--> Abstract: Exploring Silisiclastic Tight Gas Reservoir, by Jonih Rahmat, Chepy Irawan, and Sunjaya Saputra; #90072 (2007)

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Exploring Silisiclastic Tight Gas Reservoir

Jonih Rahmat, Chepy Irawan, and Sunjaya Saputra
BPMIGAS, Jakarta, Indonesia

The present day Central Sumatra Basin is one of the biggest oil and gas production basin in Indonesia, it has discovered more than 30 BBOE from 199 fields with most of the discoveries are gas discovery.
Characteristic of tight gas reservoir in the some of basin in the world is different. In the Barnett shale in North Texas consider tight reservoir as permeabilities of less than 1 µD (or nanodarcies), in the Middle East may consider permeabilities of 30 to 50 mD as tight, but in the Central Sumatra in Indonesia, tight reservoir has permeabilities average 9 mD.
This paper will only discuss about characteristic of tight gas reservoir in Mature Central Sumatra Basin, Indonesia. Based on formation evaluation and reservoir characterization, the tight gas reservoir in Central Sumatra Basin, Indonesia has character: gamma ray value 38 to 42 GAPI, small cross-over between density-neutron tools and shifting to the right that is showing very tight porosity, porosity average 13 PU, permeability 7-13 mD, coarse-pebble grain size sandstone sometime conglomeratic grain size sandstone , blocky or fining up log pattern, commonly are terrestrial deposits (fluvial deposits) from both of Non Marine Sihapas Formation (Menggala Formation) and Pematang Formation which is syn-rift system deposits. Based on thin section analyses, tight gas reservoir character is showing primary inter-particle porosity filled with authigenic minerals, primary porosity reduced to narrow cracks with secondary honeycombed grains, and inter-crystalline porosity within a fine grained, elongate matrix.
Finally, after exploration activity for tight gas reservoir, we can be produced tight gas reservoir with some of challenges consists of: 1) Quantifying the recoverable reserves and deliverability; 2) Implementing the best well-completion, stimulation, and infill-drilling strategies to accelerate and increase ultimate field productivity; 3) Combining the above issues must lead to economic success.

 

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece