## 5 Discussion  
The petrography and petrophysics of the studied outcrops and intervals are discussed in the following section, based on the preliminary data collected. The field observations and the thin sections in this study were used to outline the main features of the outcrops. The thin sections and image analysis were used to identify the porosity and pore size distribution, with geostatistics understanding the relations between the different facies and porosity distribution. The pore size distribution has shown a notable difference between the Temburong and Belait selected samples, with a better quality for Belait and pore space ranges of about 5 to 14 micrometers. Additionally, there was a range of about 2 to 5 micrometers for Temburong. The Belait Formation samples L601, L802, and L803 show a more comprehensive range of porosity, with a lesser microporosity percentage. In contrast, the Temburong Formation's samples show a tight porosity range with a higher microporosity percentage. The outliers reached more than 30 points in some of the samples presented above, which may not be a considerable number, as the total pores identified exceeded 750 pores per image. Hence, the outliers, especially in L301, L302, and L303, are less than 5% (Figure 20). The analysis of the different grain sizes in Table 3 in the results section shows the domination of a very fine sand size in most of the samples. Based on the percentages of sand, silt, and clay, the USDA classification revealed that all of the analyzed samples are classified as sand or loamy sands (Figure 21). None of the analyzed samples showed any presence of any grain size greater than a medium sand size (Figure 22). The clay size ranged between 0.36 to 2.72 percent of the total weight. The grain size cumulative frequency curves of the studied samples are presented. Figure 19: The thorium/potassium cross-plot. Figure 21: USDA sediment classification [23]. Most of the samples fall into the sand and the loamy sand ranges, mainly controlled by the silt percentage in the sample. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Size** & **\textasciitification** & **\textasciitification** & **\textasciitification** & **\textasciitification** & **\textasciitification** & **\textasciitification** & **\textasciitification** & **\textasciitification** & **\textasciitification** \\ \hline
**Phi** & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** \\ \hline L101 & 0 & 4.60 & 7.45 & 79.88 & 93.70 & 96.14 & 97.56 & 98.58 & 99.63 \\ L301 & 0 & 11.58 & 32.00 & 72.25 & 93.36 & 95.79 & 97.40 & 98.56 & 99.13 \\ L302 & 0 & 20.81 & 49.38 & 79.19 & 92.26 & 94.77 & 95.60 & 96.53 & 99.25 \\ L303 & 0 & 9.72 & 35.34 & 78.57 & 95.69 & 97.54 & 97.91 & 98.56 & 99.59 \\ L401 & 0 & 1.52 & 2.56 & 77.86 & 97.28 & 97.70 & 97.91 & 98.33 & 99.71 \\ L402 & 0 & 4.41 & 7.11 & 73.95 & 94.35 & 96.44 & 97.11 & 97.61 & 99.96 \\ L501 & 0 & 13.38 & 39.32 & 81.02 & 92.67 & 94.77 & 95.60 & 96.86 & 99.58 \\ L601 & 0 & 4.89 & 18.08 & 83.48 & 98.33 & 98.74 & 98.95 & 98.95 & 99.96 \\ L602 & 0 & 0.91 & 30.71 & 84.46 & 97.91 & 98.49 & 98.58 & 98.74 & 99.79 \\ L802 & 0 & 15.38 & 27.33 & 83.31 & 96.01 & 97.22 & 97.71 & 98.26 & 99.51 \\ L803 & 0 & 33.02 & 58.49 & 93.02 & 99.22 & 99.36 & 99.43 & 99.57 & 99.93 \\ \hline \hline \end{tabular}  
* C. S = coarse sand, M. S = medium sand, F. S = fine sand, V. F. S = very fine sand, C. Si = coarse silt, M. S = medium silt, F. Si = fine silt, V. F. Si = very fine silt, and C = clay.  
\end{table} 
Table 3: Grain size distribution data. Figure 20: A box plot of 6 samples from Temburong and Belait Formations. According to the curves in Figure 22, the primary grain size that dominated in the samples is the size between the sieves of the (0.075) mm and (0.125) mm sizes, or the Phi values of four and three, respectively, with a percentage range of 50-90% of the sizes. This result shows the domination of very fine sand in most of the samples. The samples showed a range of sorting, from poorly to moderately well-sorted samples.