Systematic Study of Barite Nucleation and Inhibition with Various Polymeric Scale Inhibitors by Novel Laser Apparatus

Abstract

This work reports a reliable and systematic study of barite nucleation kinetics in the presence of scale inhibitors from 4 °C to 90 °C and at various conditions. In this study, we designed and developed an apparatus to study the nucleation kinetics of barite scale formation by monitoring the change of photo-current created by 5 mW, 635 nm red laser. The photo-detector has a wide wavelength range where sensitivity has a peak at 960 nm. A set of convex and concave lens were used to control the beam diameter so that it can pass through more particles and increase the sensitivity. Temperature and mixing procedure was precisely controlled by an external water bath and magnetic stirplate respectively. The photo-current output was constant when the laser is shining through a clear solution prior to scale formation. Once scale occurred, laser was scattered by scale particles which causes the decrease of photo-current. This method can be expanded to study nucleation kinetics of other scales such as carbonates, other sulfates, and sulfide scales. In addition, it can be customized to perform study under high temperature, high pressure and anoxic conditions. By using this newly developed “laser” method, we successfully measured the nucleation kinetics of barite in synthetic brine (1M NaCl, 0.1 M CaCl2) under various combination of reaction parameters including temperature (T), pH, saturation index (SI), and Ba2+ to SO42- ratio (R). Furthermore, the inhibition efficiency of various scale inhibitors including sulphonated polycarboxylic acid, polyvinyl sulphonate and inulin on barite precipitation has also been investigated. Based on the experimental results, the relationship of precipitation kinetics of barite as a function of T, pH, SI and R was established. Results of this study will be incorporated into the scale prediction software to predict the risk of scale formation and the efficiency of scale inhibitors.

Mineral Precipitation Kinetics: Assessing the Effect of Hydrostatic Pressure and Its Implication on the Nucleation Mechanism

“…Note that because of the nonideal nature of ions in the mixed electrolyte system at given conditions, the concentrations of barium and sulfate ions needed to achieve the same supersaturation level at elevated pressure were considerably higher than those at lower pressure (see tables). As mentioned in the Experimental Details section, our HP dynamic flow apparatus does not allow us to monitor the nucleation time for longer than 2 h. To determine the nucleation time at ambient pressure (i.e., at 0.10 MPa), a laser light scattering detection method was used, and it was estimated to be 4.2 h. A comparison of the measured nucleation time indicates a significant effect of pressure on barite nucleation kinetics. For instance, barite nucleation time decreased from 4.2 h to 10 min when the pressure was increased to 103.42 MPa.…”

“…As mentioned in the Experimental Details section, our HP dynamic flow apparatus does not allow us to monitor the nucleation time for longer than 2 h. To determine the nucleation time at ambient pressure (i.e., at 0.10 MPa), a laser light scattering detection method 44 was used, and it was estimated to be 4.2 h. A comparison of the measured nucleation time indicates a significant effect of pressure on barite nucleation kinetics. For instance, barite nucleation time decreased from 4.2 h to 10 min when the pressure was increased to 103.42 MPa.…”

“…34,36 In some case, nucleation kinetics at lower temperature/ pressure was evaluated using a laser light scattering method and the detailed experimentations of this method have been described previously. 38 Despite the disagreement in the literature whether the mineral nucleation or crystal growth rate is a function of concentration or activities of constituents ions, 7 we used the activity concepts to account for the nonideal behavior of the ions in solution as well as to maintain the constant thermodynamic driving force under various conditions. The amount of cation and anion needed to get the desired supersaturation level with respect to mineral phases under the given experimental conditions was calculated by using scale prediction software, ScaleSoftpitzer (SSP2015), developed by Rice University.…”

Development and Application of a New Theoretical Model for Additive Impacts on Mineral Crystallization

“…Solution turbidity can be measured with a turbidity meter 31,36 or through transmitted red laser (wavelength is 635 nm) beam intensity changes. 50 The two methods have been examined and show identical results for barite induction time measurements. 50 In this study, a turbidity meter was used in measurements done by Kan, as noted in Table S1; a laser method was used in all other measurements.…”

Laboratory Evaluation and Mechanistic Understanding of the Impact of Ferric Species on Oilfield Scale Inhibitor Performance

“…The apparatus to measure barite induction time adopted in this study is based on a laser nucleation detection method developed previously. 26 In the previous study, this apparatus has been applied to test the inhibition efficiency of several scale inhibitors at different pHs, temperatures, and saturation indexes. Figure 1 illustrates the schematic of the experimental apparatus.…”