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Master's Theses Graduate College
8-1985
Subsurface Stratigrapy and Sedimentologic Control on the Productive Middle Devonian Age Richfield Member of the ucasL Formation in the Michigan Basin
Sukru Nail Apak
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Recommended Citation Apak, Sukru Nail, "Subsurface Stratigrapy and Sedimentologic Control on the Productive Middle Devonian Age Richfield Member of the ucasL Formation in the Michigan Basin" (1985). Master's Theses. 1365. https://scholarworks.wmich.edu/masters_theses/1365
This Masters Thesis-Open Access is brought to you for free and open access by the Graduate College at ScholarWorks at WMU. It has been accepted for inclusion in Master's Theses by an authorized administrator of ScholarWorks at WMU. For more information, please contact [email protected]. SUBSURFACE STRATIGRAPY AND SEDIMENTOLOGIC CONTROL ON THE PRODUCTIVE MIDDLE DEVONIAN AGE RICHFIELD MEMBER OF THE LUCAS FORMATION IN THE MICHIGAN BASIN
By
Sukru Nail Apak
A Thesis Submitted to the Faculty of The Graduate College in partial fullfilment of the requirements for the Degree of Master of Science Department of Geology
Western Michigan University Kalamazoo, Michigan August 1985
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. SUBSURFACE STRATIGRAPHY AND SEDIMENTOLOGIC CONTROL ON THE PRODUCTIVE MIDDLE DEVONIAN AGE RICHFIELD MEMBER OF THE LUCAS FORMATION IN THE MICHIGAN BASIN
Sukru Nail Apak, M.S.
Western Michigan University, 1985
The depositional system of the Middle Devonian
Richfield Member of Lucas Formation in the Michigan Basin
was delineated using well logs, cores, drillers' records,
and the literature. The Richfield Member was deposited
in Sabkha and lagoonal environments characterized by
cycles of anhydrite, dolomite, and limestone. Seven
significant productive dolomitic zones, interbedded with
anhydrite and limestone can be correlated throughout the
study area. These zones change laterally to anhydrite
towards the west flank and to dense limestone towards the
east flank of the basin. Post-depositional diagenetic
history of the Richfield was established with the aid of
scanning electron microscopy and electron probe analysis.
SEM and electron probe analysis revealed two stages
of dolomitization that were formed in the Richfield
particularly in central part of basin. This study
represents detailed regional research of the Richfield
Member in the Michigan Basin and it is hoped that it will
provide some information for further investigation of the
Richfield Member in Michigan Basin.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ACKNOWLEDGEMENTS
This paper is a master thesis submitted by the
author to the graduate faculty of Western Michigan
University. Gratitude is expressed to Dr. W. B. Harrison
who supervised this work with endless help and his great
friendship, Dr. W. T. Straw and Dr. J. Grace who also
contributed to my study with their advise and support, and
the Department of Geology that allowed me to use
department facilities.
Appreciation is also expressed to Dr. A. U. Dogan who
helped me with numerous SEM analyses at the University of
Iowa.
I would like to thank The Graduate College for
supporting my research through Graduate Student Research
Fund. I would like to thank Hunt Energy Company and
Summit Petroleum Company for contributing cores for my
research.
I must also thank the Turkish Government and Turkish
Petroleum Company for allowing and supporting me in
completing my degree in the U.S.A. This study is also
dedicated to my family for their continuing moral support.
I also hope that this study will generate some ideas for
further investigation of Richfield in the Michigan Basin.
Sukru Nail Apak
ii
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Apak, Sukru Nail
SUBSURFACE STRATIGRAPHY AND SEDIMENTOLOGIC CONTROL ON THE PRODUCTIVE MIDDLE DEVONIAN AGE RICHFIELD MEMBER OF THE LUCAS FORMATION IN THE MICHIGAN BASIN
Western Michigan University M.S. 1985
University Microfilms International 300 N. Zeeb Road, Ann Arbor, Ml 48106
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Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OP CONTENTS
ACKNOWLEDGEMENTS ...... ii
LIST OF FIGURES ...... iv
INTRODUCTION ...... 1
Previous Work ...... 1
Area of Study ...... 3
Purpose of Study ...... 3
Methods of Study ...... 5
STRUCTURE ...... 10
STRATIGRAPHY ...... 13
RICHFIELD DEPOSITIONAL ENVIRONMENT ...... 16
Sabkha Environment ...... 23
Subtidal Environment ...... 29
POROSITY TYPE AND DEVELOPMENTIN RICHFIELD ...... 33
DOLOMITIZATION ...... 35
Sabkha Type Dolomitization ...... 38
Seepage Reflux Dolomitization ...... 40
SUBSURFACE CORRELATION AND FACIES INTERPRETATION .....43
CORRELATION OF THE MAJOR ZONESWITHIN THE BASIN .....55
SEM ANALYSIS ...... 62
Anderson 1-31,Isabella ...... 63
Me Guire 1-22,Oscoda ...... 79
CONCLUSION ...... 90
APPENDIX .... 92
BIBLIOGRAPHY ...... 95
i i i
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF FIGURES
1. Study Area Location within Michigan...... 4
2. Location of Wells within Study Area...... 7
3. Illustration of Type Section in Study Area...... 8
4. Tectonic Features Surrounding Michigan Basin...... 11
5. Structure Map of Richfield Member in the Study Area..12
6. Middle Devonian Detroit River Group Showing Position of Richfield Member...... 14
7. Late Devonian Paleogeography Illustration of Michigan Basin as Subtropical...... 17
8. Generalized Depositional Cycle of Carbonates and Evaporites in the Sabkha Cycle...... 18
9. Isopach Map of Richfield Member in the Study Area....20
10. Block Diagram Schematically Showing Facies and Interpreted Depositional Environments in the Michigan Basin During Richfield Depositional Period...... 21
11. Southwest - Northeast Cross-Section Across the Study Area, Showing Facies Relationship within the Richfield Member...... 22
12. Laminated Dolomitic Algal Mats ...... 24
13. Decussate Algal Dolomicrite ...... 25
14. Anhydrite Laths Along Algal Mats Bedding Planes 26
15. Dolomitic Algal Mats...... 27
16. Dolomitic Algal Mats and Vertical Growth of Anhydrite Nodules...... 28
17. Vertical Growing Anhydrite Nodules ...... 31
18. Vertical Growing Anhydrite Nodules...... 32
iv
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 19. Dolomitization Map of the Richfield Member in the study area...... 37
20. Schematic Diagram Showing Sabkha and Seepage Reflux Type of Dolomitization...... 39
21. Correlation of Major Zones within the Richfield Member...... 45
22. Illustration of Type Section in Newaygo County...... 47
23. Illustration of Type Section in Clare County...... 49
24. Illustration of Type Section in Missaukee County...... 50
25. Illustration of Type Section in Roscommon County...... 51
26. Illustration of Type Section in Crawford County...... 52
27. Illustration of Type Section in Oscoda County...... 54
28. Porosity Map of zone-1...... 56
29. Porosity Map of zone-2...... 57
30. Porosity Map of zone-3...... 58
31. Porosity Map of zone-4...... 59
32. Porosity Map of zone-5...... 60
33. Porosity Map of zone-6...... 61
34. Type Log and Core Description of Anderson 1-31, Isabella County...... 64
35. Dolomite Crystals and Secondary Porosity Relationship...... 65
36. Dolomite Crystals, Secondary Porosity, and Pyrite Pramboids ...... 66
37. Pyrite Framboids and Dolomite Crystals...... 67
38. Micro-Calcite Cement, Dolomite Crystals, and Secondary Porosity Relationships...... 68
39. Dolomite Dissolution and Micro-Calcite Crystals...... 69
40. Dolomite Dissolution and Micro-calcite Crystals...... 70
v
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 41. Dolomite Rhombs and High IntercrystallinePorosity..71
42. Dolomite Crystals with probable Fluid Inclusion 72
43. Dolomite Rhombs and Fluid Inclusions...... 73
44. Dolomite Rhombs and Secondary Porosity Relationship.74
45. Dolomite Rhombs in the Pore Spaces...... 75
46. Dolomite Rhombs in the Pore Spaces...... 76
47. Two Sizes of Dolomite Crystals...... 77
48. Small Dolomite Crystal on Large Dolomite Crystal...... 78
49. Core Description of Me Guire 1-22, Oscoda County...... 79
50. Micritic Limestone and Salt Crystals...... 80
51. Micro-Calcite and Salt Crystals...... 81
52. Anhydrite Crystals in Micritic Limestone...... 82
53. Salt Crystals and Partly Dolomitic Limestone...... 83
54. Dolomite Crystals and Micritic Limestone...... 84
55. Star-Shaped Salt Crystals (KC1)...... 85
56. Dolomite Crystals...... 86
57. Micritic Limestone ...... 87
58. Secondary Single Calcite Crystal in the Pore Space...... 88
vi
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. INTRODUCTION
Previous Work
Due to poor outcrops in the Michigan Basin
investigation of the Middle Devonian strata have been done
based on subsurface strata by some authors. The main
purpose of this studies is to define the depositional
environment, facies relationships, and age determinations,
of the Middle Devonian rocks in the basin. However,
relatively little work has been published on the
depositional system of the Richfield Member of Lucas
Formation of the Detroit River Group in the Michigan Basin.
