Gulf Seawater Research Articles

Eco-Friendly Superhydrophobic Modification of Low-Cost Multi-Layer Composite Mullite Base Tubular Ceramic Membrane for Water Desalination

This study aimed to investigate and develop a cost-effective and superhydrophobic ceramic membrane for direct contact membrane distillation (DCMD) applications. Two types of mullite-based composite membranes were prepared via extrusion and sintering techniques. To create a small and narrow pore diameter distribution on the membrane surface, the dip-coating technique with 1 µm alumina was employed. The hexadecyltrimethoxysilane eco-friendly grafting agent was adopted to modify low-cost multilayer mullite-based composite membranes, transforming them from hydrophilic to superhydrophobic. The prepared membranes were characterized via field emission scanning electron microscopy (FESEM), energy-dispersive spectrometry (EDS), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), liquid entire pressure (LEP), contact angle, atomic force microscopy (AFM), porosity, and membrane permeability. The results of the prepared membranes validate the appropriateness of the material for membrane distillation applications. The optimized membrane, with a contact angle of 160° and LEP = 1.5 bar, was tested under DCMD using a 3.5 wt.% sodium chloride (NaCl) synthetic solution and Persian Gulf seawater as a feed. Based on the acquired results, an average permeate flux of 3.15 kg/(m2·h) and salt rejection (R%) of 99.62% were found for the 3.5 wt.% NaCl solution. Moreover, seawater desalination showed an average permeate flux of 2.37 kg/(m2·h) and salt rejection of 99.81% for a 20-h test without any pore wetting. Membrane distillation with a hydrophobic membrane decreased the turbidity of seawater by 93.13%.

Membrane distillation of saline feeds and produced water: A comparative study of an air-gap and vacuum-driven modules

Air gap membrane distillation (AGMD) and vacuum membrane distillation (VMD) are two membrane-based desalination processes that utilize temperature differences to generate water vapor for purification. This study evaluated the viability of both processes for treating different types of saline water, such as Arabian Gulf seawater and oil field-produced water. Factors such as feed temperature, feed concentration, recirculation flow rate, air gap, and vacuum space depth were investigated to understand their impact on permeate flux in AGMD and VMD configurations. The results showed that AGMD achieved higher permeate flux at lower feed concentrations, while VMD performed better at higher concentrations. Increasing the feed temperature led to increased permeate flux in both configurations, with AGMD showing a greater increase. Results also indicated that lower gaps were preferred in both configurations, and the tested membranes showcased excellent salt rejection capabilities. These findings provide valuable insights into the potential applications of AGMD and VMD in desalination, especially in regions with water scarcity or pollution.

Design and optimization of a unique pilot scale forward osmosis integrated membrane distillation system for seawater desalination

The integration of forward osmosis (FO) and membrane distillation (MD) technologies for seawater desalination applications is recently gaining more importance since the system can be easily integrated with renewable energy resources. In this study a pilot scale FO integrated air gap membrane distillation (FO-AGMD) system is designed, commissioned, and tested for the desalination of the Arabian Gulf seawater (AGS) using 70,000 ppm solution of NaCl as the draw solution (DS). During the FO-AGMD operation, the FO feed-in conductivity decreased from 66.45 mS/cm to 63.31 mS/cm while the FO feed-out conductivity decreased from 62.92 mS/cm to 60.17 mS/cm. The DI water dosing system connected to the feed loop of the FO module decreased the feed-in and feed-out conductivities to maintain a uniform Δπ across the FO membrane. As the MD flux increased, to maintain the FO-AGMD system equilibrium the FO flux was also increased by raising the DS concentration using the dosing tank containing the stock solution of NaCl. Under the optimized operating conditions, the average system water recovery stabilized at 33% at the operating temperature of the MD at 85 °C. The water flux was stable between 6.3 and 7.3 L/m2h for the FO and 3.75 and 4 L/m2h for the MD. The major power consumption by the FO-AGMD system is the heating and cooling powers for heating the feed to ∼85 ºC and cooling the permeate to ∼10 °C in the MD section which varied in the similar range of 10–12 kW/h.

