Abstract:

According to the tuning principle of reflection of thin layer,seismic reflection coming from each thin layer has a corresponding special frequency component in frequency domain,which reveals the thickness of the thin layer.The frequency spectrum imaging technique transforms seismic data into frequency domain by using the time-frequency analysis method of wavelet transform.Amplitude spectrum describes the changes of layer thickness,while phase spectrum shows the lateral continuity of geological body.In reservoirs prediction,attenuation gradient of high frequency energy can be extracted and measured to predict oil-bearing properties of reservoirs.The braided channel sandbodies in the Cretaceous Yuyang Formation are the main oil-bearing stratum in Caixue structure at the south-western edge of Jianghan basin and their optimum response of frequency spectrum is between 25 Hz and 45 Hz.The prediction with spectrum imaging technology shows that favorable oil-bearing zone is located at the east of Caixue structure and is distributed in a NNE direction.Drilling has discovered industrial oil flow,showing a high consistency with the prediction results.

Key words: wavelet transform, attenuation gradient, spectrum imaging technology, reservoir prediction, Jianghan Basin