Landes (1951) correlated the outcropping rocks of
the Detroit River Group from the type locality sections.
He has also used well logs and cores to define the
formations' depositional environment, their contacts,
diagenesis and economically important future.
Ehrnann (1964) studied stratigraphic analysis of the
Detroit River Group in the Michigan Basin. He had
subdivided the Detroit River Group into the characteristic
zones in the center of the basin andcorrelated them
in the entire basin.
1
with permission of the copyright owner. Further reproduction prohibited without permission. 2
Gardner (1974) worked on the Middle Devonian
evaporite-carbonate complex to determine the depositional
environment and diagenetic history of the rocks. He tried
to establish the paleogeographic reconstruction of strata
and the relationships of the environmental complex and
its distribution in the basin.
Matthews (1977) studied the correlation of
evaporite cycles and lithofacies of Lucas Formation
in Midland County, Michigan. This study was based
on the description of the cores which were used to
correlate the cycles and salinity of the depositional
environment in Midland county.
Briggs and Haney (1964) determined the cyclicity of
textures in evaporite rocks of the Lucas Formation in the
Michigan Basin. He pointed out that the texture could be
related to the physiochemical conditions of mineral
precipitation and specific conditions of brine
concentration at that time.
Fagerstrom (1983) researched the Lucas Formation' s
carbonate and evaporite complex and their petrological and
regional significance in the eastern Michigan Basin. He
petrologically studied the interreef rocks, transition
rocks and reefs and their type of diagenetic evolution .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3
Melvin (1984) has studied the Richfield Member of
the Lucas Formation in Gladwin and Clare Counties
in the Michigan Basin in order to establish the
depositional model and facies analyses of the Richfield
Member. She has also defined types of hydrocarbon traps
that were formed either structurally or stratigraphically.
Area of Study
The research area includes the following counties :
Crawford, Oscoda, Missaukee, Roscommon, Ogemaw, Lake,
Osceola, Clare, Gladwin, Arenac, Bay, Newaygo, Mecosta,
Isabella, and Midland . (Figure 1).
Purpose of Study
The Middle Devonian Richfield Member of the Lucas
Formation contains oil and gas reservoirs within
structures in the central portion of the Michigan Basin.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. STUDY AREA
Figure 1. Study area location within Michigan.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 5
However, productive units in some structures are non
productive on similar structures in the eastern and
western part of the basin. The purpose of this study was
to determine which parameters limit production to
structures in the central portion of the basin. Using
available subsurface materials (well logs and core
samples), objectives of this study were:
1. To divide the Richfield Member into several
distinctive, usually productive zones which can be
correlated throughout the basin.
2. To delineate lateral facies changes of the
productive zones towards the eastern and western flank of
the basin.
3. To determine the geological factors which
controlled the reservoir properties and limit production
to the central portion of the basin.
Methods of Study
Well logs, drillers' logs, cores, core analysis
reports, and literature were used as data to prepare
subsurface maps. One hundred and eighty-one well logs
(formation density, neutron, gamma ray, resistivity, and
sonic logs) were obtained from Michigan Department of
Natural Resources in Lansing, Michigan. Drillers' logs were
used for lithologic descriptions of the Richfield where the
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 6
wire-line electric well logs were not available for
this data. Well locations were chosen from nearly every
township within the study area (Figure 2.). Producing and
non producing wells from each county, in the same geologic
interval, were used to define lateral facies and
lithological changes throughout Richfield. The upper
(just below the massive anhydrite) and the lower (below
the last dolomite zones of Richfield) contacts of the
Richfield were picked from each log in the study area
(Figure 3.).
The samples from Anderson 1-31, Isabella Co., and 1-22
McGuire, Oscoda Co. were examined and sampled in detail
to construct the depositional model and determine post-
depositional diagenesis of the sediment. Petrographic
analysis were made by 1. standard petrographic
microscope, 2. scanning electron microscope , and
3. electron probe analysis. Fifty-one core samples
were examined (27 of them from Anderson 1-31, Isabella
Co. and 24 of them from 1-22 McGuire, Oscoda Co.) using
the scanning electron microscope. All of the core samples
were coated with either 1. gold and platinium, 2. gold
and palladium, or 3. carbon.
The Jeol-35C scanning electron microscope was used to
determine rock properties such as cementation,
compaction, replacement, pore geometries, sizes
and shapes of microcrystaline authigenic minerals
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 7
Osama t 11-41 ai.Ntf«a«
1-MMffin QuuMmkE. S Nm MI'i k U.T* 11 UHff„•j*a
m rm c M M i
Figure 2. Location o£ wells within study area.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 8
3 HAMILTON UNIT 18 SEC.? T1IN- R1W SE NE NC CLARE CO.,MICHIGAN1
u lULK OCNIITT M
MtUTNON POIIOtlTV
MMIIVC ANNVOHITt . 8 1 0 0 0 0 /0
SOM f 1 0 3
t O N l 2 1 8
ZONK a 22.5
IO N C 4 .
IO N I 3
8201
SONS •
IO N C 7
CLACK UMCSTONC
Figure 3. Illustration of type section in study area.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 9
(halite, quartz etc. ). Grain or crystal surface texture
and textural relationship of diagenetic minerals was
determined by using freeze fracture method (Dogan,
Personel comm. 1984).
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. STRUCTURE
The Michigan Basin is an almost circular, intracratonic
basin located in the central interior platform.
The basin covers southern Ontario, part of the upper
peninsula of Michigan, eastern Wisconsin, the northern
portion of Illinois, northern Indiana, northwestern Ohio,
and the southern peninsula of Michigan. The Michigan Basin
is bounded by ^Wisconsin arch on the west, Kankakee platform
on the southwest, Findlay arch on the east, and Canadian
shield on the north (Figure 4.). Deposition and erosion
were controlled by these tectonic features.
Many models have been proposed to define the formation
and structure of Michigan Basin. The basin was present
during Cambrian time in an embryonic form
(Fisher, 1979). Clastics and carbonates were deposited on
pre-Cambrian basement rock. The basin' s current shape
was developed in Middle Ordovician time.
