Letter-Magnolia Petroleum Corp. 777 Main Street
Suite 1490
Fort Worth, Texas 761 02
(81 7) 429-5742 (Tel)
(817) 336-4834 (Fax)
September 16,1994
Sanford Dvorin
WDS Resources, INC
5025 Arapahoe Road., Suite 350
Dallas, TX 75248
re: Magnolia Petroleum Corp.
Trigg Est.#l, Dallas Co., TX
Sanford,
I have spent some time looking at the logs on the above well. These logs include an
Electrical Log (Short, Long and Lateral resisitivity curves) and a MicroLog. The zone
of interest that I have looked at is the Barnett Shale which is from 8610'-9050'. My
experience with this formation began about 4 years ago and has been primarily in
Denton/Wise counties. Most of the wells I have interpreted have included
DIL/SFL/SP, LDT/CNL/ML/GR. In most cases the resisitivty log has offered little or
no help in interpreting the Barnett Shale due to little change in resisitivty from one well
to the next. The MicroLog on the other hand does offer some information about
potential production from the Barnett Shale. Since the primary reason the Barnett
Shale is productive is due to the presence of natural fractures and the Microlog may be
able to see these fractures if mudcake is built up. The problem with this assumption is
that there can also be some other permeable streaks within the Barnett Shale that will
build up mudcake as well. The bottom line is that this method for fracture
identification should only be used as a last resort since other tools such as the
FMS/FMI are much better at positively identifying fractures. The main log used for
interpretation of the Barnett Shale has been the LDT/CNL. The Pe (Photo-Electric
Effect) provides a good indication of lithology of the Barnett Shale. Since the Barnett
Shale is not a true shale as our industry knows it, the presence of quartz and calcite
often times means the potential for production if porosity (primary and secondary) is
great enough. While the density/neutron give us porosity they also are a good indicator
of just how clean (ie. presents of quartz/calcite) the '~hale' interval is. The
combination of Pe and the LDT/CNL porosity relationship has proven to be the best
indicator of Barnett Shale production in the Wise/Denton county area.
Now, on the Magnolia Petroleum's Trigg Estate #1, I don't have the luxury of a
LDT/CNL so I've looked at the Microlog. The Microlog does not necessarily have a
unique signature over the Barnett Shale in productive wells. I have seen some that
show a considerable amount of perm while others show very little. This well does have
some streaks of perm that is readily evident. Obviously this is a very good sign since it
indicates that there is some perm. This perm could be associated with natural fractures
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WDS Resources, INC
Magnolia Petroleum, Trigg Est. gl
or the presence of some other permeable rock such as calcareous siltstones which are
common within the Barnett Shale. Either of these cases make the Barnett Shale in this
well very interesting. Its very difficult for me to say more than this without a porosity
log since the porosity logs do provide a much more unique signature over a productive
Barnett Shale interval. I think that with the thickness of the Barnett Shale in this well,
the Microlog and the proximity to other producing Barnett wells that this should be a
good candidate to test.
Please feel free to give me call if you have any questions regarding this interpretation
or I can be of service some other way.
Sincerely,
Greg Van Belois
Schlumberger Well Services