Determination of clay minerals in Brunei's outcrops and spatial variability of the radioisotopes
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Full Text |
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Author |
Amila Abu Bakar, Stephen Tyson and Bashir Busahmin
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e-ISSN |
1819-6608 |
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On Pages
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604-611
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Volume No. |
19
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Issue No. |
10
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Issue Date |
August 10, 2024
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DOI |
https://doi.org/10.59018/052481
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Keywords |
clay, spatial variability, swelling, variogram, kriging.
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Abstract
Shale with the presence of clay minerals is one of the problematic formations to be encountered in the oil and gas
industry. Drilling into these formations will be a challenge since shale sloughs and clay swells. Clay minerals impact
hydrocarbon production and drilling operations due to clay hydration. Thus, the main objective of this paper is to identify
the clay minerals from Brunei Darussalam outcrops based on the cross plot of thorium and potassium from the components
of the radioisotopes of spectral gamma ray logging (SGRL). The majority of the outcrops in Brunei Darussalam contains
montmorillonite which swell in contact with water. Geostatistical methods are implemented to gather spatial data over an
area of interest. Variogram therefore is used to describe and characterize the variability of the radioisotopes by fitting a model
to the experimental semi-variogram. The estimation of the measured values at any unknown location are then calculated by
the kriging process. Semi variogram and corresponding kriging maps for thorium, uranium, and potassium components were
prepared. The result indicated a good spatial similarity and areas with the highest number of the radioisotopes of spectral
gamma ray logging presented the relationship of the radioisotopes in the surrounding area.
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