- Tytuł:
-
Modelowanie geostatystyczne w wyznaczaniu przestrzennego rozkładu parametrów petrofizycznych utworów ilasto-mułowcowych
Geostatistics modeling in determining the spatial distribution of petrophysical parameters of claystone and mudstone formations - Autorzy:
- Kwilosz, Tadeusz
- Powiązania:
- https://bibliotekanauki.pl/articles/1834377.pdf
- Data publikacji:
- 2020
- Wydawca:
- Instytut Nafty i Gazu - Państwowy Instytut Badawczy
- Tematy:
-
kriging
kroswalidacja
porowatość efektywna
cross-validation
effective porosity - Opis:
- Due to decreasing gas reserves in deposits found in sandstone f and carbonate formations, geological structures composed of mudstone and shale layers found in Miocene formations are growing in popularity. These deposits are characterized by high facial variability. Shale rocks have very low permeability. Therefore, the porosity determined for these rocks cannot be taken into account in the balance of the effective porosity used to estimate the natural gas reserves. Shale rock thickness should be excluded when calculating effective thickness of the gas bearing formations. The main problem of this study is the proper separation of the rocks belonging to individual lithological facies. Gamma ray logs were used to identify lithological variability of this type of rock. It should be emphasized, however, that due to the very low thickness of sandstones and mudstones, it was not possible to identify them clearly using the archival gamma ray logs. The archival gamma ray logs indicate the average values of the layer rather than that of specific laminas, because of its measurement resolution. Therefore, an estimation was made in order to calculate the percentage share of the thickness of each lithological type in the total layer thickness in each well. This division was made using the analysis of empirical distributions of gamma ray logs. It was assumed that lithological heterogeneities would be visible on experimental histograms in the form of multimodal distributions or clear changes in monotonicity. These data were used to generate a spatial distribution of parameters on the model grid at points not covered by the measurement. For this purpose, the ordinary kriging method and the kriging with trend method were used. Using the same interpolation methods, the structure maps of the top and bottom of the model were generated. The results of the porosity measurements were assigned to the previously separated lithological types of rocks. The distribution of porosity at the grid points of the deposit model was determined for each type of rock and using both kriging methods. The cross-validation method was used to assess the uncertainty of the results. Finally, the effective pore volume of the deposit model was calculated, assuming that only sandstone and mudstone rocks are sources of the effective pores. The uncertainty of the analysis was estimated. Real data from geophysical measurements for the Miocene gas field were used for the study.
- Źródło:
-
Nafta-Gaz; 2020, 76, 4; 230-238
0867-8871 - Pojawia się w:
- Nafta-Gaz
- Dostawca treści:
- Biblioteka Nauki
Artykuł