Abstract: The dataset includes subsurface stratigraphic picks of the Milk River 'shoulder' in the Alberta Plains (Townships 1 to 73, Ranges 1W4 to 2W6) made from wireline geophysical well logs. The Milk River 'shoulder' is an informal term often used to refer to a distinctive ‘shoulder’ (deflection) on resistivity, sonic, density, and porosity logs. The Milk River 'shoulder' corresponds to the top of the Milk River Formation in southernmost Alberta, where it represents juxtaposition between paralic deposits of the underlying Deadhorse Coulee Member of the Milk River Formation and overlying marine shale of the Pakowki Formation. It is characterized by a leftward deflection (decreasing resistivity) upwards across the contact, forming the distinctive 'shoulder signature'. To the north, the Milk River 'shoulder' represents the boundary between the Alderson Member (lower Lea Park Formation) and the upper Lea Park Formation (Pakowki equivalent). In these areas, silty sands and mudstones of the Alderson Member are overlain by shales of the upper Lea Park Formation. Well data were screened to detect errors resulting from deviated wells, as well as incorrect ground and kelly bushing elevation data. We used statistical methods to identify local and regional statistical outliers, which we examined individually.
Metadata:
File identifier:
DIG_2013_0025.xml
Language:
eng; CAN
Character set:
Character set code:
utf8
Hierarchy level:
Scope code:
dataset
Metadata author:
Responsible party:
Organisation name:
Alberta Geological Survey
Position name:
AGS Information Manager
Contact info:
Contact:
Phone:
Telephone:
Voice:
(780) 638-4491
Facsimile:
(780) 422-1918
Address:
Address:
Delivery point:
Alberta Energy Regulator
Delivery point:
4th Floor, Twin Atria Building
Delivery point:
4999-98 Avenue NW
City:
Edmonton
Administrative area:
Alberta
Postal code:
T6B 2X3
Country:
Canada
Electronic mail address:
AGS-Info@aer.ca
Hours of service:
8:00 a.m. to 12:00 p.m. and 1:00 p.m. to 4:30 p.m.
Role:
Role code:
pointOfContact
Date stamp:
2016-03-29
Metadata standard name:
North American Profile of ISO 19115:2003 - Geographic information - Metadata (NAP-Metadata)
Metadata standard version:
ISO 19115-1.1
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Vector spatial representation:
Geometric objects:
Geometric objects:
Geometric object type:
Geometric object type code:
point
Geometric object count:
23015
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Grid spatial representation:
Number of dimensions:
2
Axis Dimension Properties:
Dimension:
Dimension name:
Dimension name type code:
column
Dimension size:
unknown
Resolution:
uom: decimalDegrees
0.000000
Axis Dimension Properties:
Dimension:
Dimension name:
Dimension name type code:
row
Dimension size:
unknown
Resolution:
uom: decimalDegrees
0.000000
Cell geometry:
Cell geometry code:
Transformation parameter availability:
false
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Reference system:
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Reference system:
Reference system identifier:
RS Identifier:
Code:
EPSG:4269
Code Space:
http://www.epsg-registry.org/
Version:
8.4.1
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xlink: https://www.ngdc.noaa.gov/docucomp/65f8b220-95ed-11e0-aa80-0800200c9a66 title: North American Datum 1983
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xlink: https://www.ngdc.noaa.gov/docucomp/c3895520-95ed-11e0-aa80-0800200c9a66 title: Geodetic Reference System 1980
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Data identification:
Citation:
Citation:
Title:
Subsurface Stratigraphic Picks for the Top of the Milk River 'shoulder', Alberta Plains (tabular data, tab
delimited format, to accompany Open File Report 2013-17)
Date:
Date:
Date:
2014-05-08
Date type:
Date type code:
publication
Cited responsible party:
Responsible party:
Organisation name:
Alberta Energy Regulator
Role:
Role code:
originator
Cited responsible party:
Responsible party:
Organisation name:
Alberta Geological Survey
Role:
Role code:
originator
Cited responsible party:
Responsible party:
Organisation name:
Glombick, P.M.
Role:
Role code:
originator
Cited responsible party:
Responsible party:
Organisation name:
Mumpy, A.J.
