Summary

The paper presents multicomponent seismic acquisition test and the preliminary results for the clastic reservoir in Guangan structure of Sihcuan Basin. In 2005, our company acquired 2D three component data with high quality with the digital geophone, and applied micro-VSP method to investigate shear wave near-surface velocity structure. X component and Y component seismic section obtained by the multicomponent data processing technique plausibly reflected the formation anisotropy, and the lithology and fluid detection study can be completed by the joint interpretation of the PP-wave and PS-wave reflection sections. P-wave and S-wave acoustic impedance inversion results reflected the reservoir properties accurately, and the inversion results are consistent with the drilling results. The present study results indicate that the multicomponent seismic will become a practical and effective method for lithology and fluid detection.

Introduction

In recent years, along with that the lithology oil/gas reservoirs are gradually becoming the oil/gas exploration emphases and the advancement of the seismic data acquisition and processing techniques, multicomponent converted wave seismic are attached more and more importance for its unique exploration ability and rich information obtained. Compared with the conventional P-wave exploration, the converted wave (PS wave) exploration has both advantages of the P-wave and S-wave exploration.

First, the field operation of the converted wave is simple and easily implemented; Compared with S-wave exploration, the converted wave exploration is more cost-effective and can provide more information; secondly, PS wave can improve the imaging ability of some specific formations; thirdly, the joint interpretation of PP-wave and PS-wave section can provide more reasonable and abundant parameter estimations, and greatly improve the lithology and fluid detection ability and reduce the nonuniqueness of the seismic data interpretation; fourthly, compared with P-wave, the converted wave are more sensitive for anisotropy.

In 2005, our company acquired the converted wave seismic data of high quality using three component digital components in Guangan structure of Sichuan basin, which main aim is researching the multicomponent seismic exploration methods and application effects in continental clastic rock reservoir area. In the paper, the author mainly introduced the techniques and the geologic results gained in this exploration case.

Geologic Surrounding and Seismic Data Acquisition

Guangan structure is regionally located in the eastern part of the gentle structure belt in the palaeohigh of the central Sichuan, and is a local low relief anticline structure. The main structure is lain between two faults, the largest horizontal stress stretch along near east-west direction. Well GA 2 is the first commercial gas well which primary productive reservoir is Xu 6 formation of the Tertiary, the well depth is about 1700-1840m.

In this area, Xu 6 formation is primarily comprised of the consolidated sandstone, the upper and lower productive reservoirs are relatively high porous sandstone which thicknesses are 17.5m and 11.5m respectively. 2D three component seismic exploration was carried out in order to researching this new exploration field and test the application effects of multicomponent seismic new technique. Both P-wave information and the converted wave information must be acquired in three component seismic exploration.

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