsive interaction during approach at approximately 20 nm and attractive adhesion of approximately 400 pN during retraction was measured, whilst, at 1 M NaCl, no repulsion during approach was found. Still, a significantly larger adhesion of approximately 1400 pN during retraction was observed. In the presence of polymers, results indicated that F3330 displayed higher average adhesion (450–625 pN) and interaction energy (43–145 aJ) with CaCO3 than F3530’s average adhesion (85–88 pN) and interaction energy (8.4–11 aJ). On the other hand, F3530 exerted a longer steric repulsion distance (70–100 nm) than F3330 (30–70 nm). This was likely due to the lower molecular weight. F3330 adopted a flatter configuration on the calcite surface, creating more anchor points with the surface in the form of train segments. The adhesion and interaction energy of both HPAM with CaCO3 can be decreased by increasing the salt concentration. At 3% NaCl, the average adhesion and interaction energy of F3330 was 72–120 pN and 5.6–17 aJ, respectively, while the average adhesion and interaction energy of F3530 was 11.4–48 pN and 0.3–2.98 aJ, respectively. The reduction of adhesion and interaction energy was likely due to the screening of the COO− charged group of HPAM by salt cations, leading to a reduction of electrostatic attraction between the negatively charged HPAM and the positively charged CaCO3.
Hue KY, Lew JH, Myo Thant MM, et al., 2023, Molecular dynamics simulation of polyacrylamide adsorption on calcite, Molecules, Vol: 28, Pages: 1-17, ISSN: 1420-3049
In poorly consolidated carbonate rock reservoirs, solids production risk, which can lead to increased environmental waste, can be mitigated by injecting formation-strengthening chemicals. Classical atomistic molecular dynamics (MD) simulation is employed to model the interaction of polyacrylamide-based polymer additives with a calcite structure, which is the main component of carbonate formations. Amongst the possible calcite crystal planes employed as surrogates of reservoir rocks, the (1 0 4) plane is shown to be the most suitable surrogate for assessing the interactions with chemicals due to its stability and more realistic representation of carbonate structure. The molecular conformation and binding energies of pure polyacrylamide (PAM), hydrolysed polyacrylamide in neutral form (HPAM), hydrolysed polyacrylamide with 33% charge density (HPAM 33%) and sulfonated polyacrylamide with 33% charge density (SPAM 33%) are assessed to determine the adsorption characteristics onto calcite surfaces. An adsorption-free energy analysis, using an enhanced umbrella sampling method, is applied to evaluate the chemical adsorption performance. The interaction energy analysis shows that the polyacrylamide-based polymers display favourable interactions with the calcite structure. This is attributed to the electrostatic attraction between the amide and carboxyl functional groups with the calcite. Simulations confirm that HPAM33% has a lower free energy than other polymers, presumably due to the presence of the acrylate monomer in ionised form. The superior chemical adsorption performance of HPAM33% agrees with Atomic Force Microscopy experiments reported herein.
Contreras Araneda P, 2023, "Anaerobic Reactors: Specific Methanogenic Activity and Potential for Bioregeneration of Recalcitrant Compounds in Powdered Activated Carbon"
This work is focused on anaerobic reactors. The process is a complex syntrophic interaction between many different microorganisms to degrade organic compounds and obtain methane as final product; To determine the “health” of the reactor a Specific Methanogenic Activity (SMA) test is performed. Unfortunately, there is no standard for this test. Pharmaceutical Active Compounds have been appearing in effluents of wastewater treatment plants, becoming post-treatment with Activated Carbon a major area of interest, but becomes saturated and needs to be replaced; bioregeneration could be an economically feasible option to solve this issue.The aim of this work was to find the best SMA conditions to evaluate digester health and to study bioregeneration of PAC under anaerobic conditions.When testing SMA this work had better results using glucose as main carbon source rather than acetate, opposite from literature predictions. It also was found that no centrifugation was needed, indicated that possible some important cofactor was excreted by some microorganism. FISH showed a predominance of Methanosaeta in one inoculum.No results on PAC bioregeneration where found, but when less than 50 mgL-1 of diclofenac was used an increase of methane production was detected, since diclofenac was not degraded it could imply that supplies energy to methanogens.
