Reducing Emissions at Drilling Rigs with Energy Storage Systems
This project was funded in 2020 through ERA Call #5: Natural Gas Challenge and aimed to reduce system emissions at drilling rigs through the implementation of new energy savings and storage systems. It involved upgrading two existing drilling rigs to the Electronic Modular Control Panel (EMCP) 4.4 Dynamic Gas Blending® (DGB) system, fabricating a natural gas mobile power unit, and demonstrating the single system on two different upgraded rigs.
Most drilling rigs in Alberta generate power from diesel fuel or are modified to burn a combination of diesel and natural gas. This modification results in incomplete combustion, wasting fuel and increasing GHG emissions through methane leakage. In typical rig operations, significant power is wasted. To combat this, the new system uses three pure natural gas engines that fully and efficiently combust the natural gas and includes a one-megawatt energy storage system (ESS) to store power in batteries that would otherwise be wasted. The unit also uses a Smart Engine Management System (SEMS) to automatically start and stop generators in conjunction with the ESS to match the power demand of the rig without wasting power. It functions in synchronization with the active rig, allowing it to operate like a plug-and-play unit, and the standalone unit moves to any active rig with a reliable natural gas supply. These features of the system save 3,650 tonnes of emissions per year, with room for further reductions once battery performance can be optimized.
Coping With Unexpected Issues in New Technologies
Given the nature of the new technology, the project had to troubleshoot problems that had not been seen or understood before. One of the main issues encountered was the electricity from the battery inadvertently taking a path to ground rather than to the power system. Potential transformers (PTs) were also operating incorrectly, requiring regular maintenance or replacement parts. To mitigate these issues, there were several system upgrades. These upgrades include improving the power distribution, which actively keeps the generator load factors at an appropriate level while the battery contributes to the rest of the power demand. Additionally, better programming, instant feedback, diagnostics and alarms were added to improve technical support and performance. The system is performing better than when the project started, but even with these changes, further battery upgrades were deemed necessary.
Another key issue was due to cold temperatures, which impacted the natural gas supply to the rig. The pipes on site take field gas from the gas conditioning unit and direct it to the natural gas engines. Since the conditioning unit was a relatively long distance from the engines, the lower temperatures allowed for hydrocarbon condensates to form in the gas lines and for water vapours to condense and freeze. The key learnings from this were to install automatic dump valves to mitigate shutdowns occurring due to high liquid levels in the engine inlet scrubber. Before the gas enters the engine, it now goes through a scrubbing vessel to allow any liquids to drop out before the gas enters the engine intake.
What’s next?
The project was completed in 2022 and successfully transitioned from its pilot phase to commercial deployment. Since the project’s completion, the technology has been implemented across various drilling sites in Alberta, demonstrating substantial environmental and economic benefits, although it still faces some barriers to widespread implementation.