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7th Middle East Geosciences Conference and Exhibition
Manama, Bahrain
March 27-29, 2006
Pressure
Prediction before
Drilling and Petroleum System Behaviour
1 KOC Exploration Department, Ahmadi, Kuwait, [email protected]
2 BEICIP-FRANLAB, Rueil Malmaison, France
The entire Jurassic section and some areas of the Lower Cretaceous section in onshore Kuwait are characterized by high overpressures, well above the hydrostatic regime. This pattern extends apparently down to the Triassic and Paleozoic section.
The understanding of the
pressure
regime and its causes is important for
pressure
prediction before drilling as well as for
HC exploration, as
pressure
drives the flow of HC.
The
pressure
regime has been investigated through a review of available
pressure
data (well tests, mud weights) and an
integrated 3D basin modelling study, using IFP Temis package.
A consistent
pressure
model has been developed, including: 1. the presence of tight shales in Ratawi fm, in the N and NW
Kuwait, responsible for overpressure in the Lower Cretaceous; 2. the presence of an impervious fault corridor to the N,
separating hydrodynamically the Sabriyah and N Rhaudatain fields in the Cretaceous; 3. the regional extend of very low
permeability Gotnia salt, which acts as a
pressure
barrier throughout Kuwait, locally incised by poorly permeable faulted
areas (E and W of Burgan), acting as “security valves” for the overpressure regime, but allowing the
hydrocarbon
to leak
into the Cretaceous; 4. the existence of lateral barriers within the Jurassic in NW Kuwait, isolating Mutriba and Kra Al Maru
area from the Jurassic of N, E and W Kuwait which appear to be relatively well connected.
The
pressure
model characteristics in terms of Permeabilities related to the lithologies will be presented, together with its
prediction for drilling depending on the geological context.