Study of Thermal Stability of Scale Inhibitors and its Impact on Processing Plants

Abstract

Petroleum, which is one of the most complex mixtures existing in nature, is equilibrated and coexists with the aqueous phase at reservoir conditions. However, depending on the oil viscosity, strong emulsions may be formed due to the high shear imposed by the production process. As a consequence higher temperatures conditions are necessary for the oil separation treatment. Therefore it is important to assure that scale inhibitors are thermally stable and able to act in what are considered extreme temperatures such as the ones used in heat exchangers, for example 16 °C. This work aimed to evaluate the influence of temperature in the scale inhibition activity for different active materials of chemical inhibitors, such as: Nitrilotris (methylene) tri phosphonic acid (NTP), Diethylenetriamine penta (methylphosphonic acid) (DETPMP), and polyvinyl sulphonate (PVS). Aqueous inhibitor solutions were aged in the temperature conditions between 60 to 160 °C for different times (6, 12 and 24 hours). Raman spectroscopy, NMR (31P, 1H and 13C) and FT-MS techniques were used to characterize chemical species from aged and original inhibitor solutions. Different from previous works, these techniques allow identification of some degradations products. Additionally, dynamic performance tests were conducted to evaluate scale inhibitor performance of the solutions. Results of the chemical characterization of the original and thermally aged PVS showed no compositional differences. Dynamic testing for barium sulphate scale showed that minimum effective concentrations remained constant in all assays. However, for the NTP and DETPMP products, at the highest temperature (160 °C, after 24 hours of testing) some degradation products were identified, such as methyl phosphonic acid, and especially, amino methyl phosphonic acid. As a consequence of the structural breakdown of the phosphonate molecules, confirmed by chemical analysis using FT-MS and NMR, the efficiency of inhibition of barium sulphate scale was reduced. The paper presents a methodology to evaluate and understand the behavior of different chemical inhibitors for extreme temperature conditions and highlights the demand for new stable molecules for high temperatures.

Evaluation of Polyelectrolyte Complex Nanoparticles for Prolonged Scale Inhibitor Release in Porous Media

“…In contrast to DETPMP, the thermally aged PVS exhibited no degradation and remained above the effective minimum concentration of 5 mg/L PVS for barite in all tested assays. 18 Sorbie and Laing concluded that nucleation inhibition was the primary mechanism that prevented scale formation with PVS and reported a MIC of 1 mg/L PVS for mixed brines containing synthetic seawater and Brent formation water. 19 Graham et al investigated the effects of pH and other experimental variables (e.g., flow rate, run time, prescaling, and mixed scale) on MIC values for PVS and reported MICs of ∼1 mg/L at pH 2.4 and 6.0 in a 50:50 mixed Mungo formation water/seawater, 1.25−5 mg/L for low-barium sulfate scaling brine systems, and 0.25−2 mg/L for low-carbonate scaling brine systems.…”

“…Additionally, phosphate-based SIs raise environmental concerns due to large amounts of phosphorous introduced into the environment . Organic polymers such as poly­(vinyl sulfonic acid) (PVS) can tolerate high temperatures, and many studies have proven their effectiveness for barite scale at low concentrations. − For example, Rosa et al investigated the performance of several barite SIs, including DETPMP and PVS, at temperatures between 60 and 160 °C. In contrast to DETPMP, the thermally aged PVS exhibited no degradation and remained above the effective minimum concentration of 5 mg/L PVS for barite in all tested assays .…”

“…Organic polymers such as poly­(vinyl sulfonic acid) (PVS) can tolerate high temperatures, and many studies have proven their effectiveness for barite scale at low concentrations. − For example, Rosa et al investigated the performance of several barite SIs, including DETPMP and PVS, at temperatures between 60 and 160 °C. In contrast to DETPMP, the thermally aged PVS exhibited no degradation and remained above the effective minimum concentration of 5 mg/L PVS for barite in all tested assays . Sorbie and Laing concluded that nucleation inhibition was the primary mechanism that prevented scale formation with PVS and reported a MIC of 1 mg/L PVS for mixed brines containing synthetic seawater and Brent formation water .…”

Barrier behavior evaluation of polyamide 12 nanoclay composite to offshore application by electrochemical impedance spectroscopy

“…Each cell was filled with a synthetic brine solution in deionized water, composed of 33 g/L NaCl, 7.360 g/L NaHCO 3 , and 2.843 g/L Na 2 SO 4. [38][39][40] Once the tests would be carried out for a long time, the cells remained at room temperature and under mechanical agitation to maintain the physicochemical properties of the brine solution throughout the experiments. All electrochemical results were acquired with the help of a Potentiostat/Galvanostat AUTOLAB PGSTAT302N.…”

Influence of magnetic field on barium sulfate incrustation from aqueous solutions

“…In this context, the knowledge of the concentration of dissociated salts in the aqueous phase at different conditions of supersaturation, pH, temperature, and pressure allows for the monitoring of the nucleation phenomena and crystal growth kinetics of these salts. The nucleation, precipitation, and growth of inorganic crystals responsible for the incrustation can be avoided/delayed using data associated with salt precipitation rates in the presence of chemicals scale inhibitors (Antony et al., 2011; Fan et al., 2009; Rosa et al., 2016). Besides the efficiency of the scale inhibitors used, the understanding of their action mechanisms is essential to reduce environmental impacts resulting from their incorrect disposal and also to minimize cost (Reis et al., 2011).…”