During Early Silurian time , shales and carbonates
filled the basin and by Middle Silurian time
reefs were developed around the basin margin. Maximum
subsidence of the basin occurred in Paleozoic time. The
central part of the basin received 8000 feet of sediments
in Silurian and Devonian times. These sediments were
mostly limestone, evaporite, and shale (Fisher, 1979). By
Mississippian time, movement occurred along the basement
10
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 11
[study area )
CANADA \ SHIELD
UNITED STATES ' V / S - ^ - 1 - '- f ? \. v v v v si- v
CHIGAf* BASIN
ILLINOIS > BASIN'-.
DOME
MISSISSIPPI EMBAYMENT
CRETACEOUS AND TERTIARY F T ] MISSISSIPPI** AND PENNSYLVANIAN I I PALEOZOIC ROCKS OP PRE-MISSISSIPMAN AGE '
E 3 PRINCIPALLY precambrian c r t s t a l in e r o c ks
.JO O gO MILES GULF OF MEXICO 0 ISO 320 KILOMETERS
Figure 4. Tectonic features surrounding Michigan Basin. Source: Hager, 1949, 1198-1205.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 12
ma«
mar
>4030. >3140* U 4 I II*
>3270)
Figure 5. Structure map of Richfield Member in the study area.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. faults. According to Fisher (1979) vertical movements
caused NW trending folds-in the central part of the basin.
A structure map (Figure, 5.) shows the current shape of
basin. As it is seen on the map, the central part which is
main producing area is the deepest part of the basin.
STRATIGRAPHY
Middle Devonian age strata of the Michigan Basin
include from oldest to youngest, the Detroit River Group,
Dundee Formation, and Traverse Group. The Detroit River
Group (Figure 6.) is composed of Sylvania Sandstone,
Amherstburg Formation, and Lucas Formation (Gardner,1974).
Sylvania Sandstone is the basal part of Amherstburg
Formation and can be correlated in most parts of the basin
(Landes, 1951). Amherstburg Formation, which is often
called " Black Limestone " by well-site geologists is
present throughout the basin. Its lithology is dark-colored
limestone and generally fosilliferous. It is underlying
the Richfield Member. The boundary between them can be
recognized by a difference in their colors. The Upper part
of Amherstburg is a black-colored limestone, whereas, the
basal part of the Richfield is lighter and dolomitic. The
contact between them appears just below the last dolomitic
zone of Richfield member. In some areas this zone is not
13
with permission of the copyright owner. Further reproduction prohibited without permission. FORMATION MEMBERS INFORMAL GROUP NOMENCLATURE
o 5 HORNER MEMBER UPPER SPUR ZONE a o r- H a C a o < m > m w a LOWER SOUR ZONE -n CO 3J O O 3 c IUTZI MEMBER O s a H 5 • 33 • £ MASSIVE ANHYDRITE RICHFIELD < m ! 31 / RICHFIELD MEMBER Q S. 3) FREER SANDSTONE O > FILER SANDSTONE C . -n 2 OX MELDRUM ■o t a m MEMBER 3 a BLACKLIME ’
i c SYLVANIA Z a SANDSTONE O
Figure 6. Middle Devonian Detroit River Group, showing position of Richfield Member.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 15
as dolomitic and also is black color, so this may suggest
a gradational boundary between them. The Lucas Formation
lies below the Dundee Formation. The upper part of Lucas
Formation is dolomite and the basal part of Dundee Fm. is
limestone. However, the basal part of Dundee Fm. may be
dolomitic and anhydritic especially in the western part of
the basin. In the central basin Lucas Formation contains
limestone, salt, and anhydrite beds. Therefore, contact
between them is not clear in the western part of basin. It
may also suggest a gradational boundary between the two
formations.
The basal part of Lucas Formation is called the
Richfield Member which is an important oil and gas
reservoir in the central Michigan Basin. It is characterized
by several cycles of anhydrite, limestone, and dolomite
with its distinctively developed secondary porosity. These
dolomitic zones have porosities range up to 30% especially
in the central part of the basin. Towards the east and
west this porosity decreases where the dolomitic
lithology turns to anhydrite at the west flank
and to dense limestone at the east flank. The upper part of
the Richfield Member is characterized by a thick anhydrite
bed which is informally called the "Big Anhydrite" . This
anhydrite is continuous in the whole basin, but it is much
thicker in the central and northern part of the basin.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. RICHFIELD DEPOSITIONAL ENVIRONMENT
During Devonian time the basin was affected by
several marine transgressions and regressions. Multiple
cycles of limestone, anhydrite, and dolomite suggest a
restricted marine environment in an arid and hot climate
(Dott and Batten, 1981) during the Richfield depositional
period (Figure 7.). Repeated sea level fluctuations
caused vertical repetition of similar rock sequences,
local unconformities, and thickness variations within the
Richfield Member. These sea level changes were caused
by: 1. marine water flowing through the Saginaw inlet,
2. basin subsidence, and 3. changes of evaporation rates.
In a Sabkha environment sediments are deposited under
very shallow water (Figure 8 .) and they are very sensitive
to sea-level fluctuations (Schreiber, pers. comm.,1985).
Slight rises of sea level cause dissolution of
evaporites and create pore places. These pore places were
filled either by hydrocarbon or cement at the later
stage. In the lower stage of sea level evaporation rates
increased, dolomitization occurred, and sea water entered
the basin. The Richfield deposition shows a similar
environment and it is considered to be deposited under the
Sabkha and lagoonal environment. Anhydrite beds are the key
marker zones within the Richfield deposition. Laterally
continuous vertically thick anhydrite beds deposited in the
16
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 17
ITUDY AHI
Figure 7. Late Devonian Paleogeography illustration of Michigan Basin as Subtropical. Source: Dott and Batten, 1981.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 18
«
GENERALIZED DEPOSITIONAL CYCLE]
EVAPORITE STRUCTURES CARBONATE FACIE
Si
- I 3
5 ^ • • •• s g B'csa y ' •= s? u
cea ■C^
• T z z < >
i 7 5 z .= r*
l r \ r v
?U9 riDAL. May oocorne stmacrinlly exposure.! during ionq oeriocs of evaporation. l
F ig u r e 8 . Generalized depositional cycle of carbonates and evaporites in the sabkha cycle, source: Loucks and Longman, 1982.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 19
shallow water lagoon environment. Laterally discontinuous
anhydrite beds and subaerial deposits indicate a sabkha
environment. In the Richfield Member each facies is
characterized by these rocks:
Subtidal Environment: It is mainly a limestone facies; however, salinity of water caused either limestone or anhydrite deposition in this facies.
Sabkha Environment: 1. Intertidal Facies; Limestone and dolomitic limestone are the main lithologies. Dolomitization rate increases towards the upper intertidal zone. Ripple-marks, oolites, algal laminated limestone are common. This facies may be good reservoir rocks. 2. Supratidal Facies: This facies is characterized by nodular anhydrite. It is an important facies because it seals the reservoir rocks as a cap rock.
Based on an Isopach map, the Richfield Member
gradually thins eastward and northeastward (Figure 9).
According to Gardner (1974) the maximum thickness
of the Richfield Member was deposited in
Missaukee and Wexford Counties. In the study area the
maximum thickness is seen in Osceola (291 feet),
Missaukee (198 feet), Clare (254 feet), and Roscommon
(221 feet) Counties. Anhydrite, which was the dominant
lithology in these counties controlled the maximum
thickness of the Richfield Member in this part of basin.
It shows that during Richfield deposition, the west flank
of the basin was under supratidal conditions (Figure 10-11)
while other parts of basin were receiving intertidal and
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 20
174
T96i 184 1B2
|t84 231 104
180
181
181 1980 • r .107 2 00
►254
.220 108 2 5 0
161 06
Figure 9. Isopach map of Richfield Member in the study area.
