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Improved
Geohazard
Analysis for
Drilling
Favorability
Maps
Joshua T. Kelly
William C. Haneberg
ESRI Petroleum GIS
Conference
9April, 2015
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Overview
Improved Geohazard Analysis for Drilling Favorability Maps
Section 1
Introduction to Geohazards & Favorability Mapping
Section 2
Common Practices for Favorability Mapping
Section 3
New Quantitative Approach
Section 4
Conclusions, Q&A
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Section 1
Introduction to
Geohazards &
Favorability
Mapping
Improved Geohazard Analysis for Drilling Favorability Maps
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•Historically used to indicate
likelihood of discovering oil and
gas, metallic minerals, and
groundwater
History of Favorability Mapping
Improved Geohazard Analysis for Drilling Favorability Maps
Groundwater Favorability Map
of the Otter Creek Basin,
Vermont, A. Hodges, 1967
Favorability Map of Altered
Rocks at La Escondia Mining
District, Ott et al., 2006
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Geohazards
Improved Geohazard Analysis for Drilling Favorability Maps
“A geological state that may lead to widespread damage or risk”
Most common in deepwater drilling:
•Shallow gas
•Faults
•Expulsion
•Steep slopes
•High pressured sands
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Favorability Mapping for Geohazards
Improved Geohazard Analysis for Drilling Favorability Maps
• Drilling costs >$1 million/day
•Delays caused by unanticipated hazards = $$$$ (compounded by current oil prices)
•Drilling (or pipeline) favorability maps used to identify and avoid geohazards
http://www.canadian-wellsite.com/images/Photo%20Gallery/BFM/West_Vanguard_Blowout.jpg
West Vanguard blowout,
October 6, 1985
http://www.jwco.com/technical-litterature/p07.htm
Shallow gas
blowout
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Section 2
Common
Approaches to
Favorability
Mapping
Improved Geohazard Analysis for Drilling Favorability Maps
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Map Production
Improved Geohazard Analysis for Drilling Favorability Maps
•Prior to map creation, hazards are identified through interpretation of:
•3D/2D Seismic
•Multibeam Bathymetry
•Backscatter
•Side Scan Sonar
•Sub-bottom Profiler
•Shapefiles created showing spatial extent of each hazard
•Shapefiles are then combined or “stacked” on top of one another in
GIS creating a map that shows the total presence of geohazards in the
pipeline or drilling site
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Example Geohazard Data –Map View
Improved Geohazard Analysis for Drilling Favorability Maps
High Amplitude Anomalies
(indicative of shallow free gas)
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Example Geohazard Data –Map View
Improved Geohazard Analysis for Drilling Favorability Maps
Seafloor Failures
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Example Geohazard Data –Map View
Improved Geohazard Analysis for Drilling Favorability Maps
Gas Hydrates
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Example Geohazard Data –Map View
Improved Geohazard Analysis for Drilling Favorability Maps
Pockmarks or Gas Expulsion Features
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Example Geohazard Data –Map View
Improved Geohazard Analysis for Drilling Favorability Maps
Sub-seafloor Faults
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Example Geohazard Data –Map View
Seafloor Faults
Improved Geohazard Analysis for Drilling Favorability Maps
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Example Geohazard Data –Map View
Improved Geohazard Analysis for Drilling Favorability Maps
Headwall Scarps
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Example Geohazard Data –Map View
Improved Geohazard Analysis for Drilling Favorability Maps
Buried Slump Blocks
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Example Geohazard Data –Map View
Improved Geohazard Analysis for Drilling Favorability Maps
Moderate Seafloor Slopes (between 3 and 6°)
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Example Geohazard Data –Map View
Improved Geohazard Analysis for Drilling Favorability Maps
Steep Seafloor Slopes (greater than 6°)
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Favorability Preparation
Improved Geohazard Analysis for Drilling Favorability Maps
•Dan et al. (2014) detailed a rule-based system for favorability mapping and
classified areas as:
•Yellow – most favorable (gentle slopes, no hazards)
•Orange –proceed with caution (moderate slopes)
•Red –least favorable (steep slopes, gas, MTDs, etc.)
•In our experience, most drilling favorability maps produced today are based on
similar rule-based procedures
•Typical “Stoplight” red-yellow-green color scheme
Underlying Problem
Some conditions effectively prohibit exploration or production activities
(shallow gas) but other areas where less extreme level of hazards are
present may be offset by other advantages. These areas are unjustifiably
classified as least favorable based on current rule-based procedures.
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“Stoplight” Color Scheme Map
•Traditional
“Stoplight” or red-
yellow-green color
scheme indicating
level of hazard:
•Red =
Unacceptable
hazards
•Yellow =
Proceed with
caution or
investigate
further
•Green = No
known or
inferred hazards
Improved Geohazard Analysis for Drilling Favorability Maps
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Section 3
A Quantitative
Approach to
Favorability
Mapping
Improved Geohazard Analysis for Drilling Favorability Maps
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Geohazard Weighting
•Not all geohazards are the same –there is typically a range of severity
or significance that each has relative to the project objectives
•Assigning a “Geohazard Weight” or “Score” to each hazard allows
subjectivity and expertise to be introduced to favorability mapping
•Weights should be developed collaboratively by an interdisciplinary
team with expertise comprising:
•Seafloor geomorphology and geohazards
•Geotechnical and facilities engineering
•Drilling operations
•Like Dan et al. (2014), we avoid the use of green as it implies it is
acceptable to move forward with minimal caution
•Instead, we use a yellow-orange-red color scale to denote areas of
increasing but still acceptable hazard risk
Improved Geohazard Analysis for Drilling Favorability Maps
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GIS Workflow
Geohazard Shapefiles
Buffer-Dissolve-SHP to Raster
Reclassify (Assign weight)
Cell Statistics (Sum overlying
weights)
Symbolize Map
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Weighted Favorability Map
Improved Geohazard Analysis for Drilling Favorability Maps
Hazard Score
Fault 5
Shallow Gas 20
Steep Slope 10
Pockmark 8
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Python Automation
•Fully automated
•Prompts user to input
buffer distances and
hazard scores
•Create new map in
~15 minutes
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Section 4
Conclusions
Improved Geohazard Analysis for Drilling Favorability Maps
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Comparison and Conclusions
Improved Geohazard Analysis for Drilling Favorability Maps
•Easy to read
•Simplified
•Commonplace
“Stoplight” Maps
•Much greater insight
•Also easy to read
•Weights adjustable to client
and consultant opinion
•Known significant hazards not
lost in the classification
Weighted Maps
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Questions?
Improved Geohazard Analysis for Drilling Favorability Maps
William C. Haneberg ,Joshua T. Kelly ,Hallie L. Graves , and Gabriela
Dan (2015). ”A GIS-based decision-support approach to deepwater drilling-
hazard maps.” 34(4), 398–402, 404–404.
doi: 10.1190/tle34040398.1
Email for copy:
jkelly@fugro.com
