In the heart of Xinjiang, a region rich in high-volatile bituminous coal, a silent battle is being waged beneath the surface. This battle isn’t fought with conventional weapons, but with a phenomenon known as the Jiamin effect, a silent saboteur that can significantly reduce the productivity of Coalbed Methane (CBM) wells. Now, a groundbreaking study led by Xin Li from the School of Geology and Mining Engineering at Xinjiang University is shedding new light on this issue, offering hope for improved CBM extraction techniques and enhanced energy security.
The Jiamin effect, caused by well repairs and pumping suspensions, has long been a thorn in the side of the energy sector. It leads to a reduction in single-well productivity, making CBM extraction less efficient and more costly. However, Li’s research, published in the journal Meitan kexue jishu (translated to Coal Science and Technology), is changing the game.
Li and his team conducted physical simulation experiments on high-volatile bituminous coal reservoirs, using low-field nuclear magnetic resonance technology to analyze the damage process and the pore-fracture space occupied by gas after Jiamin damage. Their findings are both intriguing and commercially significant.
The study revealed that the permeability of the water phase in parallel bedding coal samples is significantly higher than that in vertical bedding coal samples. However, after Jiamin damage, both types of coal samples experienced a notable decrease in permeability. “The water phase permeability damage rate after Jiamin in parallel bedding and vertical bedding coal samples at steady-state reached 40.60% and 50.00%, respectively,” Li explained. This means that a significant portion of the water in the coal core becomes non-mobile, leading to a decrease in permeability and a reduction in drainage efficiency.
But the story doesn’t end there. The physical simulation also suggested that when a CBM well is temporarily halted for maintenance, the accumulated gas within the reservoir cannot be fully displaced by the formation water during subsequent re-opening and waterflooding. This gas tends to cluster in the medium and large pores and fractures, occupying the pore space for fluid flow. This leads to a reduction in water permeability and inhibits the effective removal of water upon re-opening of the CBM well, resulting in reduced drainage efficiency and pressure reduction.
So, what does this mean for the energy sector? The implications are vast. By understanding the characteristics of Jiamin damage, energy companies can develop strategies to mitigate its effects, leading to more efficient CBM extraction and reduced costs. Li recommends strengthening gas well management, extending well repair and pump inspection cycles, maintaining stable drainage, developing Jiamin-suppressing antifoaming agents, and implementing pulse excitation flushing methods.
As the world continues to seek cleaner and more efficient energy sources, research like Li’s is crucial. It not only provides a deeper understanding of the challenges faced in CBM extraction but also paves the way for innovative solutions. The future of energy is uncertain, but with research like this, we’re one step closer to a more secure and sustainable energy future.
