--> Abstract: Challenge the Norms: Fluvial Channel in Shallow Marine Environment. Is it Possible? A Case Study of A-1 Well in Central Luconia, Offshore Sarawak, Malaysia — An Integrated Approach Combining Seismo-Stratigraphy and Seismic Attributes Analysis, by Wafa, Sharifah S.; Mustafa, Mohd Sharir S.; Kamarudzaman, Khairul Amry A.; Sapri, Dayang Hasspariah H.; Mahmud, Othman Ali A.; #90163 (2013)
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Challenge the Norms: Fluvial Channel in Shallow Marine Environment. Is it Possible? A Case Study of A-1 Previous HitWellNext Hit in Central Luconia, Offshore Sarawak, Malaysia — An Integrated Approach Previous HitCombiningNext Hit Seismo-Stratigraphy and Previous HitSeismicNext Hit Attributes Previous HitAnalysisNext Hit

Wafa, Sharifah S.; Mustafa, Mohd Sharir S.; Kamarudzaman, Khairul Amry A.; Sapri, Dayang Hasspariah H.; Mahmud, Othman Ali A.

Central Luconia Province is an overly matured basin that is Previous HitwellNext Hit known for its Miocene carbonate plays as Previous HitwellNext Hit as the pre and post carbonate structural plays.Therefore,new approach has been adopted to look at the shallow stratigraphic plays.

Recently, A-1 Previous HitwellNext Hit drilled by PETRONAS in July 2012 has resulted to a hydrocarbon discovery in shallow reservoirs between the depth of 800m and 1300m.Multiple shallow stratigraphic plays were mapped, and two of them were identified as channel plays of Cycle V/VI Sand namely as CH-1 and CH-2.These reservoirs are stratigraphically sitting right above the Central Luconia Carbonate platforms, which were previously interpreted to be deposited in a shallow marine environment. Now the questions arise how is it possible to have fluvial channel in the area interpreted as shallow marine environment? To unveil the answer, an integrated approach was made by Previous HitcombiningNext Hit Previous HitseismicNext Hit attribute Previous HitanalysisNext Hit, recent Previous HitwellNext Hit data and Previous HitsequenceNext Hit stratigraphic study.Several Previous HitseismicNext Hit attribute maps were generated such as RMS and Maximum Amplitude using Pre Stacked Time Migration Near and Far Stack cube.Time slice taken from Spectral Decomposition shown fluvial channels geometry.In addition,based from seismo-Previous HitsequenceNext Hit stratigraphy study,several Previous HitseismicNext Hit facies and reflection terminations clearly suggest the presence of fluvial channel within the area.This evidence is further supported by the Previous HitlogNext Hit motif from Previous HitwellNext Hit data which shown a sharp erosive base fining upward Gamma ray Previous HitlogTop motifs and the presence of coal as indicated by spikes in wireline logs as an evidence of subareal exposure of Lower Coastal Plain depositional environment.The presence of alternating marine and fluvial deposits in the 1000m of the basin indicates exposure and submergence of the shelf numerous times during the Miocene.It is believed that immediately after the deposition of the Miocene carbonate in shallow marine environment a significant short drop of relative sea level has exposed entirely of the shelf,erosion occurred and fluvial channel were formed.This short drop of relative sea level will be immediately followed by transgressive and highstand systems tract periods.Hence,this process eventually return the the area to shallow marine again.

Ultimately, this study has unveiled the complexity of depositional environment within the area.By applying this concept, it basically opens up new opportunities in chasing the fluvial channels for future prospects in Offshore Sarawak.

 

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013