Saha S, Luckham PF, Garbin V, 2023, Non-linear response of colloid monolayers at high-frequency probed by ultrasound-driven microbubble dynamics, JOURNAL OF COLLOID AND INTERFACE SCIENCE, Vol: 630, Pages: 984-993, ISSN: 0021-9797
Chadha D, Williams D, Lukham P, et al., 2022, Doing design differently: hybrid teaching in the age of Covid-19, American Society for Engineering Education Annual Meeting
Yesufu-Rufai S, Georgiadis A, van Wunnik J, et al., 2022, Influence of divalent ion concentration on the adhesion behaviour of sulfonate self-assembled monolayers (SAM), Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol: 648, Pages: 129415-129415, ISSN: 0927-7757
Surfactant-assisted oil recovery is usually employed for the production of residual oil after primary and secondary recovery techniques have been exhausted. The loss of injected surfactants via adsorption on to the porous media surfaces impede the efficiency of the procedure and greatly impact process economics. To address this issue, the choice of surfactant and aqueous fluid composition are varied. In particular, the divalent ion concentration is a property that potentially influences surfactant adsorption significantly. It is this aspect which has been addressed in this study. In this study, atomic force microscope (AFM). tips were functionalised with a self-assembled monolayer (SAM) of the alkanethiol, sodium 11-mercaptoundecanesulfonate (otherwise known as MUS) with the –SO3-headgroups oriented outwards towards the aqueous solutions, this is a model for the well-studied surfactant, sodium dodecyl sulfate, SDS. The adhesion forces between these “surfactant-functionalised” tips and Bandera Brown sandstone surfaces were measured in brine solutions of varying CaCl2 concentrations. Observations deviate from previous studies where adsorption of surfactant headgroups in the bulk solution is enhanced via Ca2+ bridging with the surface. Rather, measured adhesion forces decreased with increase in CaCl2 concentration. The results are reversible and also occurs in a reducing environment when the iron in the Bandera brown is reduced for iron (III) to iron (II). The observed behaviour is interpreted in terms of Ca2+ preferentially bridging between neighbouring headgroups on the tip due to the dense packing of molecules non-representative of respective bulk behaviours and acting as a barrier to adhesive contact. Thus, this supposed micellization at the tip aided by the formation of Ca2+ salt bridges between alternate headgroups more closely mimics a surfactant micelle, rather than dispersed individual monomers. The findings of this study provide insight into
Ekanem EM, Berg S, De S, et al., 2022, Towards predicting the onset of elastic turbulence in complex geometries, Transport in Porous Media, Vol: 143, ISSN: 0169-3913
Flow of complex fluids in porous structures is pertinent in many biological and industrial processes. For these applications, elastic turbulence, a viscoelastic instability occurring at low Re—arising from a non-trivial coupling of fluid rheology and flow geometry—is a common and relevant effect because of significant over-proportional increase in pressure drop and spatio-temporal distortion of the flow field. Therefore, significant efforts have been made to predict the onset of elastic turbulence in flow geometries with constrictions. The onset of flow perturbations to fluid streamlines is not adequately captured by Deborah and Weissenberg numbers. The introduction of more complex dimensionless numbers such as the M-criterion, which was meant as a simple and pragmatic method to predict the onset of elastic instabilities as an order-of-magnitude estimate, has been successful for simpler geometries. However, for more complex geometries which are encountered in many relevant applications, sometimes discrepancies between experimental observation and M-criteria prediction have been encountered. So far these discrepancies have been mainly attributed to the emergence from disorder. In this experimental study, we employ a single channel with multiple constrictions at varying distance and aspect ratios. We show that adjacent constrictions can interact via non-laminar flow field instabilities caused by a combination of individual geometry and viscoelastic rheology depending (besides other factors) explicitly on the distance between adjacent constrictions. This provides intuitive insight on a more conceptual level why the M-criteria predictions are not more precise. Our findings suggest that coupling of rheological effects and fluid geometry is more complex and implicit and controlled by more length scales than are currently employed. For translating bulk fluid, rheology determined by classical rheometry into the effective behaviour in complex porous geometries re
