Scale Deposition Research Articles

Study on Anti-Scale and Anti-Corrosion of Polydopamine Coating on Metal Surface

Some surface coatings can protect metal surfaces and reduce scale deposition. Based on that, the biomimetic material polydopamine (PDA) can form a stable coating on many material surfaces; therefore, we propose an efficient one-step electroplating method for preparing anti-scale PDA coatings with high stability. The scale deposition test showed that the deposition weight of calcium carbonate on the coating is less than that of carbon steel after immersing in a supersaturated solution of calcium carbonate for 12 h at 70 °C and 90 °C, with a coating scale-inhibition efficiency of 55.02% and 66.96%, respectively. By using molecular dynamics simulation, it was found that water adsorption layers exist near the metal’s surface, and the existence of water adsorption layers on the hydrophilic surface is the main reason for the initial deposition of calcium carbonate. The interaction energy between the PDA molecular layer and water is weaker (−5.69 eV) for the surface with the PDA coating, and there is no dense water adsorption layer on the coating, which leads to the low probability of calcium carbonate adsorption on the PDA coating surface. Therefore, PDA coating can inhibit the deposition of calcium carbonate on the surface.

Physicochemical Characteristics and the Scale Inhibition Effect of Air Nanobubbles (A-NBs) in a Circulating Cooling Water System

Air nanobubbles (A-NBs) in a circulating cooling water system have not been investigated, although their role is significant. In this paper, the influences of the contents of main salts and other parameters on the physicochemical characteristics and scale inhibition performance of A-NBs in circulating cooling water were investigated and the scale inhibition mechanism of A-NBs in a simulated circulating cooling water system was explored. A-NBs realized a higher scale inhibition rate of 90%, which was higher than that of 1-hydroxyethane-1,1-diphosphonic acid (40%), and A-NBs stably existed for more than 5 days in the complex water environment. Four interface functions were proposed to interpret the scale inhibition effect of A-NBs in circulating cooling water as follows. First, the negatively charged surface of A-NBs adsorbed cations (Ca2+) reduced the concentration of scaling ions. Second, the negatively charged surface of A-NBs could also adsorb microcrystals, and their crystal-like seed action was conducive to the formation of large-size crystals, broke the rules of crystal growth, and reduced the adhesion of scales to the pipe wall. Third, A-NBs could also form a bubble layer after they were adsorbed on the inner surface of pipes, thereby preventing the deposition of scales on the surface. Fourth, A-NB burst caused local turbulence, increased the shear force onto the pipe surface, and reduced the scales adhering to the pipe surface. The interface effect of A-NBs in metal pipes is important in many industrial applications. This study laid the basis for the development of a new green A-NB scale-inhibiting technology.

Fabrication and performance study of a superhydrophobic anti-scaling and anti-corrosion coating

In this work, we designed and fabricated an anti-scaling and anti-corrosion superhydrophobic 1H,1H,2H,2H-perfluorodecyl triethoxysilane (PFDS)/ethylenediamine tetraacetic acid (EDTA)/anodized copper oxide (ACO) coating at the surface of a copper alloy. The water contact angle of PFDS/EDTA/ACO coating reaches 164.53°, showing superhydrophobicity, which will reduce the contact between scale crystals, corrosive medium and substrates, and help to inhibit scaling deposition and corrosion. Results show during the CaCO3 deposition test, EDTA molecules, EDTA-Zn2+ and EDTA-Cu2+ chelates stored in the micro-structure of superhydrophobic PFDS/EDTA/ACO coating are released to the interface and help to improve scaling prevention. After soaking for 48 h, the CaCO3 scaling mass of PFDS/EDTA/ACO coating was only 27.0 % that of ACO coating, and the corrosive protection efficiency of the superhydrophobic PFDS/EDTA/ACO coating was improved by 3.4 times that of ACO coating. Studies indicated that the anti-scaling and anti-corrosion of the superhydrophobic PFDS/EDTA/ACO coating contributes to the cooperation of superhydrophobic air film and the potential storage and dynamic release of EDTA, as well as the passivation layer formed on the substrate.

