An analytical model to evaluate the heating conditions for drilling in hard rock using an innovative hydrothermal spallation method. (September 2018)

• Record Type: Journal Article
• Authors: Hu, Xiaodong; Song, Xianzhi; Li, Gensheng; Shen, Zhonghou; Lyu, Zehao; Shi, Yu; Zheng, Rui
• Is Part Of: Applied thermal engineering. Volume 142(2018)
• Page Start: 709
• Page End: 716
• Publication Date: 2018-09
• Subjects: Thermal engineering -- Drilling engineering -- Thermal spallation -- Temperature difference -- Heat flux; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2018.07.043
• Languages: English
• ISSNs: 1359-4311

Abstract

Graphical abstract: Highlights: A new relationship between rate of penetration and heating conditions is obtained. The decrease of jet-impact coefficient can help to reduce the heating conditions. Sensitivity studies are performed to quantify the key parameters which affect the heating conditions. Heating conditions for granite, sandstone are compared. Abstract: Hydrothermal jet spallation drilling (HJSD) is a new drilling method suitable for drilling deep wells in hard rock formations. The characteristics of HJSD are that the rock surface is impinged by a high-velocity hydrothermal jet, causing rock breaking into small spalls. In this study, we develop an analytical model to evaluate the heating conditions (surface temperature and surface heat flux) in HJSD, in which the effect of jet impact on the heating conditions is first considered. Meanwhile, we conduct thermal spallation experiment using sandstone and granite samples. After that, the effects of jet impact on the heating conditions are investigated. Furthermore, the impacts of all physical parameters on the heating conditions are compared to clarify the key factors. Additionally, we compare the rate of penetration and heating conditions between sandstone and granite, which can provide direct understanding about the suitability of HJSD for sandstone and granite. Our study provides a further understanding of critical physic affecting the rate of penetration and heating conditions in HJSD.