Development and field application of a pulse-jet hydraulic impactor

Abstract

The current studies on hydraulic pulse jet mainly focus on the pulse jet flow field and its effect, but have never extended to the collaboration of hydraulic impact and pulse jet for rock breaking. In this paper, both hydraulic impact and pulse jet were combined effectively to develop a pulse-jet hydraulic impactor for drilling after analyzing the working principles and realization conditions. The rock-breaking capacity of this tool was verified through laboratory experiments and field tests. The following results were obtained. First, the tool can run when the weight of the impactor body is less than 60 kg. Second, the rock-breaking capacity of the drilling borehole assembly (BHA) under the synergistic action of hydraulic impact and pulse jet is obviously better than that of other drilling tools, and the tool is much more efficient than other tools in ROP enhancement. Third, the impact effect is dependent on the weight and impact frequency of the impactor and the impactor with the weight of 30 kg is better in impact effect. Fourth, the larger the impulse jet, the higher its rock-breaking capacity is. The pulse jet can be increased by reducing the diameter of the tool's nozzle. Fifth, hydraulic impact can help accelerate the breaking of high-hardness rocks, and the breaking of less-cemented rocks can be greatly enhanced by increasing the pulse jet. Field application results show that the ROP of the drilling tool based on the collaboration of hydraulic impact and pulse jet is 2.52 m/h, which is 72.5% higher than that of conventional BHAs. It is concluded that this developed pulse-jet hydraulic impactor provides a new idea to solve the problems in deep wells and horizontal wells, such as low drilling speed, obvious chip hold down effect and difficult cuttings removal.