Mississippian of the Erith-Hanlan to Caroline
Trend,
South Central Alberta
with
Integrated Report on Origin of Mississippian Dolomites,
Banff,
Pekisko to Turner Valley Fms
a multi-client project
conducted by:
Graham R. Davies, Ph.D.,
P. Geol.
GRAHAM DAVIES GEOLOGICAL CONSULTANTS LTD.
#113, 3553-31 Street NW,
Calgary, Alberta, Canada
T2L 2K7
email: gdgc@telus.net
website: www.gdgc.com
PREAMBLE
A number of factors combine to motivate this proposal:
- Discoveries in the downdip Banff and Pekisko over the
last five years or so in the Ferrier-Sunchild- O’Chiese
areas of southwestern Alberta (for example, 2/16-3-44-10W5,
Banff prod. cum., 14 Bcf), building on longer-established
Mississippian production in the overall region, have renewed
interest in Mississippian exploration in south-central Alberta
(Fig. 1).
- The recently completed GDGC Hydrothermal Dolomite Report
(2001) drew attention to the relationship between Cambrian
and Mississippian dolomites (whether hydrothermal or not)
and the ENE-WSW trending Snowbird Tectonic Zone (STZ;
Fig. 1).
- An earlier GDGC report on the Mississippian Turner Valley-Mt.
Head formations of southern Alberta (1994) documented facies,
thickness and dolomite-distribution changes in the Turner
Valley, and clinoforming of lower Mississippian units, across
the ENE-WSW trending Vulcan Tectonic Zone (VTZ:
Fig.3). That report also showed that Turner Valley dolomite
distribution was influenced by other ENE-WSW trending basement
elements (as documented by regional aeromag data).
- An earlier published paper by Chatellier (1992) delineated
strong NE-SW structural control on dolomitization in the
Banff Formation (based on cuttings) in the area bordered
to the SE by T45, R8W5 and to the NW by T63, R22W5 (Figs.
1, 2).
- Detailed analysis of facies and dolomite trends in the
Medicine River Pekisko field (centred on T39, R3W5) by Hopkins
(1999) has documented a strong NE-SW trend of medium crystalline
dolomite (dolostone) in the Pekisko in that area (Fig.4),
closely paralleling Banff trends of Chatellier (ibid.).
- Joint and associated projects between GDGC and Lorne Rosenthal
(Mannville Inc.) in south-central Alberta (Fig.1)
over the last few years have provided a data base for, and
insights into, thickness variations, subcrop edges, pre-Mississippian
structure, and relationship to Jurassic-Cretaceous erosional
events for the Banff and Pekisko, that contribute to a re-evaluation
of the Mississippian in those project areas.
- Finally, the GDGC Hydrothermal Dolomite Report presented
evidence for widespread hydrothermal dolomite reservoir
development in Devonian to Mississippian host rocks from
immediately south of the Peace River Arch in Alberta, across
the Arch and through northern Alberta, NE BC, and the Territories
(Fig. 5). This interpretation,
together with strong evidence for early emplacement of the
dolomite, is widely accepted in the petroleum industry.
However, suggestions that dolomite in the Devonian (including
Swan Hills, Leduc, Nisku and Wabamun) south of the Peace
River Arch in Alberta, and in the Mississippian (Banff,
Pekisko, Shunda, Turner Valley) in southwestern Alberta
may also be/include dolomite of hydrothermal origin (albeit
"cooler", more distal from tectonically-driven
heat source and at lower geothermal paleogradients) are
considered by some to be controversial and/or unsubstantiated
(although there is considerable evidence in support of a
‘cooler’ hydrothermal source). Given the huge reserves,
and/or production of gas and oil in Mississippian dolomite
reservoirs in southern Alberta, this "controversy"
requires addressing with a focused analysis of the origin
of Mississippian dolomite types.
OBJECTIVES
- Mapping of thickness variations and subcrop edges in
the Banff, Pekisko, Shunda and Turner Valley/Elkton formations
in an area of southcentral Alberta encompassing the Snowbird
Tectonic Zone and extending southward to the Caroline
area.
- Mapping and interpretation of facies and reservoir development
in downdip Banff and Pekisko in the project area, based
on extensive core examination.
- Integration of these Mississippian trends with underlying
structure as defined by regional aeromag data and other
structural information, with comparison (if relevant)
with established facies and other changes and clinoforming
in the Mississippian in the Vulcan Tectonic Zone further
south.
- Re-examination of the cuttings-based Chatellier (1992)
Banff dolomite trends to revaluate their significance
as an example of structural control on dolomitization,
and significance (if any) to other Mississippian dolomite
trends in the area.
