The Study of Calcium Carbonate Scaling on Low Energy Surfaces

Scale deposition (or fouling) on metal surfaces from salt-containing water considerably reduces the efficiency and performance of heat transfer equipments. In industrial practices, scale deposition could be reduced through physical or chemical methods. However, in some cases chemical methods are unpractical due to cost and contamination issues, rendering the physical methods the only feasible options. The objective of this study was to evaluate the effectiveness of two physical treatments in reducing scale depositions. One is to decrease the surface energy of the heat exchanger wall through surface modification; the other one is to change the crystallography of the small solid particles formed in the solution by applying a magnetic field. For the first method, the scale deposition on PTFE surfaces, SAMs (self-assembly monolayers) surfaces, polished copper surfaces, and polished stainless steel surfaces are investigated respectively. Copper and stainless steel surfaces were modified by micro-scale (μm thickness) PTFE (Poly-Tetrofluorethylene) films and nano-scale (nm thickness) thiolate SAMs. The surface energy of PTFE films and SAMs layers based on copper and stainless steel were significantly reduced compared with the untreated metal surfaces. To study the magnetic treatment effect on the formation of the calcium carbonate scale, a magnetic field up to 0.6 T was implemented in a simulated recirculation cooling water system. A large number of experiments were performed to study the effects of fluid velocity, heat flux, and the bulk concentration of the solution on the fouling rate and induction period of calcium carbonate on various modified surfaces. The experiments showed that the formation rate of the calcium carbonate scale was decreased on modified surfaces and the induction period was prolonged with the decrease of the surface energy. The study also showed that the nucleation and nucleate growth of calcium carbonate particles were enhanced through magnetic water treatment. In addition, using a higher flow rate and/or filtration of suspended calcium carbonate particles achieves a longer induction period.

Summary Scale is a significant operational concern in petroleum production that is commonly addressed by using chemical inhibitors. However, commercial inhibitors can potentially be pollutants depending on their composition and method of disposal. Consequently, evaluating the potential of biodegradable molecules to inhibit scale has gained attention. This study evaluates the effect of a series of carbohydrates (i.e., glucose, fructose, sucrose, maltose, maltodextrin, and soluble starch) and the aqueous extract of potato pulp on calcium carbonate precipitation and scale formation. Precipitation tests were conducted by combining aqueous solutions of sodium bicarbonate (3000 mg L−1) and calcium chloride (4000 mg L−1) in the presence of each carbohydrate, the aqueous extract of potato pulp, or a commercial inhibitor (1000 mg L−1). The precipitation was monitored through RGB (red, green, and blue) image analysis and pH measurements. The induction time in the presence of glucose, fructose, maltose, and sucrose is two to three times longer than in the blank test (in the absence of an inhibitor). This effect is slightly more pronounced in the presence of maltodextrin and soluble starch (approximately four times longer). However, the drop in pH and the mass of solids recovered is similar for all the carbohydrates tested (~0.5 mg and 120 mg, respectively), suggesting that carbohydrates slightly influence the precipitation kinetics but do not affect the precipitation equilibrium. Scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) analysis reveals that calcium carbonate precipitates as calcite and vaterite in the blank test. In the presence of glucose, fructose, maltose, and maltodextrin, calcium carbonate exclusively precipitates as calcite. However, in the presence of sucrose and soluble starch, calcium carbonate precipitates as both calcite and vaterite. Interestingly, a more prominent amount of vaterite was observed in the presence of soluble starch. All carbohydrates decrease the crystallite size of calcite, while sucrose and soluble starch increase the crystallite size of vaterite. The crystalline phases were also identified by Raman spectroscopy, ruling out the presence of any amorphous calcium carbonate phase. The inhibitory effect of soluble starch and the aqueous extract of potato pulp on calcium carbonate scale formation was evaluated in a dynamic scale loop (DSL) system. Soluble starch slightly delays scale formation even at high concentrations (1000 mg L−1). Conversely, the aqueous extract of potato pulp demonstrates enhanced performance by delaying scale formation by approximately 20 minutes for a 1-psi increase in the pressure of the tube and by more than 40 minutes for a 4-psi increase. As a result, it exhibited an impact on the kinetics of solid deposition. This agrees with the precipitation test in the presence of the potato extract (PE), which increases the induction time (from 2 minutes to 32 minutes), decreases the mass of solids (from 116 mg to 35 mg), and forms more distorted and smaller particles of calcite. These findings suggest a promising approach for the development of green scale inhibitors utilizing aqueous extracts of starchy foods or even starchy foods waste water.

The roles of gas bubbling, wall crystallization and particulate deposition in CaSO 4 scale formation

Gambier extracts as an inhibitor of calcium carbonate (CaCO 3) scale formation

Prevention of calcium carbonate scale using electrolyzed water

Calcium Carbonate Scale Formation in Pipes: Effect of Flow Rates, Temperature, and Malic Acid as Additives on the Mass and Morphology of the Scale

Effect of high-frequency electric fields on calcium carbonate scaling

Inhibition study of Piper betle leaf extracts to calcium carbonate (CaCO3) scale formation has been carried out using seeded experiment method. This study was conducted at concentration of CaCO3 growth solution of 0.075 M and at the temperature of 90 °C. The concentration of the Piper betle leaf extracts added in the growth solution of CaCO3 were 250-450 ppm. It was observed that the typical conditions were found to be efficiently inhibit the scale formation process by performing Scanning Electron Microscopy (SEM) to evaluate the morphology changes of CaCO3 crystals. The data obtained from the investigation reveals that the ability of Piper betle leaf extracts as a green inhibitor of the CaCO3 scale formation is around 30.16-46.65%. This finding support the Piper betle leaf potential as a scale inhibitor.

