Use of Pressure Data in Resolving Stratigraphic Uncertainty in Structurally Complex Reservoir

Conventional methods of stratigraphic correlation commonly involve biostratigraphic, wireline log and seismic stratigraphic analyses. In area where seismic imaging is poor (e.g. due to gas cloud effects) and microfossils are scarce (e.g. deepwater environment) accurate correlation may be difficult.

The YBL field is an example of utilisation of pressure data to reducet the stratigraphic uncertainty. The seismic data show widespread velocity pull-down effects and discontinuous reflectors within the same structure, the field assessments indicate the presence of three separate hydrocarbon culminations with different fluid properties. Wireline logs show dissimilar log patterns in the three wells.

In general, pore pressure increases as depth of burial increases, thus leaving the genetics of pore pressure to be conserved. This is what has been observed in YBL field, where the order of the sands deposited within the Upper Kinarut package are depicted with different formation pressure regime, whereby the similar timing of sand depositions will most likely preserve a similar formation pressure.

In summary, integration of pore pressure data with seismic stratigraphy and well correlations in the petroleum system evaluation has enabled to reduce the stratigraphic uncertainties in reservoir correlation in structurally and stratigraphically complex reservoirs.