Sandy Debris Flow Sedimentary Characteristics and Patterns in the Meishan Formation of Northern Lingshui Sag, Qiongdongnan Basin

Abstract

Based on drilling core descriptions and micro sedimentary features, combined with regional paleogeographic features, imaging logging and 3D seismic attribute analysis, the sedimentary characteristics and representative identification mark of sand debris flow sandstone in Meishan formation of northern Lingshui Sag, Qiongdongnan basin are discussed in detail, and the sand debris flow sedimentary pattern in the study area is established. Meishan formation sandy debris flow sandstone in the study area is mainly consist of 2 lithological associations, thick massive siltstone to very fine sandstone without sedimentary structure on the upper part and silty mudstone, mudstone and siltstone interbeds with abundant contemporaneous deformation structure on the lower part, and the “mud-encased sand” structure in massive sandstone can be used as an important symbolic evidence to identify the sand debris flow deposits. The distribution of sandy debris flow sandstone is controlled by shelf slope break, and the area with relatively gentle, constructive slope, where the slope break line is characterized by “bulge” form to the sea, is the most favorable area for the development of sandy debris flow sandstone reservoirs.