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An introduction to seismic exploration of the Micang-Dabashan foothill belt in the Sichuan Basin

Wang Jingbo, Qi Zhongshan, Jing Penggui, Zheng Tianfa, Li Yanqi, Yuan Maolin and Xiao Liang
An introduction to seismic exploration of the Micang-Dabashan foothill belt in the Sichuan Basin
Interpretation (Tulsa) (November 2018) 6 (4): SM39-SM50

Abstract

Geologic studies indicate that the platform-margin reef-shallow facies in Permo-Triassic marine strata in the Micang-Dabashan foothill belt in the Sichuan Basin are favorable exploration targets for oil and gas exploration. However, the typical dual-complexity problem (complex surface condition and subsurface structure) brings a great challenge for seismic technology targeting of those potential oil and gas reservoirs. To overcome this problem, varieties of advanced seismic acquisition and processing methods have been used to improve the imaging quality of piedmont seismic data since 2000. Some improvements have been achieved: The reflection waves from the far offset and deep layer can be acquired in shot gathers from limestone outcropped areas, and the signal-to-noise ratio (S/N) of reflection and diffraction waves in the stack section has been enhanced significantly so as to reveal amounts of valuable geologic information. The resolution and the S/N of seismic migration imaging for the strong fold zone in marine strata have been improved partially, so that the structure of the step-fault zone and the enveloping of gypsum rock are clearer than those revealed by the old seismic section. Even so, actual drilling data demonstrate that the subsurface structures of the foothill belt are far more complex than those revealed by the current seismic imaging results. Therefore, postdrilling evaluation for the validity of seismic techniques implemented in the Nanjiang and Zhenba piedmont zone has been carried out. The results indicate that the current acquisition scheme and processing workflow cannot completely fulfill the requirements of high-precision velocity modeling and migration imaging of complex structures (such as footwalls of thrust fault and small-scale fault blocks) in the piedmont zone, especially when the rugged surface and the widespread limestone outcrop appear simultaneously. Finally, we have developed some potential needs of seismic theories and techniques in the foothill belt, including seismic wave propagation, acquisition, and processing technology.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 6
Serial Issue: 4
Title: An introduction to seismic exploration of the Micang-Dabashan foothill belt in the Sichuan Basin
Affiliation: Sinopec Exploration Company, Chengdu, China
Pages: SM39-SM50
Published: 201811
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 22
Accession Number: 2019-006693
Categories: Economic geology, geology of energy sourcesApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Special section; Foothills exploration
Illustration Description: illus. incl. 2 tables, sects., geol. sketch map
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201906
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