ABSTRACT: Spectral Anomaly over Railroad Valley Oil Field, Nevada

Sandra C. Feldman, Frank R. Honey, Gary I. Ballew

Oil was first discovered in Railroad Valley, south-central Nevada, in 1954. Since that time, over 195 wells have been drilled and six oil fields have been found: Bacon Flat, Currant, Trap Spring, Eagle Springs, Grant Canyon, and Kate Spring. Two wells in the Grant Canyon field had flows

between 2480 and 4108 bbl/day in 1987 and may be the most prolific wells onshore in the continental United States.

Production in the Railroad Valley fields is from Oligocene volcanic and sedimentary rocks and Paleozoic carbonate formations. Traps are structural or structural and stratigraphic, and reservoir seals are indurated or clayey valley fill, weathered tuff, and shales in Tertiary sediments. Reservoir temperatures range between 95 and 309°F.

Previous workers have identified a statistically significant positive correlation between hydrocarbon microseepage and vegetation anomalies over the Railroad Valley oil fields with Landsat Multispectral Scanner (MSS) imagery.

Several flight lines of high spectral and spatial resolution imagery in the visible, near infrared, shortwave infrared, and thermal infrared regions of the spectrum were flown with Geoscan's MkII Airborne Multispectral Scanner to determine if there was a mineralogical signature associated with the oil fields. The 24-channel scanner collected 8-m resolution picture elements over a swath of about 8 km. Image processing strategies were developed from a knowledge of the spectral curves of minerals in the laboratory. The results from processing Geoscans MkII data were also compared with those obtained from processing Landsat Thematic Mapper (TM) imagery over the same area.

An 8 × 6 km carbonate and iron anomaly was detected on the processed MkII imagery over the Trap Spring oil field. This anomaly may be related to hot spring activity, reported by other workers, that has formed extensive calcite deposits along faults. These calcite deposits can act as seals for the oil reservoirs. Further evaluation of the anomaly in the field and laboratory is being undertaken.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990