Observed Impacts of Evaporation and Condensation on Scale and Monitoring as the Industry Drills Deeper and Hotter

As oil and gas wells continue to be drilled into deeper and, therefore, hotter formations globally, a new appreciation for simple evaporation and condensation of water within wells is developing. While distillation of a fluid may be a simple science laboratory setup routinely performed in academia, we may not immediately consider distillation within an oil and/or gas producing well. Recognizing and appreciating the ability for this process to occur in oil and gas production wells, and its potential impacts, will likely be necessary moving forward. Evaporation and condensation of water has led to production and monitoring challenges in unconventional basins in US onshore production. In the Bakken, the presence of ammonium has contributed to condensation of an ammonium carbonate brine that has led to calcium carbonate plugging challenges in surface pipelines. In southwestern Wyoming and the DJ Basin in Colorado, low production rates coupled with high downhole temperature and plunger lift systems have appeared to lead to distillation that has, in turn, caused significant decreases in analyzed total dissolved solids in produced brines. The ammonium carbonate brine was analyzed by a combination of non-dispersive infrared (NDIR) for measuring alkalinity and colorimetric method for measuring ammonia. These brines were collected in the field as well as from distillation experiments conducted in the lab with both field and synthetic brines. The brines associated with evaporation and condensation in plunger lift wells were analyzed with traditional inductively coupled plasma (ICP) and ion chromatography (IC) analyses. The identification and appreciation of how distillation may work within oil and gas wells presents the industry with a unique opportunity to revisit basic scientific principles. While easily understood, the impacts that have already been observed may be a preview of what is to come as wells in high temperature (approaching and exceeding 212 °F) formations age and depressurize. In addition to potentially impacting production chemistry selection, application, and monitoring, possible evaporation and condensation could influence well operational decisions to avoid potential production challenges.