富水砂卵石地层冻结孔钻进泥浆配比优化研究

Optimization of Mud Ratio for Freezing Hole Drilling in Water-rich Sand Pebble Formation

在富水砂卵石地层地铁联络通道近水平冻结孔钻进时,因泥浆黏度低,稳定性差,护壁及润滑作用弱造成泥浆损失及钻头磨损严重、塌孔、卡钻和断杆等问题。为了优化富水砂卵石地层下冻结孔钻进泥浆配比,通过单因素试验以及响应面分析法中的Box-Benhnken(中心组和)正交试验方法进行试验设计与数据分析,得出适用于富水砂卵石地层冻结孔钻进泥浆优化配比。基于北京地铁12号线的工程应用表明:采用优化泥浆配比,即膨润土含量为7.18%,水解聚丙烯酰胺含量为0.20%,钠羧甲基纤维素含量为0.19%,硫酸铝的含量为0.03%时,泥浆黏度提高32%,泥皮厚度增加了20%,滤失量减少了30%,润滑系数减少了60%,冻结孔钻进泥浆主要性能指标明显改善,冻结孔打钻时的减阻效果显著,钻杆所受轴力平均减少15%,所受扭矩平均减少13%,泥浆的膨润土用量和回流损失量减少了30%,材料成本明显降低,未发生塌孔、断杆和卡钻等工程事故,冻结孔钻进效率及成孔质量明显提高。

When drilling the near-horizontal frozen hole of the subway connection channel in the water-rich sand pebble stratum,the mud loss and the serious bit wear,hole collapse,stuck drilling and broken rod are caused by the low mud viscosity,poor stability,weak wall protection and lubrication.In order to optimize the mud ratio for freezing hole drilling in water-rich sand pebble formation,the experiment design and data analysis were carried out by single factor test and Box-Benhnken(central group sum)orthogonal test method in response surface analysis,and the optimal mud ratio suiTable for freezing hole drilling in water-rich sand pebble formation was obtained.The engineering application based on Beijing Metro Line 12 shows that:When the optimized mud ratio is adopted,that is,the bentonite content is 7.18%,the hydrolyzed polyacrylamide content is 0.20%,the sodium carboxymethyl cellulose content is 0.19%,and the aluminum sulfate content is 0.03%,the mud viscosity is increased by 32%,the mud skin thickness is increased by 20%,the filtration loss is reduced by 30%,and the lubrication coefficient is reduced by 60%.The main performance indexes of frozen hole drilling mud have been significantly improved,and the drag reduction effect during freezing hole drilling is remarkable.The axial force on drill pipe is reduced by 15%on average,the torque is reduced by 13%on average,the amount of bentonite and return loss of mud are reduced by 30%,the material cost is significantly reduced,and no engineering accidents such as hole collapse,broken rod and stuck drilling occur.The drilling efficiency and forming quality of frozen hole are obviously improved.