Abstract

AbstractRadial jet drilling (RJD) technology has been applied to enhance the recovery of difficult-to-produce reserves by multiple horizontal micro-holes. The micro-hole length drilled by high-pressure water jets is of vital importance for the oil and gas recovery effect and is usually tens of meters long for applications in maturing oil fields in China. The water jets are generated by multiple orifices nozzle generally. Many studies focused on improving the self-propelled force generated by water jets to increase the micro-hole length. However, there are few researches on improving the micro-hole extension capacity in terms of optimizing the flexible hose that acts as the drill pipe in conventional drilling technology. This paper firstly studied the relationship between the flexible hose length and the micro-hole extension limit according to the analytical model to calculate the micro-hole extension limit. Then, the method to optimize the flexible hose length and the flow rate was developed aiming to obtain maximum micro-hole extension limit. The results show that the micro-hole extension limit decreases logarithmically with the increase in the flexible hose length under the condition that the takes the maximum value. The optimization model is applied by a field case and is proved to be effective to increase the micro-hole extension limit. This study is significant to improve the micro-hole extension capacity. Moreover, it provides a reference for the design of the hydraulics and selection of flexible hose for the RJD.

Highlights

  • Radial jet drilling (RJD) is to drill multiple horizontal micro-holes using high-pressure water jet to break the formation rock to expose the oil and gas formation

  • Du predicted and analyzed the micro-hole length of RJD taking the swirling jet nozzle that is seldom used in the RJD system, but he did not study the resistance of the diverter on the flexible hose (Du et al 2015)

  • A method to optimize the length of the flexible hose has been developed according to the micro-hole extension limit prediction model that is verified by a field case

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Summary

Introduction

Radial jet drilling (RJD) is to drill multiple horizontal micro-holes using high-pressure water jet to break the formation rock to expose the oil and gas formation. The rock-breaking capacity of the water jets and the micro-hole extension limit have always been important researches for the RJD technology. To drill the micro-hole further needs enough propulsion force generated by water jets to pull the hose forward. Du predicted and analyzed the micro-hole length of RJD taking the swirling jet nozzle that is seldom used in the RJD system, but he did not study the resistance of the diverter on the flexible hose (Du et al 2015). Based on the operational condition of RJD, the relationship between the maximum micro-hole length and the flexible hose length is derived using the theoretical and experimental methods. We prefer to cite their model to calculate the self-propelled force, which can be expressed as follows: Fj

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Conclusions
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