Distributed Acoustic Sensing from Fotech Solutions is a valuable down-hole sensing tool which can help to improve production efficiency
Better production efficiency relies on having real-time intelligence on well activity. This includes the adoption and deployment of the latest sensing technologies to plan and monitor completion and production activities.
One of the key sensing technology breakthroughs that can offer this new level of insight is Distributed Acoustic Sensing (DAS) from Fotech.
DAS works by converting a single fibre-optic cable, which runs either in the casing or inside the production tubing, into the equivalent of tens of thousands of highly sensitive individual vibration sensors. By detecting vibrations in this noise “backscatter,” caused by acoustic disturbances at each point along the fibre, engineers can “visualise” and record what is going on down-hole at every point of the well, in real time.
These acoustic disturbances can be caused by everything from complications in a completion process to changes in flow dynamics. By adding a new dimension of knowledge to the extraction process, DAS gives engineers more clarity that ever before.
These challenges are perhaps most prominent in unconventional plays: during the fracturing procedure, operators have limited visibility of the process. By providing a real-time log of the operation, DAS can provide oversight of the fundamental processes, such as ensuring that the perforation gun fires as expected, that the packer is set properly and that the frac ball is seated correctly.
DAS also gives far more sophisticated insight during the operation to help engineers to optimise the frac fully. With an accuracy of 1-2 metres, DAS can not only assure engineers that the process is being carried out safely and efficiently, but also confirm if there are any down-hole events that need to be addressed.
For example, DAS can help engineers see where integrity issues are causing cross-stage communication issues, opening up previously fracked stages to frac fluid and potentially wasting significant amounts of resource. This could be the result of a breakdown in cement integrity, or a ball-failure event in a slide-and-sleeve operation.
Although the impact on the operation will depend on the severity of the integrity issue, it is obviously not desirable to be wasting water and proppant on stages that have already been fracked. DAS can alert engineers as soon as these cross-stage communication issues occur, enabling them to adapt immediately and maintain an effective operation.
The right combination
DAS is capable of being deployed at new wells and retrofitted to existing wells. As well as the advantages in fracturing, the technology can also enhance a range of other down-hole operations such as borehole seismic, gas lift, flood front monitoring and well integrity monitoring.
That said, DAS is not a replacement for existing monitoring tools. In fact, the sensor is most successful when used in conjunction with other technologies such as in combination with a DTS system to give a multi-dimensional and dynamic profile of well conditions.
Ultimately, the additional information that DAS can deliver is vital to removing the “guesswork” from down-hole activities. By providing accurate intelligence to well operators, DAS delivers a valuable insight into both completion and production issues and can be used to maximise operational efficiencies, increase safety and enhance real-time decision-making.