Evaluation of the Impact of Ferrous Species on the Performance of a Poly(carboxylic acid)-Based Scale Inhibitor

This work aims to evaluate, from a static and dynamic perspective, the performance of a polycarboxylic acid-based scale inhibitor in the presence of iron ions (FeIII). The static (jar test) and dynamic (tube blocking test) tests were performed according to NACE TM0197-2010 and NACE TM31105-2005 standards, respectively. The lowest inhibition concentration (LIC) was determined under flow conditions of oil wells. In addition, the influence of the concentration of FeIII ions on the precipitation process was also evaluated. The scale deposits were analyzed by X-ray diffraction (XRD), infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results demonstrated that the scale inhibitor is chemically compatible and efficient with the selected brines, possessing a LIC of 30 mg L-1 in the absence of FeIII ions. In the presence of FeIII ions, the inhibitor proved to be inefficient and incompatible, and it was not possible to determine the LIC. The combined XRD, FTIR, and SEM analyses allowed us to identify the inhibitor’s mechanism of action as being one of complexation, poly(carboxylic acid)-Ca2+. Furthermore, analyses in the presence of FeIII ions demonstrated a significant change in the morphology of the incrustation of CaCO3 crystals. Additionally, it has been proven that FeIII ions significantly affect the performance of the inhibitor. Finally, the results indicated that in the absence of high concentrations of FeIII ions, the poly(carboxylic acid) scale inhibitors can be an option to mitigate operating costs resulting from the deposition of inorganic scale in oil wells.

A Robotic Tunnel Drainage Inspection Rover

Drainage pipes in tunnels are very complicated to service but still need rather frequent inspections in order to detect the initiation of deposited scales stemming from carbonate that tends to precipitate when the pH-value of the mountain water rises with the release of gaseous carbon dioxide CO2 due to a decreasing water pressure. The drainages enable to design tunnels without resistance to ground water pressure. We present the development of a robot able to autonomously navigate through tunnel drainage pipe systems inspecting for these carbonate scale deposits, and can demonstrate that the currently available test platform is able to traverse autonomously, in between two recharging stops in manholes, a few hundred meters of tunnel pipes thereby acquiring on a localized basis various environmental parameters like pH-value, the water's conductivity, temperature, carbon dioxide concentration in addition to documenting the pipes’ condition with respect to scaling via a video clip that is recorded along with an estimated position in the pipe.

HEAT TRANSFER ENHANCEMENT AND SCALE FORMATION: EXPERIMENTAL STUDIES IN FALLING FILM EVAPORATORS USING COPPER METAL FOAM

Performance enhancement of horizontal tube falling film evaporators using thin metal foam was studied. A copper foam was brazed over the outer surface of a copper horizontal tube and used in the falling film evaporator of a desalination system. It was observed that the distillate production and heat transfer rate was enhanced by more than twice with the modified tube. Effect of feed rate, feed temperature, and subcooling on distillate production was studied for the copper foam-wrapped heat exchanger tube evaporator. A metal foam-wrapped heat exchanger tube was also used to study the effect of scale formation. The effects of temperature, flow rate, and seawater turbidity on scale formation was studied. Total scale deposit weight was observed after every 16 h of operation for a total run time of 128 h. It was observed that scale formation reduces with an increase in flow rate and increases with seawater temperature. It was also observed that scale formation is lower when the system is operated with seawater of low turbidity. The heat transfer enhancement surface promotes scale formation due to the increase in metal surface area in contact with seawater as in the copper foam-wrapped tube. Energy-dispersive X-ray spectroscopy and scanning electron microscopy were applied to investigate the mineralogy and microstructure of the deposits.

