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Capturing Micro-cores While Drilling
Low Rate of Penetration (ROP) and
lack of quality cuttings are challenges in harsh HTHP
drilling environments. With low ROP and low depth of cut
with conventional bits, resulting cuttings are extremely
small (rock flour) and not of any use for geologically
identifying any formation. Addressing this problem, Total
S.A. and Diamant Drilling Services have developed a drill
bit that generates micro-cores during conventional drilling
operations. The micro-core is generated in the center of the
bit and the design can be adapted to any type of fixed
cutter structure.
Not only does one get useable
rock cuttings, but the “No Center Bit” effect saves a
significant part of the energy used in the cutting action.
Applying this saved energy to the reduced cutting structure
leads to a higher depth of cut, increasing cutting
efficiency and overall ROP. Four runs in two field
applications have been made. In both applications, usable
rock cuttings were obtained and, importantly, significant
ROP improvements were realized in comparison with offset
performance drilling similar rock conditions.
Excerpted from “Generate Micro-Cores of Formations While
Drilling,” Hart’s E&P, February 2008, p. 69. |
Small-Drillhole Minipermeameter
Offers Advantages
Conventional techniques for
obtaining permeability in the field involve extracting a
small cylindrical sample from a drill core, placing it
inside a sleeve and injecting nitrogen at one end. But there
are many areas where friable rock makes it impractical to
extract samples. Inventor of the new small-drillhole
minipermeameter, Cynthia Dinwiddie, got the idea while in
the field, noting the many holes drilled in the rock to
secure ladders. Her idea was to use the holes, placing a
rubber seal against the rock, and inject gas in the field.
Subsequent mathematics for modeling the multi-dimensional
flow may be complex, but the approach in its simplicity
works. For this work, Dinwiddie recently received awards
from two engineering societies (American Institute of
Mining, Metallurgical and Petroleum Engineers and the
American Society of Civil Engineers).
Excerpted from “Downhole Device Idea Applauded,” AAPG
Explorer, February 2008, p. 30-31. Work also published in
SPE’s Reservoir Evaluation & Engineering, December 2005. |
Recommended Reading for Appalachian Gas Shale Players
“Study Characterizes Woodford
Shale,” The American Oil & Gas Reporter, January 2008, pp.
106-115. This article reports on analysis of 200 ft of
well-preserved Woodford Shale core. Mechanical and
poromechanical properties were measured at four scales.
Beyond comprehensively characterizing the Woodford, the
study validated using drill cuttings as an alternative to
obtaining costly cores. Also, testing confirmed that
different fluids and elapsed time of fluid exposure do
influence the strength of the Woodford, even though the clay
content is mainly illite and chlorite.
“Marcellus Begins to Meet
Expectations,” The American Oil & Gas Reporter,
March 2008, pp. 81-87. Operators are moving rapidly up the
Marcellus Shale learning curve. This article reports
insights, primarily from the service sector, in technical
sessions at the winter meeting of the West Virginia Oil &
Gas Association (early February). Topics vary from drilling
fluid selection to hydraulic fracturing fluid and proppant
selection to using geology/geophysics for optimum well
placement considering the inherent heterogeneity of the
Marcellus. |
Tech
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