The invention discloses a prediction and evaluation technology of 3D seismic optimum time window river channel sand body reservoirs, belongs to the technical field of the prediction and evaluation of the 3D seismic reservoirs, and aims at solving technical problem that the river channel predictive resolution of the traditional methods is not enough. The technical proposal is as follows: the 3D
visualization scanning is performed on each reservoir at the interval of 1-2ms, the optimum time window is determined according to the scope shown by the target river channel, the corresponding subfield is
cut out, clairvoyance and scanning are carried out on the time window properties, such as root-mean-square amplitude,
wave impedance and the like, auto-tracing is performed, top surface and bottom surface are picked up, a time isopach map is calculated and converted into a sand body isopach map, a top
surface structure diagram is formed by time-
depth conversion, and the reservoir physical properties are evaluated by
curve reconstruction, thus realizing the prediction and evaluation of the plane morphology, longitudinal thickness and the reservoir physical properties of the river channel sand body. The method adopts the optimum time window to effectively inhibit interference, is applicable to various data volumes, and can effectively predict and evaluate a thin river channel sand body with the thickness far less than 1 / 4 of a
wavelength under the condition of frequent
interbedding of sand and mudstone, the thin river channel sand body comprises the river channel sand body which is not corresponding to
wave crest or
wave trough, and the method has good application effect in
petroleum exploration and development.