Beyond Windows: Glass Solid Scale Inhibitors with Controlled Release at Elevated Temperatures for Extended Carbonate Scale Protection in the Laboratory and Field

Abstract

Gas condensate fields often have multiple reservoirs with different water chemistries, and they contain varying concentrations of carbonates and CO2 in solution. One challenge associated with these types of fields is that calcium carbonate scale may form during gas production when water sources from different zones comingle with the gas, ultimately reducing gas production. A proactive approach to mitigate carbonate scale utilized a new technology, glass solid scale inhibitors, to show extended protection in both laboratory and field studies. Laboratory tests were conducted to study the release profile of the glass scale inhibitors (SI) at 150 °C. The SI's were placed in a metal pouch, submerged in deionized water, and placed in a high temperature high pressure apparatus. The apparatus was placed in an oven, and the weight loss was monitored for over a year. The results showed that SI's were able to show controlled release of the active component for over 1 year. Minimum inhibitor concentration (MIC) testing was also conducted using field brines that showed a risk for carbonate scale formation. Dynamic scale loop (DSL) testing determined the MIC to be as low as 0.1 ppm. The results suggest that it is possible to achieve extended protection at low concentrations for over 1 year. The glass scale inhibitors were deployed in a field trial and the produced water was collected to monitor the residual SI concentration. The glass SI's are easily added with the proppant into the frac fluid and placed in the fracture along with the proppant to provide scale protection deep in the reservoir. Field data showed that the product was able to sustain the MIC up to 2 years after application, in high temperature wells of 125 °C. Three wells treated showed no indication of scale formation 9 months after application. The new technology offers an alternative method to proactively treat carbonate scale formation in wells being fractured to enhance production. With extended protection, it is possible to reduce costly squeeze treatments or continuous application, while potentially reducing extra carbon emissions associated with traditional scale treatments.