Integrated Wireless Barrier Monitoring System Improves CO2 Well Intervention Efficiency
Authors: Azevedo Vinicios , Paluruan Firman , Skwara Robert 
Published: February 2023

Abstract
An LNG plant in Australia was designed to maximize energy efficiency and minimize greenhouse gas emissions. In steady-state operations, its greenhouse gas emissions are lower than any in-country LNG project. Typically, gas supplied from two offshore fields contains CO2 (~14%) and high-volume operations run smoothly. At the time of this project, an injector well was found to have critically high CO2 levels (99%), and two other injector wells were shut-in due to pressure anomalies.
A solution was needed to confirm casing isolation and detect leakage, while maintaining well barrier integrity and monitoring pressure/temperature below the tubing hanger plug. An innovative acoustic transmission platform served as a barrier assurance tool. A transmitter module (below the plug) has pressure/temperature sensors sending data through tubular/casing walls. A receiver module (above the plug) also houses pressure/temperature sensors. Once configured and deployed downhole, barrier installation is recorded, and barrier setting is verified before pressure testing. During the pressure test, sensors record pressure/temperature (in Wireline mode or fed live to surface) from either side of the barrier, confirming its integrity.
The integrated wireless barrier monitoring solution exceeded customer expectations, with continuous acoustic and wireless communication maintained throughout the entire operation. Simultaneous monitoring of two wells for 500+ hours accurately documented the barrier integrity via pressure testing results. The system was run downhole in conjunction with a non-explosive slickline setting tool and retrievable bridge plug allowing to not only log the setting sequence for quality assurance but also record the pressure & temperature across the barrier. Conducted on-location, the customer was able to witness the plugs being successfully set. They then received positive confirmation of established well barrier, by continuous monitoring of the pressure between the two barriers and interpreting data from the wireless system in real time. This combined technology approach reduces time to troubleshoot and verify barriers, enabling quick evaluation of the leak source. Other benefits include significant time savings over traditional isolation methods, improving personnel safety in the well bay area by conducting real-time diagnostics, while also optimizing the suspension to allow efficient intervention or abandonment operations. The main objective of the operation was met, and verification of the shallow set plug was achieved. Barrier verification without the acoustic real-time wireless system would have been questionable.
During well intervention for a major LNG plant operator in Western Australia, the novel wireless barrier monitoring solution delivered efficient, real-time pressure testing and verification to ensure success. This marks the first global installation of an integrated barrier system, combining retrievable bridge plug with wireless acoustic telemetry in supercritical CO2 disposal well. It not only allows a shallow bridge plug to be verified as a leak-free barrier, but it also enables efficient evaluation of the entire well barrier envelope.