The hydraulic structure of conventional geophysical drill bit is designed for the general stratum. When conventional geophysical drill bit pierces into a limestone stratum, the shape of cuttings is large because of the high brittleness of limestone. The cuttings are ground repeatedly; this phenomenon can reduce drilling efficiency and increase drilling costs. According to the characteristics of limestone cuttings, the numerical simulation method is used to research downhole flow field characteristics of conventional geophysical drill bit. First, the influence of key hydraulic structure parameters on cuttings removal performance is found. Then, the hydraulic structure is optimized. The flow field characteristics of the hydraulic structure of the geophysical drill bit before and after optimization in the flow path is analyzed, at the bottom of the bit and the annulus area of the shaft lining. The optimized downhole crossflow area increased from 50% to 98%. No vortex was observed at the exit of the flow path and cuttings groove. The downhole pressure gradient increased from 0.12 Mpa to 0.15 Mpa. The cutting removal space in the annulus area of the shaft lining is fully utilized. Field tests show that the cutting removal and drilling performance of optimized geophysical drill bit has improved and the drilling speed increases by 20.6%.

常规物探钻头的水工结构是针对一般地层而设计的。传统物探钻头刺入石灰岩地层时，由于石灰岩脆性较高，切屑形状较大。插条反复打磨；这种现象会降低钻井效率并增加钻井成本。根据石灰岩岩屑的特点，采用数值模拟方法研究常规物探钻头的井下流场特征。首先，找出关键水工结构参数对排屑性能的影响。然后，对水工结构进行了优化。分析了流路优化前后物探钻头水工结构在钻头底部和井壁环空区域的流场特征。优化后的井下横流面积从50%增加到98%。流道和钻屑槽出口处未观察到涡流。井下压力梯度由0.12Mpa增大到0.15Mpa。充分利用了轴衬环空区域的切削去除空间。现场试验表明，优化后的物探钻头排屑及钻进性能均有所提高，钻速提高20.6%。