Sedimentary characteristics and significance in hydrocarbon exploration of sandy debris flow in Meishan Formation of the northern Lingshui Sag, Qiongdongnan Basin

Abstract

Through comprehensive analysis of core description, core slice observation and grain size data, in combination with regional palaeogeomorphology and seismic facies study, the sedimentary structure characteristics and its identification mark of the Meishan Formation sandy debris flow in northern Lingshui Sag of Qiongdongnan Basin were discussed in details.The sedimentary model of sandy debris flow in the study area is then established based on its sedimentary environment and characteristics.Two main lithological associations developed in sandy debris flow sedimentation in the Meishan Formation, which were thick massive bedding siltstone to very fine sandstone without sedimentary structure and silty mudstone, mudstone and siltstone interbeds with abundant contemporaneous deformation structure.These lithological associations formed during the process when the sediments of the delta front and the pre-delta on the shelf went frozen sliding as whole and collapsed and deposited again as sandy debris flow.Their distribution was mainly controlled by the shelf break and roughly distributed parallel to the shelf break showing tongue shaped outline.Combined with regional hydrocarbon accumulation elements study, it was thought the sandy debris flow sandstone in the study area could form lower-generation and upper-reservoir type lithological reservoirs with faults connecting to deep source rock, and this would be an important exploration break through to realize the exploration breakthrough in finding large and medium-sized oil and gas reservoirs in Qiongdongnan Basin.

Keywords

• sandy debris flow
• qiongdongnan basin
• lingshui sag
• sedimentary structure
• significance of hydrocarbon exploration