In the heart of China’s energy sector, a technological revolution is unfolding, one that promises to reshape the future of coalbed methane (CBM) extraction. At the forefront of this transformation is Fengyin Xu, a researcher from the College of Energy at Chengdu University of Technology. Xu’s latest work, published in the journal Meitan kexue jishu, which translates to Coal Science and Technology, offers a deep dive into the iterative upgrading of deep coalbed methane reservoir reconstruction technologies. The focus is on the Daji block in the eastern margin of the Ordos Basin, where depths exceed 2,000 meters, presenting unique challenges and opportunities.
The story begins in 2019 when PetroChina’s CBM Company achieved a significant breakthrough in the profitable development of deep CBM reservoirs. This success was not merely a stroke of luck but the result of meticulous technological innovation. “Advancements and iterative upgrades in reservoir stimulation technologies are key pathways for driving the profitable development of deep CBM,” Xu asserts. This statement underscores the critical role of technological progress in unlocking the potential of deep CBM reserves.
Over the past five years, the industry has witnessed a series of technological leaps. The journey started with volumetric acidizing, a method that stimulates the coal matrix to enhance gas flow. This was followed by large-scale volumetric fracturing, which aimed to create extensive fracture networks within the reservoir. The evolution continued with ultra-large-scale volumetric fracturing, pushing the boundaries of what was previously thought possible. The latest innovation is integrated geological-engineering precision fracturing, a sophisticated approach that tailors fracturing designs to the unique geological characteristics of each reservoir.
Each of these technologies has its own set of fracturing fluid systems, carefully designed to maximize effectiveness. The progression from matrix stimulation to large-scale fracture networks, and from maximizing stimulation volume to optimizing well-to-fracture network integration, reflects a deepening understanding of the complexities involved in deep CBM extraction.
However, the path forward is not without its challenges. Xu identifies several key areas that require attention. High water consumption and difficulties in managing flowback fluids during ultra-large-scale fracturing are significant hurdles. There is also a need for breakthroughs in intelligent fracturing technologies and collaborative fracturing methods. Additionally, the industry must focus on developing stimulation technologies for deep, medium-to-low-rank coal seams and improving the functionality of fracturing fluids.
To address these challenges, Xu proposes six development directions. These include advancing water-reducing fracturing techniques, researching fishbone horizontal wells combined with matrix acidizing for large-scale water reduction and production enhancement, and expanding the application of artificial intelligence in intelligent fracturing and post-fracturing evaluation. Furthermore, developing collaborative fracturing techniques, strengthening research on stimulation technologies for deep, medium-to-low-rank coal reservoirs, and innovating new fracturing materials are also crucial.
The implications of this research are far-reaching. As the energy sector continues to evolve, the ability to efficiently extract deep CBM could play a pivotal role in meeting global energy demands. The iterative upgrading of reservoir stimulation technologies not only promises to enhance profitability but also to drive reserve growth and production increases. This, in turn, could lead to a more sustainable and secure energy future.
As Xu and his colleagues continue to push the boundaries of what is possible, the energy sector watches with keen interest. The journey from volumetric acidizing to integrated geological-engineering precision fracturing is a testament to human ingenuity and the power of technological innovation. The future of deep CBM extraction is bright, and the work of researchers like Xu is lighting the way. The insights published in Coal Science and Technology offer a glimpse into a future where deep CBM reservoirs are not just a resource but a strategic asset, driving the energy transition and shaping the future of the energy sector.