A Novel Experiment Setup to Model the Effects of Temperature on Halite Scaling and Inhibition

Abstract

Abstract Halite is a common scale in oil/gas production. Freshwater is widely used to combat halite scaling, but this is costly. Therefore, halite inhibitors have also been examined in laboratory and field tests. However, there are certain flaws in the laboratory studies of halite inhibitors, the temperature decreases were so abrupt, or the experiments are limited to lower temperatures. As a result, inaccurate results and unrepresentative field conditions are produced. Our new precisely temperature-controlled method simulates halite precipitation at high temperatures up to 120+ °C with real-time monitoring using a laser and a video camera. This method uses batch reactor convection cooling to gradually increase the saturation index (SI) to trigger the halite nucleation observed by turbidity laser measurements. The cooling rate is commonly set at 0.5 °C/min to simulate a real-world downhole to surface hot brine movement, typically 25-35 °C of cooling. Low to high Ca2+ values were used to validate the experimental data with thermodynamic predictions. The experimental data and ScaleSoftPitzer™ (SSP) predictions are very close and with high precision. The high temperature inhibition properties of halite inhibitors are not well-known, and lack of information can lead to overtreating the scale with higher inhibitor concentrations than needed. By simulating the temperature drop that occurs when brine is transported from the downhole to the surface, this approach can establish the effective SI range for a specific inhibitor. Our data shows that even at low 0.1-100 mg/L concentrations, some inhibitors with carboxylate, sulfonate, and acetamide moieties can effectively treated halite scale and dramatically extend the stability range. Despite the weak thermal stability and incompatibility with high Ca2+ concentrations, potassium ferrocyanide demonstrated outstanding inhibitory effectiveness. The longer the inhibition period or brine transit distance, the lower the scaling temperature. By treating the scale with the least amount of inhibitors and combining it with less water dilution, production can continue uninterrupted at significantly enhanced cost savings. Overall, this approach is reliable while remaining straightforward. In addition, it can model field conditions in an oil/gas production system to evaluate the risk of halite scaling at higher temperatures than any previous method.