Exploitation of oil in a volcanic cone by horizontal drilling in the Elaine field, south Texas

Conference · Fri Mar 01 04:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:7170946

Martinez, P A; Kushner, P L; Harbaugh, J W

The Uvalde volcanic field west and southwest of San Antonio contains many buried volcanic cones that offer attractive places to exploit with horizontal drilling. These buried cones were formed by eruption of basaltic flows and cinders during the Cretaceous when the Austin Chalk and immediately overlying strate were deposited. The cones vary in size, some being as much as 2 mi in diameter and 1000 ft in vertical dimension. During eruptions, flows and ejecta reacted with sea water, producing intermixtures of basaltic material and limestone. These cones provide attractive targets for oil exploration. The Elaine field about 90 mi southwest of San Antonio is associated with a buried volcanic cone that is now being exploited with horizontal drilling. Horizontal Drilling and Production, Inc., ('HDP') drilled the Autumn 1 as the initial horizontal well at Elaine. A vertical hole was drilled through the cone and underlying Austin Chalk, reconfirming the presence of the oil zone at the contact between volcanics and chalk. Moving back up the hole, a cement plug was set within the volcanics, and a horizontal hole was directed on a N 70W azimuth. The inclined hole's vertical angle had progressively decreased with distance to about 30{degree} from the horizontal when the oil zone was reentered. The hole's inclination continued to decrease within the oil zone, becoming horizontal after about 600 ft. With further distance, the hole passed beneath the oil zone, where its inclination was then reversed so that it climbed gradually and reentered the oil zone before reaching its terminal distance of 1500 horizontal feet. The well was completed on August 17, 1990, with an indicated initial production of 1609 BOPD.

• OSTI ID: 7170946
• Report Number(s): CONF-910403--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 75:3
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020300* -- Petroleum-- Drilling & Production
CRETACEOUS PERIOD
DEVELOPED COUNTRIES
DIRECTIONAL DRILLING
DRILLING
EXPLOITATION
FEDERAL REGION VI
GEOLOGIC AGES
GEOLOGIC DEPOSITS
IGNEOUS ROCKS
MESOZOIC ERA
MINERAL RESOURCES
NORTH AMERICA
OIL WELLS
PETROLEUM DEPOSITS
PRODUCTION
RESOURCES
ROCKS
TEXAS
USA
VOLCANIC ROCKS
WELLS