Experimental Investigation of Rock Drillability for Three Rock Types Under Varying Wellbore Pressure Conditions
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The drillability of rocks is a comprehensive reflection of geologic and engineering parameters related to the rock’s formation and the physical properties of drilling bits. It provides an important basis for optimizing drilling performance by choosing proper parameters and bits. This concept was first proposed in 1927 by Tillson (White 1969), who suggested that drillability reflected the degree of difficulty involved in breaking rock. In other words, it is a mechanical characteristic of the rock’s crushing ability. Many scholars have subsequently carried out relevant research to enhance our understanding of drillability (e.g., Rollow 1962; Schmidt 1972; Howarth 1986; Wijk 1989; Thuro 1997; Li 2006; Deng et al. 2007; Kelessidis 2011; Yarali and Kahraman 2011).
The general approach for evaluating drillability focuses on the rock’s physical and mechanical parameters (Morris 1969; Wijk 1989; Spaar et al. 1995; Hoseinie et al. 2012) and logging information (Gstalder and Raynal 1966...
KeywordsRock drillability Wellbore pressure Basalt Clay shale Sandstone
This work was financially supported by the Open Research Fund of the State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences (No. Z016013), and the Foundation of National Natural Science Foundation of China (Nos. 51504208 and 51774248). The sixth author acknowledges the support of the Open Fund (PLN201703) of the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University).
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