Dear all,
IAGI (Indonesian Association of Geologists) East Kalimantan cordially
invites you to a luncheon talk as follows:
TOPIC : "MIGRATING FLUVIAL-CHANNEL SANDS FILLING AN INCISED VALLEY: SA
68-4 AND SA-69-0 SANDS,
SERANG FIELD, KUTAI BASIN, EAST KALIMANTAN"
DATE / TIME : Wednesday, 7 April, 2004 / 12:30 - 13:30
VENUE : Bahana Surya Hotel (Blue Sky),
Jl. Letjend. Soeprapto No.1, Balikpapan, Phone: 0542-735845
SPEAKER : KUSUMO HANDOYO (UNOCAL INDONESIA).
COST : Rp. 100.000
Reservations and cancellations will be accepted until 15:30 hours on
Tuesday, April 6, 2004 at email:
[EMAIL PROTECTED] or fax: 53-3178, or phone 53-4099 (Firdaus).
[EMAIL PROTECTED] or phone to 54-3882 (Herry Maulana)
Payment will be done at the Bahana Surya Hotel, and no show will be
charged.
Members of IAGI, IPA, and IATMI are welcome.
ABSTRACT
MIGRATING FLUVIAL-CHANNEL SANDS FILLING AN INCISED VALLEY:
SA 68-4 AND SA-69-0 SANDS, SERANG FIELD, KUTAI BASIN,
EAST KALIMANTAN
KUSUMO HANDOYO
Unocal Indonesia
SA 68-4 and SA-69-0 are the oldest sands in the main deltaic sequence in
the Serang Field, Kutai Basin, East Kalimantan. These sands form one of
the main producing-intervals in the field. The sands are very thick
(packages up to 120 ft thick) and laterally extensive (more than 4 km
wide). The sands were deposited in Late Miocene (~7 Ma) when the shelf
margin was 15-25 km to the east of Serang Field.
Based on detailed log correlation, subsurface mapping, and core study, the
sands are interpreted as migrating fluvial-channel sands. The sands were
deposited in a large valley that was incised during a lowstand of
sea-level. The correlation markers show a migrating-channel pattern.
Subsequent channel-sands were deposited in low-lying areas that have
higher accommodation. Log signatures indicate that the sands consist of
many sand bodies, which are considered to be a result of channel
migration.
The core study recognizes two fluvial-channel sand bodies, lower and
upper, from SA-2RD1 core #2 (8651.0-8742.0). Crevasse splay deposits are
observed between the two fluvial-channel sands. The lower fluvial-channel
sands overly low-energy delta front strata; therefore a basinward shift of
facies is interpreted. The scoured surface that separates the lower
fluvial-channel sands from low-energy delta front deposits is interpreted
as an unconformity. Log correlation shows that the upper scour surface,
which separates the upper fluvial-channel sands from crevasse splay
deposits, has significant erosional relief and may represent a smaller
scale incision. These two scoured surfacessare thought to be correlative
with deep-water reservoirs at West Seno Field basinward of Serang Field.
Six depositional environments are interpreted from the core: (1) crevasse
splay, (2) abandoned fluvial channel, (3) lower-energy fluvial channel,
(4) higher-energy fluvial channel, (5) low-energy delta front, and (6)
prodelta. Crevasse splay deposits are medium- to very fine-grained
sandstone, cross-laminated to ripple-laminated, contain carbonaceous
laminae, and have an overall upward-coarsening trend. Abandoned
fluvial-channel deposits are clayey siltstone, parallel- to
wavy-laminated, and contain carbonaceous laminae. Lower-energy
fluvial-channel deposits are medium- to very fine-grained sandstone with
siltstone interbeds, cross-bedded at the lower part, ripple- to
wavy-laminated at the upper part, contain carbonaceous laminae, and have
upward-fining trends. Higher-energy fluvial-channel deposits are medium-
to very coarse-grained sandstone, cross-bedded, locally parallel-bedded to
massive, and contain pebble clasts on scoured surfaces. Low-energy delta
front deposits are very fine-grained sandstone to siltstone, burrowed to
bioturbated, and contain shell fragments. Prodelta deposits are clayey
siltstone, burrowed to bioturbated, and rich in siderite nodules.
