| Weixi’nan low uplift is an important oil and gas accumulation area in Beibu Gulf Basin, which extends in
NEE-SWW direction, and is gentle in the north and steep in the south, respectively connected with No. 2 fault zone
dominated by flower-like or “Y” structural style and No. 3 fault. The serious stratum denudation and the complex
structural features restricted the accurate understanding of regional oil and gas accumulation. Based on the latest
exploration progress in this area, the complex structural phenomenon of extension, strike-slip, and compression coexisting
in the shear stress field environment of Weixi’nan low uplift and its periphery is analyzed through paleogeomorphic
restoration, elliptical stress mechanism analysis of strike-slip strain generated by right-hand couple and structural
physical simulation. It is considered that: (1) Under the action of regional dextral shear stress, the deformation
characteristics of the principal displacement zone (PDZ) and the en echelon shear faults in the shear zone in the simulated
effective area are similar to those of the No.2 fault zone. (2) The fold axes of multiple anticline and syncline alternating
fold belts forming in oblique intersection with the PDZ are in NNE direction, which is the same as the fold trend of
Weixi’nan low uplift and its periphery. (3)The stratigraphic denudation area in Weixi’nan low uplift and its periphery is
mainly controlled by the fold at the end of Oligocene. It is pointed out that the fold and strike-slip fault zones formed
under the control of dextral shear stress at the end of Oligocene are the key areas for oil and gas exploration in the next
step. |
