旋转冲击钻井方法硬岩破岩钻进特性的实验研究

Experimental study on drilling characteristics of hard rock breaking by rotary percussion drilling method

硬地层岩石硬度大、钻井参数不匹配是导致深层超深层钻井钻速慢的最主要因素之一,提高硬地层破岩效率是钻井提速关键内容。旋转冲击钻井方法是提高破岩效率的一种技术手段,然而硬岩旋冲钻井时,破岩钻进特性不够明确,导致该技术使用效果差异性显著且无法达到最佳。该文基于旋转冲击破岩实验装置开展了花岗岩破岩实验,结果表明:旋转冲击钻井方法可以提高花岗岩的破岩钻进效率,但存在钻压、转速、冲击力及冲击频率的匹配问题;旋冲钻进硬岩时,存在临界钻压与临界冲击力,只有实际钻压大于临界钻压且冲击力大于临界冲击力时,旋转冲击钻井方法方能提高破岩效率;在此工况下,增大冲击力、冲击频率能够增大岩石破碎体积,显著提高钻头的破岩效率,但上述参数并非越大越好,当超过某一值,提速效果呈现变差趋势。

The high hardness of hard stratum rock and the mismatch of drilling parameters are one of the main factors leading to the slow penetration rate of deep and ultra deep drilling.Improving the rock breaking efficiency of hard stratum is the key content of drilling speed increase.Rotary percussion drilling method is a technical means to improve the rock breaking efficiency.However,when rotary percussion drilling in hard rock,the characteristics of rock breaking drilling are not clear enough,resulting in significant differences in the application effect of this technology and can not achieve the best.In this paper,the rock breaking experiment of granite is carried out based on the rotary percussion rock breaking experimental device.The results show that the rotary percussion drilling method can improve the rock breaking drilling efficiency of granite,but there are problems in the matching of WOB,rotating speed,impact force and impact frequency.When rotary percussion drilling hard rock,there are critical WOB and critical impact force,only when the actual WOB is greater than the critical WOB and the impact force is greater than the critical impact force,the rotary percussion drilling method can improve the rock breaking efficiency.Under this working condition,increasing the impact force and impact frequency can increase the rock crushing volume and significantly improve the rock breaking efficiency of the bit,but the larger the above parameters are not the better.When it exceeds a certain value,the speed-up effect shows a trend of deterioration.