Torsional Impact Tool Based on the Problem of Stick-Slip Vibration and Its Application

PDC drill bits are widely used in deep and hard-rock formations. The stick-slip vibration causes premature damage of PDC bits, which is an important factor for the increase of the drilling cost. The model of stick-slip vibration system of PDC bits has been established to account for mechanism of analysis about stick-slip vibration. Moreover, a torsional impact tool has been developed for weakening the influence of stick-slip vibration. PDC bits optimally matched with the tool were selected by the transmission efficiency of impact energy, based on the experimental data. The laboratory experiment shows that the self-developed torsion impact tool can produce the impact frequency of 1500 r/min; the torsional impact load provided by tool can effectively inhibit the stick-slip effect of PDC bits, thereby improving the penetration rate; the ultrashort monotube bit body can help to improve performance of the torsional impact tool; when the tool is in the condition of high weight on bit (WOB) and low rotary speed, the tool can achieve the optimal speed increase effect. Furthermore, the field experiments of QG5 well in Tarim Oilfield show that the rate of penetration (ROP) after using the torsional impact tool is more than 1 times than adjacent well.