Snorre Field, North Sea

Snorre Field is located in the northern part of the Tampen Spur bordering the Viking Graben, North Sea. The main reservoir units are sandstones of the Triassic Lunde and the lower Jurassic Statfjord Formations. The Snorre structure was formed by fault block rotation during the upper Jurassic rifting (Horstad et al., 1995). The main source rock is the upper Jurassic Draupne Formation which reaches up to 1 km thickness in the basin east of Snorre Field. The Draupne Formation is a typical marine, anoxic black shale corresponding to the organic facies 3a. Snorre Field contains undersaturated black oil with variable GOR, ranging from 60-160 Sm3/Sm3. Saturation pressures vary from 7 to 20 MPa and formation volume factors from 1.25 to 1.55 Sm3/m3. Hydrocarbon generation and migration started during the late Cretaceous/early Tertiary and continue to present day (Skeie et al., 2004).

A calibrated basin model of the study area discussed in detail by Skeie et al. (2004) was available for the application of the phase predictive kinetics of the OF 3a. For this specific study we used the compositional kinetic model of the Kimmeridge Clay sample (BH263).

The kitchen area is situated to the right of the main structure. Migration into the reservoir occurs along thin sand stringers within the source rock and along the main fault into the crest of the reservoir. The accumulation in the reservoir is modelled as a cumulative phase. The charging of the highly complex, faulted and backfilled Snorre reservoir (Horstad et al., 1995) is impossible to model correctly using todays basin and flow modelling technology, hence, a comparison of the cumulative predictions from our 2D model can only provide a very general assesment of the the predictive capacity of the compositional kinetic models.

The predicted petroleum phase of the OF3a Kimmeridge Clay PhaseKinetics model reaches a GOR of 120 Sm3/Sm3, a formation volume factor 0f 1.38 Sm3/m3, and a saturation pressure of 15.3 MPa. All in all a very satisfactory match of the actually encountered fluid properties.