| description abstract | Radial jet drilling (RJD) technology is an effective method to enhance oil and gas recovery by penetrating the near-wellbore damage zone, and increasing the drainage radius greatly. Recently, it is identified as a potential technology to develop the geothermal energy. But the extension ability, one of the most critical issues of the RJD, is limited. Because only high pressure flexible hose (HPFH), which is hard to be fed in and subjected to greater resistance by the diverter, can be used as the drill stem to turn from vertical to horizontal in the casing. In this paper, an innovative method to feed in the HPFH by the drag force generated by high velocity flow in narrow annulus is proposed. The drag force model is built, validated, and modified by theoretical and experimental ways. Results show that the resulting drag force, which is equivalent to the self-propelled force, can easily achieve and feed in the HPFH. There is a power law relationship between the drag force and the average velocity; the drag force increases linearly with the length of the narrow annulus. Higher average velocity and 1–1.5 m annulus length are recommended. According to force analysis, the extension ability of the RJD can be doubled theoretically by this method. The results of this paper will greatly promote the development of RJD technology. | |