Lew JH, Matar OK, Müller EA, et al., 2022, Adsorption of hydrolysed polyacrylamide onto calcium carbonate, Polymers, Vol: 14, Pages: 405-405, ISSN: 2073-4360
Carbonate rock strengthening using chemical techniques is a strategy to prevent excessive fines migration during oil and gas production. We provide herein a study of the adsorption of three types of hydrolysed polyacrylamide (HPAM) of different molecular weight (F3330S, 11–13 MDa; F3530 S, 15–17 MDa; F3630S, 18–20 MDa) onto calcium carbonate (CaCO3) particles via spectrophotometry using a Shimadzu UV-2600 spectrometer. The results are compared to different adsorption isotherms and kinetic models. The Langmuir isotherm shows the highest correlation coefficient (R2 > 0.97) with equilibrium parameters (RL) ranging between 0 and 1 for all three HPAMs, suggesting a favorable monolayer adsorption of HPAM onto CaCO3. The adsorption follows pseudo-second order kinetics, indicating that the interaction of HPAM with CaCO3 is largely dependent on the adsorbate concentration. An adsorption plot reveals that the amount of HPAM adsorbed onto CaCO3 at equilibrium increases with higher polymer molecular weight; the equilibrium adsorbed values for F3330S, F3530S and F3630S are approximately 0.24 mg/m2, 0.31 mg/m2, and 0.43 mg/m2, respectively. Zeta potential analysis shows that CaCO3 has a zeta potential of +12.32 mV, which transitions into negative values upon introducing HPAM. The point of zero charge (PZC) is observed at HPAM dosage between 40 to 50 ppm, in which the pH here lies between 9–10.
Ekanem EM, Rücker M, Yesufu-Rufai S, et al., 2021, Novel adsorption mechanisms identified for polymer retention in carbonate rocks, JCIS Open, Vol: 4, Pages: 100026-100026, ISSN: 2666-934X
HypothesisHigh molecular weight polymers are widely used in oilfield applications, such as in chemical enhanced oil recovery (cEOR) technique for hydrocarbon recovery. However, during flow in a porous rock, polymer retention is usually a major challenge, as it may result in the decrease of polymer concentration or lead to plugging of pores with significant permeability reduction and injectivity loss. Hence, an understanding of the retention mechanisms will have a profound effect in optimizing the process of polymer flooding, in particular, for carbonate rocks, which hold more than half of the world's oil reserves. Therefore, in this study, the retention of hydrolysed polyacrylamide (HPAM) polymer, a commonly used chemical for EOR, is investigated during flow in Estaillades carbonate rock.ExperimentsA novel approach of investigating HPAM retention in Estaillades carbonate rock was carried out using Atomic force microscopy (AFM). Since Estaillades carbonate rock is ∼98% calcite, HPAM retention was first characterised on a cleaved flat calcite mineral surface after immersing in HPAM solution. Afterwards, HPAM was flooded in Estaillades carbonate to observe the effect of flow dynamics on the retention mechanisms.FindingsWe find that the dominant mechanism for retention of HPAM on calcite after fluid immersion is polymer adsorption, which we believe is driven by the electrostatic interaction between the calcite surface and the solution. The thickness of the adsorbed layer on calcite is beyond 3 nm suggesting it is not adsorbed only flat on the surface. Different types of adsorbed layers were formed representing trains, and the more extended loops or tails with the largest polymer layer thickness about 35 nm, representing the longer loops or tails. Layers of this thickness will begin to impair the permeability of the rock. However, in Estaillades, thicker adsorbed layers are observed in different regions of the rock surface ranging between 50 and 350 nm. We suggest
Luckham PF, 2021, Powders—A New Open Access Journal for Powder and Particle Studies, Powders, Vol: 1, Pages: 1-2
<jats:p>Powders and particles are ubiquitous in our daily lives and are of course present in variety of diverse products and in the majority of industries; thus, the functionality of powders is very diverse [...]</jats:p>
Armstrong RT, Sun C, Mostaghimi P, et al., 2021, Multiscale Characterization of Wettability in Porous Media, TRANSPORT IN POROUS MEDIA, Vol: 140, Pages: 215-240, ISSN: 0169-3913
- Author Web Link
- Cite
- Citations: 30
