LOGGING FACIES, SEISMIC FACIES AND SAND BODY DISTRIBUTION OF SHAXIMAO FORMATION IN THE MIDDLE WESTERN SICHUAN SAG

Through a synthetical analysis for the connexion of logging facies, seismic facies and sedimentary facies , the authers set up the relationship between the logging facies, seismic facies and sedimentary facies and reveal the sedimentary development law of the Shaximiao Formation, Middle Jurassic in the middle Western Sichuan Sag. That is, the evolution of sedimentary facies is a deepening process from a shallow lake to a seimi deep lake in Lower Shaximiao Formation, then, in the Upper Shaximiao Formation, the lake water becomes shallow and the sedimentary facies types change relatively, from the bottom to the low middle section and middle section till the top section, the sedimentary facies develop from a shallow lake to a delta front, intensely prograding delta plain and the meandering river. Therefore, these changes compose a complete prograding retrograding sedimentary sequence from a lake to a river. These provide the basis for pridicting the distribution law of sand bodies of the formation in the Middle Western Sichuan Sag.