Soil-gas Hydrocarbon Pattern Changes During a West Texas Waterflood
Gary K. Rice, John Q. Belt, Jr., George E. Berg, 2002. "Soil-gas Hydrocarbon Pattern Changes During a West Texas Waterflood", Surface Exploration Case Histories: Applications of Geoschemistry, Magnetics, and Remote Sensing, Dietmar Schumacher, Leonard A. LeSchack
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Soil-gas light-hydrocarbon (methane through n-butane) pattern changes were measured annually for five years over part of an oil field in Brown County, Texas, U.S.A. During the monitored period, additional wells were drilled, depleted, and subjected to a waterflood. Annual soil-gas measurements detected changes in light-hydrocarbon concentrations attributable to these field operations.
Soil-gas sample reproducibility was important for comparing annual data. Background concentration, which was the reference for all measurements, reproduced within 20% during the 5-year monitoring period.
An oil well drilled on the west side of the study area depleted within two years. During that time, near-surface soil-gas hydrocarbon concentrations also decreased. After depletion, this well became the waterflood injection well. Soil-gas hydrocarbon concentrations increased near the injection well within one year after the waterflood began. While the water-flood continued, soil-gas hydrocarbon concentrations increased again the following year.
Calculated hydrocarbon vertical migration rates were 0.6–2 m/day. This result can be explained by an effusion mechanism whereby gases escaped the petroleum reservoir and migrated vertically through the water table in a gaseous phase.
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Surface Exploration Case Histories: Applications of Geochemistry, Magnetics, and Remote Sensing provides an overview of successful applications of surface exploration methods. Through a series of independent case histories, this volume presents clearly documented evidence that demonstrates how surface exploration methods can significantly reduce exploration risk and finding costs: geochemical, magnetic, and remote sensing. The 19 chapters in this volume reflect the broad scope of applications for these methods: frontier basin reconnaissance, prospect development, prospect evaluation, and field development and production. The case histories span the globe: 1. North America 2. Africa 3. South America 4. Europe 5. Middle East 6. Australia. This book will interest explorationists and managers who seek to get the most out of each exploration dollar.