PETROLEUM GEOCHEMISTRYAND FINGERPRINT BIOMARKER STUDY FOR GEOLOGICAL EVENT IN OUTCROPS AND MUD VULCANOS FROM ATAMBUA AREA, TIMOR BASIN

• Main Author: YUSRIANI (NIM: 22014328), ANGGI
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/21102
• Institution: Institut Teknologi Bandung

The increasing demand in oil and gas has made exploration for new oil and gas <br /> <br /> resource becomes very important. The eastern part of Indonesia alternatively has <br /> <br /> become a new target in the search for new resources. The Timor basin is one of the <br /> <br /> basins in eastern Indonesia that has not been widely known to exist. Although some <br /> <br /> companies have made some efforts in conducting exploration, yet have not been <br /> <br /> successful in finding any commercial result. This basin is related to the complex <br /> <br /> structure of the Timor Basin. The Timor Sea Basin belongs to the tectonic region <br /> <br /> of Australia. Geographically, the Timor Sea Basin is located at 125.1 ° - 128 ° East <br /> <br /> and 9.4 ° - 11.1 ° LS. The geometry of the Timor Sea Basin is relatively long eastsouthwest <br /> <br /> and is on the southeastern part of Timor Island. The northern Timorese <br /> <br /> basin is bordered by a - tectonic complex order generated by the collision of the <br /> <br /> Australian Plate with the island arcs (Timor Trench) and in the southern part of the <br /> <br /> basin, adjacent to the Bonaparte Basin, Banda collisions, and the Timor-Tanimbar <br /> <br /> Trench acting as tectonic boundary. <br /> <br /> The source rock identification was carried out on eight traverses to obtain outcrops <br /> <br /> samples from several formations that were thought to have source rock potential. <br /> <br /> These eight traverses are Soe Traverse, Kapan Traverse, Banli Traverse, Bakulis <br /> <br /> Traverse, Kefa Traverse, Atambua Traverse, Halilik Traverse and Bakitolas <br /> <br /> Traverse. A total of forty-one rock samples were obtained for the analysis of total <br /> <br /> organic carbon and Rock-Eval pyrolysis. These rock outcrop samples came from <br /> <br /> various geological age and formations. The Permian source rocks comprise Pre- <br /> <br /> Bisane Formation, Bisane Formation and Maubisse Formation, Aitutu Formation <br /> <br /> represents the Triassic source rock, Wailuli Formation represents Jurassic source <br /> <br /> rock, Nakfunu Formation represents the early Miocene source rock and Batuputih <br /> <br /> Formation represents the late Miocene.. The results of the total organic carbon and <br /> <br /> Rock-Eval pyrolysis analyzes were applied to identify the most prospect formation as potential source rock. <br /> <br /> The Permian source rocks consists of Pre-Bisane Formation, Bisane and Maubise <br /> <br /> show very poor to excellent TOC values (0,17- 24,45%), composed by Type I-III <br /> <br /> kerogen, and suggest the ability to produce oil and gas. The Aitutu Formation of <br /> <br /> Triasic has variably poor to very good TOC values (0,13 – 6,85%), composed by <br /> <br /> kerogen Type II-III, and may generate oil and gas. One sample from Wailuli <br /> <br /> Formation of Jurassic Age has a very poor TOC value (0,33%), composed by Type <br /> <br /> III kerogen. The Nakfunu Formation from Early Miocene shows very poor to very <br /> <br /> good TOC values (0.33 - 6.57%), composed by kerogen Type II-III, and may <br /> <br /> produce oil and gas. The youngest formation of Batuputih Formation representing <br /> <br /> the Late Miocene has variably very poor to very good TOC (0,31 – 3,06%), <br /> <br /> composed of kerogen type III suggesting capacity to produce mainly gas. <br /> <br /> Based on TOC and Rock-Eval pyrolysis analysis selection were made for extraction <br /> <br /> of eight selected samples representing each formation of different geological ages. <br /> <br /> The biomarker fingerprint analysis was done using GC and GCMS method. The <br /> <br /> results of biomarkers fingerprint are applied to identify biomarker changes that <br /> <br /> occurred in every geological event in the study area. Organic material input changes <br /> <br /> and depositional environment differences become the key to any changes in <br /> <br /> geological events from the beginning of the rift to post-rift. This can be observed <br /> <br /> by geochemical method of fingerprinting. <br /> <br /> In the northern part of the study area, two mud volcanoes from the Lolowa and <br /> <br /> Bakustulama regions were sampled and correlations were made with rock outcrops. <br /> <br /> Based on the biomarker fingerprint analysis, the two seeps of those mud volcanoes <br /> <br /> showed positive correlation with the outcrops of the Triasic Aitutu Formation <br /> <br /> source rock. This is summarized by a star chart to see the correlation proximity and <br /> <br /> calculation of similarity levels based on the ratios between mud volcanoes and rock <br /> <br /> outcrops.