Research and new acquaintance of seismic calibration for complex fault block reservoir: A case study from Zilaitun area of Dagang oilfield

This study analyzes the seismic calibration of the Zilaitun complex fault block oil field, and puts forward six measures to clarify the complex well-to-seismic relationship.The following conclusions and inferences are drawn: ①there is a stable reflection seismic event between the bottom of Z5 and Ek₂¹ in the study area, which occurs because of composite wave superposition, and the bottom interface of Z5 corresponds to trough reflection with normal polarity; ②taking the target area of the Zao32 well as an example, according to logging facies, the causes of the second member of the Kongdian formation depositing first and then uplifting, and the thinning of the Z5 thickness in uplifted areas are determined; ③the calibration strategy of continuous and complex formations, and last inclined well verification is adopted to realize well seismic calibration in the complex structural area; ④by discussing the calibration function of stretch/squeeze movement, we suggest that the validity of the function should be based on the overall coincidence of logging and seismic facies; ⑤the differences between the seismic velocity and conversion velocity from AC logging are analyzed, using the advantage of the dense well networks, and calibration verification is performed using the statistics of multiple well points; and ⑥calibration can be divided into stratigraphy calibration and reservoir calibration, and the thin interbed reservoir can use the 90° phase-shifting technique.The research results can serve as a reference for fine reservoir descriptions in the Dagang oilfield, potentially enabling the seismic calibration of other complex fault blocks.