Particle impact drilling (PID) using high-speed spherical carbide steel particles to impact rock and mechanical breaking of rock as a supplement, it is a new drilling method of breaking rock. Effects of rock fragmentation were studied by different injection speed of particles, injection angle and particle diameter based on ANSYS simulation platform. The two basic types of nozzles were studied, straight-taper nozzle model and streamline nozzle model, the mathematical model of nozzle were established based on the acceleration mechanism of solid-liquid two-phase flow, and an optimized nozzle structure is designed. A rock breaking experiment device used to simulate particle impact drilling was developed. The experimental investigations were carried out by controlling the drilling parameters such as particles injection speed, injection angle, the ratio of metal particles, drilling speed and weight on bit(WOB), etc. to study the effects of rock breaking based on this experiment device. The results show that the device can simulate the rock fragmentation process of particle impact drilling completely, it proves that technological requirements of high efficiency of breaking rock can be achieve well with particle whose diameter is 1mm, shot speed 120 m/s, it also verified the theoretical analysis of fragmentation efficiency of rock for different volume fraction and jetting angle. The test provide technical support for the popularization and application of the technology.
The packer is the key element in separating geosphere layers of water injection, water plugging and fracturing operations in the oilfield. The sealing ability of the packer is depending on the contact pressure between rubber tube and the casing. The circumferential strain of casing wall was tested by the strain gauge to get the contact pressure distribution along axial direction of the tube. The friction force between the casing and the rubber tube was taken by the pressure sensor in compression process. Under the 20,60 and 100 degrees Celsius conditions, the friction forces and the contact pressure distribution were taken in work condition of single rubber tube, double rubber tubes and combination rubber tubes after oil immersion .The result shows that elastic modulus of rubber tube has little effect on the friction force and contact pressure. With elastic modulus decreasing, the friction forces has gradually decreasing trend; The friction coefficient has much impact on friction force: the friction forces under the condition of dry friction and wet friction are respectively equivalent to 48.27% and 5.38% axial compression forces. At wet friction condition, the contact pressure distribution is more uniform and the sealing effect is better.