Geology Reference
In-Depth Information
a
b
c
Figure 1.6
Irrawaddy-Andaman Basin. Oil and gas field location map.
a
. Regional
faults,
b
. Oil fields,
c
. Gas fields. Fields:
1
. Indou,
2
. Seib,
3
. Yenangyat,
4
. Mani,
5
. Laniva,
6
. Chauk,
7
. Yenangyang,
8
. Minbu,
9
. Palanion,
10
. Yathaya,
11
. Yenaima,
12
. Pyaya,
13
. Prome,
14
. Taung-Yangve,
15
. Mayang,
16
. Henzada,
17
. Payagon,
18
. Paseh,
19
. Idi,
20
. Djulo-Rajeu,
21
. Perlak,
22
. Gyeongdog,
23
. Rantau,
24
-
30
. Serang-Jaja, Tenang,
Telaga-Said, Damar, Pulau-Panjang, Pangkalan-Susu.
The Paleocene series in the northern (Irrawaddy) portion of the region
reaches 1,200 m. Most of the section is composed by the Eocene clastics
with conglomerate beds (total thickness of up to 8,000 m). The Oligocene
series (up to 3,000 m thick) comprises complexly alternating sandstones,
clays, marls and limestones. The uppermost, Neogene section (up to 6,000
m thick) includes continental (including deltaic) type rocks: loose sand-
stones, conglomerates and pebble stones. The rocks in the southern area
(the North Sumatra Depression) are mostly marine. A specific feature of
the section in the Irrawaddy-Andaman Basin is strong facies variability
causing lens-shaped nature of reservoirs. The clay content of the section
increases toward the subsided parts of the depression.
The region has asymmetric structure with its axial most subsided por-
tion offset westward, toward the Alpine folding. As a result, the western
part of the basin forms a narrow trough with the steep geosynclinal flank.
The larger eastern part of the basin is a broad complexly structured flat-
folded slope facing the Shan Massif. The sediment thickness there is much
reduced.
The transverse highs and the Pegu-Yoma anticlinorium subdivide
the northern part of the basin into a number of troughs: the Northern,
Chindwa, Minbu, Delta and Sittang.
Based on drilling and seismic results, a number of high-amplitude anti-
clines are identified within the region. They are grouped into linear zones
and are cut with regional faults mostly parallel to the general trend of the
depressions. Local highs are usually asymmetric, with low-angle western
