Prediction of oil column heights in fault-controlled tabular reservoirs through time-frequency analysis based on improved generalized S-transform
The fault-controlled carbonate area in the northern depression of the Tarim Basin possesses abundant oil and gas resources.Identifying the oil-water contact(OWC)of fault-controlled tabular reservoirs is critical for their effective exploitation.However,OWC i-dentification through drilling is costly and challenging.In contrast,it is efficient to identify the OWC using geophysical methods.This study proposed a time-frequency analysis method based on generalized S-transform.As revealed by the joint analysis of extensive time-frequency analysis results of through-well seismic channels and production performance analysis data,the depth/time-varying main fre-quency of seismic data is positively correlated with the oil layer thickness.Hence,this study proposed to identify the OWC using the ab-normal inflection point of the energy envelope of seismic channel time-frequency gather.Experimental results demonstrate that oil layer thickness results obtained are uncertain,generally reliable,and reliable in the case of oil column height(OCH)<120 m,120 m≤OCH≤250 m,and OCH≥250 m,respectively.The method proposed in this study was applied to a fault fracture zone of an area of the Fu-man oilfield,obtaining the main predicted oil layer thicknesses between 200 m and 520 m,aligning with the actual exploitation results.Therefore,the method of this study can be employed to guide exploitation.
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