Role:
Role code:
originator
Cited responsible party:
Responsible party:
Organisation name:
Alberta Geological Survey
Contact info:
Contact:
Address:
Address:
City:
Edmonton
Administrative area:
Alberta, Canada
Role:
Role code:
publisher
Presentation form:
Presentation form code:
tableDigital
Series:
Series:
Name:
Digital Data
Issue identification:
DIG 2013-0025
Abstract:
The dataset includes subsurface stratigraphic picks of the Milk River 'shoulder' in the Alberta Plains
(Townships 1 to 73, Ranges 1W4 to 2W6) made from wireline geophysical well logs. The Milk River 'shoulder'
is an informal term often used to refer to a distinctive ‘shoulder’ (deflection) on resistivity, sonic,
density, and porosity logs. The Milk River 'shoulder' corresponds to the top of the Milk River Formation in
southernmost Alberta, where it represents juxtaposition between paralic deposits of the underlying Deadhorse
Coulee Member of the Milk River Formation and overlying marine shale of the Pakowki Formation. It is
characterized by a leftward deflection (decreasing resistivity) upwards across the contact, forming the
distinctive 'shoulder signature'. To the north, the Milk River 'shoulder' represents the boundary between
the Alderson Member (lower Lea Park Formation) and the upper Lea Park Formation (Pakowki equivalent). In
these areas, silty sands and mudstones of the Alderson Member are overlain by shales of the upper Lea Park
Formation. Well data were screened to detect errors resulting from deviated wells, as well as incorrect
ground and kelly bushing elevation data. We used statistical methods to identify local and regional
statistical outliers, which we examined individually.
Purpose:
To provide a consisent set of stratigraphic picks for the Milk River 'shoulder' in the Alberta Plains.
Status:
Progress code:
completed
Point of contact:
Responsible party:
Organisation name:
Alberta Geological Survey
Position name:
AGS Information Manager
Contact info:
Contact:
Phone:
Telephone:
Voice:
(780) 638-4491
Facsimile:
(780) 422-1918
Address:
Address:
Delivery point:
Alberta Energy Regulator
Delivery point:
4th Floor, Twin Atria Building
Delivery point:
4999-98 Avenue NW
City:
Edmonton
Administrative area:
Alberta
Postal code:
T6B 2X3
Country:
Canada
Electronic mail address:
AGS-Info@aer.ca
Hours of service:
8:00 a.m. to 12:00 p.m. and 1:00 p.m. to 4:30 p.m.
Role:
Role code:
pointOfContact
Resource maintenance:
Maintenance information:
Maintenance and update frequency:
Maintenance frequency code:
notPlanned
Descriptive keywords:
Keywords:
Keyword:
alberta plains
Keyword:
bedrock geology
Keyword:
lea park formation
Keyword:
mapping
Keyword:
milk river formation
Keyword:
pakowki formation
Keyword:
stratigraphic picks
Keyword:
stratigraphy
Keyword:
subsurface mapping
Keyword:
upper cretaceous
Keyword:
well log signature
Type:
Keyword type code:
theme
Thesaurus name:
Citation:
Title:
none
Date:
unknown
Descriptive keywords:
Keywords:
Keyword:
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Keyword:
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73d
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Keyword:
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Keyword:
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Keyword:
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Keyword:
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Keyword:
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Keyword:
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Keyword:
83k
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83l
Keyword:
83m
Keyword:
83n
Keyword:
83o
Keyword:
83p
Keyword:
alberta
Keyword:
canada
Type:
Keyword type code:
place
Thesaurus name:
Citation:
Title:
none
Date:
unknown
Resource constraints:
Legal constraints:
Access constraints:
Restriction code:
otherRestrictions
Use constraints:
Restriction code:
otherRestrictions
Other constraints:
Access Constraints: Public Use Constraints: Acknowledgement of the Alberta Energy Regulator/Alberta
Geological Survey as the originator/source of this information is required as described in the Open
Government License - Alberta. Distribution Liability: The Alberta Energy Regulator/Alberta Geological
Survey (AER/AGS) licenses this information under the Open Government License - Alberta. Any references
to proprietary software in our documentation, and/or any use of proprietary data formats in our
releases, do not constitute endorsement by the AER/AGS of any manufacturer's product.
Aggregation Info:
AggregateInformation:
Aggregate Data Set Name:
Citation:
Title:
Subsurface Stratigraphic Picks for the Milk River 'Shoulder', Alberta Plains: Including Tops for the
Milk River Formation and Alderson Member of the Lea Park Formation
Date:
Date:
Date:
2014-05-08
Date type:
Date type code:
publication
Cited responsible party:
Responsible party:
Organisation name:
Alberta Energy Regulator
Role:
Role code:
originator
Cited responsible party:
Responsible party:
Organisation name:
Alberta Geological Survey
Role:
Role code:
originator
Cited responsible party:
Responsible party:
Organisation name:
Glombick, P.M.
