Schlumberger

Technical Paper: Testing the Combination of High Frequency Surface and Downhole Drilling Mechanics and Dynamics Data Under a Variety of Drilling Conditions

Society: IADC
Paper Number: 140347
Presentation Date: 2011
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Abstract

Understanding the behavior of the bit, BHA, and drillstring in drilling operations is difficult without accurate measurements of tensile load, torque, pressure, and various vibrations both at the surface and downhole. Various methods have been employed to compress measurements obtained downhole in order to transmit them to the surface with MWD mud pulse telemetry. During the last ten years some success has been achieved in making these measurements, recording the data, and then retrieving it at the surface at the end of the bit run.  Meanwhile, the complimentary measurements at the surface have limitations in terms of accuracy and calibration as well as dampening. 

NOV developed an instrumented surface sub that replaces the saver sub at the bottom of the top drive on a rig’s travelling assembly. Using accurate and calibrated sensors it measures in real-time tension/compression, torque, RPM, surface pump pressure among others at the top of the drillstring.  These measurements, made at 400 Hz are not dampened by the drill line and sheaves.  NOV also provided along-string measurements of vibration via memory only devices. Schlumberger developed a drilling mechanics sub that is part of the bottom hole assembly.  It measures tension, torque, RPM, internal and annular pressure among others between 200 and 2000 Hz.

A test was conducted in June 2010 at the Schlumberger directional drilling test facility near Cameron Texas. Four different BHA’s were run to evaluate downhole behavior for milled tooth and PDC bits and directional drilling in surface rotary mode as well as with steerable motors.  This paper presents some of the wide range of findings of the use and analysis of the data gathered in terms of static drilling mechanics as well as dynamic drillstring behaviors and downhole vibrations.

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