Sedimentary architecture of gravity flow channel-lobe system of Block B in Baiyun Sag

Gravity flow deposits were well developed during the Miocene in Baiyun Sag, the Peral Mouth Basin, and they important oil and gas producing layers. Most previous works focused on mechanism of large-scale gravity flow deposits, while detailed work and architecture study are weak. Using core, drill, seismic, property and production performance, and so on, we anatomized the sedimentary architecture and connectivity of gravity flow channel-lobe system in 7 tiers for the Miocene ZJ460 layer in B Block of Baiyun Sag. Results show that the gravity flow channel-lobe systems were common in the study area, consisting of channel, levee, and lobe. The channel architecture can be divided into deep cut, cut-and-fill, and isolate types. The cut-and-fill type contain vertical agrradational, lateral agrradational, and diagonal agrradational stackings. Compensation agrradational style is usually developed in lobe, channel agrradational styles change from cut, cut-and-fill, to isolate styles from north to south and similarly from bottom to top in the study area. There were about 10 large channel-lobe systems. Channel-levee systems were developed in the north, and they gradually evolved southward into lobe. Chaneel-levee systems were parallel to each other. Several lobes overlay each other in the south, and formed into lobe zone. The channel-levee systems are connective in the north of study area. Lobes are also connective in the south. Channel and channel terminal lobe are well connective. The distance, scale of channel, and number of small channel-lobe systems between two adjacent large channel-levee systems controlled the connectivity quality. This work not only could directly help exploration of potential, but also provide guidance for the similar gas fields.