Geological evolution, regional perspectives and hydrocarbon potential of the northwest Phu Khanh Basin, offshore Central Vietnam

TY - JOUR

T1 - Geological evolution, regional perspectives and hydrocarbon potential of the northwest Phu Khanh Basin, offshore Central Vietnam

AU - Fyhn, Michael Bryld Wessel

AU - Nielsen, Lars H.

AU - Boldreel, Lars Ole

AU - Thang, Le. D.

AU - Bojesen-Koefoed, Jørgen

AU - Petersen, Henrik I.

AU - Huyen, Nguyen t,

AU - Due, Nguyen A.

AU - Dau, Nguyen T.

AU - Mathiesen, Anders

AU - Reid, Ian Derry

AU - Huong, Dang T.

AU - Tuan, Hoang A.

AU - Hien, Le V.

AU - Nytoft, Hans P.

AU - Abatzis, Ioannis

N1 - Online and pre-print version

PY - 2009

Y1 - 2009

N2 -   Seismic stratigraphic and structural analyses of the northwest Phu Khanh Basin, offshore Central Vietnam, based on 2-D seismic data, indicate that the initial rifting began during the latest Cretaceous? or Palaeogene controlled by left-lateral transtension along the East Vietnam Boundary Fault Zone (EVBFZ) and northwest-southeast directed extension east of the EVBFZ. Rifting stopped due to transpression during middle Oligocene times but resumed by left-lateral transtension during the Late Oligocene. Thick sequences of lacustrine and alluvial sediments were deposited during the Palaeogene rift periods. The Late Oligocene rifting ended due to inversion,triggered by right-lateral wrenching near the Palaeogene-Neogene boundary. Following the onset of this inversion regional uplift andvolcanism took place in the southern half of the study area and contemporaneous subsidence and transgression took place farther north,leading to widespread carbonate deposition. As the right-lateral wrenching decreased during the early Neogene, thermal subsidence andsiliciclastic sedimentation became dominant, resulting in the buildup and southward propagation of the shelf slope. Sediment accumulation and subsidence rates increased after the Middle Miocene times due to eastward tilting of Central Vietnam and the adjacent offshore area. Potential direct hydrocarbon indicators (DHIs) in the Phu Khanh Basin include common amplitude anomalies, gas chimney-like features and seafloor gas seeps. In addition, oil seeps are found at Dam Thi Nai, immediately landward of the basin. Geochemical analyses of the oil seeps indicate the existence of at least two early to peak mature source rocks. Maturation modelling, combined with the seismic analysis, suggests the likely presence of oil kitchens 40-50km downdip in the basin, and a fairly simple oil migration route. The basin is probably charged from lacustrine syn-rift mudstones, humic coals and fore-reef marls. Potential reservoirs are turbidite, lowstand delta, shelf and coastal sandstones, as well as platform and reef carbonates and fractured basement. Various structural and stratigraphic traps formed during the Palaeogene and early Neogene, prior to the main stage of petroleum generation.

AB -   Seismic stratigraphic and structural analyses of the northwest Phu Khanh Basin, offshore Central Vietnam, based on 2-D seismic data, indicate that the initial rifting began during the latest Cretaceous? or Palaeogene controlled by left-lateral transtension along the East Vietnam Boundary Fault Zone (EVBFZ) and northwest-southeast directed extension east of the EVBFZ. Rifting stopped due to transpression during middle Oligocene times but resumed by left-lateral transtension during the Late Oligocene. Thick sequences of lacustrine and alluvial sediments were deposited during the Palaeogene rift periods. The Late Oligocene rifting ended due to inversion,triggered by right-lateral wrenching near the Palaeogene-Neogene boundary. Following the onset of this inversion regional uplift andvolcanism took place in the southern half of the study area and contemporaneous subsidence and transgression took place farther north,leading to widespread carbonate deposition. As the right-lateral wrenching decreased during the early Neogene, thermal subsidence andsiliciclastic sedimentation became dominant, resulting in the buildup and southward propagation of the shelf slope. Sediment accumulation and subsidence rates increased after the Middle Miocene times due to eastward tilting of Central Vietnam and the adjacent offshore area. Potential direct hydrocarbon indicators (DHIs) in the Phu Khanh Basin include common amplitude anomalies, gas chimney-like features and seafloor gas seeps. In addition, oil seeps are found at Dam Thi Nai, immediately landward of the basin. Geochemical analyses of the oil seeps indicate the existence of at least two early to peak mature source rocks. Maturation modelling, combined with the seismic analysis, suggests the likely presence of oil kitchens 40-50km downdip in the basin, and a fairly simple oil migration route. The basin is probably charged from lacustrine syn-rift mudstones, humic coals and fore-reef marls. Potential reservoirs are turbidite, lowstand delta, shelf and coastal sandstones, as well as platform and reef carbonates and fractured basement. Various structural and stratigraphic traps formed during the Palaeogene and early Neogene, prior to the main stage of petroleum generation.

KW - Faculty of Science

KW - Vietnam

KW - Phu Khanh Basin

KW - South China Sea

KW - Vietnam

KW - Hydrocarbon assessment

KW - Seismic facies analysis

KW - Basin analysis

KW - Extrusion tectonics

U2 - 10.1016/j.marpetgeo.2007.07.014

DO - 10.1016/j.marpetgeo.2007.07.014

M3 - Journal article

SN - 0264-8172

VL - 26

SP - 1

EP - 24

JO - Marine and Petroleum Geology

JF - Marine and Petroleum Geology

ER -