Barite Nucleation and Inhibition at 0 to 200°C With and Without Thermodynamic Hydrate Inhibitors

Abstract

In this study, we modified the commonly employed dynamictube-blocking methodology and built an apparatus to study the nucleation kinetics of barite-scale formation at high temperatures in the presence and absence of scale inhibitors. Barite formation was detected by monitoring pressure change over a micrometersized in-line filter, and this has been proved to be an easy and accurate method to study mineral-scale-nucleation kinetics at high temperatures. Additionally, we investigated the nucleation kinetics of barite at 0-25°C with and without thermodynamic hydrate inhibitors. By using this modified dynamic-tube-blocking technique, we successfully measured the nucleation kinetics of barite in 1M NaCl solutions over a temperature range from 25 to 200°C and at various supersaturation conditions. We also evaluated the inhibition efficiency of barite precipitation at this high temperature range. On the basis of the experimental results, the relationship of precipitation kinetics of barite as a function of temperature and saturation index was established. The inhibition efficiency of the phosphonate inhibitor [bis-hexamethylenetriamine-penta (methylene phosphonic) acid (BHPMP)] on barite precipitation has been evaluated over the same range of conditions. The Ca 2+ effect on the inhibition efficiency of BHPMP at a low temperature (4°C) and at high temperatures (175-200°C) was investigated also. Results of this study have been incorporated into the scale-prediction software ScaleSoftPitzer. IntroductionBarium sulfate (BaSO 4 ) is one of the major mineral scales formed in oilfield pipelines. For example, in order to maintain oil-and gasproduction pressure in a reservoir, seawater often is injected into the reservoir. Often, when seawater with high sulfate concentration is injected into a barium-containing formation, such injection can induce barite-scale nucleation (Boak et al. 1999;Bedrikovetsky et al. 2004) and cause a serious problem for oil and gas production. Although BaSO 4 -nucleation and -inhibition kinetics has been studied for many years (formation continually causes problems for oil and gas production. Because chemically removing BaSO 4 is very difficult and the cost of removing barite formed in wells, pipelines, and oil formations is very high, the most practical and efficient way to solve these problems is to prevent its formation by using scale inhibitors. Scale inhibitors generally can be characterized in two categories (thermodynamic inhibitors and kinetic inhibitors) on the basis of their inhibition mechanisms. Thermodynamic inhibitors work by decreasing the ionic-activity product by either lowering the solution pH or chelating metal ions. As a result, solution supersaturation is decreased. For example, ethylenediaminetetraacetic acid (EDTA) is a known thermodynamic inhibitor for BaSO 4 . EDTA would reduce free barium ions available to participate in the crystallization process and decrease supersaturation of solutions as a result of forming EDTA complexes with barium cations in solutions. On the other han...

A Novel and Comprehensive Study of Polymeric and Traditional Phosphonate Inhibitors for High-Temperature Scale Control

“…For some inhibitors, b has been correlated to the physical/ chemical condition of the solution, such as the SI, temperature, pH, and lattice-ion molar ratio (He et al 1996(He et al , 1997(He et al , 1998Xiao et al 2001;Fan et al 2011). This model has been used to semiempirically estimate the minimum inhibitor concentration for protecting oil-production wells from scaling.…”

“…Cationic and anionic solutions containing 1.87 mmol/L Ba 2þ and SO 4 2À were prepared in 7 mmol/L PIPES buffer and 1 mol/L NaCl. The pH of the solutions was controlled at 6.65 6 0.02 with PIPES, a buffer known to have little specific interference (Fan et al 2010(Fan et al , 2011. At the beginning of the inhibitor test, equal volumes of the cationic and anionic solutions were mixed in a glass bottle, and the resulting solution was supersaturated with respect to barite at a barite saturation index (SI) of 2.0 at 25 C. The mixed brine was stirred by a Teflon-coated magnetic-stirring bar, and the turbidity of the mixed solution was monitored by a turbidity meter.…”

Measurement and Prediction of Thermal Degradation of Scale Inhibitors

“…Extensive research has been conducted to study inhibitor thermal stability (Motekaitis et al 1980;Motekaitis et al 1982;Nowack and Stone 2000;Dyer and Graham 2003;Dyer et al 2004;Kotlar et al 2006;Wat et al 2008;Wang and Wylde 2009;Wilson and Harris 2010;Fan et al 2012;Wang et al 2013a,b). For example, Nowack and Stone (2000) studied the degradation of nitrilotris(methylenephosphonic acid) and related (amino)phosphonate chelating agents in the presence of manganese and molecular oxygen, showing that manganese can catalyze the thermal autoxidation of phosphonates.…”

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

“…Thus a better understanding of barite nucleation and inhibition over a wide range of reaction conditions is important (Jordan, et al 2006). Currently barite nucleation and inhibition is investigated by using both dynamic and static inhibitor testing under specific conditions (Yuan, et al 1998;Fernandez-Diaz, et al 1990). A flowthrough apparatus has been developed for dynamic inhibitor testing (Fan, et al 2011;Fan, et al 2012;Wang, et al 2013).…”

“…Currently barite nucleation and inhibition is investigated by using both dynamic and static inhibitor testing under specific conditions (Yuan, et al 1998;Fernandez-Diaz, et al 1990). A flowthrough apparatus has been developed for dynamic inhibitor testing (Fan, et al 2011;Fan, et al 2012;Wang, et al 2013). In addition, it was also used to perform scale inhibitor efficiency test (Fan, et al 2011;Fan, et al 2012).…”