Fractal representation of rock drillability;

Feasibility analysis of fractal characteristics of rock drillability;

Theory and approach of identification of ground interfaces based on rock drillability index;

Use of the effect measure analysis can conduct relative rating of rock blastability while at thesame time complete the systematical analysis of it,which is an information analysis method featured with simpleand fast calculation,flexible application and high adapability.

A mathematical model using the fuzzy hierarchy analysis for rock blastability appraisal is presented;the basical principle and the calculation of this method are described;and is applications are illustrated by fieldcases.

The common method of measuring drillability was based on interior experiment.

In view of many problems faced by drilling in the lower stratum in Xujiaweizi region, such as complex geologic structures, high grade value of rock drillability, low drilling rate, slow footage, and long drilling cycle, it is urgent to correctly predict the grade value of rock drillability which will provide powerful references for a better drilling plan in reasonable way.

Drillability measurement under modeling conditions of bottom hole stress is very difficult.