Modeling Rock Surface Topology

Most of the energy needs in today’s world are dependent on oil and natural gas. With the increasing demand and dwindling resources, drilling deeper wells is in greater need today. Deeper wells require longer drillstrings. The long drillstrings are essentially unstable and cause excessive vibrations. Moreover, deep wells encounter harder rock increasing the severity of vibration. The stability of a drillstring depends upon the dynamics of the drillstring, design of the bit and type of rock. For oil and gas drilling, Polycrystalline Diamond Compact (PDC) bits are used often due to increased rate of penetration. One such PDC bit is a Coring Bit. A Coring Bit produces a core and hence has lesser area of cut to be made. This makes drilling at high penetration rate possible. A special type of coring bit was used at the Hard Rock Drilling Facility (HRDF) at the Sandia National Labs (SNL). The surfaces generated by this bit are used to study the nature of vibration in drillstrings. Observation of the rock surface after the test is an old practice in drillstring research.