| Abstract |
Complex fracture network can promote the production of geothermal resources, but it’s difficult to gain a wide range of complex fracture network due to its heterogeneity and crustal stress distribution, multi-branch hydraulic fracturing can improve the shape of the fractures. Conventional sidetracking technology is too expensive to be applicated, while the radial jet drilling has the possibility of applying in this area, which is economic and environmentally friendly, but the radial jet drilling technology can’t break the granite with water jet only, so abrasive jet is introduced to the radial jet drilling technology to improve the rock breaking capacity. Due to the strong abrasive erosion, the conventional radical jet drilling technology has to be improved such as the director, the feeding string and the rock breaking nozzle. This paper proposed a sidetracking drilling technology based on the radial jet drilling, which aims to make an arc-shaped hole in the formation and extend a distance in the near horizontal section, And the existing research difficulties of this technology are proposed, many experiments are done to try to solve these difficulties. The main difficulties are diverter, feeding pipe and abrasive nozzle. The diverter is designed, processed and experimentally optimized. The feeding resistance test and deformation measurement are used to optimize the feeding pipe. The key of the abrasive jet nozzle is the impeller which directly affect the flow field shape, some flow field tests are done in order to obtain a more suitable nozzle structure. Finally, a set of downhole tool strings consists of feeding pipe; diverter and abrasive nozzle is suggested. The hydraulic sidetracking technology is dedicated to drilling multiple branches to increase the control area to improve the fracturing effect ignoring the heterogeneity and crustal stress distribution. |