College of Geo-Exploration Science and Technology��Jilin University��Changchun 130026��China

In conventional seismic exploration��complex overburden prevents us from imaging the deeper under- ground structure��because near-surface velocity model cannot be efficiently simplified and accurately estab- lished�� The virtual source method provides a promising solution��which images below a complex overburden without the knowledge of overburden velocities and near-surface changes�� In this paper��the authors simulate the forward modeling under complex overburden with sources on the surface and receivers in the horizontal well�� and reset the real sources into the horizontal well using the virtual source method��which subtly avoid the distor- tion effects of the complex overburden�� Finally the underground structure can be imaged using Kirchhoff migra- tion��so the feasibility and advantages of the virtual source method are verified��