Underwater optical wireless communication system performance improvement using convolutional neural networks

Many applications that could benefit from the underwater optical wireless communication technique face challenges in using this technology due to the substantial, varying attenuation that affects optical signal transmission through waterbodies. This research demonstrated that convolutional neural networks (CNNs) could readily address these problems. A modified CNN model was proposed to recover the original data of a non-return to zero on–off keying modulated signal transmitted optically through a tank full of Gulf seawater. A comparison between the proposed CNN model and a conventional fixed-threshold decoder (FTD) demonstrates the excellent performance of the proposed CNN model, which improved the bit error ratio (BER), signal-to-noise ratio (SNR), and effective channel length. The BER of the optical signals that are transmitted at powers of 24, 26, and 27 dBm and a bit rate of 10 Mbit/s at a distance of 3 m from the transmitter when FTD is used is 7.826 × 10−7, 5.049 × 10−8, and 8.38 × 10−10, respectively. When the CNN decoder is used at the same distance and powers, the BER is 6.23 × 10−14, 1.44 × 10−16, and 2.69 × 10−18, respectively. In conclusion, the BER decreased by about seven orders of magnitude, the effective channel length increased by four times, and the SNR decreased by about 20 dB. The simplicity of the proposed CNN decoder is independent of the prior knowledge of the channel conditions. Furthermore, the magnificent obtained results make the proposed CNN decoder an ideal substitute for ordinary underwater optical wireless communication decoders.

Determining the effect of mineral scaling formation under different injection water sources on the performance of Mishrif carbonate reservoir in Halfaya oilfield, Southern Iraq

The chief source of the oilfield scale is the mixing of incompatible waters. This study demonstrated that mixing the reservoir of Mishrif formation (Halfaya oilfield) with six types of injection water sources, including Tigris River water, producing water formation, Gulf seawater, Marshes water, Middle Kirkuk formation water, and Main Outfall Drain water (AL-Masab AL-Aam Channel), leads to the formation of salt crusts that cause the reduction of reservoir rock permeability. According to the Piper diagram, the Mishrif formation water of all extant water samples was of the sodium chloride type (NaCl), except for HF-81, which was between (NaCl) and mix (CaMgCl) type. A geochemical simulation model of water alignment (PHREEQC) was used to simulate this problem, and it revealed the mineral scaling from mixing processes. These minerals precipitate in rock pores and clog them, which then cause damage to the petrophysical properties of the reservoir and prevent the passage of liquids. Results showed that the best water types used for injection are Middle Kirkuk formation water, followed by the general downstream, then Gulf seawater, but treatment before injection is needed. The study of geochemical modeling method can help to better understand scaling issues by efficiently identifying the best injection water from various selected types with the lowest possible cost, which in turn improves oil production.

Experimental investigation on the durability of metakaolin-based geopolymer concrete in aggressive environments

The properties and performance of geopolymer concrete have been evaluated in numerous studies in recent decades. One of the fields of study is the evaluation of the durability of geopolymer concrete in aggressive environments. In this study, the influence of four experimental factors, including curing temperature (T), the weight ratio of sand to metakaolin (S/M), aggressive environment type (AE), and aggressive environment exposure time (Et) were investigated on the durability and mechanical properties of metakaolin-based geopolymer concrete (MGPC). Moreover, 5% sulfuric acid solution, 5% sodium chloride solution, and Persian Gulf seawater were used as aggressive environments. Response surface methodology (RSM) was implemented to statistically design and analyze the experiments. Mathematical models were derived for the prediction of residual compressive strength (RFc), weight changes (∆W), and compressive strength changes (∆Fc) of MGPC. The analysis of variance showed that all four factors had a significant effect on the responses, while only AE-S/M and AE-ET factors had an interaction. Design-Expert software (DX7) was employed for the optimization of design factors. Results revealed that the use of the optimum weight ratios of S/M (2.52, 2.07, and 1.29) at a curing temperature of 46 °C and an exposure time of 56 days led to RFc values of 34.12, 43.60, and 44.15 for sulfuric acid, sodium chloride, and Persian Gulf seawater aggressive environments, respectively. These results, which are higher than the minimum required compressive strength of concrete, along with the ∆Fc and ∆W values, confirm the acceptable durability of MGPC.

