Fig. 1

Structural location of the Gudong oilfield in Zhanhua Sag, Bohai Bay Basin, China. (a) Structural location of the Zhanhua Sag in the northeastern Jiyang Depression, Bohai Bay Basin, China. (b) The pink area is the Gudong Oilfield in the northeastern Zhanhua Sag. (c) The location of the block 6 and block 7 in Gudong Oilfeild. d. The well array in block 6, Gudong Oilfield. (modified from Qiao et al.,22) Figures were produced by CorelDRAW Graphics Suite X9 (https://www.corel.com/en/).