Comparative Analysis of the Effects of Monovalent and Divalent Ions on Imported Biopolymer-Xanthan Gum and Locally Formulated Biopolymers-Gum Arabic and Terminalia Mantaly

Aim: Polymer flooding is used for enhanced oil recovery. Only polymers that can withstand harsh environments work best. HPAM is mostly the polymer used for enhanced oil recovery because it is available and cheap, but it does not withstand high temperatures and high salinity reservoirs. Xanthan Gum withstands high temperatures and high salinity reservoirs, but it is expensive and plugs the reservoir. The aim of this study is to compare the salinity stability of gum Arabic and Terminalia Mantaly, a novel biopolymer, with commercial Xanthan gum. Study Design: Locally formulated biopolymers from gum Arabic exudates bought from Bauchi State in Nigeria and from Terminalia Mantaly exudates obtained from the University of Port Harcourt. The appropriate rheological tests were carried out at the laboratory. Place and Duration of Study: The laboratory experiments were carried out at the department of Petroleum Engineering, Covenant University, Ota in Ogun State of Nigeria between 2020 and 2021. Methodology: The gum Arabic, Terminalia Mantaly and Xanthan Gum powders were dissolved in deionized water to get various concentrations in ppm. The polymers were mixed and kept for 24 hours to achieve a homogenous solution. The Automated OFITE® Viscometer at different revolutions per minute (RPM) of 3 (Gel), 6, 30, 60, 100, 200, 300, and 600 was used to measure the rheological properties of the various concentrations before Sodium Chloride (NaCl) and Calcium Chloride (CaCl2) of various concentrations were added and allowed to hydrate for another 24 hours before measuring their rheological properties again. Results: The study showed that Xanthan Gum, Gum Arabic, and Terminalia Mantaly biopolymers can be used in high salinity reservoirs. Terminalia Mantaly, a novel biopolymer, is insensitive to salinity in monovalent and divalent ions. Conclusion: Xanthan gum exhibited high viscosity even at low concentrations. Gum Arabic exhibited good tolerance to salinity at NaCl 3.5%. Terminalia Mantaly was very stable with both monovalent and divalent ions. Divalent ions have more effects on polymers than monovalent ions in reservoirs. Recommendation: It is recommended that Terminalia Mantaly be investigated more, as it can replace imported biopolymers for Enhanced Oil Recovery (EOR).

Propagation of Nano Sized CDG Deep into Porous Media

Enhanced Oil Recovery (EOR) technologies become more critical as number of mature oilfields grows continually. Among the variety of chemical EOR methods, conventional application of the polymer-based solutions occupies the largest space. One of the most perspective technologies is application of polymeric fluids that do not contain a 3D polymer structure. Among such compositions, colloid dispersion systems are especially worth mentioning as they could be simultaneously used for water-oil mobility ratio control as well as permeability profile modification. Presented study considers the propagation of colloidal dispersed gels in porous media under different mineralization of formation water. For this purpose were conducted rheological measurements, Particle size distribution and Propagation experiments. The results show that divalent ions cause higher viscosity reduction due to the formation a more severe electrolyte and average particle size decreased with ionic strength increment. The presence of divalent ions improves the propagation probably by cause of repulsion forces increase.

Molecular Properties of Ca2+ Transport Through TRPV2 Channel: A Molecular Dynamic Simulations Study

TRPV channels are a category of nonselective cation channels that activated by heat and ligands, and permeate monovalent and divalent ions. The mechanism of Ca2+ transfer through TRPV2 channel is not well known. Here, we investigated the reaction coordination and energy fluctuation of Ca2+ transition in TRPV2 channel by steered molecular dynamics (SMD) simulations and potential of mean force (PMF) calculation. Results showed that electrostatic interactions between Ca2+ and residues of the first and second gates had main roles in ions transfer through the channel, and also, we recognized important amino acids in this path. Moreover, results indicated that enter and exit of calcium ions needed to overcome barrier energies in first and second gates.

Surface Complexation Modelling of Potential Determining Ions Sorption on Oil/Brine and Brine/Rock Interfaces

Previous studies on smart water effects have suggested wettability alteration as the most significant mechanism for additional oil recovery during smart water injection. Though many other mechanisms have been observed and proposed in several other studies, much more attention is paid to the detachment of oil films from rock surfaces. It is, however, clear from prevailing understanding that the activities at oil/brine interfaces might require as much attention as given to the brine/rock interfaces. This paper presents diffuse double layer surface complexation modelling of the adsorption of potential determining (Ca2+, Mg2+ and SO42-) ions on oil carboxylic and carbonate surfaces. Surface complexation models are developed by defining the adsorption sites, surface area and mass of the oil and carbonate surfaces. The chemical reactions involving the surface sites and five different brine solutions are also defined. The brine solutions include formation water, sea water, sea water diluted 20 and 50 times, and sea water with four times SO42- concentration. The amount of the divalent ions adsorbed at pH range of 5 to 8 are determined after the reactions had reached equilibrium. Adsorption of the ions on oil carboxylic and carbonate surfaces at elevated temperature for the sea water is also investigated. Results show that significant number of divalent ions are collected at the oil/brine interfaces just as adsorbed at the brine/rock interfaces. The results suggest that the equilibrium reactions and the dynamics at the two mathematical interfaces in any oil/brine/rock systems are equally important to reach a full understanding of the main mechanisms behind smart water effects. Therefore, the dynamics of ionic reactions at the oil/brine interface can play critical roles in defining smart water effects on residual oil mobilization.

Unexpectedly efficient ion desorption of graphene–based materials

Ion desorption is extensive and extremely challenging for adsorbents with superior performance, for which conventional desorption methods involving high acid or base concentrations and large consumption of reagents are widely used. Here we experimentally demonstrated the unexpectedly rapid and efficient desorption of ions on magnetite–graphene oxide (M–GO) by adding trace amounts of Al3+. The corresponding concentration of Al3+ used was reduced by a factor of at least 250 compared with the conventional desorption method. The desorption rate reached up to ~ 97.0% for the typical radioactive and bivalent ions of Co2+, Mn2+, and Sr2+ within ~ 1 min. Importantly, we achieved the effective enrichment of radioactive 60Co, with the volume of the concentrated 60Co solution reduced by approximately 10 times compared with the initial solution. Density functional theory calculations revealed that the interaction of graphene with Al3+ was much stronger than that with divalent ions, yielding the adsorption probability of Al3+ superior to Co2+, Mn2+, and Sr2+ ions, suggesting that the proposed method could be used to enrich a wider range of ions in the fields of energy, biology, environment, and materials science.