Sunday 17 February 2013. The morning was bit cool in Bukittinggi. After three days we did the geological field of Central Sumatera Basin, we spent the morning with friends visiting the Ngarai Sianok at Bukittinggi. This would the end of the field trip. We started the field trip on Friday 15 February 2013. We travelled from Pekanbaru to Bukittinggi.
In the Ngarai Sianok Bukittinggi, we visited Japanes Hole or cave. The cave was dug and constructed by the Japanes troop in the year 1944 as a bunker in the second World War. In 1944 Japanese troop landed in Belawan and soon captured Bukittinggi.
The bunker could withstand or protects the troops from a 500 TNT bomb explosion. The bunker could accommodate around 1000 troops. The Japanese troop used the Javanese romusha to dig and constructed the bunker. According to Taufik, the torist guide, It took 3 months to construct the bunker.
For us as geoscientist, Ngarai Sianok was,amazing. We coul use it as an analog to understand braided channel system configuration. We have a producing reservoir that can be understood with this Ngarai Sianok model. Our field was estimated to have 60 million barrel in place but the reservoir is very much heterogen laterally. We found different drilling result for the same reservoir in the distance of 50 meters. Different reservoir character. We imagine the reservoir is like the braided river channel within the Ngarai below. It was a stacking of braided sandstone reservoir.
From this field trip we learned how the Central Sumatera Basin was formed. The edge of the Central Sumatera Basin could be seen in West Sumatera Basin. That was why went along the West Sumatera province. We visited many typical outcrop of various geological formation that represented the composing rock of Central Sumatera Basin.
Central Sumatera Basin is one of the most prolific basin in the world that produced millionsof barrel oil. Chevron and EMP are some the big producer in this basin.
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