Application of response surface methodology for a feasibility study of producing stable semi-aphron fluids using natural materials

ABSTRACT Due to the drilling problems in fractured reservoirs, multiphase lightweight fluids are essential. To produce lightweight fluids and to achieve the desired stability, a variety of chemical and natural surfactants are used. However, natural surfactants are more in demand due to environmental issues and challenges. The goal of this research is to produce a lightweight fluid using a combination of natural materials. Moreover, colloidal gas aphron (CGA) based drilling fluids are prepared at 5,000 to 10,000 rpm stirring speed; therefore in this research, the production feasibility of stable multiphase fluid (called semi-aphron) was investigated at a lower stirring speed (1,500 rpm) without Xanthan Gum polymer. The applied natural raw materials, were Acanthophyllum bracteatum root (ABR), Glycyrrhiza glabra root (GGR), and Tetraclinis articulata fruit (TAF) powders that were mixed with Persian Gulf seawater. Three models of response surface methodology (RSM) were utilized to assess the effects of natural materials concentration (0 to 0.2%wt.) on the stability and drained volume (DV) of the liquid phase at 25°C and 70°C. The utilized models were central composite design (CCD), typical custom design (TCD), and modified custom design (MCD). Based on the results, the optimum concentration for ABR, GGR, and TAF were 0.2%, 0.1%, and 0.1% wt., respectively. The produced fluids, using the combination of natural materials, had better stability than the base fluid (using SDS). The optimum concentration of natural material delayed the drainage of the liquid by about 70% at ambient temperature (25°C), and by about 50% at 70°C. The MCD model showed better-predicted R2 at ambient temperatures and 70°C (0.91 and 0.88, respectively) than the other two models, and would estimate the amount of DV better. The results showed that ABR and TAF had an inverse effect on DV at 25°C; thus, ABR and TAF increased semi-aphron stability, whereas GGR increased DV and semi-aphron instability. The results of this study can be considered for the application of native natural materials (ABR, GGR, and TAF) in the production of light drilling fluids, which reduces the environmental challenges of drilling fluids.

Bioprospecting autochthonous marine microalgae strain from the Arabian Gulf Seawater, Kuwait for biofuel feedstocks

Bioprospecting programmes are the key to increasing the current portfolio of indigenous microalgal strains accessible for different applications in microalgal biotechnology. In this work, nine fastgrowing microalgal strains isolated from the Arabian/Persian Gulf coastal waters of Kuwait were evaluated for their potential as biofuel feedstocks. 18S rRNA gene sequencing showed that the strains belong to five different genera, namely, Chlorella, Nannochloris, Scenedesmus, Tetraselmis, and Nannochloropsis. In terms of the total lipid content, in comparison to the other strains, Tetraselmis sp. KUBS13G and Tetraselmis sp. KUBS16G displayed higher lipid contents of 29.56% dry weight (DW) and 26.13% DW, respectively, which were dominated by palmitic and oleic acids. Fuel properties calculated from the fatty acid methyl esters (FAMEs) by empirical equations were compared with EN14214 (European) and ASTM D6751-−02 (American) biodiesel standards. Multicriteria decision analysis (MCDA) methods, such as the Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE) and Graphical Analysis for Interactive Assistance (GAIA), were used to select suitable microalgae for biofuel feedstock based on their biodiesel fuel properties. Overall, the results suggested that the indigenous microalgal strain Tetraselmis, in particular Tetraselmis sp. KUBS37G, and Scenedesmus sp. KUBS17R are the most suitable strains for biofuel feedstock owing to their improved fuel properties, such as density (ρ) (0.88 g cm−3), low kinematic viscosity (3.1 mm2 s−1), high cetane number (54 and 56, respectively), high oxidation stability (14.6 hr and 14.8 hr), and cold-filter plugging point (1.0°C and -6.1°C).

