Petroleum geochemistry of Huai Hin Lat formation in Amphoe Nam Nao, Changwat Phetchabun and Amphoe Chumpae, Changwat Khon Kaen, Thailand

• Main Author: Wilairat Khositchaisri
• Other Authors: Kruawun Jankaew
• Format: Theses and Dissertations
• Language: English
• Published: Chulalongkorn University 2012
• Subjects: Petroleum geochemistry > Thailand; ธรณีเคมีวิเคราะห์ > ไทย > น้ำหนาว (เพชรบูรณ์); ธรณีเคมีวิเคราะห์ > ไทย > ชุมแพ (ขอนแก่น)
• Online Access: https://digiverse.chula.ac.th/Info/item/dc:37621
• Institution: Chulalongkorn University

Khorat Plateau is located in the northeast of Thailand where natural gas has been discovered and commercially produced from Triassic and Permian Basin. Huai Hin Lat Formation and Permian Saraburi Group are believed to be the petroleum source rocks of the gases. However, petroleum geochemical studies in this area are relatively scarce. This study includes collecting outcrop samples from Huai Hin Lat Formation and Saraburi Group and analyzing them for their geochemical properties to evaluate their potentials to be the sources of petroleum. Total organic carbon (TOC) content and extractable organic matter (EOM) were determined as the preliminary source richness evaluation. Then, vitrinite reflectance measurement, studies of nonbiomarkers and biomarkers by Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS), Rock-Eval pyrolysis were done to evaluate their thermal maturity and depositional environment. Moreover, visual kerogen analysis was done to determine the percentages of different kerogen types in samples. Huai Hin Lat Formation has TOC value of 0.79-13.80 wt% which indicates fair to excellent source potential while Nam Duk, Hua Na Kham and Tak Fa Formations have TOC values of 0.66-0.75 wt%, 1.47-1.74 wt% and 0.37 wt%, respectively. These TOC values suggest that Saraburi Group has fair to good source potential. Extractable organic matter (EOM) of all samples exceed 200 ppm suggesting that sufficient quantities of petroleum can be generated from these rocks. Therefore, they can be considered petroleum source rock. In term of thermal maturity, Rovalues of samples are 0.898-1.935% which indicates a range of maturity level of late mature to post mature. Ts/(Ts+Tm), C31 22S/(22S+22R), Pr/nC17 and Ph/nC18 and CPI values also support that samples are mature. Visual kerogen reveals that samples contain predominantly Type III kerogen. Pr/Ph, Pr/nC17, Ph/nC18 and ternary diagram of C27- C29 regular steranes all suggest that samples are of mixed organic sources between terrigenous and marine organic matters deposited in a reducing environment. Presence of gammacerane in all sample studied further suggests lacustrine environment of deposition. In conclusion, from results in this study Huai Hin Lat and Hau Na Kham Formations are likely the source of petroleum found in the Khorat Plateau area.