Typical Tectonic Styles of Strike-Slip Zone and Their Significances on Hydrocarbon Accumulation in Eastern Laizhou Bay, Bohai Offshore Area of China

Abstract

Laizhou bay sag as an important oil and gas region is located in the southern part of Bohai sea region. The east branch of Tan-Lu fault which is a typical dextral strike-slip fault belt striking NNE direction during Cenozoic went across eastern of Laizhou bay sag.sustained multiple activities of Tan-Lu fault in Cenozoic and the episodic rifting processes of the basin joint controlled the typical tectonic styles in eastern Laizhou bay, which includes inverted structure, tilted fault blocks, salt diapir structure, volcanic structure, etc. The various tectonic styles lead to different types of traps and provide the preservation conditions of hydrocarbon in strike-slip zone in the strike-slip zone. In Kenli11~17 region which placed in south of the study area, the strike-slip faults control salt diapir structure development position. The salt pierced structure as salt wall, salt stock transited to salt pillow and salt anticline from south to north in Kenli11~17 region of the strike-slip zone. Different activity intensity of the salt diapir leads to different types of traps. For example, salt pierced structure leads to salt blocked traps which distribute in south of Kenli11~17 region, the salt pillow and salt anticline structures lead to anticline traps on salt and stratigraphic onlap traps at the side of the salt. In Kenli6 region which placed in north of the strike-slip fault belt, Tan-Lu east fault branch main activity periods are the end of Eocene, the late Oligocene and Neogene. the compression deformation lead by strike slip motion formed reverse anticline traps between strike-slip faults. In addition, the stretch component of dextral strike-slip movement leads to a series of tilted fault block traps. As well, the long-term activity strike-slip faults and basement faults are the main channel of the volcanic eruption. The volcanic structure distributes along the basement faults and strike-slip faults. We can identify volcanic structure from seismic profiles and seismic slices. The volcanic rocks widely distributed in late Ed and Ng which provide a regional caprock for Kenli6 region which lead to the oil and gas enrichment in Paleogene in Kenli6 region.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015