Effect of different salts on the kinetic parameters of the carbon dioxide hydrate formation

In this study, the effects of sodium chloride (NaCl), potassium chloride (KCl), magnesium chloride (MgCl2), and calcium chloride (CaCl2) on the kinetic parameters of carbon dioxide (CO2) hydrate formation including induction time, amount of gas consumption, rate of gas consumption and storage capacity were experimentally studied. Aqueous solutions with the ion concentration same as the Persian Gulf Seawater were prepared and all the experiments were conducted at a temperature of 274.15 K and pressure of 3.5 MPa. The results showed that salts have an inhibitory effect on the kinetic parameters of CO2 hydrate formation by reducing CO2 solubility in water and electrostatic interaction between water molecules and ions. The intensity of ion inhibition depends on the ion size, ion charge, ion concentration, and the kosmotropic and chaotropic properties of ions. Examination of the kinetic parameters of CO2 hydrate formation in saline solutions with a constant concentration of 1000 mg/L of each ion showed that the Mg2+ has the greatest inhibitory effect on the kinetic parameters by increasing the induction time by 110.71% and reducing gas consumption, rate of gas consumption, and storage capacity by 48.21%, 82.14%, and 68.75%, respectively compared to pure water. The results showed that the inhibition effect of salt ions on the CO2 hydrate formation is in the following order: Mg2+> Ca2+>Na+>K+.

Study on Attapulgite as Drilling Fluid Clay Additive in Persian Gulf Seawater

Drilling fluids are a vital part of every successful well construction operation. Water based fluids are used commonly due to better environmental compatibility, lower cost and easier preparation. In offshore drilling, seawater can be used as the basis of water based fluids. Salinity of seawater restricts application of some additives. For example, bentonite settles in saline environments. In this study, a synthetic water is prepared based on Persian Gulf seawater. Bentonite, pre-hydrated bentonite and attapulgite suspensions were developed based on fresh water and prepared synthetic water. Rheological and filtration properties of fluids were tested to check their performance in synthetic seawater. Results of filtration measurements showed a thick mud cake and high filtration volume in pre-hydrated bentonite fluids. In the case of attapulgite, filtration volume of suspensions in synthetic water increased comparing to suspensions in fresh water. However, filtration properties were acceptable. Study on rheological properties revealed that Herschel-Bulkley model can predict rheological properties with a good accuracy. This is the case for suspensions in both fresh and seawaters. Also it was seen that all suspension had a flow behavior index less than 1, showing their shear thinning character. By increasing clay concentrations, higher consistency index, yield stress and gel strength values were reported. At higher clay concentration a stronger three-dimensional network of clay particles in aqueous environment and consequently a stronger gel structure were formed. Overall, it can be concluded that attapulgite can be used in the saline environment of Persian Gulf seawater.

Effects of sour oilfield produced water on direct contact membrane distillation systems

A fully corrosion-resistant direct contact membrane distillation system has been built to test the viability of desalinating oil field produced water using fluorinated polyoxadiazole (F-POD) hollow fiber membranes. This highly hydrophobic membrane material was designed to endure the harsh conditions of Arabian oil field produced waters. These waters have high salinity, and the presence of dissolved organic compounds and gases - including hydrogen sulfide (H2S). The hazards associated with H2S require special safety controls. In this paper, the desalination of sour produced water with membrane distillation is compared with Gulf Sea water from the East Coast of Saudi Arabia. The effect of the produced water on the efficiency of the membrane distillation was evaluated in terms of distillation flux and salt rejection. The high salinity, the presence of H2S, and volatile organic compounds (VOC) are found to negatively impact the flux and salt rejection.

