Wireline Pore Pressure Estimation Study in Carbonate Setting: Case Study on the Eastern Central Luconia Province, Sarawak

The pore pressure prediction of clastic sediments usmg traditional methods, such as
Eaton and Miller have been widely used in the oil and gas industry, especially when the
excess pressure is related to the disequilibrium compaction. These traditional methods
rely on the association of porosity with pressure buildup. Porosity or compaction trend is
generally predictable for the clastics. However, the compaction trend is not so obvious in
carbonate due to diagenesis and dissolution occurring in the carbonates.
Three methods involving two different equations from Eaton and Miller, using
sonic and resistivity curves, were tested to see whether these methods can be applied to
the carbonate environment. The three methods are, the 'pore pressure Miller's equation
using NCT calculated from the Miller's equation', the second method are the 'Eaton's
pore pressure equation using the visualized freehand drawn NCT on resistivity curve' and
the third method is the 'pore pressure calculation using the visualized freehand drawn
NCT using the Sonic curve'. From the analysis the best method that can be used was the
Eaton method on sonic curves.
In the second phase of the analysis, the pressure contribution factor was tested
using the basin modeling. Results from the modeling indicated that both thermal and fluid
flow as minor pressure contributors in addition to the disequilibrium compaction from
sedimentary loading.