A Novel Testing Method to Perform Static Scale Inhibition Test at High Temperatures Under Anaerobic Conditions with Well-Maintained Testing pH

Abstract Conventionally, there are two laboratory testing methods implemented throughout the industry to perform mineral scale precipitation and inhibition tests. One is the dynamic tube-blocking test, which can reproduce the dynamic fluid system as it exists in oil and gas production system under desired testing temperatures, pressures, and pH levels. However, the residence time for the tube-blocking test is generally less than 5 seconds. To accomplish a more balanced assessment of scale inhibition and hence choose the right product for application in a specific field case, another major testing method, the static "bulk" or "bottle" test, is commonly adopted in laboratory scale inhibitor evaluation tests. The static bottle test is widely used to compare the performance of different scale inhibitors over a much longer residence time (2 hours or more). However, static bottle testing requires extra effort to create an anaerobic testing environment to prevent the oxidation process if any dissolved Fe2+ is present in the testing brine, and it is not convenient to maintain the brine pH in the presence of bicarbonate. Furthermore, as the testing temperature increases over 212°F, more complicated testing designs are required to overcome the elevated water saturation pressure, which the regular testing bottle cannot handle. Here, we present a new approach to perform static scale inhibition tests at 335°F with the presence of high levels of dissolved Fe2+ for a testing period of at least 2 hours, leading to quality results. Compared to low temperatures static bottle tests, this approach does not require any new testing equipment or complicated set up. The differences between high temperature static bottle and dynamic tube-blocking test results are also discussed in this work.