## 6 Conclusions  
To identify directions for searching for an original solution, the authors observed that the fundamental components of a radial borehole drilling system typically involve nozzles crafted from robust materials such as hard stainless steel, tungsten carbide, or  
Figure 8: Drilling velocity extremes for different jet pressures depending on the exposure factor for Indiana sandstone. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Stream** & **Jetting Velocity,** & **Average Crack** & **Average Crack** & **Stream Power,** & **Specific Energy** & **of Jet Drilling** \\
**Pressure,** & **m/s** & **Depth,** & **Width,** & **kW** & **of Jet Drilling,** & **per Unit of** \\
**MPa** & **m/s** & **cm** & **cm** & **J/cm\({}^{3}\)** & **Crack Volume,** & **Y/cm\({}^{2}\)** \\ \hline
1000–1100 & 40.64 & 4.28 & 0.20 & 289 & 5160 & 1660 \\ \hline
900–1000 & \multicolumn{6}{c}{No data available} \\ \hline
800–900 & 40.64 & 4.76 & 0.20 & 223 & 4000 & 1150 \\ \hline
700–800 & 40.64 & 3.33 & 0.20 & 164 & 3740 & 1210 \\ \hline
600–700 & 40.64 & 3.60 & 0.20 & 140 & 3470 & 960 \\ \hline
500–600 & 40.64 & 2.96 & 0.20 & 106 & 3960 & 880 \\ \hline
400–500 & 40.64 & 2.75 & 0.20 & 83 & 3750 & 740 \\ \hline
300–400 & 40.64 & 2.97 & 0.20 & 57 & 1900 & 470 \\ \hline
200–300 & 40.64 & 2.69 & 0.20 & 33 & 1370 & 300 \\ \hline
100–200 & \multicolumn{6}{c}{No data available} \\ \hline
0–100 & \multicolumn{6}{c}{No data available} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Influence of the jet pressure value on the specific energy of slot cutting at a rate of penetration v = 40.64 cm/s for Indiana limestone [34]. c ceramic. These nozzles feature an outlet hole or holes located in the head or face tool of the rotary drilling nozzle, with the direction coinciding with the axis of the nozzle body or inclined in the plane of the axis. The nozzle itself can rotate relative to the axis of the nozzle head body, and the flexible hose coupling provides control over the direction of radial borehole propagation. To explore an original solution, it is crucial to consider various factors and components that directly and indirectly influence the quality of continuous hydraulic jet drilling. Based on the observations above, the following conclusions were drawn:  
* The jet exhibits high-velocity vortex motion in the bottom zone from the frontal outlet hole(s) of the nozzle. This motion allows for an erosive action, ensuring the contact of the jet with the rock surface. * Backward outlet holes either allow for or assist the advance of the high-pressure flexible hose tool during hole propagation. Depending on their angle, they may also contribute to widening the excavated borehole. * The swirling stream of fluid from the reverse openings not only aids in the advance of the flexible hose but also facilitates the cuttings transport to the main wellbore. * The swirling motion of the outlet jet(s) can be optimized by changing the angle of the nozzle back holes, possibly spiraling through the housing wall and separating the front segment of the rotating nozzle. * The ROP (Fp) is determined by the equation \(\text{Fp}=\text{Fs}\) (jet force) \(-\text{Fd}\) (pressure force acting on the nozzle face) \(-\text{Ft}\) (frictional force of the nozzle drill head, flexible hose, friction and bending of the elastic hose in the deflector knee). This force is limited by the increasing length of the hose with the head in the horizontal borehole. Equilibrium is reached when the frictional forces are equal to the jet force in the nozzle, defining the maximum end length of the borehole. * The circumferential component forces of the vortex streams induce torsional moments from both the forward and the reverse vortex streams. Balancing these moments is critical to prevent excessive torsional stresses in the high-pressure flexible hose that could lead to buckling and vibration of the whole system.