This paper presents the design of an experimental setup and mathematical and physical models to determine the dynamical characteristics of the high-pressure supercritical carbon dioxide (SC-CO2) jet with a highly potential applications in the well drilling. The effects of three major factors on the wellbore dynamical characteristics of the high-pressure SC-CO2 jet, i.e., the nozzle diameter, the standoff distance and the jet pressure are determined. It is indicated that the pressure of CO2 reduces severely in the SC-CO2 jet impact process. It is also found that the bottom-hole pressure and the temperature increase as the nozzle diameter increases but decrease with the increase of the standoff distance. The higher the jet pressure at the wellbore inlet is, the higher the pressure and the lower the temperature at the bottom-hole will be.
The development of new drilling methods is important for the exploration and production of oil fields.The pulsed jet is a drilling technology of high potentiality.This article proposes a new concept of suck-in pulsed jet with self-excited oscillation,by which a full use of the hydraulic power can be made in the annular space.A hydrodynamic analysis of suck-in pulsed jet with self-excited oscillation is carried out by numerical simulations and rock-breaking experiments.It is shown that with the jet,a negative pressure zone will be formed in the oscillation cavity to ensure automatic sucking of enough annular fluids and the formation of an efficient pulsed jet.The rock-breaking and pressure testing results have verified the reliability of the numerical simulation.The research provides a basis for the development of the pulsed jet drilling technology.
