Mitigating Downhole Calcite and Barite Deposition in the Montney: A Successful Scale Squeeze Program

Abstract

This technical paper addresses the challenges faced by Montney producers in northwestern Alberta and northeastern British Columbia due to downhole calcite and barite deposition. These scales lead to various issues such as production declines, pressure increases, decreased pump efficiency, and equipment failures. Additionally, the presence of Naturally Occurring Radioactive Materials (NORMs) associated with barite poses health concerns and disposal expenses. Continuously applied scale inhibitors are unable to reach the pay zone in the horizontal section, which has multiple fractures in a low-porosity and low-permeability formation. In response to these challenges, a comprehensive database of water analyses for the Montney was used to understand the variability in scaling ions. Scale modeling under bottomhole and topside conditions was conducted to gain insights into scaling dynamics. Laboratory performance of a range of system-compatible scale inhibitors was evaluated using dynamic scale loop and particle size analysis through focused beam reflectance measurement (FBRM) tests. The study focused on candidate wells with pump lifespans of less than three months, and scale squeezes were performed on both beam pump and gas lift wells. Drawing upon best practices from scale squeezes in the Saskatchewan, Montana, and North Dakota Bakken Formation, a scale squeeze program was developed. Monitoring during the program involved comparative water analyses, scale inhibitor residuals, and NORM monitoring. Results showed that the scale squeezes led to increased pump lifespans for beam-pumped wells, elimination of NORM in surface equipment, reduced acid cleanouts, and minimized downtime. The success of the scale squeeze program proved the feasibility of applying this approach in the Montney and offered support for its extension to other shale plays across Western Canada and worldwide.