Advancing The Application of Downhole Fibre Optics with a Novel Low Cost Disposable Deployment Method

摘要

This paper will describe how fiber optics can be introduced into wells at very low cost, for the purposes of Distributed Temperature Sensing (DTS), using a novel disposable deployment method. It was identified that the cost and risk associated with existing methods of installing fiber optics have. severely restricted the application of downhole distributing fiber-optic sensing. It’s because of this that technology has been developed that is cost effective enough to run in any well, resulting in a disposable system that uses the required materials to perform a singular operation. The system utilises bare fiber optics, located in the tool, referred to as ‘dart’ herein. The fiber optic is de-spooled during free-fall deployment into the well. The system is disposed of in the well following the distributed sensing operation, which would typically only last several hours. Tests performed in a shallow test well have shown that bare fiber optic can be successfully and reliably deployed into the well and that a Distributed Acoustic Sensing (DAS) survey can be performed on each fiber installed. It was observed that the bare fiber was paid out into the well with no detectable slack, resulting in good depth correlation, important for determining the location of any event. It was also observed that the bare fiber attached itself to the inside of the tubing, which is thought to provide a good acoustic coupling - as well as a certain level of protection versus a freely moving fiber in the well. It was concluded that the novel system is viable for use in oil and gas wells and would provide significant cost and risk reductions compared to existing methods of fiber deployment. The resulting increase in data from the application of such a system would have a considerable impact on production and well integrity, as well as offer vast cost savings in well abandonment operations.