Applicant of Seismic Sendimentology Methods to Analyze Sedimentary Facies Evolution in A Fault Depression, Biyang, East China

Geng, Xiaojie; Zhu, Xiaomin; Dong, Yanlei; Lin, Changsong

Biyang depression, a small scale fault depression, locates in the east China and is mainly controlled by two boundary faults, Tanghe-Liyuan fault in the south and Liyuan-Biyan in the southeast. Because of the active tectonic movements and adjacent provenance, sand bodies less than 1/4λ of wavelength in thickness cannot be recognized effectively, which means that high resolution seismic interpretation of sedimentary facies on the plane is not easy to carry out. However, frequency division, phases shift and strata slices which are guided by seismic sedimentology theory provide a new view and viable method to solve this problem. (1) 24-32Hz is appropriate after frequency division processing and comparison which is neither too high to reflect isochronous sedimentary interfaces nor too low to highlight lithology. (2) In contrast to the zero-phase seismic model, the one after phase shift of 90° is more desirable for geologic interpretation of thin beds. On this condition, the positive events of seismic correspond with sandstone section in impedance curves while the negative ones are consistent with mudstones apart from interference, which facilitate seismic data to interpret lithology when calibrated by well loggings and cores. (3) Boundary of a near shore subaqueous fan was indicated by strata slices at intervals of 2 ms based on time model, the provenance of which is in the southwest; nevertheless, some distributed bodies intrigued us to seek for their source. Heavy mineral and conglomerate content support that they are slumped turbidite of the fan front due to gravity, they constitute the potential exploration belts together with distributed channels in middle fan for their high quality reservoirs.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013