Exploring the Performance Parameters of a Commercial-Scale Hollow Fibre Forward Osmosis Module during the Arabian Gulf Seawater Desalination

Exploring the Performance Parameters of a Commercial-Scale Hollow Fibre Forward Osmosis Module during the Arabian Gulf Seawater Desalination

Interplay Between Ca2+, Mg2+, and SO42– Ions and Their Influence on the Zeta-Potential of Limestone during Controlled-Salinity Waterflooding

Substantially enhanced oil recoveries from carbonate reservoirs have been accredited to the modification of ionic content and salinity of the injection water and subsequent alteration of reservoir rock wettability toward more water-wet. Modification of surface charges at rock/oil/water interfaces is believed to be the main mechanism that controls the process of wettability alteration. This paper presents a systematic zeta-potential measurement study that investigates the individual and relative impacts of Ca2+, Mg2+, and SO42– ions on a limestone rock from the Middle East. The main target of the study is to understand the impact of each potential determining ion individually and in the presence of another ion for insightful explanations of the overall impact of injection water during ionically controlled waterflooding in carbonate reservoirs. The novelty of the current study is the comprehensive investigation of the interplay between potential determining ions and the resultant impact on limestone surface charges. Different modified brines were prepared based on the ionic composition of Arabian Gulf seawater, which is the main source of injection water in the region. Model oil, containing carboxylic acid, was used to represent the oil phase in aging procedures. Interactions at the rock/oil/water interfaces were assessed using zeta-potential measurements of unaged and aged limestone particles. The results show that Ca2+, Mg2+, and SO42– are potential determining ions that can alter surface charges of unaged and aged limestone. SO42– ions were found to have a profound impact on the generation of negative surface charges on limestone as well as in suppressing the preferential ability of Ca2+ and Mg2+ ions to generate positive surface charges. Results also showed that limestone possesses negative surface charges when conditioned in unmodified seawater and twice diluted seawater. Comparing the obtained results from this study with the literature suggests that similarities in the mineralogical composition of carbonates rocks do not necessarily reflect in similar electrokinetic behavior, even under the same experimental conditions. Moreover, this study shows that the zeta-potential of limestone is not linearly correlated with decreased salinity. Furthermore, it is shown that conditioning limestone in sequentially diluted seawater will result in an increase in the magnitude of the negative charges up to twice diluted seawater, after which the magnitude of the negative surface charges will start to decrease. This finding suggests that a different mechanism is responsible for the modification of carbonate surface charges during late stages of sequential low-salinity waterflooding than the mechanism that controls the modification of surface charges during early stages of the process.

Investigation on the Durability of E-Glass/Epoxy Composite Exposed to Seawater at Elevated Temperature.

In this manuscript, the durability of the E-glass/epoxy composite was determined under a seawater environment. The effect of harsh environment was investigated in terms of seawater absorption, microstructure and degradation in mechanical properties. E-glass epoxy composite specimens were conditioned in gulf seawater at 23 °C, 65 °C and 90 °C for the period of 12 months. It was observed that the mass of the samples increased after the immersion of 12 months at 23 °C and 65 °C whereas it reduced at 90 °C. The salt deposition was observed at the surface of specimens without any crack for the seawater conditioning at 23 °C and 65 °C. The swelling and crack formation were significantly visible on the surface of the specimen immersed for 12 months at 90 °C. It indicates that the degradation mechanism accelerated at elevated temperature results fiber/matrix debonding. The tensile test indicates slight variation in the elastic modulus and reduction in strength of E-glass epoxy composite by 1% and 9% for specimens immersed at 23 °C and 65 °C respectively. However, at 90 °C, the tensile strength sharply decreased to 7% and elastic modulus significantly increased in the exposure of 12 months. A prediction approach based on a time-shift factor (TSF) was used. This model predicted that the strength retention of E-glass/Epoxy composite will be reduced to 7% in 450 years after immersion in seawater at 23 °C. Lastly, the activation energy for the degradation of the composite was calculated.

