DAS/DTS: Oil & Gas Well Life-Cycle Dynamic Monitoring

Project Background

During the full life cycle of oil and gas development in Well XX, the client was confronted with the following monitoring challenges:

1. Insufficient accuracy in cementing quality evaluation, making it difficult to accurately verify the cement top height and the interface between high-density and low-density cement;
2. Complex perforation processes that require avoiding optical fibers while monitoring perforation depth and shot counts in real time to ensure operational safety and effectiveness;
3. Difficulties in locating packer failure during the pilot production phase, which hinders the judgment of liquid-producing intervals and the evaluation of packer tightness, resulting in unclear pilot production outcomes.

Our Solution

We adopted distributed optical fiber sensing technology (DTS and DAS) throughout the full life cycle of the oil and gas well to achieve multi-stage dynamic monitoring:

Cementing Phase: By comparing DTS curves with conventional acoustic variable density logging data, we verified the cement top height and the position of the cement interface;

Perforation Phase: Combined real-time DTS and DAS monitoring to track temperature and vibration responses during perforation, achieving precise matching of perforation depth and shot counts;

Pilot Production Phase: Used DTS to continuously monitor wellbore temperature changes. Through temperature curve analysis, we identified liquid-producing intervals and packer tightness, and accurately located the source of fluid flow.

Final Results

In cementing monitoring, the DTS curves showed a high degree of consistency with the acoustic variable density logging results. The cement top height was measured at 1764.00 m for both methods, and the actual interface between high-density and low-density cement was detected at 3020 m (vs. the predicted 2950 m), verifying the monitoring accuracy;

Perforation monitoring clearly identified the positions and response characteristics of 7 shots in the lower interval and 6 shots in the upper interval, with accurate depth positioning;

Pilot production monitoring revealed abnormal temperature rise in the lower interval through DTS temperature curves, while no changes were observed in the upper oil testing interval. This accurately determined that packer failure caused upward channeling of lower interval fluid, providing the client with clear evidence for fault diagnosis.

Client Evaluation

The client highly recognized the effectiveness of the full-life-cycle dynamic monitoring. They believed that the integrated application of DTS and DAS technologies had significantly improved monitoring accuracy and operational reliability. Especially in real-time perforation monitoring and packer failure location, it provided data support that was difficult to achieve with traditional methods. This solution effectively guided engineering decision-making and fault handling, and delivered key technical support for wellbore integrity management and efficient reservoir development.