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

Steamflooding has been used as one of the emerging techniques to enhance heavy oil production. Scale control during steamflooding, on the other hand, can be challenging since the high temperature of the steamflood can decompose thermally unstable inhibitors and/or lead to the precipitation of metal-inhibitor pseudo-scale. In this paper, we present the analysis of the scaling risk and scale inhibition for a pilot steamflood project in a Middle Eastern oilfield. The formation of this field is a dolomite formation interbedded with anhydrite (CaSO4) streaks. Anhydrite has been observed to be the predominant scale form, which is presumably formed due to increased production system temperature as a result of steamflooding and/or mixing of steam condensate with incompatible connate water. Anhydrite is inherently difficult to control due to its high solubility and the high temperature conditions under which it forms. Compared to barite and carbonate, only limited knowledge has been acquired for anhydrite control. To predict the scaling tendency and inhibitor need in different wells of this field with different supersaturation level and temperature, a scaling risk model has been developed. To build such a model, detailed and revised laboratory procedures have been developed to study nucleation and precipitation kinetics of anhydrite at 125-175 ºC, different supersaturation, water composition, and long reaction time. Predictions of this scaling risk model suggest a saturation index (SI) of 0.8 as a critical SI for anhydrite control at >125 ºC. For example, when the SI is above 0.8, anhydrite will be difficult to control in the presence of threshold inhibitor. Model predictions were found to be consistent with scale occurrence observations in different wells of this field. With the recommended inhibitor concentrations, anhydrite scale has been controlled in this field, which provides validation that the proposed scaling risk model is a powerful tool to optimize scale treatment plan.

show abstract

Effect of Crosslinkers on the Performance of Calcium Sulfate Scale Inhibitors at High Temperature: Impact of Zirconium

Alsaiari

AlKhaldi

Al-Taie

et al. 2016

All Days

View full text Add to dashboard Cite

With the increased desire to fracturing treatments using seawater based-fluid, the formation of calcium sulfate scale becomes a challenging problem. This is due to the presence of high concentration of calcium ions released from the reservoir after fracturing treatment and high sulfate content in the seawater. Preventing calcium sulfate formation is imperative in order to maintain conductive flow channels after the treatment. The challenge basically lies in finding an efficient scale inhibitor that works at high calcium and sulfate concentrations and high temperature without compromising the efficiency of the fracturing fluids. Zirconium is widely used in the fracturing fluid as a crosslinker for guar-based gels to increase the elasticity and proppant transport capability. Using these materials makes each crosslinker have unique reaction conditions and behavior. Unfortunately, no systematic study has been conducted to investigate the influence of zirconium on calcium sulfate scale inhibitor performance at high temperatures. This work is intended to 1) evaluate the efficiency of six different types of commercial-grade scale inhibitors for calcium sulfate (anhydrite) at high temperature and super saturation; 2) to determine the impact of zirconium on the performance of common scale inhibitors used in the oilfield. Extensive experiments have been conducted at 149°C (~300°F), pH 6.8, and 1.0 M NaCl solution at different concentrations of zirconium and with various organic and polymeric scale inhibitors. The induction time and the performance of inhibitors were detected by using an in-house developed laser technique. It was found that the presence of zirconium adversely reduced the performance of calcium sulfate scale inhibitors. The level of impact varies based on zirconium concentration, solution conditions and type of scale inhibitor present.

show abstract

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

Cited by 3 publications

References 17 publications

An assay method to determine mineral scale inhibitor efficiency in produced water

An assay method to determine mineral scale inhibitor efficiency in produced water

Calcium Sulfate Scaling Risk and Inhibition for a Steamflood Project

Effect of Crosslinkers on the Performance of Calcium Sulfate Scale Inhibitors at High Temperature: Impact of Zirconium

Contact Info

Product

Resources

About