Petroleum potential of source beds in the Cuu Long basin

Abstract

In the Cuu Long basin, three source beds are identified: lower Miocene, Upper Oligocene, upper Eocene + lower Oligocene. They are separated from each other by sand-clay layers. Only Upper Oligocene and Upper Eocene + Lower Oligocene source beds are two main source beds supplying a great part of organic matter into traps. Petroleum source potential of Upper Oligocene source bed (66.30 billion tons) is greater than Upper Eocene + Lower Oligocene bed (29.88 billion tons). Total amount of hydrocarbon has ability to take part in accumulation process at the petroleum-bearing traps from Upper Oligocene and Upper Eocene + Lower Oligocene source beds is over 2.19 billion tons and below 1.16 billion tons respectively. Thus, in whole CuuLong basin, source rocks have capacity to produce 96.18 billion tons of hydrocacbon in which accumulation is 3.35 billion tons making up 3.35 % production quantity. Applying Monte - Carlo simulation method, using Crystal Ball software to calculate production potential and total amount of organic matter taking part into migration and accumulation process give rather appropriate result with difference level ≤1.25%.. Prospecting levels are in the following order: (i) Central lift zone has the greatest prospects, next is Dong Nai lift zone, graben located in north west inclined slope, south east inclined slope, north east area of Tam Dao lift zone finally; (2) Petroleum does not only accumulate in structural, combination traps but also in non-structural traps.