New Steering Technology Using Pulsed Arc Plasma Shockwave: Plasma Pulse Steering Technology

Steering drilling technology can achieve precise control of wellbore trajectory, and related technologies have been widely used in the field of petroleum drilling. This paper proposed a new steering drilling technology based on the Pulsed Arc Plasma Shockwave Technology (PAPST),Plasma Pulse Steering Technology (PPST). PAPST transforms electric energy into mechanical energy by discharging electrodes, which can break rock. On the basis of PAPST, PPST can precisely control the discharge time and break the rock in the specified direction at the bottom of the well, so as to realize guided drilling. First, the discharge mechanism and guiding mechanism of the PPST were studied separately. Then, the discharge control model of PPST was established to explain the feasibility of using this technology to achieve drilling guidance. Finally, to verify the actual effect of this technology on rock breaking, an experiment was carried out with self-developed experimental equipment. Through the study of the mechanism and discharge control model of PPST, it is considered that it is feasible to use this technology to achieve guidance in theory. The experimental results show that the sandstone samples were damaged and a large area of pits appeared after the shockwave, and the ultrasonic penetration test results showed that there was damage inside the rock. As the number of impacts increased, the rock damage became more severe and fracture occurred. Therefore, it is feasible to apply PPST to the directional fracture of bottom hole rock. In summary, this technology has very good application prospects. For the first time, this paper proposed the idea of applying PAPST to steering drilling. Through the research on the steering mechanism and the experiment, the feasibility of this technology was proved and the theoretical basis was provided for the application of this technology in the field of oil drilling.

Numerical simulation of high-current pulsed arc discharge in air

Computational model of high-current pulsed arcdischarge in air is proposed. This is, in general, two-dimensional model with taking into account gas dynamics of the discharge channel, real air thermodynamics in a wide range of pressure and temperature, electrodynamics of the discharge including pinch effect, and radiation. One-dimensional version of the model is tested and verified on several numerical and experimental works reported recently. It is concluded that low and moderate current discharges are satisfactorily described with the developed model. Then, developed model was applied to simulate the electric discharge in air for the currents of 1 - 250 kA and characteristic rise times in 13 - 25 µs, and results of calculations were compared with experimental ones. It was concluded that most of characteristics of the discharge are predicted well. Namely, arc column radius and shock wave position agree well with experimental data for all current amplitudes and rise times considered. Radial distributions of temperature and electron density also satisfactorily agree with experimental data. It was found that pinch effect should be considered for currents higher than 100 kA.

High-current arc discharge in air

Computational model of high-current pulsed arc discharge in air is proposed. This is, in general, two-dimensional model with taking into account gas dynamics of the discharge channel, real air thermodynamics in a wide range of pressure and temperature, electrodynamics of the discharge including pinch effect, and radiation. The developed model was applied to simulate the electric discharge in air for the currents of 1 - 250 kA and characteristic rise times in 13 - 25 µs, and results of calculations were compared with experimental ones. It was concluded that most of characteristics of the discharge are predicted well. Namely, arc column radius and shock wave position agree well with experimental data for all current amplitudes and rise times considered. Radial distributions of temperature and electron density also satisfactorily agree with experimental data. It was found that pinch effect should be considered for currents higher than 100 kA.

Flow separation control on a smooth ledge using an arc discharge in a magnetic field

This paper presents results of experimental study for surface MHD arc actuator as vortex generator in boundary layer of smooth ledge. The study was held at flow velocities 20 to 50 m/s. The pulsed arc discharge was organized in external magnetic field. The amplitude of current was 80 A, while pulse duration was 80 μs. The flow velocity was measured by PIV method. It was founded that the location of the arc breakdown is critically impotent. The arc must be struck just above the separation point. The operation of the actuator in a pulse-periodic mode leads to a shift in the middle position of the flow separation point at frequencies up to 700 Hz and higher. A three-dimensional analysis of the separation region structure behind the MHD actuator shows that the main effect on the flow occurs in the interelectrode gap.

INFLUENCE OF NON-METALLIC INCLUSIONS ON THE CORROSION RESISTANCE OF STAINLESS STEELS IN ARC SURFACING

The influence of non-metallic inclusions on the corrosion resistance of stainless steel of the austenitic-martensitic class, deposited in one layer with flux-cored wire under the flux by the arc method in the mode of stationary and pulsed arc burning, has been studied. In the latter case, the wire feed impulse was 0.5 and 0.7 Hz. The selected surfacing conditions, with both methods of the process, contribute to the formation of non-metallic inclusions of complex composition and structure in the deposited metal, including those containing calcium and its compounds with other elements, which are classified as corrosive, accelerating the occurrence of corrosion phenomena.