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j
i
Figure 10. Block diagram schematically showing facies and interpreted depositional environments in the Michigan Basin during the Richfield depositional period.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 22
sw NE
i
I SUBTIDAL SUPRATIDAL INTEITI i
e*
B L A c
Figure 11. Southwest-Northeast cross section across the study area, showing facies relationship within the Richfield Member.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 23
subtidal deposits.
Sabkha Environment
Environmental factors such as temperature, sea level
fluctuations, high salinity, and high evaporation rate may
limit the distribution of organisms and sediments in the
Sabkha environment. The supratidal and intertidal zone,
collectively is defined as the Sabkha environment.
The supratidal environment of the Richfield Member,
on the west flank of the basin, is characterized by thick
anhydrite bed deposition interbedded with thin carbonate
beds that were completely dolomitized .
In the upper and middle supratidal zone, nodular
anhydrite is abundant. These nodules are mostly lenticular
or discoidal gypsum that were later altered to
nodular anhydrite (Schreiber, 1981). In the lower
supratidal and upper intertidal zone anhydrite laths are
generated within the algal mats (Figure 12, 13, and 14).
Sedimentary structures such as ripple marks, cross
bedding, oolites, and algal mats are associated with the
Sabkha environment. The most common plants found in the
intertidal zone are blue-green algae which are deposited
as algal mats within the lime mud (Figure 12, 15, and 16).
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 24
Figure 12. Laminated dolomitic algal mats. Dark anhydrite laths developed along wavy bedding planes, but oriented high angle to the bedding. The nodules appear to have formed low relief on the lagoon floor, but growth continued after deposition by revealing draping of.laminae.' Core: Anderson 1-31, depth: 4759.5 feet.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 13. Decussate algal dolomicrite. Dark anhydrite laths randomly oriented along bedding. Core: Anderson 1-31, depth: 4771.5 feet.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 14. Anhydrite laths along algal mats bedding planes. Intertidal environment. CoretAnderson 1-31, depth: 4789 feet.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 15. Dolomitic algal mats. Shallow and hypersaline environment. Core: Anderson 1-31, depth:4726 feet.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 28
Figure 16. Dolomitic algal mats and vertical growth of anhydrite nodules. These nodules grew under very shallow water (maximum depth of water is 15 cm.). Core: Anderson 1-31, depth: 4707 feet.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 29
Environmental factors explained above control the
marine organism distribution in the Sabkha environment.
In the restricted character of most Richfield lithologies
macrofossils are not common, because the environment would
not support those kind of organisms. Only the lower part
of Richfield, deposited during a transgressive cycle of
the Lucas sea contains fossils such as brachiopods and
marine plankton (Melvin, 1983). The organic-rich "black
Limestone" and the dark-colored lower part of Richfield
may be possible source rocks for the hydrocarbon that later
accumulated in the porous dolomitic zones. In the study
area, especially in central part of basin which was
mostly intertidal zone during Richfield deposition,
dolomitization occurred resulting in high secondary
porosity. Then oil and gas migrated into this area where
reservoir properties allowed for hydrocarbon trapping.
Subtidal Environment
During Richfield deposition, the eastern flank of the
basin was under subtidal condition, because of the entrance
of water from the ocean into the restricted basin. In the
study area, this facies is represented by limestone
interbedded with subaqueous anhydrite deposits. There is
almost no dolomitization in this facies (10%-0%). Different
salinity of the water, which was caused by sea-level
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. fluctuations and high evaporation, caused limestone
and anhydrite deposition in the area. At the lower stage
Of sea level, Subaqueous anhydrite was deposited due to
high evaporation and hypersaline water. This anhydrite is
characterized by vertically growing crystals (Figure 17-18).
These type of anhydrite crystals indicate that they formed
in very shallow water of about 10-15 cm. (Schreiber, 1984).
During this period, no influx of water from the ocean
occurred and high evaporation yielded laterally expansive
anhydrite deposition in the area. SEM analysis of the
McGuire 1-22, Oscoda Co. core, indicates that secondary
salt crystals were precipitated in the intercrystallini
porosity of the limestone. These salt (NaCl) crystals are
most probably secondary because they filled the
intercrystalline porosity and were precipitated on the
calcite crystals (Figure 50, 53, and 54).
In the upper part of Richfield, thick anhydrite beds
called the "Big Anhydrite" were deposited due to a high rate
evaporation and hypersaline water. Laterally it can be
correlated, particularly in the central and northern part
of basin. This vast expansion of the anhydrite beds indicate
that the area remained under subtidal conditions for
a long time. During this time the basin was mostly covered
by lakes or ponds like those found in the present day
Persian Gulf lagoon environment (Kendall, 1968). This
evaporite bed covered all previous carbonate depositions,
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 31
Figure 17. Vertical growing anhydrite nodules. Core: Anderson 1-31, depth: 4697.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 32
A
Figure 18. Vertical growing anhydrite nodules. Very shallow depositional environment, Core: Anderson 1-31, depth: 4705m.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. so most of oil and gas production in Richfield carbonates
is found beneath the "Big Anhydrite" bed. At the upper last
zone of the Richfield deposition, the area was affected by
a transgressive cycle and was covered by water which was
less saline than the previous inudations. This last
Richfield carbonate sequence was deposited mostly
in the central part of the basin. Even though the sequence
has high porosity it contains no economical hydrocarbon
accumulation. "Big Anhydrite" beds apparently blocked the
hydrocarbons from migrating up into the last carbonate bed.
After the deposition of the last carbonate unit of the
Richfield Member, the basin again became a restricted
environment and the Richfield was covered by the another
thick anhydrite bed which is called "Massive Anhydrite".
POROSITY TYPE AND DEVELOPMENT IN THE RICHFIELD
Two types of porosity are present in the carbonate
sequences of the Richfield Member, 1) primary porosity
related to the depositional environment, and 2 ) secondary
porosity related to rock diagenesis occurring after
deposition.
Primary porosity forms as a result of events which
occur during the depositional process. Certain environments
have good primary porosity while others have almost none.
33
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 34
For instance, oolites deposited in a high energetic
environment have good porosity because the fine size
materials which can fill in the pores and decrease porosity
are winnowed away by currents. However, some porosity may
be associated with chemical processes instead of physical
depositional processes. Primary porosity is modified by
compaction, solution, and cementation, which may cause
a secondary decrease or increase the porosity (Choquette
and Pray, 1970).
Secondary porosity is the result of diagenetic
alteration. Textural characteristics (grain size, shape,
and packing) also help to create and increase the
secondary porosity. All these features are controlled by
the rock's facies.
In the Richfield Member of the Lucas Formation
good to poor porosity developed in the carbonate
sequences. In the central part of basin, which is
the most productive region in the Michigan Basin,
dolomitization caused the high secondary porosity.
However, the eastern and western flank of the basin show
an entirely different picture from the central part. The
western flank, which was mostly a supratidal environment
during the Richfield deposition period, is characterized
by thick anhydrite beds. Because of this lateral
facies changes in the Richfield no porosity developed
on the west flank of the basin. On the east flank
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. of the basin, the Richfield is characterized mainly by
limestone interbedded with subaqueous anhydrite. A low
energy environment, poor water circulation, and poor
dolomitization of the limestone yielded the low porosity
in this region. The samples from Anderson 1-31, Isabella
Co. in the central part of the basin, and McGuire 1-22,
Oscoda Co. in the northeastern part of the basin were
studied to determine how the facies change laterally from
the central part to the eastern flank. In the study area,
high secondary porosity developed in the Sabkha
environment. It seems that the dolomitization which occurs
throughout the Sabkha environment, is the most important
process involved in creating secondary porosity.
