Porosity?! What are we talking about, anyway?

PRESENTER: David C. Herrick
Senior Petrophysical Advisor, Baker Hughes

DATE: Wednesday, November 12th, 2008

TIME:12:00 AM
(Cocktails at 11:30)

PLACE: Palliser Hotel
Crystal Ballroom

Abstract:

Porosity is one of the most fundamental and important petrophysical measurements made. Despite the apparently trivial nature of the concept, there has been and is considerable controversy about what constitutes porosity and how pore space can be meaningfully subdivided and classified. Much of the confusion and controversy is due to imprecision in defining the terminology used in discussing porosity.

A major contributor to the lack of precision is the confusion of measurements of rock properties with the properties themselves. The subdivision of pore space into components such as effective porosity, primary porosity, secondary porosity, interconnected porosity, vuggy porosity, dual porosity, etc. is often made but without stating exactly how the pore space is subdivided. Porosity is also partitioned by fluid content into free-fluid, bound-fluid, irreducible water, capillary-bound water, clay-bound water, etc. Such categorization is often made by interpreting measurements; however the relationship between these categories and actual rock and fluid properties is often vague.

Lacking precision in the definition of terms has resulted in misunderstanding and controversy since the early days of petrophysical measurements. Although overcoming decades of using vague terminology will be difficult, we owe it to ourselves and to the industry to make the attempt.

Biography:

David C. Herrick is Senior Petrophysical Advisor in the Houston Technology Center of Baker Hughes. Dave was trained in chemistry and geochemistry at Indiana University (B.S.) and Penn State (Ph.D.). He has conducted research, training and technical service during his thirty years in the petroleum industry for Conoco, Amoco, Mobil and Baker Hughes in the areas of geochemistry, petrology and petrophysics. Dave has given over fifty presentations and schools on petrophysics, resistivity interpretation, the meaning of porosity terminology and the impact of pore geometry on permeability and conductivity.