World's First Benchmarking of Drilling Mud Hammer Performance at Depth Conditions
Gordon A. Tibbitts, TerraTek; Roy C. Long, US Department of Energy, Brian E. Miller, BP America, Inc.; Arnis Judzis, TerraTek; Alan D. Black, TerraTek SPE Members
This paper was prepared for presentation at the IADC/SPE Drilling Conference held in Dallas, Texas, 26-28 February 2002,
Copyright 2002, Society of Petroleum Engineers Inc.
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Abstract
Operators continue to look for ways to improve hard rock drilling performance
through emerging technologies. A consortium of Department of Energy,
operator and industry participants put together an effort to test and
optimize mud driven fluid hammers as one emerging technology that has
shown promise to increase penetration rates in hard rock. The thrust
of this program has been to test and record the performance of fluid
hammers in full scale test conditions including, hard formations at
simulated depth, high density / high solids drilling muds, and realistic
fluid power levels. This paper details the testing and results of testing
two 7 ¾" diameter mud hammers with 8 ½" hammer
bits. A Novatek MHN5 and an SDS Digger FH185 mud hammer were tested
with several bit types, with performance being compared to a conventional
(IADC Code 537) tricone bit. These tools functionally operated in all
of the simulated downhole environments. The performance was in the
range of the baseline ticone or better at lower borehole pressures,
but at higher borehole pressures the performance was in the lower range
or below that of the baseline tricone bit. A new drilling mode was
observed, while operating the MHN5 mud hammer. This mode was noticed
as the weight on bit (WOB) was in transition from low to high applied
load. During this new "transition drilling mode", performance
was substantially improved and in some cases outperformed the tricone
bit. Improvements were noted for the SDS tool while drilling with a
more aggressive bit design. Future work includes the optimization of
these or the next generation tools for operating in higher density
and higher borehole pressure conditions and improving bit design and
technology based on the knowledge gained from this test program.
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