Page 150 - Drilling Technology in Nontechnical Language
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                                       DRILL BITS










                                            Overview


                    This chapter will describe the basic classifications of drill bits and the

                 major design features of each type. The process of bit selection, which is

                 actually quite complicated if done properly, will be outlined in sufficient
                 detail to show the main considerations involved. It will hopefully give an
                 accurate impression of the complexity of bit selection and how critical this
                 is to operational economics.
                    Drill bits can be separated into two major categories: roller cone bits


                 and fixed cutter bits (figs. 6–1 and 6–2).














                 Fig. 6–1. Types of drill bits


                                       Roller Cone Bits

                    Roller cone bits have one, two, or three cones that have teeth sticking
                 out of them. These cones roll across the bottom of the hole, and the teeth
                 press against the formation with enough pressure to exceed the compressive
                 strength of the rock. Roller cone bits can handle rougher drilling conditions


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