Outcrop Study and Petroleum Implication to Identify Reservoir Quality Trend on Potential Deepwater Play System at Kendeng Zone, Eastern Java, Indonesia

Chandra Negara¹, Drianto Sudarmawan¹*, Sunjaya Saputra¹, and Moh. Indra Novian^2
1BPMIGAS, Indonesia
²Gadjah Mada University, Indonesia
*[email protected]

Exploration success in the deep-water turbidite play at Makassar Strait, Kutei Basin, Indonesia, has interested explorationists to review the geological setting for other deep-water turbidite system. BPMIGAS exploration team responded by evaluating Indonesian basins with possible deep-water turbidite plays, including the Kendeng Zone. The evaluation was based on studying the regional trend of proven deep-water plays in the Makassar Strait and the field geology of the Kendeng Zone. The EW-trending Kendeng Zone forms a deep trough that contains deep-marine turbidites. In the Pliocene-Pleistocene, the setting was shallow-marine and fluviatile on its eastern part. The source rocks occur as part of the turbidite system and exclusively in association with the sands and siltstones, which contain type III terresterial kerogen. The traps are formed by a combination of stratigraphic components and anticlines associated with gravity-driven extension-toe-thrust systems. The structures become younger to the east (outer belt). Hydrocarbon migration was most likely along vertical pathways. The Kendeng Zone is similar to the Makassar Strait in some aspects. It also is a toe-thrust structure, which becomes younger to the north or to the outer belt. The presence of several oil and gas seeps and dead oil in conglomeratic sandstone in the Kabuh Formation indicate an active petroleum system. In outcrop, the Kerek Formation includes a fan lobe with cleaner sand in the turbidite systems. Unfortunately, volcanic material has reduced the reservoir quality in the southern part of Kendeng Zone. Source rocks are predicted from the Pelang and Ngimbang formation. Miocene-Pliocene rocks in the Kendeng Zone are potential reservoirs. The reservoir quality of the turbidite system improves from south to north. The toe-thrust system at outcrop may cause the trapping to be less effective. The blind-toe thrust, onlap-trapping to the toe thrust system may provide a play geometry. Another play may be the subthrust trapping on the toe thrust system.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain