Naslov
Computer program for 1D numerical variogram calculation of well data, freeware in Visual Basic

Autori
Malvić, Tomislav ; Kolak, Nediljko

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Proceedings of IAMG 2010 / Organizing Committee - Budimpešta : WECO Travel Ltd., 2010, 15-15+

ISBN
978-963-06-9829-0

Skup
14th Annual Conference of the International Association for Mathematical Geosciences

Mjesto i datum
Budimpešta, Mađarska, 29.08.2010. - 02.09.2010

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
1D variogram; porosity; lithostratigraphy; sandstone members; Lower Pontian; Pannonian Basin; freeware

Sažetak
Large majority of variogram modelling and geostatistical estimations are performed in 2D, rarely in 3D, and just occasionally in 1D. However, very often there is set of measurements oriented along borehole, very often set in vertical direction. Such sets of well measurements can be considered as 1D datasets. Large number of such datasets had been collected in oil and gas wells from northern and north-eastern part of the Bjelovar subdepression (Croatian part of the Pannonian Basin) and analyzed in 2002 and 2003. Porosity values had been selected as analytical target, and processed with own-made computer code written in Visual Basic for 1D variogram analysis. The emphasis was given on numerical variogram values, sill and range. The most reliable results were obtained in sandstones of Lower Pontian age analysed in 4 wells and 6 intervals in older lithostratigraphic member Poljana Sandstones and 5 wells and 8 depth intervals in younger Pepelana Sandstones. Porosities varied approximately between 15 and 30% and ranges from 0.27 to 1.73 m. Range was specifically calculated as relative value expressing interval between two lags where the sill had been first time crossed. Analysis assumed that input data are divided in intervals(cells) of the same size and characterised with mean values. The interval size in testing phase was 50 cm but any value could be set. Eventually, if range is multiplied with number of lag before crossing sill and interval’s size, exact range can be calculated in relevant units (cm, m). The computer code had been improved in 2010. Data can be easily loaded and saved as simple ASCII files and later transformed in other programs. Numerical values of experimental, exponential and spherical variograms are also given on the screen. Graphical plot can be simple drawn importing ASCII results in Excel™ worksheet.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

Napomena
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