Field test of radial jet drilling technology in a surface formation

The radial jet drilling (RJD) technology is an efficient formation stimulation and injection technology that drills multiple laterals perpendicular to the central well. Extensive research has been on jet rock breaking, lateral extension, productivity prediction, and technological processes. However, little public literature illustrates the overall drilling performance of the RJD systems. Herein, a field test is conducted in the surface sandstone formation. Eight laterals are successfully drilled using the self-rotating multi-orifices nozzle with a 35–40 MPa (5.08–5.80 ksi) jet pressure. The cumulative length of the eight laterals is 21.1 m (69.2 ft), with the longest one being 5.7 m (18.7 ft). The lateral diameter is 50 mm (1.97 in), drilled at the fastest drilling rate of 3.6 m/h (11.8 ft/h). The auxiliary traction device can provide extra feed-in force to the high-pressure hose. The lateral trajectories are measured with their accuracy confirmed by the coring well. During the field test, a lateral trajectory up-warping problem is found, of which the possible causes and the suggestions are provided. According to the internal shape of the lateral obtained by endoscopic imaging, the lateral section exhibits a ring structure, indicating the high rock breaking efficiency of the self-rotating multi-orifices nozzle. The formation anisotropy and natural fracture have little influence on the lateral trajectory but affect the lateral section shape. The research results prove the reliability of the RJD system developed and can contribute to future development and application of RJD technology.