Role:
Role code:
originator
Cited responsible party:
Responsible party:
Organisation name:
Mumpy, A.J.
Role:
Role code:
originator
Cited responsible party:
Responsible party:
Organisation name:
Alberta Geological Survey
Contact info:
Contact:
Address:
Address:
City:
Edmonton
Administrative area:
Alberta, Canada
Online Resource:
Online Resource:
Linkage:
URL:
http://ags.aer.ca/
Role:
Role code:
publisher
Presentation form:
Presentation form code:
documentDigital
Series:
Series:
Name:
Open File Report
Issue identification:
OFR 2013-17
Other citation details:
ISBN: 978-1-4601-0115-5
Association Type:
Association type code:
crossReference
Spatial representation type:
Spatial representation type code:
vector
Language:
eng; CAN
Topic category:
Topic category code:
geoscientificInformation
Extent:
Extent:
Geographic element:
Geographic bounding box:
West bound longitude:
-119.20098
East bound longitude:
-110.005644
South bound latitude:
48.999148
North bound latitude:
55.309733
Temporal element:
Temporal extent:
Extent:
Time period:
Description:
ground condition
Begin date:
2008-01-01
End date:
2013-01-01
Supplemental Information:
Language: In English;
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Feature catalogue description:
Included with dataset:
false
Feature catalogue citation:
Citation:
Title:
Entity and Attribute Information
Date:
Other citation details:
Detailed Entity and Attribute information is provided with the dataset, formatted as Federal Geographic
Data Committee (FGDC) Content Standard for Digital Geospatial Metadata.
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Distribution:
Distributor:
Distributor:
Distributor contact:
Responsible party:
Organisation name:
Alberta Geological Survey
Position name:
AGS Information Manager
Contact info:
Contact:
Phone:
Telephone:
Voice:
(780) 638-4491
Facsimile:
(780) 422-1918
Address:
Address:
Delivery point:
Alberta Energy Regulator
Delivery point:
4th Floor, Twin Atria Building
Delivery point:
4999-98 Avenue NW
City:
Edmonton
Administrative area:
Alberta
Postal code:
T6B 2X3
Country:
Canada
Electronic mail address:
AGS-Info@aer.ca
Hours of service:
8:00 a.m. to 12:00 p.m. and 1:00 p.m. to 4:30 p.m.
Role:
Role code:
distributor
Transfer options:
Digital transfer options:
Online:
Online Resource:
Linkage:
URL:
https://static.ags.aer.ca/files/document/DIG/DIG_2013_0025.zip
Name:
Tabular Data
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Data quality:
Scope:
Scope:
Hierarchy level:
Scope code:
dataset
Report:
Absolute external positional accuracy:
Name of measure:
Horizontal Positional Accuracy
Measure description:
Evaluation method description:
The horizontal datum for the well locations is the North American Datum of 1983 (NAD83). The latitude and
longitude coordinates for well surface and bottom-hole locations are from IHS (Petra® software). The
horizontal positional accuracy is unknown.
Result:
Quantitative result:
Value unit:
Base unit:
Identifier:
Units system: xlink: http://www.bipm.org/en/si/
Value:
Report:
Absolute external positional accuracy:
Name of measure:
Vertical Positional Accuracy
Measure description:
Evaluation method description:
The vertical datum for elevations in this data set is the Canadian Geodetic Vertical Datum of 1928
(CGVD28). In vertical wells, the subsurface elevation of a pick in a well, measured with respect to sea
level (pick elevation), is calculated by taking the elevation of the kelly bushing (on the drilling
platform) and subtracting the measured depth of the pick on the geophysical well log. Some uncertainty
in the vertical depth of the pick will result if the borehole is not entirely vertical. The bottom-hole
latitude and longitude of each well location were compared with the surface latitude and longitude for
each well to ensure they were the same. If either the surface or bottom-hole latitude and longitude are
incorrect, some degree of vertical error may result. In general, the amount of vertical depth due to
deviations from the vertical in boreholes is deemed negligible with respect to other potential sources
of vertical error in this study. Perhaps the greatest source of vertical uncertainty in this study is
potential error in the elevation of the kelly bushing (KB). Any errors in surveying the ground elevation
of the well site can result in vertical error. In addition, once the ground elevation is determined, the
site is usually prepared for the drilling rig. If the original survey marker is disturbed or moved, this
can result in potential vertical errors. The KB elevation is usually derived from adding the height of
the drilling platform above the ground surface to the survey ground elevation. If this is not done
correctly, it can introduce vertical error in the KB elevation, which is then propagated in the measured
depth to the pick and the pick elevation. Although incorrect KB elevation data can be difficult to
detect, the data were screened by comparing the ground elevation and the KB elevation (derrick height)
for each well. An acceptable range of derrick height (calculated by subtracting ground elevation from KB
elevation) of zero to eight metres was used. Wells with derrick heights outside this range were
excluded. Vertical error in the pick elevation value can also result from human error due to uncertainty
or incorrect placement of the pick on the well logs. The occurrence and magnitude of this error is
difficult to identify, but comparison with existing published pick datasets and checks for internal
consistency (such as identification of global and local outliers using statistical methods and gridding
data while picking) minimized this source of error as much as possible.
