Permeability

Question 1

k is a constant under 3 conditions (Darcy’s Law)

Answer 1

• laminar flow
• no rock-fluid reaction
• a single flowing fluid

Question 2

How does capillarity affect relative permeability experiments?

Answer 2

• Flow rate should not exceed limit set by capillary number to achieve a more piston-like displacement
• Ultimate saturation that can be achieved is influenced by capillary pressure

Question 3

How is relative permeability measured?

Answer 3

• Steady state technique (preferred)
• Unsteady state technique (viscous fingering at high mobility ratios)
• Centrifuge technique (gravity stable unsteady state technique)

Question 4

Why is relative permeability important?

Answer 4

Used to generate production curve

Question 5

How is air permeability measured?

Answer 5

• Ruska permeameter (routine)
• Mini permeameter (more detailed profile)
• Pressure pulse permeameter (for low k)

Question 6

When is Klinkenberg effect the greatest?

Answer 6

• low pressure
• low k
• low fluid density

Question 7

What corrections need to be applied for core permeability measurements?

Answer 7

• Klinkenberg
• Brine permeability (clay effects)
• Stress

Question 8

What are the 3 methods of permeability averaging?

Answer 8

• Arithmetic (flow parallel to layers; highest k dominates)
• Harmonic (flow perpendicular to layers; lowest k dominates)
• Geometric (random flow; chooses path of least resistance)

Question 9

What are the methods of estimating horizontal permeability from poro-perm?

Answer 9

• Arithmetic shift using rms (analytical)
• Binning method (linear average of k per bin)
• Swanson’s method

Question 10

Why log kh and well test kh do not match?

Answer 10

• fractures
• core data under samples high k
• regression is geometric average
• upscaling
• log-based Rock Type model is not robust
• uncertain h of well test
• completion issues: skin of test