CPL GIS & Geospatial Technology 3 — Questions and Answers
Question 1: Which type of GIS analysis would a landman use to determine how much of a proposed lease block falls within a federally designated wilderness area?
- Geocoding
- Overlay analysis (Correct answer)
- Network analysis
- Raster reclassification
Correct answer: Overlay analysis
Overlay analysis combines two or more spatial layers to identify areas of intersection, allowing a landman to calculate acreage of a proposed lease that overlaps restricted federal land.
Question 2: In GIS, what is a 'geodatabase' and why is it preferred over shapefiles for complex oil and gas land management projects?
- A web mapping service that streams live data
- A spatial database format that supports domains, subtypes, and topology rules (Correct answer)
- A raster catalog for storing satellite imagery
- A GPS data logger format for field collection
Correct answer: A spatial database format that supports domains, subtypes, and topology rules
A geodatabase is a relational database structure for GIS data that supports advanced features like attribute domains, relationship classes, and topology rules, making it superior to shapefiles for managing complex lease datasets.
Question 3: A landman needs to locate a well described as being in the SW/4 of Section 12, T2N, R3W. What GIS tool would most efficiently identify the correct 40-acre parcel?
- A raster DEM query
- A PLSS-based spatial query against a BLM GCDB layer (Correct answer)
- A geocoding service using the street address
- A satellite imagery classification tool
Correct answer: A PLSS-based spatial query against a BLM GCDB layer
A spatial query against a BLM GCDB PLSS layer using township, range, and section attributes allows a landman to precisely locate and select the described quarter-section parcel.
Question 4: What is the primary purpose of a 'digital elevation model' (DEM) in oil and gas GIS applications?
- To display ownership boundaries for surface estates
- To represent terrain elevation for pipeline routing and drainage analysis (Correct answer)
- To store well completion data in tabular format
- To define royalty interest ownership across a unit
Correct answer: To represent terrain elevation for pipeline routing and drainage analysis
DEMs represent terrain surface elevation as a raster grid and are used in pipeline routing, flood zone identification, and slope analysis critical to oil and gas operations planning.
Question 5: Which of the following best describes 'geoprocessing' in a GIS workflow for a land department?
- The process of printing paper maps for field use
- Automated spatial analysis operations that manipulate, transform, or analyze geographic data (Correct answer)
- Manual digitizing of lease boundaries from paper plats
- The act of loading GPS coordinates into a spreadsheet
Correct answer: Automated spatial analysis operations that manipulate, transform, or analyze geographic data
Geoprocessing refers to GIS operations like clipping, merging, buffering, and overlaying datasets to automate spatial analysis tasks such as identifying open acreage or calculating lease statistics.
Question 6: A landman discovers that two adjacent lease polygons in a GIS layer have a sliver gap between them due to digitizing error. Which operation best corrects this?
- Reprojecting the data to a different coordinate system
- Running a topology repair or edge-snapping tool (Correct answer)
- Exporting the data to a CSV and re-importing it
- Applying a dissolve based on operator name
Correct answer: Running a topology repair or edge-snapping tool
Topology repair or edge-snapping tools close unintended gaps between adjacent polygons by moving shared vertices into coincidence, fixing sliver errors caused by imprecise digitizing.
Question 7: When a GIS layer uses the NAD83 datum but a well location is collected in WGS84, what must be done before combining these datasets?
- The data can be combined without any adjustment since the datums are nearly identical
- A datum transformation must be applied to align coordinates accurately (Correct answer)
- The WGS84 data must be converted to a shapefile first
- The well must be re-surveyed in the field
Correct answer: A datum transformation must be applied to align coordinates accurately
Although NAD83 and WGS84 are very similar, a datum transformation is required for precise work because small coordinate differences can cause positional errors in critical lease and well boundary mapping.
CPL GIS & Geospatial Technology 3
Which type of GIS analysis would a landman use to determine how much of a proposed lease block falls within a federally designated wilderness area?