Strike-slip structures and hydrocarbon accumulation in complex fault blocks in Subei Basin

Abstract

The research on basin formation and hydrocarbon generation and accumulation in the Subei Basin was carried out based on structural geometry and kinematic analyses. The Subei Basin has experienced three evolutionary stages: rift-subsiding, fault depression and depression. During the tectonic development dominated by extension and tension in the Himalayan period in the eastern China, there were echelon, pinnate, broom-like and other strike-slip fault combinations in the basin, and it has been found that oil reservoirs and traps were directionally arranged and closely related to strike-slip actions. The extension and strike-slip process controlled basin formation and evolution, which resulted in the oblique arrangement of sags, and formed multiple hydrocarbon generation sub-sags in each sag. The differential development characteristics of basin-controlling and sag-controlling faults controlled the main migration directions of oil and gas, forming three migration modes. The oil and gas migration patterns under the control of echelon and pinnate sag-controlling faults were quite different. The fault transform zone and structural high zone formed by secondary fault combination and formation deformation are important places for oil and gas enrichment, and many types of fault nose and fault block reservoirs were formed.

Keywords

• extension and strike-slip
• fault transform zone
• structural high zone
• oil and gas enrichment
• subei basin