SHALE GAS POTENTIAL OF KUANTAN FORMATION TABEK PATAH AND SURROUNDING AREAS, SUMATRA BARAT

• Main Author: FEBRI YENI, YULIA
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/17680
• Institution: Institut Teknologi Bandung

Shale gas is gas contained in the fine grain reservoir and trapped in it. Unlike the conventional hydrocarbons, shale gas does not have to meet the requirements for petroleum system because it does not require migration or cap rock. Kuantan Formation is Carbon – Perm age rock formation which is part of West Sumatra Block and in the research area can be classified into three units, there are Metamorphic Unit, Shale Unit, and Limestone Unit. Shales of Kuantan Formation deposited on the coastal regions associated with marine environment. The tectonic on research area begins from Carbon to Recent. The geological structures that develope are fold, fault, and joint. Fold with trending relatively NNE-SSW direction formed anticline on Metamorphic schistose biotite-pelite Unit and fold with trending relatively NW-SE direction on Shale Unit and Limestone Unit. There are faults with the NW-SE direction which cut all rock units in the research area, due to the relative direction parallel to the Sumatra Fault then the fault is interpreted as a dextral strike-slip fault. Total Organic Content (TOC) of Kuantan Formation shale obtained from five samples shale is 0.09 wt% - 0.7 wt% with Hydrogen Index (HI) 0-15 mg / g. Based on the results of geochemical analysis, Hydrogen Index (HI) value which < 50 mg/gC, the kerogen type of Kuantan Formation shale is type IV, from the cross-plot between HI and OI values on the van Kravelen diagram, also indicates that Kerogen type of Kuantan Formation shale is type IV. However, based on comparison with the percentage of vitrinite and inertinite, shale in the research area has a greater percentage of vitrinite ie 6-16% whereas inertinite ranged from 1.6-3,2%, it is estimated that these rocks are not derived from type IV. TAI value of shale in the research area is 2 to 2 + / 3 - with intervals of maturity from early mature to late mature or similar to the value of Ro 0.6% - 0.9% and the Tmax 435-450. Kerogen types I, II and III can turn into type IV due to the increased level of maturity due to high temperatures and will cause an increasing of carbon (C) and started to lose Hydrogen (H) and Oxygen (O) due to release of H2O and CH4. Based on the analysis of petography, graphite is found thought to be caused by rocks that are exposed to high temperature and causing the organic content is lost and turned into graphite. <br /> To determine the initial value of TOC and total hydrocarbons that have been lost, restoration is performed on three samples of shale. Based on the <br /> average value obtained from the restoration, the TOC quality of Kuantan Formation shales is quite good as a source rock especially the shale sample from Talao and Tabek Patah area that has TOC value of 0.5 wt% -1.5 wt%. <br /> Based on the results of SEM and EDX analysis, the main clay minerals present in the shale rocks are illite, chlorite and kaolin. Quartz is present as a major component of constituent rocks. The percentage of SiO2 contained in rocks is 40% - 95%. The result of megascopic and microscopic rock analysis shows the shale in research area is containing pyrites which indicates rocks deposited in an reduction reaction environment, not on the oxidation reaction environment.