DOLOMITIZATION
Certain conditions are necessary for the formation of
dolomite in carbonate sequences. The first and the most
important one is that a source of Mg ion must be present
in the environment. Other factors include the Mg:Ca ratio
sulfate concentration, organic material, iron content, and
bacterial activity in the environment (Longman, 1981).
Several models have been proposed for the formation of
dolomite. These models are: 1. primary precipitation, 2.
seepage refluxion 3. solution cannibalization, 4.
capillary concentration, 5. mixing of fresh and marine
35
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 36
waters, and 6 . subsurface brines (Longman, 1981).
Dolomite can be either primary or secondary in the
carbonate sequences as suggested by Zenger, 1972. Primary
dolomites are associated with evaporite and they are
mostly found in the Sabkha environment. Secondary
dolomitization occurs by replacement of pre-existing
carbonate materials. A number of factors control the
dolomitic replacement of carbonate. Composition and grain
size are significant controlling factors. Aragonite, high
Mg-calcite, and fine-grained size materials such as
micrite become dolomitic faster than coarser-grained sizes.
During Richfield deposition, the Michigan Basin was a
restricted basin which was characterized by several cycles
of regressions and transgressions. High evaporation, dry
climate, and high salinity of the water resulted in thick
anhydrite bed deposition in the Sabkha environment. There
is also abundant dolomitization in this area (Figure 19).
Complete dolomitization of the carbonate beds in the
supratidal environment can be explained by Sabkha-type of
dolomitization (Figure 20).
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 37
0|ti
HI
Clin •tl
Figure 19. Dolomitization map of the Richfield Member in the study area. f
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 38
SUPRATIDAL intertidal SUBTIOAL
ANHYDRITE , AAAaONITE+MgCALCITE
EEEPAQE .HEFLUXION ZONe
'!
Figure 20. Schematic diagram showing sabkha and seepage reflux type of dolomitization.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 39
Sabkha Type Dolomitization
Normal marine water contains more sulfate ions than
Ca++ and Mg++ ions . When the sea is allowed to
evaporate, gypsum is precipitated until all Ca++ ions
have been used up, and the rest of sulfate remains in
residual brines. Major seawater ions and this sulfate
reaction are listed below.
Na+
Mg++
K+
Ca++
(Eg. 1) Ca + SO4 = CaS0 4 + residual SO4
Cl”
SO4
Precipitation of gypsum increases the Ca:Mg ratio
which promotes dolomitization of the carbonate host rocks.
For example, in Newaygo, Mecosta, and Osceola Counties
the thin carbonate beds are all dolomitic.
(Eg. 2) Mg + 2CaC03 = CaC03 MgC0 3 + Ca++
As a result of these reactions additional SO4 ions
combine with Ca++ ions to make more CaS0 4 , shown below
(Shearman, 1978).
(Eg. 3) Ca + SO4 = CaS0 4 + residual SO4
(Eg. 4) Mg + 2CaC03 = CaC03 MgC0 3 + Ca++
(Eg. 5) Ca + residual SO4 = CaS0 4 (Gypsum)
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 40
The reaction explained above, allows for, more calcium
sulfate to be produced in the carbonate Sabkha. That is
why the thickest part of the Richfield is deposited in the
supratidal environment.
Seepage Reflux Model Dolomitization
In the central part of basin, similar thick anhydrite
and dolomite beds are preserved. During Richfield
deposition, the restricted Lucas sea had a different
salinity than the adjacent open sea. Sea level fluctuations
were caused by the difference salinity of each transgressive
and regressive cycles. This resulted in anhydrite and
limestone deposition in the central part of basin. Loss
of water by evaporation caused lowering of sea level and
increased the concentration of the remaining brine. Then
waters entered from the adjacent open ocean. This
remaining brine sank and while incoming water from the ocean
flowed along the surface and maintained water circulation
across the shelf. At this time the Ca++ ions reacted with
with the hypersaline brine to make CaSC>4 . Than, Mg-rich
sea water seeped towards the sea and the Mg++ reacted with
the CaC0 3 , which caused the limestone to turn to dolomite
in this zone. This circulation is called seepage reflux by
Adams and Rhodes (1960), (Figure 20). It seems that Sabkha
and seepage reflux models are the appropriate model for
the widespread dolomitization in the Sabkha environment.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 41
The important question is why the dolomitization did
not occur or, was only slightly formed in subtidal
environment. According to Kastner, (1983) the important
condition for the dolomitization is not the high Ca:Mg
ratio as it was previously thought. She states that a low
dissolved sulfate (S0 4 ) content is very important for
dolomitization. High dissolved sulfate in the sea water
inhibits dolomite formation in the environment. The eastern
flank of the basin was a subtidal depositional environment
at this time. The lithology is mainly micritic limestone
and subaqueous anhydrite. A low energy environment and
poor dolomitization created little porosity in the
limestone. Due to low water circulation in the subtidal
environment, removal of sulfate ions from Sabkha
environment, either by the seeping of the sulfate-rich sea
water from intertidal to subtidal or by being washed by
water circulation, increases the amount of free sulfate
ion concentrations. This excess of sulfate ions inhibits
the dolomitization in the subtidal environment.
SEM analysis which was done in two wells, revealed
that two types of dolomite crystals formed within the
Richfield. They were formed at a slightly different
time during Richfield diagenesis. At the first stage, the
limestone beds were dolomitized (Seepage Reflux Method)
and big dolomite crystals were formed. They are not rich
in Mg content. A loss of volume due to dolomitization
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 42
created secondary porosity of the limestone (see in the
SEM section). At the second stage small dolomite crystals
were formed on the big dolomite crystals and in the pore
spaces. The second type of crystals are very small in size
and have a high Mg content. SEM result are given about the
two types of dolomitization in the SEM analysis section.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. SUBSURFACE CORRELATION AND FACIES INTERPRETATION
The Richfield Member of Lucas Formation is
characterized by Sabkha and lagoonal facies type
deposits. It is underlain by a dark-colored coralline
rich "Black Limestone". The differences in lithologies
between the "Black Limestone" and the Richfield
Member indicates normal marine conditions in the
basin during the "Black Limestone" depositional period.
These conditions changed to a widespread shallow
lagoonal and Sabkha-type depositional environment
during Richfield deposition. On the west flank and central
portion of the basin, a thick Sabkha-type deposit occurs,
whereas, on the eastern side of basin lagoonal carbonates
were deposited. In the upper part of the Richfield, the
"Big Anhydrite" covers all previous Richfield deposits
as a cap rock.
The top contact of Richfield is located between the
"Massive Anhydrite" and the carbonate bed deposited
during the last influx of sea water from the Saginaw
inlet, after "Big Anhydrite" accumulated. As mentioned
before the Richfield is composed of anhydrite, dolomite,
and limestone beds. Sabkha deposits occur in the
supratidal and intertidal environments. These lithologies
can be correlated in the basin (Figure 21). Anhydrite beds
43
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. are mainly laminar, vertical growth crystals, and
nodular type of deposits. In the supratidal zone nodular
anhydrite beds are mostly discontinuous as many of them
were deposited subaqueously in ponds on the upper intertidal
or lower supratidal zones. Most were not deeper than 15cm.
The Richfield Member is herein subdivided into seven
zones which are generally dolomitized in the central part,
change laterally to anhydrite towards the west flank,
and change to limestone towards the east flank of the basin
(Figure 21).
