In
    marine seismic exploration, OBC bin fold is impacted by the depth and velocity
    of target layer, as well as the water depth and velocity, etc. Therefore, on
    the basis of the Snell’s law, the authors derive a quartic equation of OBC reflection
    point coordination of the model with two horizontal reflection interfaces. From
    the quartic equation, accurate solutions of the reflection point are obtained
    and determined analytically based on the different actual conditions, expressed
    as a function of water velocity, water depth, offset, underwater target depth
    and velocity at the reflection point. The new method is adaptive to the
    variation of water depths and target-layer velocity and improves the
    calculation efficiency and accuracy of OBC bin fold.