Definition: Physics of rocks (with emphasis on applying it to well logging technology)

Well Logging -- Goal (oil business): locating and quantifying the amount of oil and gas in underground formations as well as the existing fluid flow properties (permeability)

• Accomplished by exploiting rock properties to yield insight into
• Porosity
• Fluid composition in the pores
• Permeability of the pore network (fluid flow properties)
• Rock composition
• Properties used
• Interaction with electromagnetic waves
• Low frequencies – resistivity
• The birth of well logging by the Schlumberger brothers based on the contrast between the salty formation water (low resistivity) and oil (high resitivity)
• High Frequencies – dielectric (polarization) [refer below for brief history]
• Interaction with nuclear radiation (gamma rays, neutrons)
• Natural electrochemical effects (spontaneous potential[SP])
• Acoustic properties
• NMR behavior of the fluids in the pores

Brief History of Dielectric Logging R&D

• Had its origins in the pioneering research done in the 1960’s (the same goes for NMR)
• Motivation was due to some formation waters being low in salinity (high resistivity) masking the usual contrast with any oil present
• Simplistic idea -- exploit the contrast between the dielectric constant of water (~80) and oil (~2) [the real situation is much more complex]
• Early discoveries pointed to developing well logging tools around 1 GHz (a region of minimal frequency and salinity effects)
• Complication—limited depth of penetration into the formation (a few inches)
• Led to the development of lower frequency tools having greater depths of penetration but in a much more complicated frequency region
• Development of lower frequency logging tools (mainly in the 10-100 MHz region)
• Done without an existing/viable interpretation
• Led to a great amount of research in the 1980’s
• The almost universal failure to discover such an interpretation led to the premature demise of interest (refer to Mark Rosen's program below)
• It appeared to be too complicated and undoable
• No program better illustrates the reasons for failure than the very largest R&D effort at Schlumberger
  • Lack of a practical approach
    • Search for the "ultimate" theory rather than one that solves the problem at hand
  • Biased by pet ideas (this also hampered Mark Rosen's approach which was initially driven by the incorrect IP work of Harold Vinegar and Monroe Waxman -- refer below)
  • Failure to examine the trends in the measurements
  • Failure to express the behavior in terms of useful petrophysical parameters (i.e., "platiness" -- a construct that is not very useful)
  • BAD DATA (measurements) -- probably the most critical factor for failure
    • The history of rock dielectric measurements is littered with questionable measurements
    • Schlumberger's measurements are just another example as shown in the attached GRAPH

Mark Rosen ’s R&D Program (1980-1985)

• Focused on sandstones with clay present (shaly sands) – what initially seemed to be the most complicated system (carbonates are actually the hardest to model)
• Discoveries
• Polarization due to clay appears to be diffusion limited in the 10-100 MHz region
• A new petrophysical parameter Qbv (Cation Exchange Capacity [CEC] per unit bulk volume of the rock) correctly quantifies the polarization due to clay in the formation from low to high frequencies (a simple but profound breakthrough)
  • Major correction to Induced Polarization (IP) of Shaly Sands work of Harold Vinegar and Monroe Waxman (learning that their approach was wrong back in 1985, they continued to present their work uncorrected to the technical community in the form of presentations and patents)
• The quantification of clay polarization in the RF does not appear to depend on whether the clay is dispersed or laminated
• For water wet state, the presence of oil has little effect on the polarization due to clay in the 10-100 MHz region (only for low values of Qbv)
• Formulated an approach to compensate for salinity effects on the clay polarization
• Devised a viable approach to the interpretation for the RF dielectric behavior of low salinity shaly sands in terms of practical petrophysical parameters (porosity, shaliness, saturation)
• The only known R&D program to succeed

 Abridged Presentation: RF Dielectric Behavior of Shaly Sands (PDF)

First Research Paper "The RF Dielectric Response of Brine Saturated Shaly Sands" (PDF)

Michael Myers' Plagiarized 1991 SCA Paper -- A Textbook Case of Research Misconduct

New 21st Century Technology -- The Gas/Oil (GO) Log

• New idea for exploiting polarization behavior
• Especially sensitive to the presence of oil/gas (extremely valuable for FRESH WATER formations -- what the dielectric log failed to deliver)
• Potentially immune to invaded zone effects
• Simple -- no complicated inversion or mixing relationship needed
• Potential Disruptive Technology
• Applicable to all rock types / salinities
• Unique Technology -- Significant Competitive Advantage