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| Foote,
R. S., 1996, Relationship of near-surface magnetic anomalies to oil- and
gas-producing area, in D. Schumacher and M. A. Abrams, eds., Hydrocarbon
migration and its near-surface expression: AAPG Memoir 66, p. 111-126.
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Abstract
Observation
of aeromagnetic patterns associated with the Cement oil field initiated
a continuing program to investigate the association of shallow magnetic
anomalies with the presence of oil and gas reservoirs. If local magnetic
anomalies are detectable from an aircraft, the source of such anomalies
will necessarily be present in the near-surface sedimentary strata as magnetic
minerals sufficiently concentrated to allow airborne detection and identification
by magnetic susceptibility measurement of drill cuttings. The results of
analysis of cesium vapor magnetometer data are supported by exploration
drill hole rock magnetic susceptibility data from four separated areas:
(1) Caddo and Grady counties, Oklahoma; (2) Cheyenne County, Colorado;
(3) San Juan County, Utah; and (4) southwestern Alabama. Results indicate
a strong correlation of oil- and gas-producing areas with magnetic anomalies
produced from the aeromagnetic data and with intervals of enriched magnetic
rock strata in the shallow sedimentary environment. For the areas studied,
78-90% of oil and gas exploration drilling within the magnetic bright spot
(MBS) anomalies is productive. Outside these anomalies, only 5-16% is productive.
Analyses of minerals by X-ray diffraction and Mossbauer effect measurements
have identified maghemite and greigite as the major iron-bearing minerals
in the anomalous magnetic sedimentary intervals. |
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