Maximum drillable length of the radial horizontal micro-hole drilled with multiple high-pressure water jets

Abstract

Radial horizontal jet drilling technology is designed to provide multiple lateral micro-holes to enhance petroleum production by using high-pressure water jets to break the rock formation. The micro-hole length is a key parameter in this technology, and it has a significant influence on the design of drilling operation and petroleum production. This paper presents a model for calculating the maximum drillable micro-hole length by combining a theoretical analysis and experimental methods. The pressure loss of the circulation system, the pressure and flow rate of the pump, and the self-propulsion effect of the multiple-jet nozzle are included in the model. The results indicate that the flow rate is the dominant factor in the radial horizontal jet drilling process, and a high flow rate contributes to the creation of long micro-holes. The jetting force generated by multiple water jets is the only propulsion used to elongate the micro-hole. However, the friction of the flexible hose moving in the diverter and micro-hole is the main resistance limiting the length of the micro-hole. A comparison of this model with a field case result indicates that the model is sufficiently accurate for predicting the maximum drillable length of the micro-hole. The model and results presented in this paper can provide guidelines for the design of radial horizontal jet drilling operations.