Three-Dimensional
Seismic Data and Its Role in the Renewed Exploration for Carbonate Reservoirs,
Offshore Northwest Madura, East Java Sea, Indonesia
Carter, David C.1,
Dwi Mandhiri1, Robert K. Park1,
Imron Asjhari1, Syaiful
Basyuni1, Sergey Birdus2, John P. Bradfield1, Ary Iriawan1, Meutia
Nasfiah1, M. A. Agung Nugroho1 (1)
Kodeco Energy Co. Ltd, Jakarta, Indonesia (2)
Paradigm Geophysical
3-D seismic
methods have played a key role in the exploration and delineation of Oligocene
- early Miocene carbonate reservoirs, offshore NW Madura
in the East Java Sea.
3-D seismic data acquired in 1999, has resulted in a subsequent period of
exploration success in an area previously considered to have limited
exploration potential. Targeted reservoirs include thinly bedded carbonates,
as well as isolated carbonate buildups. In addition, a newly identified barrier
reef complex forms the target of the South Poleng
Field discovery made in 2004. Seismic interpretation methods include amplitude,
interval thickness, acoustic impedance, seismic facies,
and amplitude variations with offset (AVO). These techniques work to varying
degrees, being dependent on local conditions and reservoir type. The area is
overlain by a series of large Late Miocene-Pliocene carbonate buildups that
produce severe seismic distortion of the underlying main reservoir intervals.
Consequently, velocity estimation techniques, including coherence inversion,
horizon based seismic tomography and pre-stack depth migration are important in
some hydrocarbon discoveries. The South Poleng oil and gas discovery, which
approximately doubles the size of the combined Poleng
accumulation, incorporates the use of all the above seismic methods and
incorporates a new understanding of the carbonate platform paleogeography.
This hydrocarbon discovery is also remarkable in that it was made more than 30
years after the nearby Poleng Field discovery in
1972.