On the west flank, the Richfield Member is composed
of thick anhydrite beds interbedded with thin dolomitized
carbonate beds. These deposits are found in Newaygo,
Mecosta, and Osceola counties and formed in the supratidal
environment. Therefore, none of the seven carbonate zones
can be identified in this area (Figure 22). Lutz 1-27/A
(Newaygo Co.), Schwalm 1-15, Leach 1-4, and R.Quart 1-30
from Osceola Co.,and R.Thelma 1-12 from Mecosta Co. are
typical wells in the western flank.
In the central part of basin, Richfield was deposited
in an intertidal environment. In the regression cycle, the
lower stage of sea level, influx of water from the sea
affected the environment. Dolomitization occurred and
progressed towards the central area and decreased towards
the eastward edge of the basin. This dolomitization caused
high secondary porosity in the central part of basin.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CRAWFOftB
OSCEOLA
MECOSTA
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 47
1 -2 7 A LUTZ SEC.1T T18H-R11W BW MW SC NEWAYGO CO., MICHIGAN
3.0 GAMMA «AV 2.0 BUU D1N1ITT 2.3 NVUINON R0AQI1TV 400 4.5 3 0 13
i V 4264 I
SWWWl .4300« \ \ v
ftmwv 2
-4400
Figure 22. Illustration of type section in Newaygo County.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 48
Wells used in this study which represent deposition in
the central basin, include the Hamilton Unit 3-18 (Clare
C o.), Molhoek 9-31 (Missaukee Co.), Helveston 4-25 (Crawford
Co.), and Porter Hogan 1-8 (Roscommon Co.). It is seen in
these wells that the Richfield lithology can be correlated
from well to well. In the Hamilton Unit 3-18 (Clare Co.)
seven carbonate zones and anhydrite beds are seen.
The porosity range in this well from 9% (zone-6) to
22.5% (zone-3 ), (Figure 23).
In the Molhoek 9-31 (Missaukee Co.) similar
carbonate zones and depositional cycles are seen. The only
difference between them is that the anhydrite beds are
much thicker than in the Hamilton Unit 3-18. It seems
reasonable because the Molhoek 9-31 is much closer to the
west flank of the basin. The porosity range is 8% (zone-4)
to 16% (zone-2), (Figure 24).
The Porter Hogan 1-8 (Roscommon Co.) is located in
the central part of study area. The porosity range is from
7% (zone-2) to 18.5% (zone-6), (Figure 25).
The Helveston 4-25 (Crawford Co.) is in the northern
part of study area. It is very similar to the Porter Hogan
1-8. Its porosity range is from 6.5% (zone-4) to 15%
(zone-2), (Figure 26).
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3 HAMILTON UNIT 18 »eC.T TUN-MW SENENI CLARE CO.,MICHIGAN•
M ______»um BIHIIft,,
Figure 23. Illustration of type section in Clare County.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 50
9 r 31. MOLHOEK SEC 31 T22N - ROW NW NWSW
MISSAUKE CO., MICHIGAN
NIUM09 POROIIVV u ______ac______is
Ispi-l II
i d i i i _ 4 . . 1 .
■lac* umiioMi__
Figure 24. Illustration .of type section in Missaukee County.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. PORTER HOGAN 1-8 8IC.I N-II'W NE BE tW ROSCOMMON CO., MICHIGAN flmm iit miLi.nmiiii
JOMB t •
4 0 N t | F
IDMI S IJ
....CJU*
Figure 25. Illustration of type section in Roscommon County.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 52
HELVESTON 4-25
SEC >1 TilN • R 1 W NE S W NE CRAWFORD CO., MICHIGAN
Figure 26. Illustration of type section in Crawford County.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 53
The cycles of regressions and transgressions
caused many unconformities within the Richfield
Member. That is why individual dolomite or anhydrite beds
would disappear from one field to another one.
The McGuire 1-22 well is located, Oscoda Co., in the
northeastern portion of study area. It was completed as a
dry well. The depositional environment is subtidal and
has poor dolomitization and low porosity within this
portion of the Richfield Member. The porosity range is
0% (zone-1) to 14% (zone-7), (Figure 27).
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 54
1-22 MC GUIRE SEC.23 T25N - R2E SW NE SW OSCODA C0„ MICHIGAN
b«mm« ■» _iUt« 91
-011- _14-
UAttW I AMHU1MTI - o & - t o u t
IO N I I
I O N I I 10
IO N I I
IO N I I 9
icmi r u
•LACK UMKIfONI
T
Figure 27. Illustration of type section in Oscoda County.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CORRELATION OF THE MAJOR ZONES WITHIN THE BASIN
Major zones followed throughout the basin are well
developed especially in the central part of basin. For
zone-1 (top of Richfield) to zone-6 porosity maps were
made to establish porosity patterns in each different
zone. The highest porosity developed in the central part
of basin, and each zone's porosity decreased and approached
zero towards the east and west flank of the basin.
Although the precise pattern and actual value of the
porosity changes from zone-1 to zone-6, the similarily is
enough to allow some general statements about the origin
and the relationships of the porosity in different zones.
The similar pattern of the porosity maps from these
six zones indicates that the same depositional environment
was dominant during the deposition of these major carbonate
zones. Because of the dolomitization, porosity is much
better developed in the central part of the basin. In the
supratidal zone (west flank), porosity becomes very low
and zero in Mecosta and Newaygo Counties. Because of the
high concentration of anhydrite in the eastern flank of
the basin, dolomitic carbonate zones turn into impermeable
limestone and porosity drops down to zero. The limestones
are deposited seaward of the environments affected by the
dolomitizing fluids.
55
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 56
* r
i it *12
i
*S| • I t
Qiiull t i 1U • s
n s
17
I I
••r
Figure 28. Porosity map of zone-1.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 57
18.7
0 | i m 1.1 IS*
•IS
Figure 29. Porosity map of zone-2.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 58
t2J
O a iu li
aa1
127
Figure 30. Porosity map of zone-3.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 59
Oicodt
> • ?
Figure 31. Porosity map of zone-4.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 60
it* •«
Oo
• 0 •Iu
00
»•»
Figure 32. Porosity map of zone-5
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 61
>u
UJ
•11
• 0 • 0 •t
° !DO ’*0 #
'•IT
•14(
•r
*•1
lia b a ltt
Figure 33. Porosity map of zone-6. ,
I
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. SEM ANALYSIS
The Middle Devonian Richfield Member of the Lucas
Formation in the Michigan Basin, consists of alternated
anhydrite, limestone and dolomite. The post-depositional
history of the Richfield Member was determined by using
Scanning Electrone Microscope (SEM) and Transmission
Electron Probe (TEP) as well as the standard
petrographic microscope. Study samples were taken from
subsurface cores of the Anderson 1-31; Isabella Co., and
McGuire 1-22; Oscoda co. The resolution of the light
microscope is not sufficiant to resolve fine details less
than 30 microns in diameter, however SEM with its maximum
resolution of about 100a, is adequate to study the grain to
grain relations, grain to cement relations, and the pores
of the rocks. Samples cut to about 2 by 1 inches and
dipped in liquid nitrogen for a couple of minutes, than
applying pressure breaks it into two pieces. One of them
is dried and coated with either C or Au+Pd to make it
conductive then analysed under SEM .
Scanning electron microscopy (Jeol Jsm-35c) and
Energy Dispersive X-Ray micro analysis (Kevex 7000)
revealed that the Richfield Member has complex diagenetic
history. Analysis result from two wells are as follows.
62
with permission of the copyright owner. Further reproduction prohibited without permission. 63
1) Anderson 1-31 Rosebush field T16N R3W Isabella Co.,Michigan
The Anderson 1-31 was completed as a dry hole. It was
off structure and was about 30 feet deeper than the closest
producing well in the area. According to cores of the
Anderson 1-31 the Richfield was deposited in mostly
upper intertidal environment ( Figure 34 ). SEM analysis
shows that these authegenic minerals observed in the
Richfield Member's carbonate sequences .
