APPLICATION OF SEQUENCE STRATIGRAPHY TO THE STUDY OF DIAGENESIS OF SILICICLASTIC ROCK—Take the Lower Tertiary of Ya13-1 gas field as an example

On the basis of comprehensive study of the single well section and the sequence analysis of the link-well seismic cross-section in Ya13-1 gas field in QDN basin,South China Sea,this paper analyzed the sedimentary and diagenetic marks of various system tracts by combining the sedimentary process analysis and the diagenesis analysis of the system tracts in the sequence.On the unit of the third-class sequence diagenetic environment,including reservoir-forming backgroud surroundings and the origin water chemistry of the reservoir,it summed up the diagenetic unit model of the lower Tertiary Yacheng Fm and Lingshui Fm which are comparable to the system tracts.It also inquired into the interact relation between the sedimentary system tracts and the diagenesis and its influences on the sandstones reservoirs.