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The Huai Hin Lat Formation has a high-potential resource, and the Ban Nong Sai part was researched and sampled. To achieve this goal, petrographic analysis (kerogen types), geochemical analysis (total organic carbon content, TOC), vitrinite reflectance (Ro), and Rock–Eval (RE) pyrolysis were carried out in this study. According to the findings, types II, III, and IV were identified using a modified Van-Krevelen diagram because the higher mature source rock showing hydrogen index (HI) and oxygen index (OI) are continuously depleted and raised. However, microscopic observation describes macerals as primarily sapropelic amorphinite, therefore, type I is important. The TOC was determined to be between 1.90% and 7.06%, which is considered very good to excellent. The original total organic carbon (TOCo) was decided to use its maceral components to determine how to convert extremely mature TOC to TOCo. It varies between 5.13% and 10.74% and reaches a maximum of 57.21% which is comparable to TOC. At 0.82%–1.04%, 443–451 °C, 0.50%–38.10%, and 69.00%–99.59% are the vitrinite reflectance (Ro), maximum temperature (Tmax), production index (PI), and transformation ratio (TR), respectively. Late peak maturity refers to a mixture of oil and gas, whereas most TR ratios refer to the main gas phase. Similarly, the petroleum residual shows no indication of gas trapped at a volume of 6309.50 mcf/ac-ft. In summary, source rock potential was assessed within a suitable risk range defined by Tmax (445.70 °C), Ro (0.91%), TR (90.63%), TOC (8.15%), shale thickness (46 m), and kerogen type (type I). [ABSTRACT FROM AUTHOR]

Petrography and geochemistry analyzing Dat Yai section can describe paleoproductivity and past-redox condition. Paleoproductivity proxies consisted of AOM, phytoclast, TOC, excess SiO2, Ba/Al, and P/Al as high values through sections which similarly indicate high productivity. High productivity in Beds 3 and 27 showed lower peak TOC which is explained by poorer preservation. Lower productivity of Bed 18 showed a high TOC peak indicating good preservation. Paleoredox condition was evaluated using Ni/Co, U/Th, V/Cr, V/(V+Ni), Ni/V, and (Cu+Mo)/Zn. Values for V/(V+Ni) ranged from 0.67 to 0.85 exceeding the cutoff value of 0.46 for a reducing environment. The average value of V/Cr (2.07) exceeded 2.0 of anoxic. Bed 9 consisted of the highest peak of TOC that does not reflect the excellent preservation resulting from dominantly high paleoproductivity. Bed 21 exhibited lower productivity and lowest TOC which indicated a poverty-reducing effect. AOM and phytoclasts were supplied and kept in the benthic floor by extreme redox. Sediments became black shale which expelled oil and some gas. [ABSTRACT FROM AUTHOR]