Members of the flywheel battery research team in the lab at TAMUQ
The tools used in oil and gas exploration pummel through a myriad of harsh conditions to get data for underground mapping. However, pressure, 150°C+ heat and the vibration during drilling challenge the process. To start with, the downhole conditions are among the most unsuitable for power supplies, be they cords or batteries. Researchers in Qatar are looking at a way to improve the power source for drilling equipment, which could greatly enhance its performance and capabilities over time.
“In the oil field they used to use lithium batteries for supplying sensors and measurement devices inside the well,” said Dr. Ahmed Mohammed Massoud, Associate Professor in the Department of Electrical Engineering at Qatar University. “But leaking batteries are chemical, not rechargeable, and are affected by temperature. They don’t offer much time before they need to be replaced. All of these are reasons for looking at another solution for supplying power to sensors inside the wells.”
Dr. Massoud’s research team includes Dr. Shehab Ahmed, Assistant Professor in the Department of Electrical Engineering at Texas A&M University at Qatar (TAMUQ), Dr. Alan Palazzolo, Professor, Department of Engineering, TAMUQ, and Ahmed Elantably, President and CEO at General Machines Corporation and former lead engineer at General Motors Corp.
Drawing from their complementary expertise, the team is working on an alternative battery model based on flywheel technology. This power source would be electromechanical—vs. chemical—rechargeable and resilient to many of the adverse conditions within the wells. The technology could mean not only higher efficiency in terms of time and power, but also higher resolution findings due to more compact and intelligent design around the equipment, namely measurement while drilling (MWD) and logging while drilling (LWD) machinery.
“First of all, you need the battery to be small because of the limited diameter of the well,” said Dr. Massoud. “We need them to be lightweight, too. It’s a very harsh environment, so we need long-lasting devices and long-lasting batteries that withstand heat, damp and vibration … and they can never deplete. Lithium batteries are not rechargeable, and their lifetimes are very short.”
The team is working on batteries that are powered by tiny—16 cm in diameter—flywheels. These rotating, mechanical devices spin fast and rely on sustained movement, or inertia. They either store or provide energy based on changes in the rotation speed. As the equipment moves downhole, the flywheel will be driven by mudflow surrounding it and will store excess energy. When the equipment comes to a full stop for the connection of the next drill pipe or for capturing high-resolution data, the mudflow will cease, and the flywheel alone will power the machinery until it moves again. This is akin to the spinning wheels of an electric car—when it’s moving passively downhill, it stores up excess energy from gravity-spun wheels, which it will spend when it is in active, drive, mode.
When the flywheel’s motion alone kicks in as the power source, its momentum must last long enough to collect 15 to 30 minutes of data at a specific depth. At this point, the heat around the unit typically rises due to the tight surroundings and lack of mud circulation. However, Dr. Massoud said that this heat buildup would be addressed by the new technology.
A large-scale flywheel to be tested at Texas A&M University at Qatar
A major source of heat within moving devices is friction, he explained. Friction within the team’s power source would be cut significantly, however, because the flywheel’s components will be moving around magnetic bearings, i.e., without touching. The magnetic interface between components is also energy saving.
“The mechanism will be frictionless because of magnetic bearings,” Dr. Massoud explained. “Typical mechanical bearings mean energy [momentum] losses due to friction. Magnetic bearings haven’t any physical contact between the stationary part and the rotating part.
“In my opinion this is one of the most important and challenging things—we are suffering from a harsh environment, particularly vibration,” he continued. “It’s tricky as we are working against this to get a high level of control around the magnetic bearings, which is expected to be one of the major contributions we are developing.”
Their publications so far reflect detailed research into specific areas—such as voltage and frequency support in wind generators; power control strategies for flywheel systems; enhancing (steadying) the behavior of renewable energy sources during disturbances due to faults in a power system network; effects of high speeds at various temperatures on the flywheel components, etc.—without giving away overarching details of technology itself.
“So we are working on several issues but we are set on a product. We hope that we can bring it to market in the end,” Dr. Massoud said. “Eventually, we hope to test this product. On the publications side, we are doing very well right now.”
Dr. Massoud said they should be able to start testing the flywheels in the lab by the end of the year.
A rechargeable environmentally friendly alternative to lithium batteries in MWD and LWD applications