Root cause analysis of the Circular hole corrosion failure of N80 tubing

During well repair operations in an oil field, a Φ73.02 mm×5.51 mm N80 grade flat oil pipe with a circular hole was found. The depth of the well is between 550 meters to 2100 meters, with a usage cycle of 120 days. In order to figure out the root cause of the circular hole failure, a series of experiments were carried out. The chemical composition, yield strength, tensile strength, and elongation of the oil pipe meet the requirements of API SPEC 5CT-2018 standard. The microstructure of the oil pipe matrix consists of ferrite and pearlite, and there are no obvious cracks. The grain size of the material is all above 8.5 levels, and there are no coarse grains or non-metallic inclusions exceeding the standard. The perforation of the oil pipe is caused by internal corrosion, mainly due to CO2 corrosion and dissolved oxygen corrosion. The coexistence of Ca2+ and Mg2+ ions, iron bacteria, and corrosive bacteria in the wellbore fluid can lead to scale deposition inside the pipe, causing under-deposit corrosion, and the accelerating effect of Cl ions on corrosion ultimately leads to perforation of the pipe.

Some technological aspects of cleaning pipes of heat exchangers from solid scale deposits

This article discusses possible solutions to one of the problems associated with the low efficiency of existing thermal power plants. These factors are due to both the depreciation of equipment and the lack of any effective technologies for intensifying heat and mass transfer processes. The relevance of research topics is also confirmed by the fact that at the state level it is proposed to legally oblige the subjects of the heat and power industry to carry out preventive measures aimed at optimizing existing enterprises. The description of the reasons for the occurrence of scale deposits that appear in the in-line cavities is given. Due to the fact that the thermal conductivity of solid deposits is much less than the thermal conductivity of the metals from which the heat exchanger tubes are made, they significantly reduce the intensity of the processes and the intensity of heat transfer. Solid deposits lead to a decrease in the coolant flow rate, an increase in fuel consumption and a violation of the technological mode of operation of the entire heat exchange unit. The authors analyzed various technological aspects of various methods for cleaning heat exchanger tubes from solid scale deposits, on the basis of which the advantages of the electrohydraulic treatment method are substantiated. A schematic diagram of the device is given and a brief description of the method of cleaning the pipes of heat exchangers from solid scale deposits is given using electro-hydro-pulse action. The results of the application of this technology for cleaning heat exchange pipes at specific heat and power enterprises are shown, which confirm its advantages over other cleaning methods, both in terms of processing time and energy costs. The influence of the degree of purification of heat exchange pipes from solid deposits on the thermophysical parameters and efficiency of the heat exchanger is considered.

Experimental research of electrical characteristics combined solar-electric air heater

Poor water quality in district heating systems leads to failure of boilers and pipelines in heating networks. The main reason for this is corrosion and scale deposits. The presence of these factors shows the low efficiency of water treatment systems. The article presents the results of the introduction of non-traditional water treatment technologies for district heating systems based on the experience of the Zhytomyrteplokommunenergo utility company of the Zhytomyr City Council in 2007-2021. In the boiler houses of the enterprise, water treatment systems were modernized, and the production chemical service was reorganized. In particular, chemical deaeration was launched in combination with traditional sodium cationization, as well as chemical deaeration in combination with complexonate water treatment against the classical water treatment technology - ion exchange. Installed magnetic sludge separators with magnetic inserts. The technology of water softening with anti-corrosion protection using Redox filters has been introduced. Gravimetric corrosion sensors of our own design have been developed and installed. The database of processing and statistical analysis Access "Corrosion damage of pipelines of heat networks" was created and put into operation. The experience of modernizing the water treatment system has shown that work in this direction increases the reliability of operation of district heating systems by reducing the consumption of energy carriers and material resources. In addition, the problem of improving the operational reliability of the heat exchange equipment of thermal stations needs to be solved. The projected start of the use of heat recovery devices on water heating boilers in operation, in condensation or partially condensation modes, will also bring with it a number of problems with the neutralization of condensate and its return to the heat supply system. The end result is an increase in production reliability, environmental friendliness and a reduction in the cost of heat for district heating systems.

