Locating Subsurface Energy Resources

Activity Source: Society for Exploration Geophysicists

 

Grade Levels: 6-12

Background

Geophysical techniques are used to identify subsurface formations related to valuable energy resources, such as fossil fuels or geothermal sources, as well as rock layers that could be used for carbon sequestration. Each geophysical technique transmits a specific type of energy into the ground (e.g., electrical, magnetic, or mechanical) to create images of subsurface rock formations For example, seismic surveys send sound waves through the ground, and the reflection of these waves helps detect differences in the Earth’s subsurface (see video). Images created from seismic surveys are called seismic profiles, which can be interpreted to identify subsurface formations, such as saline aquifers where carbon dioxide could be injected and stored. This activity will introduce you to the interpretation of seismic profiles to consider how they could be used during exploration to locate saline aquifers.

Materials

  • Computer with internet access
  • Tracing paper and pencils or acetate sheets and dry-erase markers
  • Printer access (color ink optional)

Procedure

  1. Print an image of an outcrop.
    • Place tracing paper or acetate over it.
    • Trace over the areas where you notice differences in the layers.
  2. The image you created on the tracing paper is like a seismic profile, showing the boundaries between subsurface features like rock type, angle, and density.
  3. Go to the image source to see where scientists have noted changes in the shown outcrop (image b).
  4. Open a video tutorial on seismic profile interpretation.
    • Make the video full screen and pause it to take a screenshot of the seismic profile. Print the image, if possible.
    • Repeat steps 1a-b with this image to indicate subsurface features. Alternatively, use an image editing program to annotate the profile.
    • Skip to time 12:30 in the video to see the features noted on the seismic profile. How do your annotations compare?
    • Optionally, watch the video to see an explanation of the features, or repeat these steps with another video to look at a variety of subsurface features.

Analysis

  1. Imagine you are a geologist tasked with interpreting the seismic profile you traced in Step 1. What conclusions can you draw about the geological history of the area based on the changes in subsurface features you identified?
  2. Learn more about carbon capture and storage. Go to the section titled “Carbon dioxide storage” and read “Saline aquifers”.
    • How do you think the properties of rocks that hold saline aquifers affect the speed at which seismic waves travel through them? How would this help in the identification of saline aquifers? Explain your answer.
    • The water in many saline aquifers is confined, meaning that it is surrounded by rock that helps hold the saltwater in place. How do you think the properties of these rocks differ from the rock layers that hold the saline aquifer.

Further Steps

Annotate seismic profiles that show saline aquifers (scroll down to “Learn More” to find a K–12 education pdf).

Watch a short video on advancements in seismic surveys used to find energy resources.

NGSS Connections

  • SEP: Analyzing and Interpreting Data
  • DCI: PS4.C: Information Technologies and Instrumentation; ESS2.B: Plate Tectonics and Large-Scale System Interactions
  • CCC: Patterns

SDG Connections