In the heart of China’s coal-rich Shanxi province, researchers are reimagining how to extract energy from some of the most challenging reservoirs. A groundbreaking study led by Hecheng Xiao from the Taiyuan University of Technology has unveiled promising insights into a novel fracturing technique that could revolutionize the energy sector. The research, published in Meitan xuebao, or the Journal of the China Coal Society, focuses on N2 foam fracturing, a method that could significantly enhance the productivity of low-pressure, low-permeability coal measures reservoirs.
Traditional fracturing methods often rely on large volumes of water and can cause significant damage to the reservoir, reducing its productivity over time. Xiao’s research, however, explores the use of nitrogen (N2) foam, a gas-liquid mixture, to create more efficient and less damaging fractures. “Foam fracturing offers a unique combination of low water consumption, low reservoir damage, and high flowback efficiency,” Xiao explains. “This makes it an attractive option for developing challenging reservoirs.”
The study compared the fracturing characteristics of N2 foam with different foam qualities (the volume percentage of gas in the foam), clean water, and N2 gas. The results were striking. Foam, with its compressibility between water and N2 gas, allowed for longer fracturing pressurization times, especially at higher foam qualities. Moreover, the foam’s high viscosity and low filtration properties led to higher rock breakdown pressures, a crucial factor in creating effective fractures.
One of the most compelling findings was the impact of flow rate on rock breakdown pressure. At flow rates of 40 and 20 mL/min, the breakdown pressures of 90% foam quality were significantly higher than those of clean water. “The flow rate of fracturing fluid directly affects the rock breakdown pressure,” Xiao notes. “This is a critical factor to consider when designing foam fracturing operations.”
The research also revealed that foam fracturing resulted in higher hydraulic input energy and acoustic emission energy, indicating more effective fracture creation. Furthermore, the study found that foam fracturing led to larger, rougher fractures with higher conductivity, a key factor in enhancing reservoir productivity.
The implications of this research for the energy sector are substantial. In regions where water is scarce or where reservoirs are highly water-sensitive, foam fracturing could provide a more sustainable and effective solution. It could also enhance the productivity of existing wells, making it an attractive option for operators looking to maximize their assets.
As the energy sector continues to evolve, the need for innovative solutions to extract energy from challenging reservoirs will only grow. Xiao’s research, published in Meitan xuebao, offers a glimpse into the future of fracturing technology, one where sustainability and productivity go hand in hand. As the energy sector grapples with the challenges of a changing climate and increasing demand, innovations like foam fracturing could play a pivotal role in shaping its future. The study provides a theoretical foundation for high-efficiency fracturing and permeability enhancement in strong water-sensitive coal-bearing reservoirs, paving the way for more efficient and sustainable energy extraction.
