The case for enhanced coalbed methane using hydraulic fracturing in the geostructural belt

Abstract

Coal and gas outbursts mostly occur during mining at geostructural belts. Pre-drainage coalbed methane using hydraulic fracturing is one of the methods to prevent outbursts. However, the coal in geostructural belts is to be soft and crushed with special mechanical properties and pore structure. To explore the feasibility of hydraulic fracturing in geostructural belts, a field investigation on enhanced coalbed methane using hydraulic fracturing with vertical well was conducted at the Yangquan Coalfield, China. This case puts forward a method for the location selection of vertical well in geostructural belts. In addition, a triple-control technology for hydraulic fracturing, which is characterized by pressure control, flow control and sand ratio control of fracturing fluid, is presented. The results show that the average gas production and maximum gas drainage capacity of the test well were 5.67 and 12.88 times than those of the regular well, respectively, achieving good drainage effects.

Experimental Study on Hydraulic Fracturing of Laminated Sandstone Combined with Industrial CT and L-NMR

“…This work is financially supported by the National Natural Science Foundation of China (52130409 and 51904310) 19 Geofluids and Zhongyuan Talent Program-Zhongyuan Top Talent (ZYYCYU202012155).…”

“…In recent years, horizontal well hydraulic fracturing has been used in some mining areas to enhance permeability. However, due to a large amount of engineering and huge capital investment, the application of technology is restricted [19,20]. Besides, the hydraulic disturbance was carried out in the coal seam or immediate roof through drilling holes across the seam, and hydraulic fracturing was carried out through a long borehole in the roof or floor of the coal seam, which promotes the development of hydraulic fracturing in gas control of the soft coal seam [21][22][23].…”

Effect of Electrolyte pH on CH4 Adsorption and Desorption Behavior in Electrochemically Modified Lean Coal

“…Coalbed methane (CBM) extraction not only has importance in the current world in need of clean energy supplies, also an important technical means to reduce methane accidents during the coal mining process. However, the occurrence state of methane in coal is mainly the adsorption state, and the methane adsorption capacity is closely related to the surface area of coal. , Previous research studies mainly focused on cracking coal seams to accelerate methane extraction like hydraulic fracturing and hydraulic flushing, − which often reckon without the influence of O-containing functional groups on CH 4 adsorption characteristics. Besides the specific surface area, O-containing functional groups on the surface of coal and mineral matters (MM) in coal also play a significant role in the adsorption behavior of methane.…”

The Adsorption and Desorption Behavior of CH4 on Jincheng Anthracite Modified in Fe3+ and Cu2+ Ion Electrolytes

“…Thus, it is very important to study the CH 4 adsorption/desorption behavior in anthracite for commercial CBM development. Existing studies have mainly focused on hydraulic fracturing and hydraulic flushing, which often cause sensitivity problems in engineering practices and cannot quickly discharge direct residual fracturing fluid or residual water, thus affecting the overall efficiency of gas extraction. − Researchers have suggested that an electrochemical method can effectively solve sensitivity problems . Shapiro and Probstein pointed out that the advantages of electroosmosis drainage are controllability of direction, uniform distribution of electroosmotic flow, and insensitivity to pore size .…”