Petroleum Geology of Kate Spring Field, Railroad Valley, Nye County, Nevada

FRENCH, DON E., Independent Geologist, Billings, MT

Kate Spring field was opened by Marathon Oil Company at the 1 Kate Spring well in December 1985. Because of poor market conditions and production problems, the well was not produced and the field was not confirmed until the Evans 1 Taylor well was completed in October 1987. As of August 1990, five wells have produced over 575,000 bbl of oil and have the capacity to flow at rates of several hundred to several thousand barrels per day. The oil is 10-12 degree API and is saturated with gas. The oil is used for road asphalt which limits its marketability. Production is from landslide blocks of Paleozoic and lower Tertiary strata that were emplaced in Miocene-Pliocene time, during the structural development of the Railroad Valley basin. The slide blocks are overlain by valley fill and prob bly correspond to similar blocks encountered within the valley fill at Eagle Springs field, adjacent

to the north. The pay is at a depth of 4500 ft. Kate Spring is a part of the fault-block bench that contains Eagle Springs field and is situated on the east flank of the Railroad Valley graben. There is east-west closure on the structure of the field, but the north end of the field has not been defined. The accumulation is sealed by the unconformity at the slide block-valley fill contact. The nature of the reservoir implies that the production is controlled by fractures and precludes useful extrapolation of any measurable matrix porosity. Based on volumetric calculations, the field will probably produce 2-3 million bbl of oil.

AAPG Search and Discovery Article #91010©1991 AAPG Rocky Mountain Section Meeting, Billings, Montana, July 28-31, 1991 (2009)