New insights into the CH4 adsorption capacity of coal based on microscopic pore properties

The commercial production of coalbed methane (CBM) in China has made significant achievements. To further improve the production of CBM and realize its development, it is necessary to establish a unique, high-efficiency CBM production method that considers the characteristics of coal reservoirs in China. This paper presents the current status of China’s CBM exploitation over the past 15 years from three aspects: reservoir characteristics, production mode, and exploitation technology. The achievements, in terms of exploration and development of CBM resources in China, were summarized. The CBM reservoirs in China are characterized by high coal rank, low permeability, high gas content, and low reservoir pressure gradient. Strategic measures for coal and CBM co-mining were proposed creatively as “Huainan”, “Jincheng”, and “Songzao” modes. CBM production enhancement measures have achieved significant innovations and breakthroughs in drilling and completion technologies and reservoir reconstruction, effectively reducing development costs and increasing single well production. Finally, based on existing basic research, this study proposes efficient CBM exploitation technologies suitable for the characteristics of CBM reservoirs in China. In particular, the uniform permeability enhancement measures of hydraulic grid slotting and fracturing have the advantages of safety, high efficiency, economy, feasibility, and broad application prospects under complex mining conditions. It is of great strategic significance to improve the CBM recovery rate and optimize China’s energy structure.

Current Status and Effective Suggestions for Efficient Exploitation of Coalbed Methane in China: A Review

The technology of liquid carbon dioxide phase change fracturing (LCPCF) was used to enhance the permeability of coal seams. The combination of mechanical tests, scanning electron microscopy (SEM) and high-pressure mercury intrusion porosimetry was adopted to study the damage characteristics of coal micro-structures. LCPCF had mechanical damage effects on coal micro-structures to varying degrees, and the maximum reduction in compressive strength reached approximately 25%. SEM results confirmed that surface morphology of coal was remarkably altered after conducting LCPCF. The fractal dimension (D) of coal subjected to LCPCF ranged from 1.5186 to 1.8794, demonstrating the three-stage changing trends. HP-MIP results showed that LCPCF mainly affected pores of > 100 nm within coal, and pores   1.5 m, the obvious reduction in macro-pore and micro-fracture volumes implied that the fracturing effect was attenuated with the increase in distance. Once distance was > 6.0 m, pore and fracture structures within coal tended to be stable. Thus, in this study, the influence scope of LCPCF was around 6.0 m for a single fracturing borehole.

Micro-structural Damage to Coal Induced by Liquid CO2 Phase Change Fracturing

Effect of supercritical CO2 extraction on CO2/CH4 competitive adsorption in Yanchang shale

Pore distribution characteristics of various rank coals matrix and their influences on gas adsorption

Full-size pore structure characterization of deep-buried coals and its impact on methane adsorption capacity: A case study of the Shihezi Formation coals from the Panji Deep Area in Huainan Coalfield, Southern North China

Reservoir characteristics and coalbed methane resource evaluation of deep-buried coals: A case study of the No.13–1 coal seam from the Panji Deep Area in Huainan Coalfield, Southern North China

Research on the Optimal Allocation Method of Source and Storage Capacity of Integrated Energy System Considering Integrated Demand Response

Pore structure characterization of deep-buried coals and its implications on methane adsorption capacity are of great significance for further understanding the adsorption mechanism of methane mole...

Methane Adsorption Capacity of Deep-Buried Coals Based on Pore Structure in the Panji Deep Area of Huainan Coalfield, China

Since monolithic movement is considered a promising technology to relocate historical buildings, corresponding real-time monitoring is of great interest due to the buildings’ age and poor structural integrity. However, the related paperwork and practical applications are still limited. This paper describes a wireless sensor network (WSN)-based strategy as a non-invasive approach to monitor heritage curtilage during monolithic movement. The collected data show that the inclination of the curtilage is almost negligible. With the aid of finite element simulation, it was found that the crack displacement curves changed from −0.02 to 0.07 mm, which is affected by moving direction while the value is not enough to cause structural cracks. The deformation of the steel underpinning beam, which is used to reinforce masonry walls and wooden pillars, is obviously related to the stiffness in different directions. Additionally, the strain variations of the steel chassis, which bear the vertical loads from wooden pillars and masonry walls, are less than 0.04%. This indicates that they are kept within the elastic range during monolithic movement. This work has proved that the WSN-based approach has the potential to be applied as an effective route in real-time monitoring of the monolithic movement of an historic building.

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Wenwei Zhu

Papers

Full-size pore structure characterization of deep-buried coals and its impact on methane adsorption capacity: A case study of the Shihezi Formation coals from the Panji Deep Area in Huainan Coalfield, Southern North China

Reservoir characteristics and coalbed methane resource evaluation of deep-buried coals: A case study of the No.13–1 coal seam from the Panji Deep Area in Huainan Coalfield, Southern North China

Research on the Optimal Allocation Method of Source and Storage Capacity of Integrated Energy System Considering Integrated Demand Response

Methane Adsorption Capacity of Deep-Buried Coals Based on Pore Structure in the Panji Deep Area of Huainan Coalfield, China

Real-Time Monitoring for Monolithic Movement of a Heritage Curtilage Using Wireless Sensor Networks