Summary of Research Methods About the Sequence Stratigraphy of the Fine-Grained Rocks

To analyze the distribution rule of high quality reservoir of fine grained rocks(FGR)of unconventional petroleum in the formation,domestic and abroad status of FGR sequence stratigraphy are researched and discussed.Resultsshow that a variety of methods are put forward to solve the difficulty of FGR sequence stratigraphy by the former scholars.Mineral composition,lithology,geochemistry,logging curves and bioturbation have been used to study the sequence stratigraphy of FGR,limited to the recognition of third-and fourth-order sequences.Division methods of the fifth-order sequence(parasequence)are proposed only by few scholars for FGR.It is identified and divided through the analysis of logging curves and organic geochemistry.This paper argues that the deep analysis of FGR sedimentary characteristics(lithofacies and causes)is the basis to solve its sequence division.Third-and fourth-order sequences division can be divided into two steps,vertical integrated division and transverse contrast tracking.In the stratigraphic framework of third-and fourth-order sequences,according to the lithofacies and in combination with the changes in mineral compositions,contents and ratios of geochemical elements,logging curves,and wavelet values,multi-method analysis and mutual verification are implemented in the division of parasequence.Eventually,from shallow water to deep water,from conventional glutenite to unconventional FGR,sequence framework can be built with all levels throughout the whole basin.