Result:
Quantitative result:
Value unit:
Base unit:
Identifier:
Units system: xlink: http://www.bipm.org/en/si/
Value:
Report:
Completeness commission:
Result:
unknown
Report:
Completeness omission:
Evaluation method description:
The authors used a minimum well density of one well per township (about 100 square km). However, in most
areas the well density greatly exceeds that number, especially in areas with anomalous structures.
Result:
unknown
Report:
Conceptual consistency:
Measure description:
The data are tabular (point data with X, Y and Z values). The authors made all of the stratigraphic picks.
All picks are ranked the same in quality. As the dataset includes only vertical wells, all location data
and well identifier data (UWI and UWI_MODIFIED) are unique. In non-vertical wells, surface and
bottom-hole latitude and longitude should be different, and several wells might share a common surface
location but have different bottom-hole locations. By choosing only vertical wells, this problem was
avoided. The data are from the Alberta Plains where deformation of the Cretaceous sedimentary succession
is relatively minor. All points are east of the deformation front at a given latitude. Thus, rocks
should not be thrusted or structurally duplicated. Therefore, the Milk River "shoulder" pick should only
occur once in any given vertical well. No data are missing. Attribute values were checked to ensure
reasonable values. For instance, the author plotted the well locations on a map and observed no obvious
anomalous locations. A query checked for any deviations from vertical of the well surface location
compared with the bottom-hole location. Wells for which well surface coordinates differed from
bottom-hole coordinates were removed from the dataset. As all remaining wells should be vertical if the
surface and bottom-hole coordinates are correct, measured depth and true vertical depth should be equal.
Result:
unknown
Report:
Non quantitative attribute accuracy:
Measure description:
A stratigraphic pick in a well is a point defined in three dimensions (X, Y and Z).
The accuracy of the pick depth, either in measured depth from the kelly bushing or with respect to sea
level (elevation), is difficult to quantify and includes (but is not necessarily limited to) errors in
- well surface or bottom-hole latitude and longitude (X and Y);
- well ground elevation (Z);
- well kelly bushing elevation (Z);
- human error resulting from errors in picking the incorrect stratigraphic top (Z);
- data entry or data transfer (X, Y and/or Z); and
- incorrect well log depth calibration (Z)
Result:
inapplicable
Lineage:
Lineage:
Statement:
The authors used a minimum well density of one well per township (about 100 square km). However, in most
areas the well density greatly exceeds that number, especially in areas with anomalous structures.
Process step:
Process step:
Description:
Prior to making picks for a given surface, the authors studied the published geological literature
with emphasis on type and/or representative sections. Studies including both core and geophysical
well logs were particularly valuable, as they provided a link between the rock and geophysical
signatures.
Geophysical well logs (both digital and raster format) were examined using Petra® and Accumap®
software and picks were recorded in a database. When sufficient well density and log availability
permitted, we selected wells according to the following criteria:
1) vertical wells only;
2) wells with a spud date between 1975 and the present; and
3) wells with down-hole geophysical well log suites that include gamma-ray, density or sonic, and
resistivity logs.
The author gave preference to wells where the bottom of surface casing shoe was at a depth of less
than 50 metres below the kelly bushing. If sufficient well density was not available using the above
criterion, the criterion was expanded to include wells with the bottom of surface casing in the
50-150 metre depth range. A minimum well density of one well per township was used, although, in
most areas, well density greatly exceeded that number, especially where an anomalous structure was
detected.