Eco-Friendly Innovation for Electrical Conductivity Reduction of Persian Gulf Sea water Using Highly Efficient Recyclable Sorbent

The use of sea water containing of Reverse Osmosis effluent is very serious for the daily living of the coastal residents especially for farmers. In this study, one-year field test was carried for electrical conductivity reduction of Persian Gulf sea water in Iran, during 2017 and 2018. The test was conducted in two filters each with diameter 2.5 cm (or 0.025 m) and 18.5 cm (or 0.185 m). In the filters, crumb mineral mussel was used as one of main components from filter materials. The minor components of filter materials were comprised of coarse-grained gravel, fine-grained activated carbon, and fine-grained sand. The well water as low-saline water for background of sea water treatment and sea water as super-saline water were treated. The test was performed as pilot, batch, and column design with three replicates. The volume of daily treated sea water and efficiency of reduction electrical conductivity and salinity were determined. Volume of treated sea water by each of the filters was at least 10 times diameter each of those. Maximum reduction efficiency of electrical conductivity and salinity in filter with 2.5 cm (or 0.025 m) diameter was 97.09% (from 85.2 to 2.48 mS/cm or from 8.52 to 0.248 S/m) and it was 98.2% (from 61 to 1.1), respectively. Maximum reduction efficiency of the parameters in filter with 18.5 cm (or 0.185 m) diameter was 97.5% (from 84.8 to 2.12 mS/cm or from 8.48 to 0.212 S/m) and it was 97.69% (from 60.7 to 1.4), respectively. Electrical conductivity in outlet water from filters was less than 3 mS/cm (or 0.3 S/m), below the permissible limit recommended by World Health Organization and also Iranian Department of Environment for agriculture and irrigation usage. Based on these results a non-continuous method seems promising in the biological growing phase in filters.

Application of ion-engineered Persian Gulf seawater in EOR: effects of different ions on interfacial tension, contact angle, zeta potential, and oil recovery

In this study, we initially performed interfacial tension (IFT) tests to investigate the potential of using the Persian Gulf seawater (PGSW) as smart water with different concentrations of NaCl, KCl, MgCl2, CaCl2, and Na2SO4. Next, for each salt, at the concentration where IFT was minimum, we conducted contact angle, zeta potential, and micromodel flooding tests. The results showed that IFT is minimized if NaCl or KCl is removed from PGSW; thus, for solutions lacking NaCl and KCl, the IFT values were obtained at 26.29 and 26.56 mN/m, respectively. Conversely, in the case of divalent ions, minimum IFT occurred when the concentration of MgCl2, CaCl2, and Na2SO4 in PGSW increased. Specifically, a threefold rise in the concentration of Na2SO4 further reduced IFT as compared to optimal concentrations of MgCl2 or CaCl2. It should be mentioned that eliminating NaCl from PGSW resulted in the lowest IFT value compared to adding or removing other ions. Whereas the removal of NaCl caused the contact angle to decrease from 91.0° to 67.8° relative to PGSW and changed surface wettability to weakly water-wet, eliminating KCl did not considerably change the contact angle, such that it only led to a nine-degree reduction in this angle relative to PGSW and left wettability in the same neutral-wet condition. At optimal concentrations of MgCl2, CaCl2, and Na2SO4, only an increase in Na2SO4 concentration in PGSW could change wettability from neutral-wet to weakly water-wet. For solutions with optimal concentrations, the removal of NaCl or KCl caused the rock surface to have slightly higher negative charges, and increasing the concentration of divalent ions led to a small reduction in the negative charge of the surface. The results of micromodel flooding indicated that NaCl-free PGSW could raise oil recovery by 10.12% relative to PGSW. Furthermore, when the Na2SO4 concentration in PGSW was tripled, the oil recovery increased by 7.34% compared to PGSW. Accordingly, depending on the conditions, it is possible to use PGSW so as to enhance the efficiency of oil recovery by removing NaCl or by increasing the concentration of Na2SO4 three times.

