Passive Seismic (IPDS) Case Studies in Exploration & Monitoring Areas

Karim Akrawi Phd¹ and Ahmed A. Khouri^2
1Snr. Petroleum Geologist, Abu Dhabi, United Arab Emirates
²Team Leader Exploration & Geophysics, Abu Dhabi, United Arab Emirates

The observation of passive seismic spectroscopy results in unique signals of earth tremor phenomena over hydrocarbon reservoirs. This has been reported in more than ninety (92) case studies worldwide since 1997.
Infrasonic Passive Differential Spectroscopy (IPDS) also called Passive Seismic Spectroscopy is a departure from classic reflection seismic for direct hydrocarbon reservoir indication (DHI) and field monitoring.
The technique is based on the principles of non-linear behaviour of multiphase fluid systems in porous media. Hydrocarbons in the pore system can be detected at surface as a characteristic deformation of the normal signature of the natural earth's noise signal in the low frequency range between 0.1 Hz and 10 Hz.
This IPDS signal signature is not effected by any rock types (salt, igneous, coal layers & etc.). The signature is only depending on the presence of absence of hydrocarbons in the rocks matrix.
IPDS technology can be used to monitor hydrocarbon reservoirs from the surface. The technology is gaining momentum and its potential in field monitoring and exploration areas is now strongly being realized by oil community.
The objectives of the Passive seismic IPDS campaigns was to run such surveys as exploration, delineation and reservoir monitoring tool under different geographical onshore conditions and in addition, to provide information concerning detailed aerial hydrocarbon and vertical distributions. Up to date, 92 surveys have been executed worldwide (Nine of which for ADCO).
Over 15,000 data sets were acquired – worldwide areas. The profiles pass through over hundreds of exploration, appraisal, producer, and injector wells. The correlation with proven hydrocarbon cumulative net pay zones from these wells and Geospectra IPDS data shows a correlation coefficient more than 80% (ADCO).
The technology appears to be highly promising, time and cost saving and environment friendly. More work is required to identify depth & stack reservoirs.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece