From water analysis to scale and corrosion control improvements: A Permian Basin example

Abstract

Oil and gas production and geothermal energy exploitation generate large volumes of produced water (PW), which is causing various operational challenges including environmental sustainability, scale, corrosion, and other economic and safety issues. Using the Permian Basin as an example, this study traced the PW sources and developed a new procedure for scale and corrosion management improvements based on the PW compositions from U.S. Geological Survey National Produced Waters Geochemical Database (USGS PWGD). Both correlations between the major ions and Br− and between the water isotopes (δD versus δ18O) showed that most PW samples evolved from seawater, and a group samples from foreign sources were detected. The downhole pH, CO2% and calcite saturation index (SI) at surface were predicted by assuming PW is at equilibrium with calcite at downhole conditions. The SI values of barite, halite, and gypsum were also predicted. A dosage of 1 mg/L of NTMP (nitrilotris(methylene phosphonic acid)) was recommended to control such scale formations for >95% Permian wells. Furthermore, this study incorporated a mechanistic corrosion module to calculate the corrosion rate, which correlated well with the measured Mn2+ concentration. Such good correlation suggested that Mn2+ concentration can be utilized as a proxy for the steel corrosion. This recommended procedure has been shown to provide vital information for formation water source evolution analysis and scale and corrosion management improvements based on produced water composition with nonideal data.