MRCSP Phase I Geologic Characterization Report - Midwest ...

APPENDIX A: UPPER CAMBRIAN ROSE RUN SANDSTONE
71
range from approximately 50 feet per mile in northeastern Ohio and
northwestern Pennsylvania to approximately 100 feet per mile in
southeastern Ohio, and western West Virginia.
The major tectonic features affecting Rose Run structure occur
in northeastern Ohio, western Pennsylvania, eastern Kentucky, and
western West Virginia. In western Pennsylvania, these include the
Tyrone-Mt. Union and Pittsburgh-Washington lineaments, which
have been interpreted as northwest-southeast trending wrench
faults (Riley and others, 1993). In addition, numerous growth faults
above basement rifts have been proposed that have been offset by
movement along these major wrench faults (Laughrey and Harper,
1986; Harper, 1989; Riley and others, 1993). In northeastern Ohio,
the major tectonic features indicated by regional mapping are the
northwest-southeast trending Akron-Suffield-Smith and the Highlandtown
fault systems, which also have been suggested to be
wrench faults (Riley and others, 1993). These are extensions of the
Pittsburgh-Washington lineament in Pennsylvania. In eastern Kentucky
and western West Virginia, the Rose Run structure is broken
by the east- to northeast-trending Rome trough. Locally, small-scale
features are present that are not evident on the regional-scale maps.
A relationship between basement faults and paleotopographic highs
on the Knox or Rose Run has been proposed as a controlling factor
in reservoir development and hydrocarbon production (Coogan and
Lesser, 1991; Riley and others, 1993).
The Rose Run sandstone interval thickens gradually from zero
feet at the western limit of the subcrop to about 200 feet throughout
the area of eastern Ohio and northwestern Pennsylvania (Figure A4-
3). The irregular nature of the Rose Run isopach map in Ohio near
the subcrop is a result of erosion on the Knox unconformity. Various
paleotopographic features, including numerous erosional remnants,
are present along the subcrop trend as a result of paleodrainage.
East of this broad zone of gradual thickening, the contours become
narrower in western Pennsylvania as a result of the rapid thickening
that is present in the Rome trough. Various authors have indicated
that the Rome trough was actively subsiding during Rose Run deposition
(Wagner, 1976; Harper, 1991). Approximately 470 feet of
Rose Run was encountered in the Amoco #1 Svetz well in Somerset
County, Pennsylvania before drilling was stopped at 21,640 feet;
most of that thickness occurred in the uppermost sandstone body.
The depositional pattern of the Rose Run in south-central Ohio
and north-central Kentucky suggests control by the Waverly arch, a
north-south trending feature that was first identified by Woodward
(1961). Isopach maps of the Knox by Janssens (1973), and the Prairie
du Chien by Shearrow (1987), indicate thinning over the feature.
This thinning is also coincident with a facies change in the Rose
Run in which it is sandstone-dominant on the east side and carbonate-dominant
on the west side of the Waverly arch (Riley and others,
1993). A rather abrupt thinning occurs on the isopach map across the
state line boundary of Ohio and Kentucky. This is, in part, an artifact
of how the base of the Rose Run is interpreted differently in Ohio
and Kentucky as discussed previously. In eastern Kentucky, changes
in the contours along the Rome trough indicate that this fault influenced
Rose Run deposition.
DEPOSITIONAL ENVIRONMENTS/
PALEOGEOGRAPHY/TECTONISM
Following the Rome trough aulacogen and deposition of the basal
sandstones described in an earlier section, Late Cambrian recycled
sands, including those of the Rose Run, continued to be deposited
across the present-day Appalachian basin area. These sands were
mixed with shelf carbonates that eventually dominated this passive
margin (Riley and others, 1993). Provenance studies of the Rose
Run sandstone suggest that they are compositionally mature and
were derived from the crystalline Precambrian shield complexes
and overlying platform rocks (Miall, 1984; Riley and others, 1993).
The widespread Knox unconformity developed during the initial
collision of the passive margin and the lowering of eustatic sea level
in the Middle Ordovician (Mussman and others, 1988; Read, 1989).
The progressive westward truncation of Knox units along this regional
unconformity created and exposed the Rose Run subcrop
trend (Figures A4-1, A4-3 and A4-4).
Deposition of the Rose Run and adjacent Knox units has been
attributed by various authors to represent a peritidal to shallow
subtidal marine environment (Mussman and Read, 1986; Anderson,
1991; Gooding, 1992; Ryder, 1992a; Ryder and others, 1992; Riley
and others, 1993). The Rose Run is part of a heterogeneous assemblage
of interbedded siliciliclastic and carbonate facies in the Knox
that were deposited on a carbonate shelf, which Ginsburg (1982)
referred to as the “Great American Bank.” The Rose Run represents
lowstand deposits of siliciclastic sediments that were transported
onto the peritidal platform and reworked during subsequent sealevel
rises (Read, 1989).
Many authors have interpreted tidal flat deposition for the Rose
Run and equivalent strata (Mussman and Read, 1986; Anderson,
1991; Enterline, 1991; Riley and others, 1993) based upon core and
outcrop description. Sedimentary features supporting this include
herringbone cross bedding and basal lags of dolostone and shaly
dolostone indicating scour along tidal channel thalwegs. In outcrop
in central Pennsylvania, a shallowing-upward tidal flat sequence
is recognized and include the following subfacies: 1) storm sheet
deposition with flat pebble conglomerates; 2) algal patch reefs with
thrombolitic bioherms; 3) subtidal ooid-peloid sand shoals with
cross stratified ooid grainstones; 4) lower intertidal mixed sandmud
flats with ribbon rock; 5) upper intertidal algal flats with prismcracked
wavy laminites; and 6) supratidal flats with mudcracked
flat laminites (Riley and others, 1993). Subsurface cores in Ohio
also indicate a supratidal facies from the presence of digitate algal
stromatolites, mudcracks, and nodular anhydrite and chert replacing
evaporites. Extensive mottling from bioturbation indicative of intertidal
and subtidal environments is pervasive throughout the Rose
Run and adjacent Knox units.
SUITABILITY AS A CO 2
INJECTION TARGET OR SEAL UNIT
Suitability of CO 2 injection for the Rose Run can be subdivided
into three geographic areas for discussion: 1) within the Rose Run
subcrop trend; 2) downdip of the eastern edge of the subcrop; and
3) within the Rome Trough. In most of these areas, the Rose Run
occurs at depths greater than 2,500 feet, which should be within the
preferred condition to obtain adequate minimum miscibility pressures
for CO 2 sequestration. Availability of subsurface well data
is greatest within the subcrop trend, where most of the petroleum
exploration and production from this formation has occurred. Thus,
knowledge of reservoir characteristics is best within the subcrop
trend, where thousands of oil and gas wells have targeted the Rose
Run, and decreases basinward away from the subcrop.
Within and adjacent to the Rose Run subcrop, reservoir quality
is controlled by erosional truncation and paleotopography on the
Knox unconformity. Erosional remnants are found along the subcrop
trend, typically 80 acres or less in area. Large-scale injection
of CO 2 in Rose Run remnants would be difficult because of their
limited size. However, reservoir quality within these remnants is