Overview:

• How It All Fits Together
• Computer Mapping and Surface Representation

What:

• A map represents and helps us interpret the world

Why:

• Computer mapping can:
  • Speed up map production
  • Speed up geologic interpretation
  • Work with large data sets
  • Produce a legal audit trail
  • Let us focus on understanding geology
  • Integrate new information and ideas quickly

How:

• Using the right tools for the job:
  • Computers don't make maps - You make maps
• Methods used to represent surfaces and properties:
  1. Gridding
  2. Contouring without gridding
  3. Direct surface modeling
  4. Combination Methods

Gridding:

• Putting It All Together
• Know Your Tools

Kinds of Data:

• Continuous - Ideal for map grids. Examples:
  • Temperature & pressure weather maps
  • Air pollution concentration maps
• Continuous with discontinuities - Hard to work with. Examples:
  • Subsurface structure maps. This is most of our world in the Oil Patch! Congratulations.
• Discrete - OK for grid manipulation. Examples:
  • Outcrop / subcrop maps
  • lease maps
  • Congressional District maps
• Discontinuous - OK for grid manipulation. Examples:
  • Satellite images
  • land use classification
  • vegetation cover
• Directional &/or Linear - It can be done with grids. Examples:
  • Sand transport direction
  • lineations on satellite photos
  • fracture mapping

Goals in Making Maps:

• What do you want to learn about:
  1. Structural highs
  2. Reservoir limits
  3. Volumetrics for equity determination
  4. Where to drill
  5. Competitor strategies
  6. Geologic understanding - such as 3-D visualization

How much do you know about the area:

• How much can you Interpret about the area:
• In terms of adding value to your company, the interpretation part is where you can shine. Here you can put logical constraints into maps, make and test predictions, and combine independent sources of information to zero in on the unseen opportunity.
• Grid It! - Representing the world with a regular grid of numbers: Computers don't make maps - You make maps. Considerations:
  • Size of the features your looking at
  • Data Bias
  • Data Distribution
• Gridding methods and rules of thumb:
  1. Stability.
  2. Remember the 1/2 feature gridding rule.
  3. Local surface fitting methods - These include splines, biharmonic filters, Laplacian filters, moving least squares, moving weighted average, projected slope, and Kriging.
  4. "Global" surface fitting methods - These include polynomial trend surfaces, Fourier Transform surfaces, numerical modeling from process equations, and surfaces generated from physics equations.
  5. Control Grids and grid arithmetic.
  6. Practical work-arounds.

About the Instructor:

Samuel D. LeRoy, Ph.D. Exploration geologist and seismic interpreter. Worldwide experience including the Gulf of Mexico (shelf, deepwater, and sub-salt), West Africa, California, Australia, and Alaska. Special skills in statistics, multi-attribute seismic stratigraphy, and continental margins analysis using gravity and magnetics integrated with geologic and seismic data. He has worked with computer mapping and gridding since 1978. Ph.D from the University of Southern California. Oil company experience with Texaco and Conoco.