Using Well Logs in the Petroleum Industry

Walter S. Borowski, Eastern Kentucky University
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Summary

This exercise shows how well logs are used in the petroleum industry. It is designed as a first exposure to well logs for undergraduate geology majors and introduces not only well logs and their interpretation as proxies for stratigraphic sections, but also investigates concepts of porosity and permeability, oil reservoirs, and structural traps.

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Context

Audience

This exercise shows how well logs are used in the petroleum industry. It is designed as a first exposure to well logs for undergraduate geology majors and introduces not only well logs and their interpretation as proxies for stratigraphic sections, but also investigates concepts of porosity and permeability, oil reservoirs, and structural traps.

Skills and concepts that students must have mastered

Students should know about shale versus sandstone lithology, different bed thickness, and the concepts of porosity and permeability, and general depositional models for various depositional environments.

How the activity is situated in the course

This is a stand-alone exercise to demonstrate how concepts of sedimentology and stratigraphy are used in geologic professions, here referring to the petroleum industry.

Goals

Content/concepts goals for this activity

Use of electric logs in determining lithology and fluid content, pertinent to the petroleum industry, showing the practicality of geological knowledge.

The exercise:
  1. Instructs students to recognize mudstone vs. sandstone lithology using spontaneous potential logs.
  2. Teaches the concept of resistivity and conductivity and their underlying causes in pore fluids.
  3. Shows how to recognize briny pore fluids and hydrocarbons using resistivity logs.
  4. Demonstrates lithostratigraphic correlation using well logs.
  5. Introduces the concept of oil/water contacts, based on differing density of petroleum and water.
  6. Tests the concept of horizontal oil/water contacts within the subject oil field.
  7. Shows students how to calculate elevations of rock units relative to a datum (sea level).
  8. Illustrates a structural trap, thereby pointing out the trapping nature of most oil fields.
  9. Points out the necessity of geologists in the petroleum industry and the use of depositional models.

Higher order thinking skills goals for this activity

  1. Analysis of data, using electric logs to interpret lithology and fluid content.
  2. Hypothesis formation and testing (oil/water contacts).

Other skills goals for this activity

Spatial and three-dimensional thinking.

Description and Teaching Materials

Teaching Notes and Tips

Instructors should have students work through the exercise in groups of 2 to 3, but also bring the class together for detailed explanations at pertinent points within the exercise.

Assessment

By grading and annotating their lab exercises, making sure that their explanations are sharp and correct.

References and Resources

I used no outside resources except the well logs were purchased from a log broker, Cambe.