Abstract: A method for evaluating rock drillability by a nano-indentation test on a rock cutting includes: conducting a nano-indentation test on a rock cutting sample, acquiring a displacement-load curve of an indenter, and calculating a micro-hardness under the nano-indentation test; calculating mineral composition of the rock cutting sample based on a statistical distribution characteristic of the micro-hardness, and transforming the micro-hardness under the nano-indentation test on the rock cutting sample into a macro-hardness; and calculating a rock drillability grade characterized by the micro-hardness under the nano-indentation test on the rock cutting sample based on a correlation between the macro-hardness of the rock cutting sample and the rock drillability grade. In the context of few downhole rock samples and high cost, the method overcomes the limitation of sample size and shape on conventional testing and solves the difficult problem of mechanical parameter testing of deep rocks.

Abstract: A method for evaluating rock drillability by a nano-indentation test on a rock cutting includes: conducting a nano-indentation test on a rock cutting sample, acquiring a displacement-load curve of an indenter, and calculating a micro-hardness under the nano-indentation test; calculating mineral composition of the rock cutting sample based on a statistical distribution characteristic of the micro-hardness, and transforming the micro-hardness under the nano-indentation test on the rock cutting sample into a macro-hardness; and calculating a rock drillability grade characterized by the micro-hardness under the nano-indentation test on the rock cutting sample based on a correlation between the macro-hardness of the rock cutting sample and the rock drillability grade. In the context of few downhole rock samples and high cost, the method overcomes the limitation of sample size and shape on conventional testing and solves the difficult problem of mechanical parameter testing of deep rocks.