Analysis and Improvement of the Rotary Percussion Drilling Tool in Oil Wells

Abstract

Experience over the few years has proved that rotary percussion technology is an effective method to improve the rate of penetration in drilling petroleum wells. The drilling speed of the rotary percussion drilling is about forty percent larger than the common drilling. Research finds that rotary percussion drilling technology is still not mature in the aspects of high-efficiency, long-life, and low-cost. With the structure of deep wells becoming more complicated, designing new percussion tools with better impact performance and longer life has become the most remarkable research direction in drilling engineering. By analysing the shortcomings of existing percussion tools, a new idea of using the downhole motor driving the hammer piston to produce impulse force was proposed, and a novel rotary percussion drilling tool was made based on this principle. This new tool uses screw drill driving the hammer piston to rotate, meanwhile the hammer impact the susceptor to generate impulse pulse. In order to analyse the working state of the tool, the dynamic model of this percussion tool was established. Parameters of this novel drilling tool were tested by ground experiment, and the testing data and the computational value of dynamic model in a single impact process are very similar, so the model can be helpful in adjusting this tool's impact performances. The impulse force of this tool is about 0.2~0.5 times to the bit weight; the impact frequency is the product of the rotary rate of the motor and the teeth number. The interval time of two impact processes is the same; the fluctuation of impact load is less than 10%. Therefore, this rotary percussion drilling tool will be very helpful in improving the drilling speed in unconventional oil and gas reservoir. This tool's new principle and good performance can be helpful to the further development of rotary percussion drilling tool.