复杂地层顺层定向钻孔轨迹设计方法优化

Optimization of directional drilling path design methodin complex formation

金泰煤矿M6煤层具有顶底板破碎、视倾角由双倾角控制(XZ视图倾角17°、YZ视图倾角3°)、煤层厚度薄且厚度变化差异大(1.08~1.68 m)的复杂产状特征,在顺层定向钻孔施工中,钻孔平面拐弯段采用原有的轨迹设计方法存在轨迹实控难度大、易偏离煤层进入不稳定顶底板而无法钻进、多分支孔施工降低施工效率和无效进尺的难题。本文基于视倾角计算公式,引入钻孔沿工作面走向倾角参数,针对钻孔平面拐弯段优化轨迹设计方法,并在金泰煤矿开展验证试验。结果表明:优化的钻孔平面拐弯段轨迹设计方法相对于原有轨迹设计方法,能够保持钻孔沿煤层中部钻进,克服煤层厚度变化干扰,实现钻孔平面拐弯段精确沿煤层钻进,有效进尺率分别为48.82%、76.72%和100%。8~10号试验钻孔瓦斯监测数据均呈现出较好的瓦斯抽采效果。

The M6 coal seam in Jintai Coal Mine has complex occurrence characteristics such as roof and floor breakage,apparent dip angle controlled by double dip angle(XZ view inclination 17°,YZ view inclination 3°),thin seam thickness(1.08~1.68m)and large variation in thickness.In the construction of directional drilling along strata,there are some problems such as difficulty of actual control,easy deviation from coal seam into unstable roof and floor,lower construction efficiency and ineffective penetration in multi⁃branch hole construction.Based on the calculation formula of apparent dip angle,this paper introduces the dip angle parameter of borehole along the working face to optimize the trajectory design method for the plane turning section of borehole,and carries out the verification test in Jintai Coal mine.The results show that:Compared with the original trajectory design method,the optimized trajectory design method can keep the borehole drilling along the middle of the coal seam,overcome the interference of the thickness change of the coal seam,and realize the accurate drilling along the coal seam of the plane turning section of the borehole,and the effective footage rates are 48.82%,76.72%and 100%,respectively.The gas monitoring data of test borehole No.8~10 show good gas extraction effect.