In 2004, Anadarko Petroleum Corporation initiated a comprehensive geophysical program to evaluate how to best image over-pressured tight gas sands in the East Texas Basin, USA. These Upper Jurassic sands have a low acoustic impedance contrast with the encasing shales leading to a weak P-P reflectivity series. This program included the following elements: 3-D Seismic Imaging. A 72 square mile conventional 3-D seismic survey was recorded with single-component analog geophones. The seismic source consisted of buried explosive charges infilled as needed with vibroseis source points, Multicomponent Seismic Imaging. A 9 square mile three-component 3-D survey was recorded with a static spread of Vectorseis accelerometers centrally embedded within the larger conventional 3-D survey. All source points for the conventional P-wave survey were recorded concurrently by the Vectorseis spread, Multi-offset, multicomponent VSP survey. The objectives of the VSP program were (a) to provide direct observation and comparison of P-P versus P-S imaging of these tight gas sands, (b) to provide calibration of the P-P and P-S surface seismic data to well log data, and (c) to provide a means of registering the P-P and P-S data. The VSP program, presented in an accompanying poster display, provided strong encouragement for the use of 3-D surface multicomponent seismology to image these tight gas sands. The P-P 3-D survey was also quite successful, producing significantly improved imaging of the target interval compared to previous 2-D data. However P-S imaging of these deep targets (10,000' - 16,000') was disappointing, with poor signal/noise, limited bandwidth, and image quality inadequate for mapping purposes. In this paper we present the P-P and P-S 3-D seismic results, and discuss possible factors that may have influenced the multicomponent imaging results.


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