--> ABSTRACT: Permanent Reservoir Monitoring Onshore Using Simultaneous Active and Passive Seismic, by Forgues, Eric; Rebel, Estelle; Denis, Michel; Coton, Julien; #90141 (2012)

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Permanent Reservoir Monitoring Onshore Using Simultaneous Active and Passive Seismic

Forgues, Eric *1; Rebel, Estelle 1; Denis, Michel 1; Coton, Julien 1
(1) Land Acquisition Division, CGGVeritas Services SA, Massy, France.

Time-lapse seismic monitoring of reservoirs onshore faces a significant challenge in terms of 4D repeatability. Variations in near-surface conditions, both daily and seasonal, can introduce travel time and amplitude effects which can obscure the 4D signature of the reservoir. A solution to this problem is to use a permanently installed system with both the seismic sources and receivers buried below the weathering layer.

Active seismic methods can provide access to amplitude changes and timeshifts at the reservoir which can be related to the movements of fluids, it can be difficult to disentangle this from the affects of pressure and temperature. Further insight may be gained from the recording and interpretation of microseismic events, which could be easily achieved with a permanent system.

A continuous 4D seismic monitoring project using such a system with novel piezoelectric mini-vibrator sources and associated buried sensor arrays has been conducted for Shell Canada. The high accuracy of the acquisition system allowed the continuous and simultaneous measurement of both the seismic signal (active part) and the microseismic events (passive part). The 4D variation could be measured on a weekly or even daily basis.

Transit time and amplitude variation through the reservoir could be measured on a weekly or even daily basis. The time variations were observed where steam was injected while the amplitude variations were only present where oil was produced. Additionally, we were able to simultaneously detect and localize microseismic events with the system.

We present the initial results of the this project and note that further work should be done to link 4D attributes measured with fluid, pressure, temperature and geomechanical effects induced by steam injection and oil production.


AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain