Abstract: It is difficult to predict reservoir with wave impedance inversion in areas where the sonic seismogram has no distinct differences between reservoir layers and non-reservoir layers. Curve reconstruction is used in the areas and obvious effects could be obtained. Since the traditional curve reconstruction method changes the original time-depth chart, horizons after inversion have fairly big errors with the original seismic horizons. To reconstruct type curves with a special approach, which makes the mean values of the type curves equal zero, can not only reveal the lithological changes of the targets, but also remain the actual geologic features represented by the original curves. Hence problems occurred in curve reconstruction can be well solved and the reliability of constrained log inversion be improved. The application of this technique in Putaogou region shows that the areal changes of four sand layers of Qiketai formation can be properly predicted in accordance with the geologic understandings.

Key words: reservoir prediction, well log, type curve reconstruction, constrained log inversion