Butler EL, Reid B, Luckham PF, et al., 2021, Interparticle Forces of a Native and Encapsulated Metal-Organic Framework and Their Effects on Colloidal Dispersion, ACS APPLIED MATERIALS & INTERFACES, Vol: 13, Pages: 45898-45906, ISSN: 1944-8244
- Author Web Link
- Cite
- Citations: 2
Savulescu GC, Rücker M, Scanziani A, et al., 2021, Atomic force microscopy for the characterisation of pinning effects of seawater micro-droplets in n-decane on a calcite surface, Journal of Colloid and Interface Science, Vol: 592, Pages: 397-404, ISSN: 0021-9797
Hypothesis: Roughness is an important parameter in applications where wetting needs to be characterized. Micro-computed tomography is commonly used to characterize wetting in porous media but the main limitation of this approach is the incapacity to identify nanoscale roughness. Atomic force microscopy, AFM, however, has been used to characterize the topography of surfaces down to the molecular scale. Here we investigate the potential of using AFM to characterize wetting behavior at the nanoscale.Experiments: Droplets of water on cleaved calcite under decane were imaged using quantitative imaging QI atomic force microscopy where a force-distance curve is obtained at every pixel.Findings: When the AFM tip passed through the water droplet surface, an attraction was observed due to capillary effects, such that the thickness of the water film was estimated and hence the profile of the droplet obtained. This enables parameters such as the contact angle and contact angle distribution to be obtained at a nanometer scale. The contact angles around the 3-phase contact line are found to be quasi-symmetrically distributed between 10–30°. A correlation between the height profile of the surface and contact angle distribution demonstrates a quasi-proportional relationship between roughness on the calcite surface and contact angle.
Yesufu-Rufai S, Georgiadis A, Berg S, et al., 2021, NANOSCALE ASSESSMENT OF SANDSTONE WETTABILITY DURING REDOX TREATMENT BY ATOMIC FORCE MICROSCOPY (AFM), Pages: 1117-1121
A key step in de-risking chemical enhanced oil recovery (cEOR) projects is to assess the incremental recovery for the field of interest in customised laboratory experiments that mimic conditions within target reservoirs. Any deviation from these conditions, as is oftentimes the case, leads to discrepancies which call the reliability of laboratory results into question, thereby affecting the economics of the cEOR projects. Concerning iron-bearing formations, one approach is to treat samples with a reducing fluid in order to mimic native reservoir redox conditions. In this study, investigations into the effect of a solution of the reducing agent, Sodium Dithionite, in brine on surface wettability were performed using Atomic Force Microscopy (AFM) to quantify interactions between model crude oil components and an iron-bearing sandstone under varying redox conditions. Results show that the adhesion of the oil components to the sandstone surface decreased in the order -NH2 (~70%) > -COOH (~36%) > -CH3 (~3%) on introduction of the reducing fluid, potentially providing a basis for deployment in core floods to ascertain the suitability of cEOR procedures.
Wang K, Jiang G, Li X, et al., 2020, Study of graphene oxide to stabilize shale in water-based drilling fluids, Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol: 606, ISSN: 0927-7757
Wellbore instability frequently occurs in shale formation when water-based drilling fluids (WBDFs) are used. To mitigate and avoid the wellbore instability of shale formation, graphene oxide (GO) was used to plug the nano-sized pores, to inhibit water invasion into shale, and to prevent clay minerals of shale swelling. The GO was prepared and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The linear swelling tests, filtration experiments, imbibition tests and uniaxial compressive strength measurements were conducted to systematically evaluate the protection of GO sheets on shale. Meanwhile, other commonly used shale inhibitors and nanomaterials (nano-silica) were compared with the GO. The results indicated that GO exhibited an improved performance on preventing clay minerals from swelling, plugging nano-sized and micron-sized pores, inhibiting water invasion into the interior of the shale core, and maintaining the shale strength, compared to the commonly used inhibitors. The GO sheets form the large and unbroken film to protect the shale, and the soft and flexible GO sheets can easily deform to plug and fill the different shapes of shale pores. Therefore, GO displays great potential to protect and stabilize shale in WBDFs.
