Jun 2024

Visual Identification of Permeable Zones on Logs

Visual Identification of Permeable Zones on Logs

5 Steps to Visually Define Permeable Zones on Wireline Logs

“When I ask my students what they enjoyed most from my petrophysical lectures at the University of Leoben, it is usually the intuitive log reading exercises”, says Dr Claudia Steiner-Luckabauer, HOT’s Principal Petrophysicist and former university lecturer.

Intuitive and qualitative check on the main physical principles and lithologies?
Can this be real?

Yes, this is possible! By just knowing some fundamental basics and connecting the dots.

This might be useful in

  • Data rooms
  • Pre-selecting printed logs for digitisation
  • Checking common sense of petrophysical work
  • On-site interpretation

The formation’s specific physical properties result in varying responses on different logs.

➡ Neutron / density log combination:

  • the total porosity
  • the shale content
  • the lithology

➡ Resistivity arrays, permeable:

  • Different water chemistry / conductivity per depth of investigation
  • Different absolute values per depth of investigation on resistivity arrays

… or

➡ Resistivity arrays, impermeable:

  • Similar water chemistry / conductivity per depth of investigation
  • Similar absolutes values per depth of investigation on resistivity arrays

Found nothing matching on your logs from this content?

  • Your reservoir might be tight
  • It might be a different lithology
  • It might be a young sediment
  • The logs show unwanted logging effects from bad hole conditions.

Intuitive log reading is a daily practice and helps checking logs and interpretation for common sense. This is useful 😊

  • 5 steps to visually define permeable zones on wireline logs: Vintage logs, invasion profile, intuitive log reading.
  • Permeable Zones: Slide 1. Check Physical Principle: Porosity logs show the total porosity, not separating between effective and ineffective pores according to the fluid movement. Resistivity logs show the hydraulic conductivity, separating between effective and ineffective pores according to the fluid movement.
  • Permeable Zones: Slide 2. Check similarities: Low resistivity values and high porosities - uusually associated with clayey intervals. Higher, but different resistivities and moderate porosities - usually associated with permeable intervals.
  • Permeable Zones: Slide 3. Check Log Characteristic: Neutron / density logs show specific characteristics depending on the "compatible scale" used. Clayey intervals would appear as crossover, where N>D. Quartz sands would appear as crossover, where N
  • Permeable Zones: Slide 4. Let the chemical and dynamic processes show you the path! Mud filtrate invasion in permeable zones is seen via salinity contrast. Resistivities show different value per depth of investigation. Borehole Environment:
  • Permeable Zones: Slide 5. Enjoy insights: Likely the logs show: Clastic environment, impermeable shale layers, shale layers as vertical barriers, permeable sand interval, eventually holding some shale volume within the sand interval. Not visible: the clay type within the sand interval.

Would you like to learn more about intuitive log reading?

Our course “Fundamentals in Petrophysical Log Interpretation”, taught by the author of this article, explains the fundamentals of logging techniques and petrophysical models. It focuses on intuitive log reading and a mindful petrophysical setup.

Petrophysical Log / (c) HOT Energy GroupFundamentals in Petrophysical Log Interpretation: Theory and Practice (PPH23)

Info & Enquiry

About the Author

Claudia Steiner-Luckabauer, Principal Petrophysicist and Geothermal Expert at the HOT Energy Group

  • Dr Claudia Steiner-Luckabauer is the Principal Petrophysicist and geothermal expert at the HOT Energy Group. She has been working in a leading role on numerous integrated reservoir characterisation and field development projects, focussing on integrated petrophysical evaluation and formation evaluation.
  • As HOT’s subject matter expert, Claudia has extensive experience assessing mature oil fields, heavy oil fields, gas condensate fields, gas fields, underground gas storage, clastic and carbonate settings, low-salinity environments, unconsolidated reservoirs, and fractured reservoirs (chalk, carbonate, granite basement, sandstone). She is also an experienced instructor of academic and industry workshops on various topics in geosciences and has authored numerous papers.

HOT is your trusted partner for geothermal consulting services.

We support our customers in identifying locations of high-quality geothermal resources, in mitigating the risk of subsurface tremors associated with geothermal applications, and in designing and developing geothermal projects.

Talk with us to see how HOT can propel your geothermal project to success!

Book a Consultation