An Unconventional Approach to Unconventional Reservoirs

PRESENTER: David C. Herrick PhD
Consulting Petrophysicist

DATE: Tuesday, October 13th, 2009

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

PLACE: Fairmount Palliser Hotel

Abstract:

An Unconventional Approach to Unconventional Reservoirs

David C. Herrick, PhD

The rocks for which Archie (1942) devised his saturation equation were clean sandstones with only inter-granular porosity and without complications such as thin inter-beds, bimodal pore systems or gradations in grain size. Archie discovered that he could obtain simple relationships between his formation resistivity factor and porosity as well as between the resistivity index and saturation if he used graph paper with log-log scales. His use of a graphical logarithmic transformation resulted in the power-law relationships that have become the industry standard and have attained the status of a “law.”

Many, if not most, reservoir rocks we are faced with at present do not fit the lithologic criteria required to be “Archie rocks” for which his equation is appropriate. Rather than attempt to modify Archie’s equation for uses for which it was not intended, it is better to emulate Archie’s approach: seek relationships between electrical properties, porosity and saturation and use them.

Examples are given to demonstrate a more general approach to developing relationships useful for predicting saturation and permeability for several kinds of non-Archie rocks.

Biography:

Dave Herrick has recently retired and is now consulting. Dave is an innovative petrophysicist with more than 30 years experience in the petroleum industry. He was trained in chemistry and geochemistry at Indiana University (B.S.) and Penn State (Ph.D.). He has conducted research, training and technical service for Conoco, Amoco, Mobil and Baker Hughes in the areas of geochemistry, petrology and petrophysics. Dave has many publications as well as having given numerous presentations and schools on petrophysics, resistivity interpretation, and the impact of pore geometry on permeability and conductivity.