The 90°phase conversion and slicing techniques are two important seismic sedimentology research approaches.However

tracing and correlation of small-scale isochronal seismic interfaces are challenging in reality

as the 90? phase conversion technique could not correctly reflect the relationship between lithology and seismic responses.The solution to the problem is to use SpecDecomp technology to trace the small-scale isochronal seismic interfaces and then improve seismic resolution with drilling-constrained mix-phase wavelet deconvolution technology while ensuring a rational signal-to-noise ratio.During the process

the seismic section is dephased and geological information is extracted from seismic responses.The new approach had been applied to the study of the 9

th

sand group of the fourth member of the Xujiahe Formation (T

3

x

4(9)

) in Xinchang area of western Sichuan Basin.The result shows that sandbodies are well developed inside the group and are superimposed with one another as the underwater distributary channels moved and shifted frequently.According to the extension direction of the sandbodies

the authors judge that the Longmengshang island group in the north is the provenance.The central Xinchang area contains the thickest sandbody of all as a result of the superimposition of multiple phases of underwater distributary channels.As the compaction resistance of conglomerate can protect the pores of sandstone

the sandbodies in areas with superimposed underwater distributary channels have favorable physical properties

therefore are considered potential exploration targets.