Lignosulfonate-Based Calcite Scale Inhibitors for Topside and Downhole Applications

Abstract

Abstract Scale inhibitors (SI) are widely used in upstream oil and gas industries to prevent insoluble inorganic salts from depositing near or inside the production well or in flow lines. Commercial scale inhibitors like polyacrylates or polyvinylsulfonate offer good calcite scale inhibition, but none of them belong to the PLONOR (PLONOR = Pose Little Or NO Risk) list of oilfield chemicals that can be discharged safely to the environment without any prior measure. Often commercial SIs also have problems like limited Ca-ion compatibility (polyacrylates) or thermal stability (polyaspartates). Sodium lignosulfonates (SLS) fall within the PLONOR list of chemicals but have poor inhibition efficiency towards calcite scaling. When modified by a cost-efficient, and environmentally-friendly method, the lignosulfonates showcased remarkable improvement towards calcite scale inhibition. The modified lignosulfonates achieved a 10-20 fold boost in inhibition efficiency compared to the parent SLS, as measured by a high-pressure dynamic tube blocking scale rig. The modified lignosulfonates also showed an appreciable level of Ca-ion tolerance and retained the same level of efficiency after anaerobic hydrothermal treatment at 130 ºC. In summary, we have developed a range of PLONOR-listed, thermally stable, brine compatible products derived from natural wood, which are suitable for both topside and downhole calcite scale inhibition applications.