Anadrill, Inc.

Michael Sheppard

Zhian Hedayati

David Curry

The invention relates to a method of determining the porosity of an undergound formation being drilled by a rotating drill bit mounted at the lower end of a drill string. The torque (TOR) and the weight (WOB) applied on the bit when drilling the underground formation are measured; the effect of the geometry of the drill bit on the torque and weight on bit response is determined; the porosity (phi) of the formation being drilled is derived from the measured TOR and WOB taking into account the effect of the geometry of the drill bit. Preferentially, the porosity phi is determined from the following equation:

Method of determining the porosity of an underground formation being

A variety of flow and pressure measurements are obtained to characterize the drilling fluids hydraulics system of the borehole drilling process. Notably, a differential pressure measurement which measures the difference between the pressure internal to and external of the drill bit is made close to the drill bit. From this and other measurements are obtained valuable information on whether a change in pressure drop is due to a leak or a lost bit nozzle, on corrections to the downhole weight on bit measurement, on the rate of rotation of a downhole positive displacement drilling motor, on the efficiency of the drilling motor, and on an indication of whether a leak in or a blockage of the drill string has occurred and its location.

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Missouri City, TX, United States of America

Michael Sheppard