Assessment of sediment yield and deposition in a dry reservoir using field observations, RUSLE and remote sensing: Wadi Assarin, Oman

Soil erosion, sediment yield, and sediment transport associated with flash flooding in arid regions result in reservoir storage losses, decreased infiltration, high evaporation rates, and degradation of downstream channels. However, the lack of observational data from wadi systems and an empirical formula to compute sediment yield has hindered reservoir trapping evaluation, maintenance, and management. Therefore, this research aimed to estimate the annual soil loss in the upstream catchment area of a reservoir based on the Revised Universal Soil Loss Equation (RUSLE) with a remote sensing dataset. The sediment trapped in the Assarin Dam reservoir in Oman was estimated by coupling unmanned aerial vehicle (UAV) surveys with photogrammetry analysis to assess the reservoir siltation. Among the previous sediment trapping events, seven sets of field observation data were collected to investigate the relationship between soil loss at the catchment scale and sediment deposition volumes in the reservoir. The RUSLE method was applied to estimate soil erosion using independent factors such as rainfall erosivity, soil erodibility, topography, cover management and conservation practices. A remote sensing dataset and geographic information system (GIS) environments were used to analyse the quantitative and spatial distribution of the RUSLE parameters. Two drone surveys were conducted over the reservoir before and after a flash flood. The trapped sediment volume was estimated to be approximately 9,075 m3 (11,343 ton) per event, representing approximately 1.26 % of the total reservoir capacity. This computed volume was validated using measurements from monitored sediment scale bars sited throughout the Assarin Dam reservoir, yielding an accuracy of 79 %. From the RUSLE results, the annual soil erosion was estimated to be 196,599 ton/ha yr−1, of which approximately 5.8 % was trapped in the reservoir. Spatial-temporal variability in the rainfall patterns and the corresponding runoff discharges led to high sediment delivery at the outlet of the basin. After analysing available data from previous field surveys in Oman, a new formula for estimating the sediment yield in Wadi Assarin was developed. The results of this research, which represent the first of their type in the Middle East and North Africa (MENA) region, can support reservoir management practices and show that UAV-based photogrammetry is suitable for measuring trapped sediment volumes.

Novel assessment of in-operations mapped stainless steel elbow pipe internal wall for detection of corrosion and scale deposition

Novel assessment of in-operations mapped stainless steel elbow pipe internal wall for detection of corrosion and scale deposition

THE SIMULATION OF INTERMOLECULAR INTERACTIONS OF CARBOXYLIC AND AMINE GROUPS WITH CALCIUM CARBONATE

Surface facilities including tubing and valves at the oilfield have been plagued by mineral scale deposits, which are constitute of calcium carbonate (CaCO3). Penta-potassium diethylenetriaminepentaacetic acid salt (DTPA-K5) has a higher affinity for the metal cations complexes during the chelation process. The eight complexing sites (five carboxylate and three amines) empower the metal ion interactions. This work investigated the molecular dynamics simulations between the DTPA-K5 with the calcium carbonate, CaCO3 scale. The interaction was performed through molecular dynamic (MD) simulation using condensed phase optimised molecular potentials for atomistic simulation studies (COMPASS) force field and the Ewald summation method in Material Studio. The simulation trajectory files examined the intermolecular interactions for radial distribution function (RDF). The simulation shows strong DTPA-K5 with calcium interactions, which revealed the metal ion complexes contributing to the chelation process through the reactive carboxylic and amine functional groups, which were O7 == Ca at radius, r, 2.25 Å with g(r) of 10.09 and N1 -- Ca at radius, r, 2.25 Å with g(r) 2.51.

Understanding of tunnel drainage scale formation by in-situ monitoring

Drainage systems in (geo)technical environments are facing a common problem. So called scale deposits precipitate from the hugely diverse drained waters in form of carbonates, sulfates, silicates and – often associated with microbial activities – also Fe-(hydr)oxides. This is causing serious problems, like clogging, which eventually leads to the loss of structural integrity of e.g. tunnel linings, due to the increase of the hydro-static pressure.To get a better understanding of the scaling processes, a drainage test-track was setup in an active construction site of an Austrian railway tunnel using a locally discharging highly mineralized groundwater to decode scaling related processes by monitoring the pH, the electric conductivity (EC), the redox potential (pe) and the water-temperature (T) at high temporal resolution. The discharge (Q) was measured point-wise and analyses of water and solid samples by ICP-OES, IC, XRD and SEM complemented the study.The results indicate a coupled binary system, mainly controlled by the level of the discharge (Q), which can be monitored by T adapting to the atmosphere. With sufficient discharge (and therefore sufficient supply of aqueous Fe2+) microbially induced Fe-(hydr)oxide formation embedded in an organic matrix is promoted, which is strictly pe sensitive. At prevailing stagnant water-flow conditions, inorganically driven CaCO3 precipitation due to enhanced CO2 degassing is favored, which can be followed and assessed by an EC decrease and rising pH.The high-resolution monitoring of drainage water by pH, EC, pe and T provides a promising tool kit for in-situ decoding and assessing of scaling related processes, which allows for proper drainage system design and well-targeted maintenance actions.

