Abstract: The dataset includes subsurface stratigraphic picks of the tops of the Horseshoe Canyon/Wapiti and Battle formations in the west-central Alberta Plains (Townships 15 to 67, Ranges 16W4 to 3W6) made from wireline geophysical well logs. The dataset supplements Alberta Geological Survey Open File Report 2011-08, which describes the methodology. We screened the well data to detect errors resulting from deviated wells, as well as incorrect well-header ground and kelly bushing elevation data. Statistical methods identified local and regional statistical outliers, which were examined individually.
Metadata:
File identifier:
DIG_2011_0002.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:
17036
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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
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row
Dimension size:
unknown
Resolution:
uom: decimalDegrees
8.9831528411952133e-009
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:
Tops of the Horseshoe Canyon, Wapiti and Battle Formations in the West-Central Alberta Plains: Subsurface
Stratigraphic Picks and Modelled Surface (tabular data, tab delimited format, to accompany Open File
Report 2011-08)
Date:
Date:
Date:
2011-07-21
Date type:
Date type code:
publication
Cited responsible party:
Responsible party:
Organisation name:
Energy Resources Conservation Board
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:
Hathway, B.
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 2011-0002
Abstract:
The dataset includes subsurface stratigraphic picks of the tops of the Horseshoe Canyon/Wapiti and Battle
formations in the west-central Alberta Plains (Townships 15 to 67, Ranges 16W4 to 3W6) made from wireline
geophysical well logs. The dataset supplements Alberta Geological Survey Open File Report 2011-08, which
describes the methodology. We screened the well data to detect errors resulting from deviated wells, as well
as incorrect well-header ground and kelly bushing elevation data. Statistical methods identified local and
regional statistical outliers, which were examined individually.
Purpose:
To provide a set of internally consistent and accurate picks for the tops of the Horseshoe Canyon/Wapiti and
Battle formations in the west-central 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:
battle formation
Keyword:
bedrock geology
Keyword:
geophysical logs
Keyword:
horseshoe canyon formation
Keyword:
scollard formation
Keyword:
stratigraphic picks
Keyword:
stratigraphy
Keyword:
subsurface mapping
Keyword:
upper cretaceous
Keyword:
wapiti formation
Keyword:
well log signature
Type:
Keyword type code:
theme
Thesaurus name:
Citation:
Title:
none
Date:
unknown
Descriptive keywords:
Keywords:
Keyword:
82i
Keyword:
82j
Keyword:
82n
Keyword:
82o
Keyword:
82p
Keyword:
83a
Keyword:
83b
Keyword:
83c
Keyword:
83d
Keyword:
83e
Keyword:
83f
Keyword:
83g
Keyword:
83h
Keyword:
83i
Keyword:
83j
Keyword:
83k
Keyword:
83l
Keyword:
alberta
Keyword:
alberta plains
Keyword:
canada
Keyword:
west central alberta
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:
Tops of the Horseshoe Canyon, Wapiti and Battle Formations in the West-Central Alberta Plains:
Subsurface Stratigraphic Picks and Modelled Surface
Date:
Date:
Date:
2011-07-21
Date type:
Date type code:
publication
Cited responsible party:
Responsible party:
Organisation name:
Energy Resources Conservation Board
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:
Hathway, B.
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 2011-08
Other citation details:
ISBN 978-0-7785-8649-4
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:
-118.5
East bound longitude:
-112
South bound latitude:
50.2
North bound latitude:
54.8
Temporal element:
Temporal extent:
Extent:
Time period:
Description:
ground condition
Begin date:
2008-01-01
End date:
2010-01-01
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_2011_0002.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 latitude and longitude co-ordinates 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:
In vertical wells, the subsurface depth of a pick in a well, measured with respect to sea level, 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 author compared the bottom-hole latitude
and longitude of each well location 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 subsea pick depth. 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 two
to six metres was used. Wells with derrick heights outside this range were excluded. To check for
potential gross errors in the ground elevation for wells, ground elevations were compared with
shuttle-radar digital elevation model (DEM) elevations extracted for well surface locations. If the
difference between the ground elevation and the elevation derived from the DEM data was more than 2 ± 9
metres (i.e., -7 to 11 metres; approximately the mean of this difference plus or minus three standard
deviations for all wells in the Alberta Plains), the data from those wells were excluded. This method
potentially excluded wells for which well ground elevation values are correct, but for which the DEM
data for that well location are incorrect. It also may have not detected relatively small errors in
either ground or KB elevation data for a well, as long as those values met the screening criteria.
However, it did detect large errors in well KB or ground elevation data. Vertical error in the pick
subsea elevation can also result from human or geological error resulting from uncertainty or incorrect
placement of the pick on the well logs. The occurrence and magnitude of this error is difficult to
identify, but 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 author used a minimum well density of one well per township (about 100 square km). However, in most
areas, the well density greatly exceeded that number. About 655 townships were picked, resulting in an
average well density of 13.5 wells per township for the top of the Horseshoe Canyon and Wapiti formations.
