AAPG Studies in Geology No. 48 / SEG Geophysical References
Series No. 11, Chapter 15: Numerical Identification of Microseeps in Surface
Soil Gases of Western Venezuela, and Its Significance for Hydrocarbon Exploration, by
Francisco Callejon and Hans H. von der Dick, Pages 381 - 392
from:
AAPG Studies in Geology No. 48 /
SEG Geophysical References Series No. 11: Surface
Exploration Case Histories: Applications of Geochemistry, Magnetics, and Remote Sensing,
Edited by Dietmar Schumacher and Leonard A. LeSchack
Copyright © 2002 by The American Association of Petroleum Geologists and the
Society of Exploration Geophysicists. All rights reserved.
Chapter 15
Numerical Identification of Microseeps in Surface Soil Gases of Western Venezuela,
and Its Significance for Hydrocarbon Exploration1
Francisco Callej
n
PDVSA Exploracin y Produccin
Laboratorio Geolgico
Puerto La Cruz, Venezuela
Currently with Petroleum Systems and Geochemistry Institute, University of Houston,
Houston, Texas, U.S.A.
Hans H. von der Dick
ChemTerra Exploration (CTE)
Roetgen, Germany
ABSTRACT
A soil-gas survey was conducted over a number of prospects in the plains
("llanos") and the Andean foothills regions in the Barinas-Apure Basin of
western Venezuela. Initial attempts to numerically distinguish a seep-gas signal from
background gases failed. Basic statistics allow only a tenuous differentiation between
background gases and possible seep-gas populations having slightly anomalous
hydrocarbon-gas concentrations. Further data processing on this specific population using
advanced vector analysis facilitated the discrimination within a variety of soil-gas
sources and distinguished suites of samples with weak, seepage-related surface-gas
patterns that resemble normal condensate/wet-gas sources at depth.