Novel Nanocomposite Coated Proppants for Enhanced Scale Inhibition Lifetime in Tight Shale Formations

Controlling scale deposition in tight formations such as shale is commonly achieved by combining fracturing stimulation with squeeze treatment. The squeeze treatment process’s success relies on the targeted formation’s ability to adsorb the right amount of scale inhibitor and slowly release it during hydrocarbon production. The inhibition lifetime of a standard squeeze treatment lasts from 3 to 6 months depending on the compatibility between the formation and scale inhibitor–operators desire a prolonged inhibition lifetime. Herein, a novel approach of resin-based nanocomposite coated proppants is developed to act as a propping agent and high active surface platform for scale inhibitors to be adsorbed and subsequently slowly released during oil production. In this study, proppants were coated with a thin layer of polyurethane, followed by a layer of carbon-based nanomaterials (Multi-Wall Carbon Nanotubes (MWCNTs) and Graphene Nanoplatelets (GNPs)), and characterized using Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Analysis (EDX). Due to the concerns of climate change, polyurethane was selected due to its quick curing at lower temperatures and minimal environmental impacts. The potential of the proposed proppant to enhance the adsorption and slow the desorption of a Diethylenetriamine Penta (DTPMP) scale inhibitor, the necessary strength to withstand closure stress, and its thermal stability were evaluated. FESEM and EDX results revealed that an ultrathin uniformed coating layer was established. The stress resistance data showed that the proposed proppants (MWCNTs-RCP and GNPs-RCP) could withstand closure stress as high as 68.9 MPa with less than 10 wt % fines production. In addition, the thermal stability of MWCNTs-RCP and GNPs-RCP reached 347 °C. Scale inhibitor adsorption experiments showed that MWCNTs-RCP and GNPs-RCP adsorbed 583.5 mg/kg and 832.0 mg/kg of DTPMP, respectively. Desorption results indicated that MWCNTs-RCP and GNPs-RCP extended the inhibition lifetime of DTPMP by 400% PV compared to a conventional proppant. Intraparticle diffusion was found to dominate the desorption of DTPMP from MWCNTs-RCP and GNPs-RCP, which explains the slow desorption rate they exhibited. Therefore, the developed proppants could be a promising multifunctional proppant in the oil and gas industry.

SiO2 etching and surface evolution using combined exposure to CF4/O2 remote plasma and electron beam

Electron-based surface activation of surfaces functionalized by remote plasma appears like a flexible and novel approach to atomic scale etching and deposition. Relative to plasma-based dry etching that uses ion bombardment of a substrate to achieve controlled material removal, electron beam-induced etching (EBIE) is expected to reduce surface damage, including atom displacement, surface roughness, and undesired material removal. One of the issues with EBIE is the limited number of chemical precursors that can be used to functionalize material surfaces. In this work, we demonstrate a new configuration that was designed to leverage flexible surface functionalization using a remote plasma source, and, by combining with electron beam bombardment to remove the chemically reacted surface layer through plasma-assisted electron beam-induced etching, achieve highly controlled etching. This article describes the experimental configuration used for this demonstration that consists of a remote plasma source and an electron flood gun for enabling electron beam-induced etching of SiO2 with Ar/CF4/O2 precursors. We evaluated the parametric dependence of SiO2 etching rate on processing parameters of the flood gun, including electron energy and emission current, and of the remote plasma source, including radiofrequency source power and flow rate of CF4/O2, respectively. Additionally, two prototypical processing cases were demonstrated by temporally combining or separating remote plasma treatment and electron beam irradiation. The results validate the performance of this approach for etching applications, including photomask repair and atomic layer etching of SiO2. Surface characterization results that provide mechanistic insights into these processes are also presented and discussed.

