Research on Seismic Identification Technology for Thin and Narrow Channel Wells in S Formation, a Development Zone Changyuan Oilfield Daqing

The S Formation in the A Development Zone of Daqing Changyuan Oilfield has developed a delta front subfacies underwater distributary channel sandbody reservoir. However, the S Formation channel sand body is affected by the narrow width on the plane, thin thickness in the vertical direction, and interactive sedimentation with sheet sandbodies, which makes it difficult to accurately predict the boundaries, scale, and direction of the narrow channel sandbody using conventional seismic attributes. This restricts the scale increase and production of the S Formation reservoir. To this end, a joint identification technology for thin and narrow river channel well seismic in the S Formation is proposed. Firstly, construct a seismic forward geological model of the S Formation and identify the characteristics of the river sandbody wave group on the seismic profile; Secondly, establish a well seismic combined isochronous stratigraphic framework that approximates the sedimentary unit level, and use the stratigraphic slicing optimization technique based on the Analytic Hierarchy Process to analyze the stages of narrow channel sandbodies; Finally, using the continuous wavelet frequency division transform technique, the seismic data volume is transformed from the time domain to the frequency domain. Three seismic single frequency volumes that can represent the effective prediction of reservoir thickness in the study area are selected and fused to form a new seismic data volume. The root mean square amplitude attribute is extracted to accurately predict the threshold value of river sandbody boundaries. The results indicate that when the sandbodies in the S Formation channel develop, there is a reflection characteristic of “peak amplitude energy enhancement” on the seismic profile; The stratigraphic slicing optimization technique based on Analytic Hierarchy Process can effectively identify the evolution stages of narrow channel sandbodies; The fusion technology of three single frequency body attributes selected in the frequency domain can accurately identify the boundaries, scale, and direction of river sandbodies between wells. The research results have guided the large-scale submission of proven geological reserves in the S Formation of the A development area, achieving good results.