The project "Key Technologies and Applications for Regional Gas Control in Horizontal Wells in Deep and Strong Coal Seams in Huainan" jointly completed by CCTEG Xi'an Research Institute and Huainan Mining (Group) Co., Ltd. was appraised by the expert group of the Coal Industry Association and reached the international leading level recently.
The project pioneered a "six-in-one" surface horizontal well regional gas control and outburst prevention technology system and model. In response to the special gas prevention and control needs of deep high-stress, broken, soft and strong outburst coal seams, the "pre-drilling + drilling + post-drilling" integrated horizontal well trajectory precision control technology was developed, and the drainage and production technology of industrial horizontal wells was innovated. Innovative fracturing optimization design methods for small-spacing horizontal wells for gas extraction and outburst prevention and a dynamic mixed injection mode of fracturing fluid were proposed, forming a complete evaluation index system and evaluation method for the outburst prevention effect of surface staged fracturing horizontal wells.
The project effectively solved the problem of comprehensive prevention and control of gas outbursts in broken, soft and strong coal seams, and achieved a major breakthrough in new types and new areas. At present, this research result has been widely promoted and applied in 6 coal mines and 29 horizontal wells in Huainan Mining Area. According to calculations, the maximum daily gas production of a single well reaches 7000m³/d, and the cumulative gas production is as high as 1672×104m³, effectively creating economic value of more than 150 million RMB for the local area.