- Utilizing petrographic, geochemical and fluid inclusion
data, determine the origin or multiple origins of dolomite
in the Banff, Pekisko to Turner Valley formations, incorporating
Turner Valley sample material from an earlier GDGC Mississippian
project in southern Alberta.
- Construct and interpret burial-thermal history plots
for the Mississippian in the project area, and to evaluate
thermal history relevant to timing of dolomitization and
to organic maturation.
- Integrate all of the preceding data into an exploration-oriented
summary.
AREA
The project area (Fig.
1, 2 ) follows
the regional NNW-SSE Banff, Pekisko to Turner Valley (Elkton)
subcrop edge trends (Fig.
2) from the Snowbird Tectonic zone southward to the
general Caroline area. The selected area deliberately avoids
(where possible) the intensely drilled subcrop edge Mississippian
field trends, and focuses on the downdip Banff-Pekisko section.
The area also lies inboard of the first major thrust-faulted
Foothills structures (Figs.
1, 2).
The southwestern corner of the project area is T33, R2W5.
The northwestern corner is T47, R15W5. The western and eastern
boundaries are stepped to follow a NNW-SSE trend roughly
paralleling the subcrop edges. The area encloses 121 Townships.
The project area overlays parts of the Rosenthal (Mannville
Inc.)- GDGC Mannville Phase 2 and 3 report areas (Fig.
1). Part of the Paleozoic data base created for these
projects will be used as a starting point for isopach and
structural mapping. The southern boundary of the proposed
project area lies four (4) Townships south of the northern
boundary (T28) of the GDGC – MacDonald Turner Valley-Mt.
Head project area (completed 1994). Selected data on basement
structural control, dolomite distribution, and core samples
from this earlier report will be incorporated where relevant
(for example, dolomite origin report) into the proposed
project.
The boundaries of the proposed project area may be modified
to some degree based on client input.
WELL CONTROL
An initial search indicates there are approximately 3370
wells penetrating into or through the Mississippian section
within the proposed project area. Some of these wells occur
in clusters in large fields along subcrop edges. Picks will
be made for the majority of wells outside these larger field
areas, plus selected wells within the fields. Although a
precise figure has not yet been calculated, it is estimated
that at least 2500 wells will be incorporated into the database
(depending on log suite; older wells with only e-logs may
not be used, or used only on a selective basis). Depending
on location and eastward erosional truncation, picks for
structure and isopach maps will be made for Banff, Pekisko,
Shunda and Turner Valley/Elkton.
CORE CONTROL
Facies and reservoir characteristics for the Banff and
Pekisko will be based on core examination. Preliminary data
base search indicates 149 wells with Pekisko cores and 57
wells with Banff cores. The majority but not all of these
cores will be described. Some Shunda and Turner Valley cores
may also be included. Core descriptions will be presented
in a computer graphic display in hard copy and in CD.
CUTTINGS EXAMINATION
Although the emphasis in this proposal is on the use of
core for facies and reservoir characterization in the Banff
and Pekisko, key intervals in selected wells lacking core
control will be examined and sampled in cuttings. These
descriptions will be provided in graphical summary form.
DATA BASE
All relevant formation/unit picks, dolomite data, and other
relevant digital information will be provided in hard copy
and in CD format.
STRUCTURAL CONTROL
Published and other available (for example, open file,
GSC) sources will be used to construct a structural framework
for the project area. This will be integrated with regional
aeromagnetic data (probably reprocessed digital maps). Detailed
outlines of the Swan Hills, Leduc (and Nisku?) platform
margins and reefs will be included to determine their relationships
to Mississippian deposition/facies and/or reservoir development.
Specific attention will be given to the structural expression,
if any, of the Snowbird Tectonic Zone (STZ), and similar-trending
basement features. Comparisons may be drawn between the
STZ and the Vulcan Tectonic Zone as expressed by earlier
work (Davies-MacDonald, 1996; Fig.
3).
SEISMIC DATA
GDGC does not have direct access to seismic data in the
project area. We welcome any suggestions that participating
companies may make regarding access to seismic data and
integration in the area.
CORE PHOTOGRAPHY
Representative and unusual facies, diagenetic fabrics,
and reservoir characteristics will be documented by core
photography. These photographs will be made available in
digital form (CD) as well as used selectively in text figures.
THIN-SECTION PHOTOMICROSCOPY
Thin-sections will be prepared from selected core and cuttings
samples, and photomicrographs will be presented in digital
form (CD) and also used in some text figures.
