|
Note:
This
report is proprietary and confidential and may only be released to the
project sponsor. The material below is presented to illustrate ESRI-USCs'
research capabilities and activities.
In a five county area south and east
of the Jackson Dome 27 drilling leads were generated using the premises
developed in the Phase 1 portion of the project. Both regional and local
seismic data was used and sedimentation history of the area was interpreted
using those concepts. Although the focus of the work was confined to the
pre-Selma/ post-Smackover, leads were also noted in the Smackover.It is probable
that we have previously mapped prospects in the area and subsequently drilled in
locations that are offset to the crest of major features.
ORGANIZATION OF REPORT
The report is organized along
the lines of the focus of the project, i.e., Part 1) Leads, Part 2) Regional,
and Part 3) Recommendations for future work. In addition, comments are
included which have to do with the integrity of the database which we believe to
be extremely important for pursuing future activity in the Mississippi Salt
Basin.
DATABASE AVAILABLE FOR THIS
PROJECT
The following represents a
listing of the data available for the project. The maps included in the
report show the location of the data.
-
Well Logs; 104 logs
mostly with SP and resistivity curves
-
Seismic profiles; paper copies of
lines shown on Maps 2 and 3, approximately 97 lines both regional and
prospect oriented lines shot over the period from 1967 to 1993. Most
of the data is of the mid to late 1970’s vintage. Most has been migrated.
Apparently Pennzoil does not have all of the tapes of these lines.
-
Tops from wells in the Pennzoil
database which is from the GCS database (Geological Consulting Service).
These data were send via E-mail in Excel format. This sort of data
transfer was very effective during the course of the project.
-
GCS maps (2/1/97 version)
were sent to ESRI covering the area of focus. These have been
helpful for comparison.
-
Several sets of maps that were
generated by Sherry Enciso from the Pennzoil database for the area.
Most of these show well penetrations of wells targeted at different
horizons and part of the seismic control for the area.
-
Scout tickets on some wells.
-
Trowebridge logs on a few of the
wells.
-
Public domain data regarding the
area.
NOTE:
No production reports were used in this project.
As discussed in the report, there is
caution that must be exercised in using the GCS data base. Many errors
were found in the log picks and also the scout ticket top picks do not agree in
many cases with the GCS tops. The Mooringsport to Cotton Valley section is
difficult to work with because of the numerous sands that occur in the
Rodessa and Hosston section. The question arises in this type of project
as to what can one use to be consistent. That question has not been
entirely resolved here. It is mentioned because of the apparent errors in
the tops that are used by most people in companies for their mapping data.
It is a factor that Pennzoil needs to deal with in the future, prior to
any additional regional mapping projects.
STATEMENT OF INTENT
When phase 1 of this project was
initiated it seemed that we might be covering the same old ground that others
have tread many times. Then it occurred to us that in order for this time,
work and money to be effective we might consider this as a project where we have
a limited database in a completely unknown basin and then see where that might
lead us. We all know that it is very difficult for a human being to forget
old ideas and concepts and to start over in trying to find other alternatives
with the same dataset (especially geologists !). But that has been the
attempt throughout this project. In order to attempt to find new reserves
one has to think in new regimes sometimes. Old and relatively new concepts
have been challenged, predicted events have been questioned, and we have
challenged our own interpretations with which we have lived with for many years.
Because there are always alternative concepts to be built from like datasets.
We may not like the new ideas and we may not feel comfortable on this new ice
but at times we must question those things that , ‘we know to be true.’
“Conflicts of
representation are painful for a variety of reasons. On a very practical
level, it is painful to have a model of reality that conflicts with those of the
people around you. The people around you soon make you aware of that.
But why should this conflict worry people, if a model is only a model, a best
guess at reality that each of us makes? Because nobody thinks of it in
that way. If the model is the only reality you can know; then that model
is reality, and if there is only one reality, then the possessor of a different
model must be wrong.”
Derek
Bickerton, 1990
SUMMARY OF CONCLUSIONS
The history of faulting is more
complex than we have probably mapped in the past. Faults that are
antithetic to master faults and rejuvenation of faults are probably major trap
controlling elements that have probably gone unnoticed in the basin. This
has been caused in large part by basement fault rejuvenation and stress changes
since the Triassic. It is likely that 3D seismic will be required to
fully understand this. Certainly interactive modeling will be required to
match reality with concept even on presently available data.
-
We have probably missed seeing some
closures caused by movement of salt features during the
rejuvenation of faults. Some of these faults extend from basement to
the surface, or very near the surface. This implies that fault
rejuvenation, at least one period, is young, has most probably changed the
pre-existing traps, migration paths and the dynamics of the petroleum
system. We need to examine some of the lead areas with this in mind.
-
In the past we have probably not
paid enough attention to lateral movement of faults in this basin. In
some cases even the GCS maps show some indication of sissors movements and
lateral movements which have possibly been the result of rejuvenation.
Even though we have excellent documentation in the region of strike slip
faulting we have probably not fit this into our thinking of the petroleum
system (This comment is based of what I have seen from many other companies
and work by independent geologists in the area. I certainly do
not imply that no one has ever considered this.)
-
Our seismic coverage in the area
probably has not been shot with subtle, low relief features in mind,
except for exploration of the turtle structures. The Hosston and
Rodessa interval needs to be examined with this as a concept especially in
the area of major faults. The closures are more likely to be further
away from the faults than in many cases have been drilled. This is
true for other reservoirs but the focus here was primarily on the
Mooringsport to Cotton Valley interval.
-
The thickest sediments in the
interval of Selma to Smackover in the basin apparently trends through
the area of focus - in a NE to SW direction - i.e.,
normal to the strike of the basin. Although this has apparently been
documented in the past it appears that this is a trend that has significant
structural and stratigraphic implications for understanding the petroleum
system. Many of the leads presented in Part 1 are in this area.
In addition, in recontouring structural control on the Mooringsport to Salt
units, several NE to SW re-entrants can be mapped from the well data.
|
