Geologia Croatica, Vol. 61 No. 1, 2008.
Izvorni znanstveni članak
Selection of the most appropriate interpolation method for sandstone reservoirs in the Kloštar oil and gas field
Davorin Balić
orcid.org/0000-0002-4342-6488
; INA-Industrija nafte
Josipa Velić
; Rudarsko geološko naftni fakultet
Tomislav Malvić
; INA-Industrija nafte
Sažetak
The distribution of porosity data collected at the Kloštar field is analysed. This field is located in the north-western part of the Sava depression, and represents one of the most long-standing fields with respect to oil production in Croatia, where production has been on going for mo re than 50 years. Several reservoirs of very diverse lithology and stratigraphic age have been discovered. The oldest reservoirs (with minor oil re serves) occur in basement rocks of the
Tertiary system (in formally named the »temeljno gorje«), then in Badenian coarse-grained clastics, as well as sandstones of Panonian and Pontian ages. Major reservoirs, with respect to size, number and volume, are located in sediments of the Upper Pannonian and Lower Pontian. These are medium-grained sandstones, mostly quartz-mica
grains, mutually separated by mar ls. Reservoirs of Lower Pontian age occur within whole structures (anticlines) at Kloštar, while the Upper Pannonian has been developed only in the south–west part. Earlier studies on the reservoirs have included only several measured values of reservoir porosity. These values have not been mapped, but only a unique average value, characteristic for the whole reservoir was calculated. Reinterpretation of e-logs in creased the number of in put values to 20 points of data. Rules are determined for the distribution of porosities in the largest reservoir of the Lower Pontian named »T«. These re ularities can be translated to the other sandstone reservoirs. Several interpolation methods were selected (inverse distance, nearest neighbourhood and moving average), with special emphasis on kriging. The interpolated maps are different. Based on a comparison of iso porosity, lines, sha es, and cross-validation results, kriging was evaluated as the most appropriate method for porosity interpolation.
Ključne riječi
oil; 1st sandstone series; porosity; geostatistics; kriging; Pontian; Kloštar; Croatia
Hrčak ID:
24886
URI
Datum izdavanja:
2.7.2008.
Posjeta: 1.412 *