Dolomite : Two types of dolomite crystals are
present in the samples. SEM and X-Ray analysis show
the large dolomite crystals have less Mg content than
small dolomite crystals(see photos). In the first stage of
dolomitization, calcite altered to large dolomite crystals.
Due to volume loss secondary porosity created (see
photos). Subsequently, Mg rich water came into the pores and
small dolomite crystals formed. Their size is much smaller
than the first generation dolomite. The different Mg content
indicates that slightly different conditions affected the
area during its diagenetic history.
Micro-calcite is seen in the samples' photographs as
cement 3-5 microns in size.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. OEPOSITIONAL ENV
CORE NEUTRON
HIQH LOW 4678 0 % SUBTIOAL
Algal Lamlnalad M u d ilo n a
4700
Nodular Anhydrlta Cryal.
.O o lita a
4800 4797
Figure 34. Type log and core description of Anderson 1-31, Isabella County.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Authigenic quartz: it is found as a trace element in
the samples.
NaCl ; x-ray analysis revealed that Na and Cl are
found in the samples. Salt is the reasonable assumption.
Authegenic pyrite and some zeolite like minerals are
presented in these samples. Analysis results on the
samples of Anderson 1-31, Isabella Co. are;
Figure 35. Dolomite crystals and secondary porosity relationship. Depth=4679 feet (1426,15 M.) magnification=300x, scale= 1 micron.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 36. Dolomite crystals, secondary porosity, and pyrite framboids. Notice that the sample is mostly dolomitized and has good porosity. Closer look to pyrite framboids. Perhaps indicate pressure of organism and reducing environment. Depth=4679 feet (1426,15 M.), magnification=1000x, scale= 10 ' microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 67
Figure 37. Pyrite framboids and dolomite crystals. Depth=4679 feet (1426.15 M.), magnification =5000x, scale= 1 micron.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 38. Micro-calcite cement, dolomite crystals, and secondary porosity relationships. Depth=4679 feet (1426.15 M.) magnification = lOOOx, scale=10 microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 69
Figure 39. Dolomite dissolution and micro calcite crystals Depth=4679 feet (1426.15 M.), magnification=3000x, scale= 1 micron.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 70
. Figure 40. Dolomite dissolution and micro calcite crystals. Depth=4679 feet ,(1426,15 M),magni£ication=5000x, scale =1 micron.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 71
Figure 41. Dolomite rhombs and high intercrystaline porosity. Mg=1680 and Ca=24515. Depth=4684 feet (1427.68 M . ),magnification=500x scale=10 microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 72
Figure 42. Dolomite crystals with probable fluid inclusions. Notice the high secondary porosity. Depth=4686 feet (1428,29 M.), magnification=1000x, scale= 10 microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 73
Figure 43. Dolomite rhombs and fluid inclusions. Depth=4686 feet (1428,29 M.) magnification = 5000x, scale= 1 micron.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 44. Dolomite rhombs and secondary porosity relationship. Depth=4699 feet (1432,25 M.), magnification=100x,scale=100 microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 75
Figure 45. Dolomite rhombs in the pore spaces. Dolomite crystals have diffferent compositions. Large crystals have low Mg content and small crystals have high Mg content. Depth=4699 feet (1432,25 M.) , magnification=200x,scale=200 microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 46. Dolomite rhombs in the pore spaces. Depth=4699 feet (1432,25 M.j magnification=200x, scale=200 microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 47. Two sizes of dolomite crystals. At the center, large and small crystals are seen. In the small crystal, Mg content is high, in the large crystal Mg content is low.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 48. Small dolomite crystal on large dolomite crystal. SEM counts and result are given below.
Figure 47-48 Large crystal Small crystal 1 2 3 1 2 3 Mg 1518 2807 2917 12815 13209 17515 Ca (L) 17450 23939 29365 37205 35150 38423 Ca (B) 2633 3482 3989 4601 4271 4465
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 79
1) McQuire 1-22 Big Creek Field T25N R2E' Oscoda Co.,Michigan
McQuire 1-22, located in the Big Creek Field (SE SE SW),
was completed as a dry hole. In this well, the Richfield
Member is characterized by micritic limestone with little
porosity and subaqueous type-anhydrite (Figure 49).
DEPOSITIONAL EIMV. DENSITY (Pb) CORE HIOH LOW 4168 4170 ; llylotltee
Snliy^rA l* cry.
Mud atone eery IhUl .laminated
C loieU packed anhydrite ety»
4250 : Thin laminated mudelenc.
4367
Figure 49. Core description of McGuire 1-22, Oscoda County.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 80
Fi,gure 50. Micritic limestone and salt crystals. In the micritic limestone these elements have been counted; Na = 9646 Cl =90012 Mg = 505 Si = 701 Ca = 7440 As it seen besides the NaCl the samples contains a few dolomite crystals and Si which was also found in the Anderson 1-31 as a trace element. Depth=4169 feet (1270,71.m),magnification=1000x scale-10 microns."
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 81
Figure 51. Micro-calcite and salt crystals. The lithology is micro-calcitic limestone and the porosity was filled by salt crystals. Depth=4173 feet (1271,93M.) magnification= 1500x, scale= 10 microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 82
Figure 52. Anhydrite crystals in micritic limestone . These elements have been counted. Ca = 51318 S = 47696 Si = 578 Depth=4178 feet(1273,45M.), magnificati9 n=6 0 x, scale=100 microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 53. Salt crystals and partly dolomitic limestone. SEM counting results are given ; Ca = 30603 Mg = 6449 Depth=4180 feet(1274 M.), magnification=2000x, scale=10 microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 84
Figure 54. Dolomite crystals and micritic limestone. Triangle shape dolomite crystals (Mg = 1224 and Ca=51512). Depth=4180 feet ( 1274M.) magnification=3000x, scale=10microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 55. Star-shaped salt crystals (KC1). Notice the poor porosity in the sample. The following elements have been counted. Ca = 75293 Mg = 950 Cl = 32203 K = 352 Star-shaped minerals seen on the photo are probably KC1. Magnification=1000x, scale=10 microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 86
Figure 56. Dolomite crystals. Mg=5484 and Ca=43313 have been counted. Depth=4231 feet(1289,60M.), Magnification=1000x, scale=10 microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. i 87
Figure 57. Micribic limestone. No Mg has been found . Notice the intercrystaline porosity in the sample. Depth=4201 feet(1280,46M.), magnification=100x,scale=100 microns.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 88
2 0 KU 8 5 0 0 0
Figure 58. Secondary single Ca crystal in the pore space. Depth=4201feet(1280,4M), magnification =5000x, scale=l micron.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 89
According to SEM results, the Richfield Member has a
complex diagenetic history. In the central part of the
basin, which is the major oil producing area, dolomitization
resulted in high intercrystalline porosity. The oil wells
occur in the central, deep part of basin as seen on the
structure map, are mostly productive. Some are
non productive in spite of their high porosity.
The reason is that they are either off structure or
that anhydrite beds, laterally extended in a different
interval, did not let hydrocarbons migrate upward. It seems
that different producing zones in the central part of the
basin were caused by lateral extention of anhydrite beds.
As is clearly seen, porosity, structure, and anhydrite beds
are the most important factors controlling the production
in the central part of basin. On the eastern flank of the
basin, the Richfield has a different character than in the
central part of the basin as is seen in the McQuire 1-22.
