Page 178 - Geochemical Remote Sensing of The Sub-Surface

Light hydrocarbons for petroleum and gas prospecting 155

Fig. 5-12. Relation of near-surface gases to deep faults and oil fields along a traverse in the
Cholame Valley, California (reproduced with permission of the American Association of
Petroleum Geologists, whose permission is required for future use, from Jones and Drozd, 1983,
AAPG Bull., vol. 67, no. 6, Fig. 12, p. 942, AAPG 9

Mamyrin (1979), King (1980b), Reimer (1980), Shapiro et al. (1981, 1982), Mooney
(1982) and Pirkle and Jones (1983). Particularly intriguing examples have been
published by Antropov (1981) of atmospheric methane flux related to petroleum deposits
(Fig.5-14) and seismic shock (Figs. 5-15 and 5-16). These measurements were made
with adsorption-type gas lasers: one type makes point measurements of the sample in an
adsorption tube (Iskatel-2); the other (Luch) measures the specific gas adsorption along a
path length (1-100 m).

SAMPLING AND MEASUREMENT METHODS

There are a variety of sample collection and hydrocarbon analysis methods use in
geochemical surveys for oil and gas deposits. In the case of free gas, samples are
collected either in the atmosphere or, more usually, within the soil. For bound gas soil or
rock is collected and the gas is liberated by one of several methods. In practice, however,
it is rarely possible to determine solely free gas or solely bound gas.

Atmospheric techniques

The detection of hydrocarbons above the ground surface offers obvious advantages:
continuous sampling, no permit requirements, access over rough and hostile