The effect of chemistry of nanoparticle modifier groups on the PVDF membranes for membrane distillation

Recently, the synthesis of nanoparticles including their hydrophobic modifications for the synthesis of membranes for membrane distillation has shown incredible improvements in the; intrinsic physical and morphological properties, transmembrane flux, rejection, and life of the membrane. This study evaluates the effect of three different hydrophobic nanoparticles on the morphological, physical, and hydrophobic characteristics of the PVDF membranes. The octadecyl dihydrogen phosphate modified calcium carbonate (OC), octadecylamine modified Montmorillonite (OM), and Heptadeca- fluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane modified silica (HS) nanoparticles were incorporated into the polyvinylidene difluoride (PVDF) membrane matrix in different compositions. The real seawater desalination performance of the newly synthesized membranes was tested in direct contact membrane distillation configuration for desalting the Arabian Gulf Seawater as feed. The PVDF membrane comprised of HS filler was the top performer with the highest water vapor flux of 42.3 LMH owing its CF2 functional groups, small chain length, small size and high electronegativity of F atoms, a stable C–F bonding interaction, and a low surface energy C–F compared to OC and OM nanoparticles. Also, HS incorporated membrane witnessed the highest anti-wetting and reliability by rejecting >98.7% ions from seawater.

Effects of salinity, ion type, and aging time on the crude oil-brine interfacial properties under gravity condition

In this study, the impacts of salinity, ion type, and aging process were investigated on coalescence and spreading of crude oil interfaces (including an oil droplet and an oil film) under gravity, through drop rest time measurement techniques, aided by an image analysis system. Three different salt solutions of NaCl, Na2SO4, and MgCl2 were studied at different ionic strengths, ranged from 1% to 150% of Persian Gulf seawater ionic strength. According to the results, aging the oil droplet in the brine increased the interfacial rigidity. Addition of a gas phase - by thinning the surface oil film - almost doubled both rest time and spreading time values. In the aged mode, the presence of salt in the water phase increased both rest time and spreading time, depending on the salt type and concentration. Increasing salinity, especially in the case of MgCl2 and Na2SO4 salt solutions, resulted in higher interfacial rigidity and lower oil-brine interfacial tension.

Experimental and modeling study of wettability alteration through seawater injection in limestone: a case study

Water flooding is widely applied for pressure maintenance or increasing the oil recovery of reservoirs. The heterogeneity and wettability of formation rocks strongly affect the oil recovery efficiency in carbonate reservoirs. During seawater injection in carbonate formations, the interactions between potential seawater ions and the carbonate rock at a high temperature can alter the wettability to a more water-wet condition. This paper studies the wettability of one of the Iranian carbonate reservoirs which has been under Persian Gulf seawater injection for more than 10 years. The wettability of the rock is determined by indirect contact angle measurement using Rise in Core technique. Further, the characterization of the rock surface is evaluated by molecular kinetic theory (MKT) modeling. The data obtained from experiments show that rocks are undergoing neutral wetting after the aging process. While the wettability of low permeable samples changes to be slightly water-wet, the wettability of the samples with higher permeability remains unchanged after soaking in seawater. Experimental data and MKT analysis indicate that wettability alteration of these carbonate rocks through prolonged seawater injection might be insignificant.

A comparative study of two different forward osmosis membranes tested using pilot-plant system for Arabian Gulf seawater desalination

A comparative study of two different forward osmosis membranes tested using pilot-plant system for Arabian Gulf seawater desalination