TECTONIC INVERSION IN SYN-RIFT SEDIMENTS AND ITS IMPLICATION ON HYDROCARBON TRAPPING IN NORTH SUMATRA BASIN, ANDAMAN SEA REGION
Andaman Sea is part of the deep-water area of the North Sumatra basin, with water depths ranging from 500 meters to 1500 meters. Deepwater exploration activities with the target reservoir syn-rift sediments on the structure of the inversion still received little attention because of previous e...
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| Format: | Theses |
| Language: | Indonesia |
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| Online Access: | https://digilib.itb.ac.id/gdl/view/73134 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Andaman Sea is part of the deep-water area of the North Sumatra basin, with water
depths ranging from 500 meters to 1500 meters. Deepwater exploration activities with
the target reservoir syn-rift sediments on the structure of the inversion still received little
attention because of previous exploration drilling focused on the target reservoir is
shallow marine post-rift sediments on the limestone Peutu Formation and sandstone
Baong Formation.
Research on syn-rift sediments and structure inversion obtained by conducting seismic
interpretation of the data from 2D marine multi-client seismic surveys with a long
streamer through the Andaman Sea and surrounding areas. Several deep-water drilling
exploratory wells are used as data for analysis of petroleum systems and types of
hydrocarbons in the syn-rift sequence. Based on seismic data and analyzed petroleum
system is generated the trapping mechanism of hydrocarbon in syn-rift sediments as
resulted of tectonic inversion.
Based on mapping the isopach on syn-rift sequence and seismic horizon flattening on top
syn-rift can be interpreted that there are two patterns of syn-rift that developed in this
area. The first is North-South trending rift developed in the South and North study area,
while the second is Southwest-Northeast trending rift developing in the Central area.
From observation we can conclude that the formation of rift systems in this area is
controlled by major faults trending North-South trending. The faults is assumed to move
horizontally to the right to form such a pattern that controls transtention rift basin. The
northern part of the basin shows tectonic inversion of very large geometric pattern shown
by the high relief of Harpoon-shaped structure, while the southern part shows a small
inversion tectonics is indicated by the low-relief structure. Moreover, structural mapping
of Top Syn-rift revealed that structural pattern of the inversion structure trending
Northeast-Southwest dipping toward Sourheast.
Hydrocarbons on the inversion structure can be found in the rift depocenter, as the
result of Mergui-1 well which discovered gas in the Andaman Sea region of Thailand.
Hydrocarbons can also be found on the rift shoulder near the bounding fault, such as
drilling results JAU-1 and ITU-1 which discovered gas reservoirs in sandstone
Parapat Formation. Meanwhile, wells BLD-1 did not find hydrocarbons in drilling
target syn-rift sediment in area flexural margin. Based on these facts, inversion faults
may be responsible for the flow of hydrocarbon migration from source rocks to
sandstone Parapat Formation. |
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