Individual Approach to Fields with Identical Depositional Environment Based from Low Cretaceous Depositions Example in NW of Eastern Siberia

Galina Rozbaeva, Olesia Grechneva, and Tatyana Pospelova
TNNC, Tyumen, Russian Federation

Identifying depositional facies types, detecting their habitat, updating lithologic heterogeneity distribution, and justifying prospect hydrocarbon targets is the essential process for reservoir development.

The confidence to put a field into production comes from seismic and geological modeling based on seismic and log data, lithologic and facial modeling, as well as 3D modeling.

We analyzed productive layers of two fields, constantly applying the above procedures. Finally, we realized that underestimated data can lead to wrong results.

In the studied region the Nizhnyaya Kheta productive interval is associated with Neocomian stratigraphic sequence represented by the lateral shelf edge thickening and clinoform bodies gradually renewed E to W.

As for chronostratigraphy, those reservoirs are identical. Seismic modeling shows that only coastal marine, shallow marine and marine shelf depositions are well-developed in the target interval which is confirmed by log and core data.

Sedimentary core analysis for those fields shows structural, textural, and trace-fossils differences which confirm the idea of different distance to the shore line during sand deposition process. Coarse-grained material accumulation was also irregular, most of it deposited on geomorphologic and hydrodynamic barriers.

The productive interval in the 1st field is a key development target. The field is referred to as high flow rate (Qoil≈10-300 MT/day), the reservoir consists of medium poroperm properties sandstone (Poro=18%, Perm=70mD, Net pay=6.2m).

The productive interval in the 2nd field has the following properties: Poro=16%, Perm=20mD, Net pay=4m, but the reservoir produced no commercial flow.

So, to estimate oil-bearing capacity, the data on HC generation, migration, accumulation, and integrity need to be added to the research.

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