In the heart of China’s Ordos Basin, a technological revolution is unfolding beneath the surface, promising to reshape the future of coalbed methane (CBM) production. Researchers, led by Xipeng He from the Key Laboratory of Deep CBM Exploration and Production at SINOPEC in Nanjing, have made significant strides in unlocking the potential of deep, thin coal seams, a feat once deemed challenging due to their complex geological characteristics.
The Yanchuannan CBM field, with its middle-deep, thin coal seams, has long been a conundrum for energy explorers. Characterized by strong heterogeneity, ultra-low permeability, and high in situ stress, these seams have posed significant obstacles to large-scale commercial CBM production. However, He and his team have systematically analyzed the field’s geological characteristics, identifying primary factors controlling CBM enrichment and high productivity.
One of the key findings is the crucial role of fracturing performance in determining the production characteristics of the CBM field. “Gas wells subjected to conventional guided fracturing exhibit late gas shows and production addition combined with limited single-well productivity and recoverable reserves,” He explains. “In contrast, gas wells subjected to fracturing with fractures effectively propped demonstrate rapid production addition and high single-well productivity and recoverable reserves.”
The team’s innovative approach involves a series of geology-engineering integrated technologies tailored to the unique challenges of the Yanchuannan field. They have developed an indicator system for the quantitative evaluation of geology-engineering “dual sweet spots,” guiding play fairway selection. Moreover, they have established multi-scale pore-fracture characterization technology, enabling the quantitative characterization of reservoir spaces on various scales.
The researchers have also focused on optimizing fracturing technologies, shifting the production philosophy from slow and long-term drainage to optimal rapid production addition. This advancement has led to the formation of a production system characterized by four stages, two pressuring, and three controlling factors. A “node-region-center” three-level pressure boosting model has been developed to maximize productivity.
The commercial impacts of this research are profound. The Yanchuannan CBM field has achieved stable production growth, with the daily production of a single directional well increasing significantly. This success story serves as a valuable reference for the commercial production of similar deep, thin CBM resources in China and beyond.
The implications for the energy sector are vast. As the world seeks to diversify its energy mix, the efficient exploration and exploitation of CBM resources become increasingly important. The technological systems developed by He and his team could pave the way for similar advancements in other regions, driving forward the global energy transition.
The research, published in the journal Meitian dizhi yu kantan, which translates to ‘Petroleum Geology and Engineering,’ marks a significant milestone in the field of CBM exploration and production. As the energy sector continues to evolve, the insights and technologies emerging from the Ordos Basin could shape the future of energy production, making it more efficient, sustainable, and commercially viable.
The story of the Yanchuannan CBM field is a testament to human ingenuity and the power of technological innovation. As researchers continue to push the boundaries of what is possible, the energy sector stands on the cusp of a new era, one where deep, thin coal seams are no longer a challenge but an opportunity.