Yesufu-Rufai S, Rucker M, Berg S, et al., 2020, Assessing the wetting state of minerals in complex sandstone rock in-situ by Atomic Force Microscopy (AFM), Fuel, Vol: 273, Pages: 1-11, ISSN: 0016-2361
Low salinity waterflooding is a low-cost method of enhancing oil recovery although, no consistent concept has been established explaining why some oil-fields show an increase in oil production when the salinity of the injected brine is reduced, while others do not. Various studies were conducted investigating the underlying mechanisms of the ‘low salinity effect’ using different crude oil, brine and rock compositions. Core floods of sandstone rock and analyses of molecular interactions using model systems indicate that clay content may play a dominant role. However, the spatial configuration of the sheet-like clay particles, which may vary from rock to rock, complicate comparisons of these model scenarios with reality.In the present study, we report the development of a pre-screening method using Atomic Force Microscopy (AFM) to assess rock-fluid interactions, which has previously only been used either on artificial model systems or minerals from crushed rock, by exploring the capability to operate in-situ in complex rock without crushing. The orientation of clay particles within a pore of an outcrop sandstone, Bandera Brown, was investigated with AFM and these particles were further assessed for changes in adhesion in brines of differing salinity. The results show a decrease in adhesions between CH3-functionalised AFM tips and the rock surface in low salinity brine, predominantly at the clay edges. This demonstrates that the edges of the clay particles, which may pin the oil phase after wettability alteration and therewith prevent oil from getting produced, lose this capacity when exposed to low salinity brine.
Xiong R, Zhang Y, Zhou W, et al., 2020, Chemical activation of carbon materials for supercapacitors: Elucidating the effect of spatial characteristics of the precursors, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, Vol: 597, ISSN: 0927-7757
- Author Web Link
- Cite
- Citations: 2
Yesufu-Rufai S, Marcelis F, Georgiadis A, et al., 2020, Atomic Force Microscopy (AFM) study of redox conditions in sandstones: Impact on wettability modification and mineral morphology, Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol: 597, Pages: 1-10, ISSN: 0927-7757
Laboratory core flood experiments performed to establish chemical enhanced oil recovery (cEOR) procedures often make use of rock samples that deviate from prevailing conditions within the reservoir. These samples have usually been preserved in an uncontrolled oxidising environment in contrast to reducing reservoir conditions, a discrepancy that affects rock wettability and thus oil recovery. The use of a reducing fluid is a predominant method, particularly regarding iron-bearing minerals, for restoring these samples to representative redox states.In this study, the adhesion of polar (NH2 and COOH) and non-polar (CH3) crude oil components to the pore surfaces of Bandera Brown, an outcrop of similar mineralogy to reservoir sandstones, was investigated using Atomic Force Microscopy to determine the potential of a reducing fluid of Sodium Dithionite in seawater to alter surface wettability. This novel workflow for the observation of redox condition effects illuminates the nanoscopic interaction forces at the rock/fluid interface responsible this phenomenon.The results obtained show that adhesion forces between the oil components and the Bandera Brown surface after treatment with the reducing fluid decreased in the order: NH2 (∼70 %) >COOH (∼36 %) >CH3 (∼3 %), due to diminishing affinity of the surface for the polar functional groups when the oxidation state of iron was altered from iron III to iron II. The morphology of Bandera Brown is noted to be affected as well with some dissolution of the mineral composition within cemented pores observed.The results demonstrate that redox state is indeed important for the assessment of wetting properties of surfaces as measurements performed in oxidising environments may not be representative of reservoir reducing conditions. Also, complete reduction of iron oxides on the mineral surfaces seems unlikely without altering the prevailing pore structure. These findings have relevance not only in EOR cases but can fin
Wang T, Yang L, Jiang G, et al., 2020, Enhanced foam-stabilizing performance by the addition of clays: A comparison of magnesium aluminum silicate with sodium bentonite, Applied Clay Science, Vol: 189, Pages: 1-12, ISSN: 0169-1317
