SEDIMENTARY CHARACTERISTIC AND PHYSICAL PROPERTY OF BRAID DELTA OF TRIASSIC IN LUNNAN REGION

There is wide distribution of Triassic formations in Lunnan area,the detailed research of the distribution of sand bodies and the characteristics of the reservoirs will be valuable to fine exploration in the area.On the basis of sequence frame,by means of the such data as outcrops,well logging and log,the lithology,texture and structure of Triassic formations and the physical property of the reservoirs are analyzed,the characteristics of deposition and reservoirs of Triassic formation in the area are summarized.The sedimentary system in Triassic formations in the area is alluvial fan-braided river dalta-lacustrine system,distributing from south to north,the main sedimentary bodies are braided river delta plain,braided river delta front margin,lakeside and shallow lacustrine ones.Reservoir sand bodies are dominated by branched alluvial channel and under water branched alluvial channel deposition.Pores are dissolved inter-particle and intra-particle ones,reservoirs are of good porosity and permeability.On plain,the physical property gets better southwards from north,vertically,the property gets worse upwards.In the area,reservoirs in the formations develop well,the key factors for reservoir to form are the conditions of trapping and hydrocarbon source.