ITB Geology Webinar Uncovers the Cause of Overpressure Occurrence in Sedimentary Basin.

Oleh Adi Permana

Editor -

March 17, 2021 - ( update : 30-03-2021 )

BANDUNG, itb.ac.id – Webinar series from Geological Engineering ITB under the title of “ITB Geology Greets: Solidarity for Nation” returning with the 14th webinar edition theming “Overpressure in Sedimentary Basins: The Indonesia’s School of Thoughts”. This time, the speaker is Agus M. Ramdhan, Ph.D., who is a lecturer from Applied Geology Research Group on Saturday (6/3/2021).

Webinar begins with defining overpressure. Agus showed participants several real illustrations of overpressure such as Champion Field Blowout (1979), Piper Alpha (1988), Lumpur Sidoarjo (2006), and BP Deepwater Horizon Disaster (2010). Agus then conclude that overpressure is a hydro-geology phenomenon when water is rising more than ground level. The rising water could reach 4 to 5 km height.

Overpressure caused by one of these two things, which are loading overpressure or fluid expansion. Loading overpressure happen when pressure on the surface constantly increasing but the sediment layer fails to settle causing the water unable to escape naturally and lead to leakage. It is also often referred to as “The Gulf of Mexico (GoM) School of Thought”. Meanwhile, fluid expansion or “The North-Sea School of Thought” is a condition when fluid increase suddenly on the sediment or decreasing effective stress value.

Agus mention about will there be “The Indonesia’s School of Thought” considering that Indonesia has a long record of drilling the most daring wells in the world since 1970s up until now. This idea brought him to do a further research on overpressure in Durham University in 2007.

He picked Lower Kutai Basin (LKB) in Indonesia as his main research object. “Along with this, I bring what could possibly be the most precious data in the world regarding overpressure”, he said.

He explained the reason behind his statement is, apart from LKB has a very ideal condition, he state that the main cause of LKB overpressure is not loading as it has been believed, but fluid expansion. This obviously provoked a lot of criticism and discussion from different parties. After doing reinterpretation on his journal, it is concluded that LKB has both loading and fluid expansion factors, with ratio of fluid expansion is more dominant proven by formula with physics approach which he made.