In comparing production, the eastern flank has a lower
potential of hydrocarbon accumulation. Micritic limestone
was deposited in this part of basin, which was mostly a
subtidal environment during the Richfield depositional
period. According to SEM results, poor dolomitization was
the reason for low porosity development on the east flank
of the basin. The conditions of a low energy environment of
deposition, poor dolomitization, and low porosity make the
area less important in hydrocarbon production.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CONCLUSION
The Richfield Member of Lucas Formation was deposited
in a coastal, shallow marine setting which included sabkha
and lagonal facies. It overlies the "Black Limestone"which
represents an open marine shelf facies. Early Richfield
deposition contains some fossils such as brachiopods,
ostracods, and marine plankton. This organic-rich
lower part of Richfield could, along with the "Black
Limestone", have been the source of the hydrocarbons in
the Richfield. After the basal part of the Richfield was
deposited, the area became a restricted environment and the
salinity of water increased. In this depositional period
several cycles of emergence and submergence affected the
basin. As a result of this cyclicity, basin-wide
depositional conditions on the west flank and central part
of basin produced interbedded sabkha type sediments of
mixed carbonate and anhydrite. On the east flank of the
basin, subtidal types of limestone beds were deposited.
Sabkha-type deposits are characterized by nodular and
subaqueous-type anhydrite, algal-laminated and micritic
limestone, and dolomite beds.
Sabkha and seepage reflux-type of dolomitization
occurred by replacement of carbonate in the sabkha
environment and two types of dolomite crystals were
90
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. formed during two separate stages. High concentration of
sulfate ions inhibited the dolomitization in the eastern
flank of the basin. In the upper part of the Richfield,
a thick accumulation of "Big Anhydrite" indicates that
a hypersaline lagoon depositional environment covered the
basin. This anhydrite bed sealed the previous Richfield
deposits as a cap rock. Above the "Big Anhydrite" the
Richfield is characterized by a carbonate bed. It was
deposited in less saline water that again flooded the
basin.
Hydrocarbon production mostly comes from the porous
dolomitic carbonate zones. Trapping by various anhydrite
beds on structurally high positions yield the production
from the different dolomitic zones. More detail mapping of
local facies distribution and geologic or geophysical
mapping of structures should help to increase oil and gas
production in the near future in the Michigan basin.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX
List of Wells
Name County T rR,S. Q.Sec Permit No
1-35 Morley Arenac 19N,3Ef 35 NE NW SW 35969
1-33 A.Edwin Arenac 19Nr5E,33 SWNW NW SW 32397
1-30 Maday Arenac 19N,4E,30 NW NE NW 35566
1-29 Magyar Arenac 19N,4E,29 NW SW NW 34313
1-30 K.Ronald Arenac 19N,4E,30 NWNENE 34679
1 B.Peter Arenac 19N,4E,30 NW NW NE 33868
1-29 Ackerman Arenac 19N,4E,29 NW NW NW 34163
1-31 Greniuk Arenac 18N,4E,31 CNW SE 36495
1- 1. C ,Adams Bay 18N,3E, 1 (IE NW NW 33618
1-21 Hugo Bay 14N,6E,21 NW NE NE 33753
2- 2 Kryszak Bay 14N,6E,22 NW NE NE 34500
1 - 7 Gallagher Clare 17N,4W, 7 NW NW NE 33097
3-18 Hamilton Clare 19N,3W, 7 SE NE NE 34330
1-20 Prackelton Clare 18N,5W,20 SE NW NE 32858
1- 8 Harrington Clare 17N,3W, 8 SWNW NW SW 32546
5-7 Summerfield Clare ’ 20N,5W, 7 NE SW NW 34706
2-7 Summerfield Clare 20N,5W, 7 NWNW NW 34698
4-7 Summerfield Clare 20N,5W/ 7 NW SE NW 34700
1-30 Dale L.Bray Clare 20N,6W,30 NE SW NE 32385
5-29 Beulah June Clare 20N,6W,29 NE SW NE 32384
4-29 Blackledge Clare 20N,6W,29 SENE NW 32296
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13 St.Bea.Cr. Crawford 25N,4W, 7 SWNE SE 33710
1-33 St.Lovells Crawford 27N, 1W, 33 CSWNW 35726
4-25 Helveston Crawford 25N,2W,25 NE SW NE 34905
1-17 S.Branch Crawford 25N,2W,17 SE NENW 35072
1- 3 Mc.Crandell Gladwin 17N,1E, 3 SE SE NE 34374
1-12 W. Butman Gladvin 20N,1W,12 NE SE SW 35746
1/A Smith Vera Isabella 14N,3w, 2 NE SW NW 35540
1-31 Anderson Isabella
1-12 R.Thelma Mecosta 16N,8W 12 NW NW NE 35426
9-31 Milhoek Missaukee 22N/6W/31 NW NW SW 33819
11-31 Milhoek Missaukee 22N,6W,31 NW SWSW 34981
4-140 N.Unit TR. Missaukee 24N,5W,13 NW SE NW 36100
4-109 N.Unit TR. Missaukee 24N,5W,13 NW NW NW 33506
4-89 N.Unit Tr. Missaukee 24N,5W,14 33592
1-36 R.Edwards Missaukee 22n,7W,36 NWNENE 32139
2-36 F.powers Missaukee 22N,7Wf 36 NW SE NE 32223
9-36 W.Muellen Missaukee 22N,7Wf36 NW SE NW 34005
8-36 P.school Missaukee 22N,7Wf 36 NW NW SE 34000
3-36 AN.Tacoma Missaukee 22N,7Wf 36 NW NW NE 32421
1-31 Fritsch,B. Montcalm 9N,5W,31 NE SE SE 35474
1-27/A Lutz Nevaygo 16N,11W,27 SW NW SE 34906
1-15 B.Ronald Ogemaw 22N,IE,15 SE NE NW 34701
1-30 M.Norman Osceola 17N,8Wr 30 NW NE SW 33466
1- 4 Leach Osceola 17N,9W, 4 SW SE SE 35025
1-30 R.Quart Osceola 20N,7W,30 SE SE SE 35089
1-27 Mc.Cormick Osceola 18N,8W,27 SWNE NW 33813
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1-19 Gerber Osceola 17N,10W,19 SW SE SW 35997
1-15 Schalm Osceola 17N,10W,15 SE SE SE 33505
1-23 USA Big.Cr. Oscoda 25N,2E,23 SWNESW 34748
1-22 USA Big Cr. Oscoda 25n,2E,22 SW SW SE 35131
7-23 USA Big Cr. Oscoda 25N,2E,23 SE NE SE 35765
2-23 USA Big Cr. Oscoda 25N,2E,23 NE SW SE 34749
1-22 Me.Quire Oscoda 25N,2E,22 SE SESW 35069
48-15 Helen Unit Roscommon 24N,1W,30 SW NE NE 35443
50-15 Helen Unit Roscommon 24N,1W,28 SW NW NW 35385
1-28 St.Backus Roscommon 22N,2W,28 NW NE SE 36310
2-27 St.Backus Roscommon 22N,2W,27 NE SW NW 36269
6 Enterp.Unit Roscommon 23N,4W,18 SE SW NW 35767
16-6 Norwich U. Roscommon 24N,4W, 7 S2 SW NE 33683
F-l St.Lyons Roscommon 24N,4W, 6 S2 S2 NW 30978
17-6 Norwich U. Roscommon 24N,4W,18 S2 NW NE 34061
1-20 St.Lyons Roscommon 24N,4W,20 SE SE SE 36166
13-6 Norwich U. Roscommon 24N,4W, 7 33339
15-6 Norwich U. Roscommon 24N,4W,18 SW SW NW 33681
1-17 Ida Hogan Roscommon 22N,4W,17 NE NE NW 32356
1- 8 Ida Hogan Roscommon 22N,4W, 8 NE SE SW 32355
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. BIBLIOGRAPHY
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Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.