Early downhole battery monitoring focused on estimating remaining runtime based on battery capacity alone. Today, advanced software systems add current draw, temperature, vibration, shock and rotation data to improve runtime estimates, with the added benefit of revealing valuable insights into the downhole environment.
According to Bob Fay, Regional Manager at Ultralife’s Houston facility, this is creating new opportunities to improve battery utilization, investigate tool performance and optimize drilling operations.
When battery management was based primarily on capacity-based runtime estimates, operators often took a conservative approach to battery replacement. One measurement while drilling (MWD) operator later found that batteries were being retired with an estimated 50-60 per cent of usable capacity still remaining, representing approximately $1.9 million per year in avoidable costs. Findings such as these highlighted the value of better downhole visibility.
This increased demand for more advanced monitoring systems that take into account the impact of downhole conditions on battery performance. Such systems monitor tool behaviour, including vibration, shock and rotation, as elevated levels can increase power demand and accelerate battery depletion.
“When battery monitoring systems began incorporating these additional metrics, operators could use them to manage their tools as well as their batteries. Not only could this data indicate accelerated battery depletion, but it could also alert engineers to severe downhole conditions requiring tool retrieval. Given its value, operators increasingly want access to this information in real time rather than waiting until the mission is complete.
The specific analytics provided vary by vendor, with some systems offering additional operational insights. For example, Ultralife’s Criterion 5 delivers live inclination reporting accurate to within 1°, enabling operators to monitor wellbore trajectory and identify when drilling angle adjustments may be needed. The data can be accessed through Criterion software or the EFR100 Compact Field Reader for field-based analysis.
Accessing important data quickly
Although the fundamentals of downhole battery monitoring remain unchanged, with a compact gauge embedded within a lithium thionyl chloride (LiSOCl₂) battery pack for its operational life, the way data is handled has evolved significantly. Earlier systems simply recorded battery and environmental data for later retrieval, meaning the tool had to be brought back to the surface before the information could be accessed and analysed.
Modern systems, by contrast, can continuously transmit this data while the tool remains downhole, providing near real-time visibility through software at the surface. This allows operators to identify abnormal conditions and investigate potential tool issues as they arise, enabling more informed decisions during the run. In turn, this can reduce operational risk, improve tool reliability and minimise non-productive time (NPT).
While modern battery monitoring systems provide significantly greater visibility into downhole conditions than ever before, they are not intended to replace downhole tool control systems. Instead, they provide a complementary and independent source of information. Although dedicated control systems continue to offer broader diagnostics and analytical capabilities, the additional insights provided by intelligent battery systems are becoming increasingly valuable as downhole operations grow more complex.
The future of downhole intelligence
As drilling operations move into deeper, hotter and more challenging environments, including geothermal applications, the demand for reliable downhole intelligence will continue to increase. By combining high-temperature power solutions with advanced monitoring capabilities, specialist battery manufacturers such as Ultralife are helping to deliver not only the energy required to power critical tools, but also additional operational insights that support safer, more efficient and more informed drilling operations.
To learn more about reliable power solutions for oil and gas and other demanding applications, visit https://ecommerce.ultralifecorporation.com/
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