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The recently published book "Soil Gas and Related Methods for Natural Resource Exploration" by Dr. Ronald Klusman contains fundamental errors concerning soil iodine geochemistry.
Klusman's explanations and presentation of the iodine tool are not derogatory or negative; they are simply uninformed and mistaken. Even though he describes his book as a literature review and critique, time must not have allowed him a review of the iodine method.
Klusman states on pg. 81 that one should expect, in areas of microseepage a "relative decreas in iodine in the soil." Regardless of what Dr. Klusman "might expect", no paper concerning iodine and its relationship to hydrocarbon seepage has ever observed, proposed or even debated whether iodine anomalies are positive or negative. Regardless of the shape, size, configuration, position or name (halo, apical, target, etc.), iodine anomalies are always HIGHS.
Working on his assumption that iodine anomalies are lows, Klusman proposes a "mechanism" to account for the opposite of the actual phenomena. He selects a small number of the great multitude of "probable" reactions involving soil iodine. Building the case that iodine is easily replaced, becoming volitile and mobile in the process. Iodine is indeed volatile and mobile but it is also one of the most reactive elements. His final equation actually encompasses the dominant forms of iodine in the soil. Had he looked further, he would have discovered the incomparable organophilic reactivity of iodine. It is this reactivity that turns his "expected" iodine lows into the well documented iodine highs.
Klusman's final equation is:
Here the intermediate steps, moving from reactants to products, is a soil environment, could fill the rest of his book. It's true that the oxygen ultimately wins the battle for the carbon atoms, but it is the intermediate reactions, the incomplete oxidation steps, that hold the key to the iodine. Although Klusman shows iodine not directly associated with the organics on both sides of his equation, most of the iodine in the soil is bonded to organics, with very little in either the I2 or I states. The constant addition of reactants to the left side of the equation (seepage providing hydrocarbons and iodine released by his, and other, replacement reactions) produces the anomalous accumulations of iodoorganics that soil iodine surveys measure.
The mechanism that I proposed in 1986 (Allexan et al.) still functions as model for the iodine - hydrocarbon associations we have observed. Klusman never mentioned this mechanism, even to challenge it, and seemed unaware that anyone had ever addressed the relationship between iodine and hydrocarbons in the soil.
I hope that future revisions will take care of these problems.
Sincerely,
Chuck Goudge
Atoka Exploration Labs, Denver, Colorado
Dear Editor, March 20, 1994
Mr. Chuck Goudge of Atoka Exploration states that my book, "Soil Gas and Related Methods for Natural Resource Exploration" contains fundamental errors concerning soil iodine geochemistry.
Published research through 1989 by Atoka principals and other shows halo-type iodine anomalies around new and older oil and gas fields. The redox hypothesis I advanced on pp. 80-81 is consistant with a halo anomaly, and in turn is consistant with their previously published examples which I show on pp. 213-215. I state on p. 81 that the redox hypothesis has not been experimentally tested. More recently, Atoka principals have stated that apical iodine anomalies should be expected for new fields, which may become halo anomalies with production. The have stated that microseeping light hydrocarbons react with iodine to produce iodoorganic compounds which are stable in the surface soil and in the stored samples for years (Tedesco and Goudge, 1989, APGE Bull., v. 5, p. 51). The stability of these compounds is inconsistent with a rapid change in the character of the anomaly from an apical-to a halo-type. The apical anomaly is more consistant with their hypothesis of a photocatalytic reaction of iodine with microseeping light hydrocarbons.
Table 1 of the Allexan et al. (1986) article (APGE Bull., v. 2, pp. 71-93) appears to be a tabulation of the boiling points of selected organic compounds and some iodo-derivatives of these compounds. It appears to be from a Handbook of Chemistry and Physics, or an organic chemistry test, though there is no reference given. The title of the table indicates it is not a list of iodo-organic compounds extracted from soils and measured by the authors. I agree there is a statistical relationship between iodine and soil organic matter as shown in very old Russian literature.
There also seems to be an inconsistency between the Atoka principals about the energy required to bring about the hypothesized photochemical reaction. The Allexan et al. (1986) paper states on p. 72, "the threshold for breaking diatomic iodine into free radicals requires light in the near- infrared at a wavelength of 7800 angstroms." This threshold implies a maximum wavelength, or minimum energy required at ambient temperatures. This means visible and ultraviolet light will be the range where photolysis is expected. However, one of the Atoka principals stated in a 1993 letter to myself that the infrared wavelength was necessary, inconsistant with Allexan et al.(1986). This is also inconsistant with one of the standard methods in organic chemistry for halogenating organic compounds where ultraviolet light is used. It is also inconsistant with the literature of atmospheric chemistry on the formation of free radicals in the the atmosphere under conditions of strong sunlight such as occurs in Denver in the winter. Clearly some laboratory and closely controlled field experimentation is necessary to elucidate the mechanism(s) in the formation of iodine anomalies.
Surface geochemistry has had a credibility problem, which is slowly being overcome. This has not been the case for geophysics, nor organic geo-chemistry, which has only been around approximately 20-25 years. I have seen a large amount of surface geochemical data from many techniques, and I am convinced that microseepage does exist above many, if not most, hydrocarbon reservoirs. If I did not believe in the potential of surface geochemistry, I would not have worked in the field as long as I have.
The most difficult problem is experimentally verifying how light hydrocarbons migrate from the level of the reservoir to the surface. The second most difficult problem with surface geochemistry is the development of a sound understanding of the physical, chemical, and microbiological processes which occur in the near-surface and surface environment. The interactions and reactions of microseeping light hydrocarbons in this environment are complex, and relatively poorly understood. The indirect methods in particular are based on an understanding of these processes.
This is where empirical geochemistry seem most prevalent, and where progress in developing scientific understanding has been limited. This is also an area where significant progess could be made, which would allow surface geochemistry to overcome much of the credibility problem.
An important objective of my book, as discussed in the Preface, was to bring together a diverse, scattered, and sometimes empirical literature. If this book drives a discussion of mechanisms, and a designing and carrying out of scientific experiments which support of refute various hypotheses, the book will serve an important purpose. Some of the hypotheses presented in Chapter 4 will likely be proven wrong, but it is important to stimulate the research to fine the correct mechanism(s). In this way, surface geochemisty can advance scientific, rather than continue to collect more empirical data.
Sincerely,
Ronald W. Klusman
Colorado School of Mines, Golden, Colorado