In the heart of Sichuan province, a groundbreaking discovery is reshaping our understanding of coalbed methane (CBM) reservoirs and opening new avenues for the energy sector. Researchers have unveiled a unique model for helium-rich CBM reservoirs in the Junlian Mu’ai core area, a region that has already made history as the first successfully commercialized CBM field in southern China. This breakthrough, led by Zhaobiao Yang from the Key Laboratory of Coalbed Methane Resources & Reservoir Formation Process at China University of Mining and Technology, could significantly impact the future of energy exploration and extraction.
The Junlian Mu’ai core area is not just another CBM field; it’s a geological marvel with unusually high helium content and extreme salinity. The average helium content here is 0.074%, a figure that might seem small but is significant in the context of CBM reservoirs. “The helium anomaly and the CBM enrichment area have a synergy,” Yang explains, highlighting the interconnectedness of these geological phenomena.
The research, published in Meitan kexue jishu, which translates to Coal Science and Technology, reveals that the CBM enrichment is not random but follows a distinct pattern. The main coal seams in this area have an average CBM content of 15.58 cubic meters per ton, characterized by high ash content, high CBM saturation, and, notably, high helium content. This enrichment is primarily found on the Mu’ai fault side of the Tiechanggou syncline axis and the western and southern edges of the block.
What sets this area apart is its exceptionally high groundwater salinity, with an average Total Dissolved Solids (TDS) value of 10,638.3 mg/L. This is far higher than typical shallow CBM production areas, both domestically and internationally. The water here is not just salty; it’s rich in chloride and sulfate ions, a distinctive feature that Yang attributes to the area’s unique geological history and location at the edge of the Sichuan Basin.
The researchers propose a new model for CBM reservoirs: the structure-mixed hydrodynamic sealing helium-rich CBM accumulation model. This model suggests that the unique structure of the area, including reverse faults and syncline axes, along with the interplay of mudstone compaction centrifugal flow and atmospheric precipitation centripetal flow, contributes to the formation of these helium-rich CBM reservoirs. The high salinity, high CBM content, helium anomaly, and overpressure phenomenon are all interconnected, with the helium anomaly likely originating from the degassing of water-soluble helium in deep centrifugal flow.
The implications of this research are vast. Understanding the formation and enrichment of helium-rich CBM reservoirs could lead to more efficient extraction methods and open up new possibilities for helium production, a gas with numerous industrial applications. Moreover, the synergism between water, CBM, and helium gas in these reservoirs could serve as an important indicator for CBM enrichment in other areas.
As the energy sector continues to evolve, insights like these are invaluable. They challenge our existing knowledge, push the boundaries of what’s possible, and pave the way for future developments. Yang’s work is a testament to the power of scientific inquiry and its potential to transform industries. As we look to the future, it’s clear that the Junlian Mu’ai core area will continue to play a pivotal role in shaping the energy landscape.