石油钻采工艺2025，Vol.47Issue(2)：235-244,10.DOI:10.13639/j.odpt.202411043
煤层脆性与地应力耦合条件下瓦斯抽采方案探讨
Discussion on gas extraction schemes under the coupling conditions of coal seam brittleness and in-situ stress
摘要
Abstract
Weijiadi Coal Mine is characterized by complex geological structures,significant heterogeneity in the spatial distribution of coal reservoir brittleness and current in-situ stress field,and an unclear geological control mechanism on the variability of gas extraction efficiency.In light of this,based on the geological data from Weijiadi Coal Mine,Petrel 3D modeling software was employed to conduct modeling of the spatial distribution of coal seam elastic properties and simulation of the in-situ stress field.The results indicate that,through the superposition of zoning based on the elastic modulus and Poisson's ratio of the coal seam,three brittleness zones were delineated.In the study area,the maximum horizontal principal stress(σH)significantly exceeds both the minimum horizontal principal stress(σh)and the vertical stress(σv).Based on the relative magnitudes of σh and σv,two types of stress regime zones were classified.Research indicates that coal seam brittleness is the primary controlling factor governing the propagation of hydraulic fracturing fractures.coal seams with relatively high brittleness is conducives to fracture propagation,demonstrating good gas drainage performance.Conversely,coal seams that are not in this condition are unfavorable for fracture propagation,resulting in poor gas drainage effects.Therefore,for coal seams with low brittleness,L-shaped wells are more suitable for gas drainage to achieve the goal of coalbed methane(CBM)pressure reduction and desorption.For coal seams with relatively high brittleness,appropriate well types should be selected based on the relative magnitudes of σv and σh.When σv＞σh,fractures are less likely to extend within the coal seam,and it is recommended to adopt L-shaped wells to achieve gas drainage objectives.When σh＞σv,fractures are more prone to propagate in the horizontal direction of the coal seam,which is beneficial for CBM pressure reduction and desorption.In this case,both vertical and L-shaped wells can be considered,and both types of wells can achieve relatively good gas drainage effects.Based on engineering case analyses,it is considered that during the fracturing process of either vertical or horizontal wells,the water-bearing property of the roof strata must be taken into account simultaneously.When the roof is a water-bearing layer,L-shaped wells should select the coal seam as the horizontal section and implement small-scale fracturing.When the roof is a non-water-bearing layer,the horizontal section stratum should be chosen according to the coal seam's brittleness.Drawing from successful cases of L-shaped wells in mining-induced stress relief zones,it is suggested that"one well for dual purposes"engineering layouts should be considered in the design of in-situ gas extraction L-shaped wells.关键词
煤层/瓦斯抽采/脆性/地应力/耦合/魏家地煤矿Key words
coal seam/gas extraction/brittleness/in-situ stress/coupling/Weijiadi Coal Mine分类
能源科技引用本文复制引用
李作泉,屈争辉,王勃,王文龙,权继业,张建江,苗在全,王贝贝..煤层脆性与地应力耦合条件下瓦斯抽采方案探讨[J].石油钻采工艺,2025,47(2):235-244,10.基金项目
国家科技重大专项"多气合采钻完井技术和储层保护"(编号:2016ZX05066002) （编号:2016ZX05066002）
甘肃自然科学基金"煤与瓦斯突出灾害孕育演化机制及分级预警研究"(编号:24JRRD003). （编号:24JRRD003）
