Project Background
In May 2022, when the client was conducting optical fiber leak monitoring in ultra-deep wells (well depth ≥ 6000m), they were confronted with technical challenges in laying optical cables outside the casing. The ultra-deep well environment imposes extremely high requirements on the high temperature resistance, high pressure resistance and long-term stability of optical cables. Meanwhile, it is necessary to ensure cementing quality and optical cable laying success rate, which are difficult to be achieved by traditional processes.
Our Solution
Targeting the characteristics of ultra-deep wells, we developed and implemented a complete set of solutions:
- Adopted independently developed cable-penetrable stage collars to ensure safe and smooth laying of optical cables outside the casing;
- Selected domestically produced carbon-coated high-temperature fiber cores to guarantee the stable operation of optical cables in extreme environments with long-term operating temperature > 175℃;
- Captured signal abnormal sections accurately through the triple pressure test and repeated measurement process, combined with dynamic pressure monitoring and optical cable position adjustment.
Final Results
During the construction on May 23, 2022, through the analysis of DAS monitoring data, continuous abnormal signals > 200Hz were detected in the well depth range of 715.0-750.0m. Among them, the vibration signals at 727-736m showed significant anomalies, which were accurately determined as the casing leakage location. The process was implemented smoothly and the optical cable laying was successful, achieving the goal of permanent dynamic monitoring under ultra-deep well conditions.
Client Evaluation
The client highly recognized the construction process and results of this project. They believed that the solution had effectively overcome the technical bottlenecks in laying optical cables outside the casing and conducting long-term monitoring in ultra-deep wells, improved the accuracy and reliability of wellbore integrity monitoring, and provided important technical support for the subsequent safe operation and maintenance of ultra-deep wells.
