Maokou Sedimentary Microfacies Of Shunan Region

This thesis focuses on Shunan area to research the stratigraphy and sedimentary facies of Maokou Formation, by making full use of logging,drilling and core data, and by the guidance of theories and methods of modern sedimentology, combined with regional survey data, analyse the background of regional sedimentary, re-determine the deposition pattern and clarify the main types of sedimentary facies in the region. Through the analysis of the type of lithological association, sedimentary fabrics, fossil assemblages, deposition mechanism and so on of Maokou Formation in area, the study proposes that the Shunan area’s depositional stage of Maokou Formation is characterized by the development of open platform, further can identify the three sub-facies those are intra-platform shoal, beach interact sea and open sea, and six micro-facies.In the logging sequence of Carbonate strata, the GR curve can be more accurate to reflect the link between rock structure and electrical properties of the curve, and then on its basis to complete the division of sedimentary facies. Using Log response of the core segment established the standard of grainstone and non-grainstone in Shunan area, and explain the lithology of non-coring wells in the region.Based on sedimentary facies’types of single well, the comparison of three north-south well-tie’s stratigraphy and sedimentary facies shows:the horizontal comparison of sedimentary facies shows that the development of grain shoal is obviously layered; in the Maokou period, the changes of sea level makes the geological period mainly develops open sea facies; the development of shoal body is jointly controlled by the ups and downs of the ancient landform and Transgression-Regression, the the ancient landform highlands and the stage of transgression and early regression is most conducive to the development of grain shoal.In the carbonate platform of continental sea, can use the thickness of grainstones to recover the microrelief of exposed shoal period approximately. In Shunan area,the early exposure time of grainstones in every section of Mao II member is middle-short term, the development degree of pinhole grainstones dissolved by atmospheric fresh water and the ancient landform closely related, so the development area of the pinhole grainstones is the ancient landform highland of deposition that develop the sedimentary microfacies of high-energy shoal.