This article presents the prediction of calcium carbonate and calcium sulfate scale formation by water injection in oilfields at different mixing injection water-to-formation water ratios. The experimentally measured chemical analyses of formation water and injection water were input to the OLI ScaleChem model to determine the tendency of scale formation. The scaling tendency of CaCO3 and CaSO4 at reservoir temperatures and pressures is presented. This model has been applied to investigate the potential of calcium carbonate and calcium sulfate scale precipitation in Iranian oilfields in onshore and offshore fields as a method of secondary recovery or reservoir pressure maintenance.

Inhibition of calcium carbonate (CaCO3) scale formation by calix [4] resorcinarene compounds

Many oil producers in the Rocky Mountains region, USA, make use of electrical submersible pumps (ESP) to assist the lift of produced fluids. This region of the country is well known for its very harsh winters, with outside temperatures as low as −40 °F (−40 °C).ESP failures resulting in increased lifting costs due to workovers, lost oil, and logistics can be caused by many factors, including reservoir solids eroding the ESP or being trapped within the intake and pump stages, mechanical and electrical problems, and scale deposition. ESPs are particularly sensitive to calcium carbonate scale formation due to the extreme skin temperatures that can develop and often require continuous chemical injection to control this problem.Calcium carbonate scale formation in ESPs is a well known contributor to ESP failures. Large pressure drops combined with high temperatures increase the risk of calcium carbonate deposition even in mildly scaling systems. Scale formation on the motor housing acts as insulation, preventing heat transfer from the motor to the well fluids, causing the motor to be insufficiently cooled. Any scale deposition on the pump impellers can cause an imbalance and vibration, degrading pump performance.Continuous scale inhibitor treatment of ESPs to mitigate calcium carbonate scaling is a common practice. However, the choice of scale inhibitor requires careful consideration due to the high skin temperatures that can develop and can lead to inhibitor decomposition. Effective continuous treatment of ESPs during the winter months in regions where very low temperatures can be expected require product formulations capable of withstanding these harsh conditions without significant changes to their physical properties.This paper presents and discusses, with the aid of laboratory and field data, the development and deployment of a thermally stable scale inhibitor suitable for treatment of ESPs that can also be deployed in very cold climates, along with the monitoring tools used to ensure effective treatment.

Monitoring of aggregation and scaling of calcium carbonate in the presence of ultrasound irradiation using focused beam reflectance measurement

The formation of calcium carbonate scale in the perforations and near well bore formation sandstone is one of the major factors affecting production in the Prudhoe Bay field. Previous work (1–11) has shown that squeeze treatments using certain phosphonate scale inhibitors help to control the formation of calcium carbonate scale in low water-cut wells. However, the desorption rate of the phosphonate from the formation may cause the effectiveness of the treatment to be decreased dramatically as the water-cut in the wells increases. It has been observed that scale inhibitor squeeze treatments employing polymer-phosphonate blends appear to last longer in high water-cut wells than those treated only with phosphonate. This study evaluated the effect of various polymers on the desorption rate and inhibitive character of the phosphonate determined by Meyers (1) to be the most effective in inhibiting calcium carbonate scale in Prudhoe Bay. Standard NACE scale inhibitor tests were conducted to evaluate the effectiveness in preventing scale for the various systems. Flow tests in formation cores were run to determine the feedback rate of the phosphonate from various systems. The core studies were monitored for the amount of phosphonate desorbed as a function of water-cut and total pore volumes of brine flowed through the core. Results showed that a high molecular weight maleic copolymer to be the most effective in decreasing the desorption rate of the phosphonate.

The formation of scale in hot springs and geothermal brines can be detected quickly and easily using optical fiber-based scale sensors. This paper describes the development of a portable sensor for the in situ detection of scale in geothermal water. This sensor was used to detect the formation of calcium carbonate and silica scale and to assess the effectiveness of their inhibitors. The performance of the sensor was evaluated using calcium carbonate scale. In laboratory experiments using both the newly developed sensor and a conventional nonportable sensor, the strength of the transmitted signal was found to decrease significantly as the amount of scale increased. It was considered that this sensor can accurately evaluate only scale formation without being affected by turbidity. The scale that was deposited on each material (optical fiber core, glass plate, polyvinyl chloride (PVC), and SUS304) was observed using a shape analysis laser microscope. Based on these observations, we concluded that this sensor could be used to predict the amount of scale deposited in real time. In situ evaluation of the sensor was conducted at a blowout carbonated hot spring on Rishiri Island, which is located off the coast of Hokkaido, Japan. The results obtained from experiments using hot spring water showed a similar sensor response within a comparable time range as those obtained from the laboratory experiments. The results of this study thus demonstrate that this novel portable scale sensor is suitable for use in geothermal power plants and investigating effectiveness of inhibiters under different conditions.

kemenyan (Styrax benzoin Dryand) extract as green inhibitor of calcium carbonate (CaCO3) crystallization