Result:
unknown
Report:
Conceptual consistency:
Measure description:
The data are tabular (point data with X, Y and Z values). The author generated all 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 for each stratigraphic formation. In
non-vertical wells, surface and bottom-hole latitude and longitude may be different, and several wells
may share a common surface location but have different bottom-hole locations. By choosing only vertical
wells, this problem was avoided. The author collected the data 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
tops of the Horseshoe Canyon/Wapiti and Battle formations 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 the vertical of the well surface location compared with the bottom-hole
location. These wells were removed from the dataset. If a well is deviated, its surface and bottom-hole
co-ordinates should be different. As all remaining wells should be vertical if the surface and
bottom-hole co-ordinates 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, 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);
- geological or 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 author used a minimum well density of one well per township (about 100 square km). However, in most
areas, the well density greatly exceeded that number. About 655 townships were picked, resulting in an
average well density of 13.5 wells per township for the top of the Horseshoe Canyon and Wapiti formations.
Process step:
Process step:
Description:
Prior to making picks for a given surface, we studied the published geological literature with
emphasis on representative sections. If available, we examined outcrop sections and drillcore (with
associated geophysical well logs) to provide a link between the rock and downhole geophysical
signatures.
Geophysical well logs (both digital and raster format) were examined using Petra and Accumap software
and picks were recorded in a database. If well density and log availability were sufficient, the
author selected wells according to the following criteria:
- vertical wells only;
- wells with a spud date between 1975 and the present; and
- wells with downhole geophysical well-log suites that include gamma-ray, neutron, density or sonic,
and resistivity logs. This requirement was relaxed in areas where the Battle Formation is close to
surface and logs were obtained through casing.
A minimum well density of one well per township was aimed for, although well density greatly exceeded
that number in most areas. Data tended to be sparser where the Battle Formation is shallow, and in
those areas all available wells were picked. We picked about 655 townships, resulting in an average
density of about 13.5 wells per township for the top of the Horseshoe Canyon and Wapiti formations.
To facilitate correlation, wells were never picked in isolation, but always on cross-section, with a
maximum well spacing of 13 km. In most areas, we used a much smaller well spacing. During the
process, picks were gridded using the triangulation method to identify and check outliers, which
appeared as ‘bull’s eyes’ on a structure contour map.
After making picks and prior to modelling the surface, we eliminated or minimized errors resulting
from incorrect
- depth data (well deviation);
- well-header kelly bushing (KB) elevation data;
- well-header ground elevation data; and
- pick depth (due to human error).
Picks and well-header information, including KB elevation, ground elevation, 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 format. The
datum for the well location is NAD83. The picks are in metres, given as measured depth relative to
KB elevation. Pick elevations relative to sea level were calculated by subtracting measured depth
(MD) from the KB elevation.
A query of the well surface location compared with the bottom-hole location checked for any deviations
from the vertical. If a well was deviated, its surface and bottom-hole co-ordinates should be
different; therefore, these wells were removed from the dataset. As all remaining wells should be
vertical if the surface and bottom-hole co-ordinates are correct, measured depth and true vertical
depth should be equal.
Although incorrect KB elevation data can be difficult to detect, we 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 2 to 6 m was used. We
excluded wells with derrick heights outside this range.
To check for potentially gross errors in the ground elevation of wells, we compared well-header ground
elevations with shuttle-radar digital elevation model elevation data extracted for well surface
locations. If the difference obtained by subtracting the well-header ground elevation from the
elevation derived from the DEM was more than 2 ± 9 m (i.e., -7 to 11 m; about the mean of this
difference plus or minus three standard deviations for all wells in the Alberta plains), that well
was excluded. This method potentially excluded wells for which well-header ground elevation values
were correct, but for which the DEM data for that well location were incorrect. It also may not have
detected relatively small errors in either ground or KB elevation data for a well, as long as those
values met the screening criteria. It did, however, detect large errors in well-header KB or ground
elevation data.
Data were then screened for both global and local outliers. Outliers are values outside a specified
normal range compared with the entire dataset (global outliers) or within a local area (local
outliers). If they are caused by errors, outliers can have detrimental effects on an interpolated
modelled surface, and should be either corrected or removed before the final surface is created.
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 that are not marked as such and have either incorrect surface or bottom-hole location
data;
- incorrect stratigraphic pick data due to human error; or
- geological structure.
A variety of geostatistical methods was used to identify outliers, including examination of
neighbourhood statistics, inverse distance weighting interpolation and Voronoi maps. Outliers were
flagged and the well data and geophysical logs examined to determine whether each outlier was the
result of geological variability or bad data. In cases where no error could be identified,
additional data were gathered to refine the definition of local structure. In these cases, if a
stratigraphic surface anomaly caused by a single outlier remained and no geological evidence was
present to corroborate structure, then the outlier was removed.
Once initial outliers were either removed or confirmed, the outlier screening process was repeated at
least three times. This iterative process identified increasingly subtle outliers. As each pick was
made during this project and all statistical outliers were examined and some removed, the largest
source of error and uncertainty in the elevation of the stratigraphic surfaces is likely related to
the surveyed KB (and ground elevation) for a given well.
Date and time:
2011-01-01T00:00:00
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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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