ABSTRACT: Structural evolution and petroleum systems of the Cuu Long and Nam Con Son basins offshore southern Vietnam

Lee, Gwang Hoon¹ and Joel S. Watkins²
(1) Kunsan National University, Kunsan, South Korea
(2) Texas A&M University, College Station, TX

Multi-channel seismic reflection profiles revealed that the Cuu Long and Nam Con Son basins offshore southern Vietnam have developed from rifting to regional subsidence. Initial rifting began in the Eocene-early Oligocene, followed by the uplift and rotation of the crustal blocks at the onset of drifting in the southwestern South China Sea. The erosion of the uplifted blocks in the late Oligocene resulted in an unconformity, marking the transition from rifting to regional subsidence. A second phase of rifting began in the Nam Con Son basin in the Miocene while the postrift subsidence continued in the Cuu Long Basin. Inversion or contractional deformation in the late Miocene terminated the second-phase of rifting in the Nam Con Son basin. The data compiled from the published reports suggest two general trends of petroleum systems in the area. The Cuu Long basin is oil-prone with the oil reservoired mainly in fractured basement highs whereas the Nam Con Son basin is generally gas-prone with the gas trapped in Miocene sands and late-Miocene carbonates. These distinct trends of petroleum systems may be attributed to differences in timing of trap formation and oil and gas generation and the disruption of trap integrity due to the prolonged rifting and the inversion in the Nam Con Son basin.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia