| The proportion of low production wells in the development of coalbed methane in Fanzhuang block in the south of Qinshui Basin is increasing.How to effectively improve the current situation of low production wells and maintain stable production has become an urgent problem.Based on the systematic analysis of the key factors affecting the low production of CBM vertical wells in Fanzhuang block,this paper designs and verifies the secondary fracturing reconstruction scheme,which provides a strong theoretical support for the stable production / production increase of CBM in Fanzhuang block.The main coal seams in Fanzhuang block are 3# coal seams in Shanxi group and15# coal seams in Taiyuan group,both of which belong to low porosity and low permeability reservoirs,and the permeability generally decreases with the increase of the buried depth of the coal seam;the low efficiency wells are mostly distributed in the relatively low gas content,fault development,large buried depth,the edge of the area pressure reduction unit,etc.;the main modifiable key factors affecting the low production of the vertical wells in Fanzhuang block In order to improve the depth of burial,the development of structural coal,the damage of fracturing fluid to the reservoir and the blockage of pulverized coal,four targeted secondary fracturing technologies are proposed and tested: the staged sand secondary fracturing technology can effectively transform the fracture network of buried deep reservoir,and in 15 wells,13 wells are effective,with an effective rate of 87%;the roof perforation technology can improve the structure of coal and rock,resulting in fracture and fracture It’s difficult.There are 20 construction wells in the mine,15 of which have been effective,with an apparent efficiency of 75%;chemical agent unblocking technology effectively increases the permeability of coal reservoir,explores 15 wells,with 11 effective wells,with an apparent efficiency of 73%;fracture fracturing construction has a good unblocking effect,with an effective rate of 80% on a large scale and 75% on a small scale.There are 82 figures,19 tables and 67 references in this paper. |
