Novel Approach to Extend Electrical Submersible Pump Run Times In the Williston Basin

Abstract

Abstract Williston Basin oil-producing wells utilizing Electrical Submersible Pump (ESP) lift undergo severe challenges with respect to scale and corrosion due to high TDS brines (250,000 – 320,000 mg/L) and high shear and high temperature operating conditions (275ºF-325ºF at the ESP). Corrosion most commonly attacks the ESP, lower tubing, andannular space locations where the cable armor contacts the metal. Scale is primarily calcium carbonate due to ~20,000 mg/L of calcium in the brine and is commonly seen around the ESP where temperatures are highest. The severity of these conditions canlimit ESP run times to 3-4 months until failure. Challenges for suitable protection from scale and corrosion include using specialty chemicals that provide temperature stability (325°F for the ESP environment and -40°F for winter temperatures at the surface), capillary qualification (the preferred delivery method), high TDS brine compatibility, and custom performance needs to address the various corrosion mechanisms. To this end, two strategies were developed combining uniquely qualified chemistries with specialized application. A new high temperature/high TDS scale/corrosion inhibitor was developed for delivery down the capillary (Menendez et al. 2019). A corrosion inhibitor was then identified formitigating cable armor-tubing corrosion suitable for application as a pre-conditioning batch treatment during ESP installation. Using ESP run time as a metric and comparing treatments with a conventional scale/corrosion inhibitor combination, it was found that the new combination product provided a 73% increase in run time (230 v. 132 days). When the pre-conditioning corrosion inhibitor treatment was done in conjunction with the new combination product, the run time showed a 100% increase (264 v. 132 days). These findings are discussed in conjunction with improved practices for ESP management under severe corrosion and scale challenges. It is important to consider that any extension in ESP run time gained through mechanical or chemical means offers improved well production, lower operating expense, and improved profitability to the producer.