Application and Visualization of Fluorescent-Tagged Antiscalants in Electrodialysis Processing of Aqueous Solutions Prone to Gypsum Scale Deposition.

Membrane scaling is a serious problem in electrodialysis. A widely used technique for controlling scale deposition in water treatment technologies is the application of antiscalants (AS). The present study reports on gypsum scale inhibition in electrodialysis cell by the two novel ASs: fluorescent-tagged bisphosphonate 1-hydroxy-7-(6-methoxy-1,3-dioxo-1Hbenzo[de]isoquinolin-2(3H)-yl)heptane-1,1-diyl-bis(phosphonic acid), HEDP-F and fluorescein-tagged polyacrylate, PAA-F2 (molecular mass 4000 Da) monitored by chronopotentiometry and fluorescent microscopy. It was found that cation-exchange membrane MK-40 scaling is sufficiently reduced by both ASs, used in 10−6 mol·dm−3 concentrations. PAA-F2 at these concentrations was found to be more efficient than HEDP-F. At the same time, PAA-F2 reveals gypsum crystals’ habit modification, while HEDP-F does not noticeably affect the crystal form of the deposit. The strong auto-luminescence of MK-40 hampers visualization of both PAA-F2 and HEDP-F on the membrane surface. Nevertheless, PAA-F2 is proved to localize partly on the surface of gypsum crystals as a molecular adsorption layer, and to change their crystal habit. Crystal surface coverage by PAA-F2 appears to be nonuniform. Alternatively, HEDP-F localizes on the surface of a deposit tentatively in the form of [Ca-HEDP-F]. The proposed mechanisms of action are formulated and discussed. The application of antiscalants in electrodialysis for membrane scaling mitigation is demonstrated to be very promising.

Preparation and Laboratory Testing of Polymeric Scale Inhibitor Colloidal Materials for Oilfield Mineral Scale Control.

Mineral scale refers to the hard crystalline inorganic solid deposit from the water phase. Although scale formation is very common in the natural environment, deposited scale particles can seriously threaten the integrity and safety of various industries, particularly oilfield productions. Scale deposition is one of the three most serious water-related production chemistry threats in the petroleum industry. The most commonly adopted engineering approach to control the scale threat is chemical inhibition by applying scale inhibitor chemicals. Aminophosphonates and polymeric inhibitors are the two major groups of scale inhibitors. To address the drawbacks of conventional inhibitors, scale inhibitor colloidal materials have been prepared as an alternative delivery vehicle of inhibitors for scale control. Quite a few studies have reported on the laboratory synthesis and testing of scale inhibitor colloidal materials composed mainly of pre-precipitated metal-aminophosphonate solids. However, limited research has been conducted on the preparation of polymeric inhibitor-based colloidal materials. This study reports the synthesis approach and laboratory testing of novel polystyrene sulfonate (PSS) based inhibitor colloidal material. PSS was selected in this study due to its high thermal stability and calcium tolerance with no phosphorus in its molecule. Both precipitation and surfactant surface modification methods were employed to prepare a barium-PSS colloidal inhibitor (BaPCI) material with an average diameter of several hundred nanometers. Experimental results indicate that the prepared BaPCI material has a decent migration capacity in the formation medium, and this material is superior to the conventional PSS inhibitor in terms of inhibitor return performance. The prepared novel BaPCI material has a great potential to be adopted for field scale control where environmentally friendly, thermal stable, and/or calcium tolerating requirements should be satisfied. This study further expands and promotes our capacity to fabricate and utilize functional colloidal materials for mineral scale control.

