Abstract: The second member of Shanxi formation is a marine facies braid river delta sedimentary system in Changbei gas field,Ordos Basin.In order to reveal small layer sand body development scale and space distribution in different time,in this paper,taking high resolution sequence stratigraphic analysis as foundation,facies-controlling modelling as guiding ideology,short base-level cycle as formation unit and equitime stratigraphy framework as constraint condition,sequence indicator simulation method is used to simulate four short sequence braid river delta distributary channels,submerged distributary channels and river mouth bar small layer sand body development scale and space distribution on the second member of Shanxi formation in Changbei gas field．Sand body space distribute simulation result shows the channel flows from north to south and SSC1─SSC4 short base-level ascending phase is the best phase for sand body development.The channel width turned wider,sediment thickness increased,physical property turned to better,and these are good for reservoir to develop,but in descending phase,channel width turned thinner and small layer sand body thickness decreased.The small layer sand body three-dimensional simulation result gets a good validation according to actual exploration in this area.

Key words: sequence indicator simulation, sequence stratigraphy, three-dimensional modelling, small layer sand body, Ordos