Sedimentary characteristics and favorable reservoir prediction of Longtan Formation in Huangqiao area, Jiangsu Province

Effected by the fold and uplift of the Indosinian movement,the Longtan Formation in the Lower Yangtze area was locally eroded.Drillings revealed that the lateral variation of the residual Longtan Formation sandstones had changed obviously.The comprehensive analysis of cores,log curves and 3D seismic interpretations showed that the Longtan Formation was a delta front sedimentary sequence,with the characteristics of coarsening-upward,and the types of sand body were mainly frontal sheet sand and distributary channel sand in Huangqiao area,Jiangsu Province.The results of logging constrained impedance inversion and porosity inversion showed that high-impedance sandstones spread in three delta front flower-like bodies in the plane.The average porosity of the Longtan Formation sandstones ranged from 4% to 10%,and became bigger as the present depth increasing.