Comprehensive experimental investigation of the effective parameters on stability of silica nanoparticles during low salinity water flooding with minimum scale deposition into sandstone reservoirs

Recent studies showed the high potential of nanofluids as an enhanced oil recovery (EOR) agent in oil reservoirs. This study aimed to investigate the effects of salts and ions, the salinity of aqueous solution, total dissolved solids (TDS), scale deposition of mixing brines, surface charge as zeta potential (ZP) value, and pH of injected brines as low salinity water (LSW) on the stability of silica nanoparticles (NPs). The experiments were conducted on the stability of silica NPs at different concentrations and brines to determine optimum salinity, dilution, cations, and anions concentrations. The results showed that 10 times diluted seawater (SW#10D) was optimum low salinity water (OLSW) as injected LSW and water-based nanofluids. Results showed that by decreasing the salinity, increasing seawater dilution, and removing Mg2+ and Ca2+ cations, the amount of scale deposition decreased, and the brine's brine's brine stability of NPs in brine improved. At the optimum salinity and dilution conditions, compared with other salinities, there was less scale formation with more nanofluid stability. Obtained results from ZP measurements and dynamic light scattering (DLS) showed that by removing divalent ions (Mg2+ and Ca2+) of water-based nanofluid (low salinity hard water (LSHW) composition), more NPs were attached to the surface due to the reduction in repulsive forces between the NPs. Therefore, at optimum low salinity soft water (OLSSW), more wettability alteration occurred compared with optimum low salinity hard water (OLSHW) due to the more stability of NPs in OLSSW. The obtained results from the contact angle measurements, surface adsorption of the NPs by FESEM images, and ZP measurements showed that the predominant mechanism in enhancing oil recovery by nanofluid was the wettability alteration by disjoining pressure. According to wettability alteration results, the silica NPs with an optimized concentration in the optimized LSHW and LSSW compositions could be improved the wettability alteration by up to 23.37% and 55.81% compared with the without NPs. The optimized LSSW compared with LSHW composition could be improved the wettability alteration by up to 11.69%. In addition, OLSSW-based nanofluid compared with OLSHW could be increased wettability alteration toward strongly water-wet by up to 33.44%.

Silicate Scaling Formation: Impact of pH in High-Temperature Reservoir and Its Characterization Study

Silicate scaling tends to form and be aggravated during high pH Alkaline Surfactant Polymer (ASP) floods and this silicate scale deposition affects oil production. Hence, it is important to examine the conditions that lead to silicate scale forming. The severity of the silicate scaling reaction, the type and morphology of silica/silicate scale formed in an experimental ASP flood were studied for pH values 5, 8.5, and 11, whilst the temperature was kept constant at 90 ℃. In addition, the impact of calcium ion was studied and spectroscopic analyses were used to identify the extent of scaling reaction, morphology type and the functional group present in the precipitates. This was performed using imagery of the generated precipitates. It was observed that the silica/silicate scale is most severe at the highest pH and Ca:Mg molar ratios examined. Magnesium hydroxide and calcium hydroxide were observed to precipitate along with the silica and Mg-silicate/Ca-silicate scale at pH 11. The presence of calcium ions altered the morphology of the precipitates formed from amorphous to microcrystalline/crystalline. In conclusion, pH affects the type, morphology, and severity of the silica/silicate scale produced in the studied scaling system. The comprehensive and conclusive data showing how pH affects the silicate scaling reaction reported here are vital in providing the foundation to further investigate the management and prevention of this silicate scaling. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

Spatial Analysis of Groundwater Hardness, Electrical Conductivity, pH, and Underlying Causes for Variations in Ratnapura District, Sri Lanka

Hardness in drinking water may not be harmful to human health, though it can cause a variety of problems at both the domestic and industrial levels, most notably its objectionable taste and scale deposition. Excessive hardness in groundwater of the Ratnapura district has been perceived, particularly in the district’s dry and intermediate zones. Despite the fact that many residents rely on groundwater for their daily needs, no previous groundwater hardness investigation has been conducted in the area. In this context, this research aims to analyze the spatial distribution of groundwater hardness as well as pH and electrical conductivity (EC), including possible underlying causes. Georeferencing and spatial interpolation techniques were used to visually analyze the spatial variation of these three parameters over the area. Results revealed contrasting differences in all three parameters in the wet zone of the district compared with the dry and intermediate zones as well as alarming ranges of parameter values that exceed the standard limits for drinking water. Further, the study reveals that both climate conditions and geological conditions play a vital role in deciding the constituents of groundwater.