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7th Middle
East
Geosciences Conference and Exhibition
Manama, Bahrain
March 27-29, 2006
Model
for Low Frequency Pore Liquid Oscillations Observed in
Hydrocarbon
Microtremor
Analysis (HyMAS)
1 Spectraseis Technologie AG, Giessereistrasse 5,
CH-8005 Zurich, Switzerland, phone: +41-433213840, fax: +41-433213841, [email protected]
2 Physics Department, University of Zurich, Zurich, Switzerland
Hydrocarbon
Microtremor Analysis (HyMAS) is an innovative passive technology identifying the
hydrocarbon
content of
geological structures by analyzing low frequency seismic signals.
Hydrocarbon
indicating information is extracted from
spectral modifications of naturally occurring seismic background noise waves in the 0.01 – 10 Hz range passing through
hydrocarbon
bearing porous structures.
In this paper, a simple description of this reproducibly observable phenomenon in terms of a one -dimensional linear
model
of an oscillating liquid filled porous medium is presented and its relevance for an explanation of the underlying basic HyMAS
signal creating mechanisms and related parameters are discussed. Observed values of about 3 Hz for the oscillation and
2·10-6 m/s for the amplitude of the vertical surface movement velocity could be reproduced by introducing realistic
parameter values for the geophysical properties in the
model
.
hydrocarbon
indicator, HyMAS is an ideal complement to 2D- and 3D-seismic structural imaging technologies.
Numerical modeling of suitable geological structures both in the macroscopic as well as in the microscopic domain shows
how the seismic background noise spectrum can be modified in a different way when interacting with geological structures
containing
hydrocarbon
filled pores compared to interacting with similar structures not containing hydrocarbons. Pure
HyMAS data can already be used to qualify areas for adequate geological programs. Integrated with existing geophysical
and geological data. HyMAS allows for cost and time saving optimization of well placement during exploration, appraisal
and production. HyMAS is fast, safe, cost-effective and environmentally unobtrusive.