High-temperature-resistant foam stabilizers are desperately required for high-temperature conditions, such as in geothermal wells. In this study, nano‑magnesium aluminum silicate (NMAS) and micro‑magnesium aluminum silicate (MMAS) particles have been studied and compared with sodium bentonite (Na-Bent) as high-temperature-resistant foam stabilizers. It is found that increasing the temperature could facilitate aggregation of clay dispersion, and the increase of particle size results in significant positive effect on apparent viscosity, interface dilational modulus, foam film thickness, and eventually drainage half-life (T0.5) of the foam. Simultaneously, it leads to a negative impact on the initial foam volume (V0) and foam diameter. Moreover, NMAS even possesses excellent foam stabilization effect after being aged at 320 °C for 16 h that it could still dramatically extend T0.5 to 9.78 h, compared to 45.52 and 13.78 min for MMAS and Na-Bent, respectively. Furthermore, V0 of Na-Bent-stabilized foam cannot resist the influence of NaCl and CaCl2 even when only 1.0 wt% NaCl or 0.1 wt% CaCl2 is added. By comparison, V0 of NMAS- and MMAS-stabilized foam drilling fluids are comparatively insensitive to NaCl and CaCl2 until the concentration of 3.0 wt% and 0.2 wt%, respectively. Not only has this study provided a guideline for using clay minerals as foam stabilizers under various high-temperature conditions, but we have also discovered an outstanding high-temperature-resistant foam stabilizer, NMAS, which produces an excellent foam-stabilizing performance even at temperatures as high as 320 °C.
Reinoso D, Martín-Alfonso MJ, Luckham PF, et al., 2020, Flow behavior and thermal resistance of xanthan gum in formate brine, Journal of Petroleum Science and Engineering, Vol: 188, Pages: 1-9, ISSN: 0920-4105
Drilling and completion operations in HP/HT environments demand the use of environmentally friendly fluids with suitable properties such as solid-free high-density and pseudoplastic behavior. Xanthan gum solutions in different brines may be an interesting alternative to ensure a suitable thermo-rheological behavior and biodegradability. Nevertheless, xanthan exposed at high temperature experiences thermal degradation that can modify the flow properties over time and limits the ceiling temperature of oilfield applications. To gain insight on this issue, this paper characterizes the flow behavior of low concentration XT solutions in calcium and potassium brines, evaluating the effect that potassium formate exerts on both the flow properties and the resistance to thermal degradation of xanthan solutions as a function of the biopolymer concentration. Xanthan in formate brine retains the pseudoplastic behavior up to 190 °C, however, low concentrate solutions undergo a thermal degradation that decreases the recovery of pseudoplasticity after being exposed to high temperature.
Ekanem EM, Berg S, De S, et al., 2020, Signature of elastic turbulence of viscoelastic fluid flow in a single pore throat, Physical Review E: Statistical, Nonlinear, and Soft Matter Physics, Vol: 101, Pages: 042605 – 1-042605 – 14, ISSN: 1539-3755
When a viscoelastic fluid, such as an aqueous polymer solution, flows through a porous medium, the fluid undergoes a repetitive expansion and contraction as it passes from one pore to the next. Above a critical flow rate, the interaction between the viscoelastic nature of the polymer and the pore configuration results in spatial and temporal flow instabilities reminiscent of turbulentlike behavior, even though the Reynolds number Re≪1. To investigate whether this is caused by many repeated pore body–pore throat sequences, or simply a consequence of the converging (diverging) nature present in a single pore throat, we performed experiments using anionic hydrolyzed polyacrylamide (HPAM) in a microfluidic flow geometry representing a single pore throat. This allows the viscoelastic fluid to be characterized at increasing flow rates using microparticle image velocimetry in combination with pressure drop measurements. The key finding is that the effect, popularly known as “elastic turbulence,” occurs already in a single pore throat geometry. The critical Deborah number at which the transition in rheological flow behavior from pseudoplastic (shear thinning) to dilatant (shear thickening) strongly depends on the ionic strength, the type of cation in the anionic HPAM solution, and the nature of pore configuration. The transition towards the elastic turbulence regime was found to directly correlate with an increase in normal stresses. The topology parameter, Qf, computed from the velocity distribution, suggests that the “shear thickening” regime, where much of the elastic turbulence occurs in a single pore throat, is a consequence of viscoelastic normal stresses that cause a complex flow field. This flow field consists of extensional, shear, and rotational features around the constriction, as well as upstream and downstream of the constriction. Furthermore, this elastic turbulence regime, has high-pressure fluctuations, with a power-law decay ex
Rücker M, Bartels W-B, Bultreys T, et al., 2020, Workflow for upscaling wettability from the nano- to core-scales, International Symposium of the Society of Core Analysts