To correlate and check internal consistency, a series of north-south and east-west cross-sections,
with a spacing of approximately 10 km (one township), was used to make picks. Therefore, a pick in a
well was typically compared with three to four picks in nearby wells to ensure consistency. During
picking, picks were gridded using the triangulation method using Petra® to identify and check
outliers, which appear as "bull's eyes" on a structure contour map.
After making picks, and prior to modelling the surface, steps were taken to detect errors in:
- depth data (true vertical depth compared with measured depth data for non-deviated wells);
- kelly bushing (KB) elevation data for wells;
- ground elevation data for wells; and
- pick depth due to human error.
Picks and well header information, including kelly bushing elevation, ground elevation, well surface
location (longitude and latitude in decimal format) and bottom-hole location (longitude and latitude
in decimal format), were exported from Petra® (IHS) software into a comma-separated value file. The
horizontal datum for the well location is the North American Datum of 1983 (NAD83) and the vertical
datum is the Canadian Geodetic Vertical Datum of 1928 (CGVD28). The picks are in metres, given as
measured depth relative to KB elevation. Pick elevations were calculated by subtracting measured
depth from the KB elevation.
A query of the well surface location compared with the bottom-hole location was run to check for any
deviations from vertical; we removed these wells from the dataset. If a well is deviated, its
surface and bottom-hole coordinates should be different. As all remaining wells should be vertical
if the surface and bottom-hole coordinates are correct, measured depth and true vertical depth
should be equal.
Although incorrect KB elevation data can be difficult to detect, the author screened the data by
comparing the ground elevation and the KB elevation (derrick height) for each well. An acceptable
range of derrick height (calculated by subtracting ground elevation from KB elevation) of zero to
eight metres was used. Wells with derrick heights outside of this range were excluded.
Data were then screened for both global and local outliers. Outliers are those values that are outside
a specified normal range, compared with the entire dataset (global outliers), or within a local area
(local outliers). If caused by errors, outliers can have several detrimental effects on the
interpolated surface. One should either correct or remove outliers before creating a surface.
Outliers may result from one or more of the following factors:
- incorrect ground elevation and/or KB elevation data not detected during the initial screening;
- incorrect location data for a well;
- deviated wells which are not marked as such and have either incorrect surface or bottom-hole
location data;
- incorrect pick data due to human error; and
- geological structure.
The inverse-distance weighted interpolation method was useful in locating outlier data points, which
appeared as bull's eyes on the resulting map. Outliers were flagged and the well data and
geophysical logs were examined to determine whether the outlier was due to geological structure or
incorrect data. In cases where no error could be identified, additional data were gathered to refine
the definition of local structure. In these cases, if the data were a single point and no geological
evidence corroborated the structure, then the data point was removed.
Once outliers were either removed or confirmed, we repeated the outlier screening process at least
three times. This iterative process identified increasingly more subtle outliers. As each pick was
made during this study and all statistical outliers were examined and some removed, the largest
source of error and uncertainty in the elevation of the pick is likely to be related to the surveyed
kelly bushing (and ground elevation) for a given well.
Date and time:
2013-01-01T00:00:00
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Legal constraints:
Access constraints:
Restriction code:
otherRestrictions
Use constraints:
Restriction code:
otherRestrictions
Other constraints:
Metadata Access Constraints: none Metadata Use Constraints: none
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Maintenance information:
Maintenance and update frequency:
unknown
Maintenance note:
This metadata was automatically generated from the FGDC Content Standard for Digital Geospatial
Metadatastandard version FGDC-STD-001-1998 using the January 2013 version of the FGDC CSDGM to ISO 19115-2
transform.
Metadata author:
Responsible party:
Organisation name:
Alberta Geological Survey
Position name:
AGS Information Manager
Contact info:
Contact:
Phone:
Telephone:
Voice:
(780) 638-4491
Facsimile:
(780) 422-1918
Address:
Address:
Delivery point:
Alberta Energy Regulator
Delivery point:
4th Floor, Twin Atria Building
Delivery point:
4999-98 Avenue NW
City:
Edmonton
Administrative area:
Alberta
Postal code:
T6B 2X3
Country:
Canada
Electronic mail address:
AGS-Info@aer.ca
Hours of service:
8:00 a.m. to 12:00 p.m. and 1:00 p.m. to 4:30 p.m.
Role:
Role code:
custodian
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