Hydraulic extension ability of radial jet drilling with multi-nozzles jet bit

Abstract

Radial jet drilling technology, which utilizes hydraulic energy of jet to create multiple radial micro-laterals in different layers from the main borehole, has been used widely as an effective approach to enhance the oil recovery, and the extreme extension length of radial micro-laterals affects the effect of simulation directly. However, the prediction model for hydraulic extreme extension ability of RJD has been rarely studied. In this study, a modified model for hydraulic extreme extension ability is proposed based on the force analysis of RJD system and related calculation models for frictions are developed by theoretical and experimental methods. In order to obtain the maximum extension length, the influential factors including flow rate of drilling fluid, specifications of flexible hose, and structure parameters of jet bit are investigated. The results indicate that the hydraulic extension ability of RJD presents a significant positive correlation with the flow rate of drilling fluid and the inner diameter of flexile hose. Although an increase of the number of backward nozzles or its diameter can improve the extreme extension ability of RJD, there is still an optimal value for both the number and diameter of backward nozzles. Without sacrificing the rock-breaking and expanding ability of jet bit, the number of forward nozzles and the angle of backward nozzles should be minimized. Furthermore, a field case of RJD proves the prediction model is favourable for drilling engineering, with a model error of less than 8.5%.