Rucker M, Bartels W-B, Garfi G, et al., 2020, Relationship between wetting and capillary pressure in a crude oil/brine/rock system: From nano-scale to core-scale, Journal of Colloid and Interface Science, Vol: 562, Pages: 159-169, ISSN: 0021-9797
HypothesisThe wetting behaviour is a key property of a porous medium that controls hydraulic conductivity in multiphase flow. While many porous materials, such as hydrocarbon reservoir rocks, are initially wetted by the aqueous phase, surface active components within the non-wetting phase can alter the wetting state of the solid. Close to the saturation endpoints wetting phase fluid films of nanometre thickness impact the wetting alteration process. The properties of these films depend on the chemical characteristics of the system. Here we demonstrate that surface texture can be equally important and introduce a novel workflow to characterize the wetting state of a porous medium.ExperimentsWe investigated the formation of fluid films along a rock surface imaged with atomic force microscopy using ζ-potential measurements and a computational model for drainage. The results were compared to spontaneous imbibition test to link sub-pore-scale and core-scale wetting characteristics of the rock.FindingsThe results show a dependency between surface coverage by oil, which controls the wetting alteration, and the macroscopic wetting response. The surface-area coverage is dependent on the capillary pressure applied during primary drainage. Close to the saturation endpoint, where the change in saturation was minor, the oil-solid contact changed more than 80%.
Russell AW, Kahouadji L, Mirpuri K, et al., 2019, Mixing viscoplastic fluids in stirred vessels over multiple scales: An experimental and CFD approach, Chemical Engineering Science, Vol: 208, ISSN: 1873-4405
Dye visualisation techniques and CFD are used to characterise the flow of viscoplastic CarbopolTM solutions in stirred vessel systems over multiple scales. Centrally-mounted, geometrically-similar Rushton turbine (RT) impellers are used to agitate various Carbopol 980 (C980) fluids. The dimensionless cavern diameters, Dc/D, are scaled against a combination of dimensionless parameters: Rem-0.3Rey0.6n-0.1ks-1, where Rem, Rey, n and ks are the modified power-law Reynolds number, yield stress Reynolds number, flow behaviour index and impeller geometry constant, respectively. Excellent collapse of the data is demonstrated for the fluids and flows investigated. Additional data are collected using a pitched-blade turbine (PBT) with cavern size similarity being shown between the RT and PBT datasets. These results are important in the context of scale-up/scale-down mixing processes in stirred vessels containing complex fluids and can be used to show that flow similarity can be achieved in these systems if the processes are scaled appropriately.
Shaffee SNA, Luckham PF, Matar OK, et al., 2019, Numerical investigation of sand-screen performance in the presence of adhesive effects for enhanced sand control, SPE Journal, Vol: 24, Pages: 2195-2208, ISSN: 1086-055X
In many industrial processes, an effective particle-filtration system is essential for removing unwanted solids. The oil and gas industry has explored various technologies to control and manage excessive sand production, such as by installing sand screens or injecting consolidation chemicals in sand-prone wells as part of sand-management practices. However, for an unconsolidated sandstone formation, the selection and design of effective sand control remains a challenge. In recent years, the use of a computational technique known as the discrete-element method (DEM) has been explored to gain insight into the various parameters affecting sand-screen-retention behavior and the optimization of various types of sand screens (Mondal et al. 2011, 2012, 2016; Feng et al. 2012; Wu et al. 2016).In this paper, we investigate the effectiveness of particle filtration using a fully coupled computational-fluid-dynamics (CFD)/DEM approach featuring polydispersed, adhesive solid particles. We found that an increase in particle adhesion reduces the amount of solid in the liquid filtrate that passes through the opening of a wire-wrapped screen, and that a solid pack of particle agglomerates is formed over the screen with time. We also determined that increasing particle adhesion gives rise to a decrease in packing density and a diminished pressure drop across the solid pack covering the screen. This finding is further supported by a Voronoi tessellation analysis, which reveals an increase in porosity of the solid pack with elevated particle adhesion. The results of this study demonstrate that increasing the level of particle agglomeration, such as by using an adhesion-promoting chemical additive, has beneficial effects on particle filtration. An important application of these findings is the design and optimization of sand-control processes for a hydrocarbon well with excessive sand production, which is a major challenge in the oil and gas industry.