FLUID INCLUSION ANALYSIS
For the Mississippian dolomite component, fluid inclusion
analysis will be conducted to obtain homogenization temperature
and salinity data. Some mass spectrometry of fluid inclusions
may also be conducted (as for dolomite in the GDGC Hydrothermal
Dolomite Report). These analyses will be conducted by Ron
Spencer, Ph.D., Dept. Geology, University of Calgary.
ISOTOPIC ANALYSES
Selected dolomite samples will be analyzed for stable C
and O isotopic composition. In addition, Sr isotopic analyses
may also be conducted.
DATING OF DOLOMITE: EXPERIMENTAL
A newly-created mass-spectrometry laboratory at the University
of Calgary offers the potential to date dolomitization by
a number of techniques, either from associated minerals
or possibly from the dolomite itself. Although not confirmed
at proposal preparation time, this application will be evaluated
and depending on cost, applied to selected samples in the
project sample set.
MAPPING
Isopach and structure maps (with subcrop edges) will be
prepared for the Banff, Pekisko, Shunda, and Turner Valley
(Elkton) within the project area. Residual maps will be
constructed on some of these maps to identify anomalies.
Facies and dolomite/porosity trend maps will be constructed
for the Banff and Pekisko. Maps will be made available in
digital form. A minimum of 13 maps at 150/175,000 scale
will be provided with the report.
CROSS-SECTIONS
A grid of stratigraphic cross-sections will be constructed
through the project area, with a minimum of 8 east-west
and 2 north-south sections. Additional more detailed sections
across field areas, as well as selected structural sections,
may also be constructed.
REPORT
A comprehensive report will accompany the maps and sections,
supplemented with text figures utilizing selected core photographs
and thin-sections photomicrographs. This report will include
hard copy of data base and core descriptions as well as
CD digital copies. An integral sub-report will present data
and interpretations on the origin of Mississippian dolomites
in southern and south-central Alberta
NUMBER OF PARTICIPATING COMPANIES
This project will require a minimum of six (6) companies
to commence.
CONFIDENTIALITY
The report will be confidential for one (1) year after
completion and delivery to participants.
FIELD TRIP
Depending on the outcome of discussion with GSC personnel,
a field trip to examine Mississippian outcrops and dolomite
sections may be organized for the spring of 2003. This will
be open to all participants but at cost (that is, not built
into the price of the report).
MID-PROJECT REVIEW
A short review of the status and any available findings
will be presented to each participating company at about
mid-project time.
COMPLETION SEMINAR
A seminar will be presented at the end of the project to
cover all aspects and conclusions. This may be given in
conjunction with the core seminar, and (depending on number
of participants), either as exclusive to each company or
a combined presentation.
CORE SEMINAR
A one-day core seminar will be presented to participants
at the completion of the project. This will be held at the
AEUB Core Research Laboratory. Some limits may be set for
the number of participants from each company.
TIMING
This report will require 10 months for completion. It will
commence when the minimum number of participating companies
(6) is signed on. This may occur in September 2002, giving
a projected completion in July 2003.
PRICE AND PAYMENT
STRUCTURE
The standard price of the report is $29,500.00 + GST. Payment
schedule is 50% ($14,750.00 + GST) at commencement, 25%
($7,375.00 + GST) after the mid-project review, and 25%
at completion.
To encourage early participation, the price for initial
participants up to September 30th, 2002, will
be $27,000.00 + GST, with similar payment schedules
as above.
FOR FURTHER
INFORMATION:
Contact Cheryl Wright, Director of Marketing and Business
Development, (403) 259-8544 or email at info@gdgc.com.
REFERENCES
Chatellier, J-Y.D, 1992, Structurally-controlled diagenesis
of a carbonate ramp (Banff Formation, Alberta,
Canada). Sedimentary Geology, v. 79, p. 77-90.
Davies, G.R., 2001, Hydrothermal (Thermobaric) Dolomite
Reservoir Facies. GDGC Multi-client report,
548p. text, 506 text figs., 24 Tables, 480 core descriptions
(from 153 wells), maps, posters.
Davies, G.R., and MacDonald, R.W., 1994, Regional stratigraphy,
lithofacies and reservoir trends,
Mississippian Turner Valley-Livingstone-Mt. Head formations,
western plains and Foothills of
southwestern Alberta. GDGC Multi-client report, 203 p.
text, 81 text figs., 66 core descriptions,
67 maps, 20 cross-sections.
Hopkins, J.C., 1999, Characterization of reservoir lithologies
within subunconformity pools: Pekisko
Formation, Medicine River Field, Alberta, Canada. American
Association of Petroleum Geologists
Bull. v. 83, no. 11, p. 1855-1870.
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