陕西煤炭

针对煤-天然气同采区煤层高强度开采引起的覆岩移动变形导致气井失稳问题，基于小保当二号煤矿地质、开采技术条件及现场实测数据，通过数值模拟研究了超长超宽工作面高强度开采条件下，气井套管-水泥环组合体的剪切受力及水平变形特征，分析得到了沿套管轴向易发生变形的位置及岩层分布特征对气井稳定性的影响。结果表明，关键层以上至地表范围内覆岩以拉伸变形为主，关键层及下伏相邻岩层以剪切变形为主。倾向上132204-132206工作面多重采动影响下气井套管最大剪应力为208.5 MPa,为许用剪切强度255 MPa的81.76%,最大水平位移为87.3 mm。沿132205工作面走向留设180 m宽气井保护煤柱，工作面自二次切眼推进250 m后，套管达到最大剪应力169.5 MPa,为许用剪切强度的66.5%,最大水平位移为83.1 mm,留设180 m宽保护煤柱能够保障气井的完整性。研究结果对于合理确定小保当二号煤矿井田内其他气井保护煤柱尺寸、预防井筒失效、实现煤-天然气资源协同开发具有重要价值和意义。

Aiming at the problem of gas well instability caused by the moving deformation of overburden caused by high-intensity mining of coal seams in the coal-gas co-mining, based on the geological and mining technological conditions of Xiaobaodang No.2 Coal Mine and the on-site measured data, the shear force and horizontal deformation characteristics of the casing-cement ring combination of gas wells under the conditions of high-intensity mining of ultra-long and ultra-wide working face were investigated by numerical simulation.The influence of the easily deformed locations along the axial direction of the casing and the rock formation's distribution characteristics on the gas well's stability were analyzed and obtained.The results show that tensile deformation dominates the overburden above the key stratum to the surface, while shear deformation dominates the key stratum and the underlying adjacent rock layers.The maximum shear stress of gas well casing under the influence of multiple extractions in 132204-132206 working faces on the tendency is 208.5 MPa, which is 81.76% of the permissible shear strength of 255 MPa, and the maximum horizontal displacement is 87.3 mm.Along the 132205 working face, 180 m wide gas well was left to protect the coal pillar.After advancing 250 m from the second setup entry, the casing reached the maximum shear stress of 169.5 MPa, which was 66.5% of the permissible shear strength, and the maximum horizontal displacement was 83.1 mm, so the gas well with 180 m of coal pillar protection was able to maintain a good integrity.The results of the study are of great value and significance for rationally determining the size of protective coal pillars of other gas wells in the Xiaobaodang No.2 Coal Mine field, preventing wellbore failure and realizing the synergistic development of coal-gas resources.