Yang L, Wang T, Yang X, et al., 2019, Highly stabilized foam by adding amphiphilic Janus particles for drilling a high-temperature and high-calcium geothermal well, Industrial and Engineering Chemistry Research, Vol: 58, Pages: 9795-9805, ISSN: 0888-5885
Fabricating Janus particles that consist of two distinct functional regions is an intriguing research topic. In this study, wax colloidosomes were successfully prepared by the Pickering emulsion method. After hydrophilic modification with an amino-containing silane agent and separate hydrophobic modification with several silane coupling agents with different carbon chain lengths, a series of Janus particles that differed in their hydrophilic lipophilic balance were facilely fabricated. The results show that the (3-aminopropyl)triethoxysilane-SiO2-dodecyltrimethoxysilane (NH2-SiO2-12C) Janus particles possess the best foam stability. As a result of their suitable contact angle of 80°, high positive ζ-potential, and good surface activity, these foams display the characteristics of low surface tension, high dilational elasticity, nonspherical shapes, large sizes, and thick films, which together result in the extension of the drainage half-life of the foam from 448 to 778 s in comparison with the foam of pure foaming agent solutions. Moreover, compared with a foam with no stabilizer or those stabilized by a soluble foam stabilizer and homogeneous hydrophobic-modified silica particles, NH2-SiO2-12C-stabilized foam can extend the drainage half-life to 668 s after hot rolling for 16 h at 280 °C and resist a CaCl2 concentration of 0.8 wt %. Benefiting from their excellent thermal stability and salt tolerance, these Janus particles are expected to be promising candidates for use as foam stabilizers in high-temperature and high-calcium conditions, including drilling, enhanced oil recovery, “waterless” fracturing, and, especially, in geothermal wells.
Yang L, Yang X, Wang T, et al., 2019, Effect of Alkyl Chain Length on Shale Hydration Inhibitive Performance of Vinylimidazolium-Based Ionic Liquids, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, Vol: 58, Pages: 8565-8577, ISSN: 0888-5885
Yasin S, Shakeel A, Iqbal T, et al., 2019, Effect of experimental conditions on nano-indentation response of low density polyethylene (LDPE), JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY, Vol: 56, Pages: 640-647, ISSN: 1060-1325
Leivers M, Seddon JM, Declercq M, et al., 2019, Measurement of forces between supported cationic bilayers by colloid probe atomic force microscopy: electrolyte concentration and composition, Langmuir, Vol: 35, Pages: 729-738, ISSN: 0743-7463
The interactions between supported cationic surfactant bilayers were measured by colloidal probe atomic force spectroscopy and the effect of different halide salts was investigated. Di(alkyl iso-propyl ester) dimethyl ammonium methylsulfate (DIPEDMAMS) bilayers were fabricated by the vesicle fusion technique on muscovite mica. The interactions between the bilayers were measured in increasing concentrations of NaCl, NaBr, NaI and CaCl2. In NaCl the bilayer interactions were repulsive at all concentrations investigated, and the Debye length and surface potential were observed to decrease with increasing concentration. The interactions were found to follow the Electrical Double Layer (EDL) component of DLVO theory well. However Van der Waals forces were not detected, instead a strong hydration repulsion was observed at short separations. CaCl2 had a similar effect on the interactions as NaCl. NaBr and NaI were observed to be more efficient at decreasing the surface potential than the chloride salts, with the efficacy increasing with the ionic radius.
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.