General Geology and Hydrocarbon Potential of Carbonaceous Shale in Kampung Ibok, Chukai, Terengganu
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PLATFORM - A Journal of Engineering GENERAL GEOLOGY AND HYDROCARBON POTENTIAL OF CARBONACEOUS SHALE IN KAMPUNG IBOK, CHUKAI, TERENGGANU Nur Izzati Izwani Yusri*, Askury Abd Kadir Geoscience Department, Faculty of Engineering, Universiti Teknologi PETRONAS Email: [email protected] ABSTRACT Various chemical analyses such as Total Organic Carbon (TOC), Source Rock Analysis (SRA), Vitrinite Reectance (VR) and X-Ray Diraction (XRD) have been performed to study the properties of carbonaceous shale and its hydrocarbon potential at Kampung Ibok, Cukai, Terengganu. The TOC content of carbonaceous shale in Chukai area is ranging from 1.24% to 15.3% and increases towards southern part. This may indicate that the southern part might be the deepest part of shallow marine environment. The SRA conrms that the carbonaceous shale in the study area has poor capability in generating any hydrocarbon. However, the results from VR suggested that the shale could have the possibility in producing shale gas. Keywords; carbonaceous shale, shallow marine environment, hydrocarbon potential, shale gas INTRODUCTION PROBLEM STATEMENT The study area is located in Kampung (Kg.) Ibok, Coastal Terengganu especially south of Kuala Chukai and also known by the name of Kemaman City. Terengganu to Kemaman, is mainly composed of Chukai is the biggest town in Southern Terengganu, low- grade metamorphic rocks originated from the Malaysia. As it is located between the state capitals of sedimentary rock. Some of the rocks are black in Kuantan and Kuala Terengganu, and it is proximity color, which might indicate that the rock contains to the oil town of Kerteh, geographically has turned high organic content becomes carbonaceous shale. Chukai into a major commercial hub for the region. Some exposures in Chukai area have shown these Located nearby is the Kemaman Port, that serves characteristics. However, very limited study has been both as a fishing port and supply base for oil platforms conducted to study the properties of these exposed off the Terengganu coast. black materials. Therefore, this research was conducted based on the limitation that have been The location of the study area, which consists of analyzed from the previous research and to focus on five outcrops denoted as Outcrop 1 to Outcrop 5 analysis of hydrocarbon potential of the carbonaceous respectively. These five outcrops represent different shale of the study area. lithologies for the Chukai. All of the outcrops of this study area are easily accessible as the outcrops are located along the federal main road. VOLUME TWO APRIL 2018 PLATFORM 15 PLATFORM - A Journal of Engineering OBJECTIVE consists of the geological map and cross-section of the outcrop were performed during the outcrop The main objective of this research is to have a survey, which include identification and classification better geological understanding of the Chukai area of the lithology. Rock samples have been taken from which comprises of Sungai Perlis bed, and to evaluate each outcrop for further geochemical analysis as the hydrocarbon potential of the carbonaceous shale for hydrocarbon potential validation of the outcrop which involving Total Organic Carbon (TOC) test, observation. The study was emphasized on the Source Rock Analysis and Vitrinite Reflectance test general geology and the hydrocarbon potential of for determination of level maturation and the type of the carbonaceous shale found in Sungai Perlis bed kerogen. specifically in Kg. Ibok, Terengganu. Figure 1 Location of study area, Chukai, Terengganu SCOPE OF STUDY Geology and tectonic framework on the eastern belt The Eastern Belt of Peninsular Malaysia (Figure 2) The study includes the interpretation of the general is the east part of Lebir fault including the eastern geology of Chukai area in Terengganu as shown in part of Johor [1]. This belt includes east of Kelantan, Figure 1, which involves in lithology identification and Terengganu and east of Johor that composed of structural features that requires details observation formations aged from Paleozoic to Cenozoic. The and sample collection to identify the properties northern part of the Eastern Belt consists of the of each rock. Hand specimens are collected for Carboniferous meta-sediments, igneous rocks and petrography study and geochemical analysis in the Jurassic Cretaceous continental deposits. laboratory. During the outcrop survey, the study was emphasized in the description of general geological It consists of the Carboniferous meta-sediments based characteristics such as lithology, texture, mineralogy on the fossils found in Ulu Paka, Terengganu [2], some and primary geological structures. The primary data other localities in north Pahang and Terengganu [3] 16 PLATFORM VOLUME TWO APRIL 2018 PLATFORM - A Journal of Engineering and Batu Rakit [4] and is known as the Sungai Perlis metasediments are composed of meta- quartzite, Bed [2]. carbonaceous phyllite and slate. The meta-sediments are the most dominant while Previous researchers have shown that the whole the continental deposits occur in a number of small Paleozoic metasediment are known as Kuantan isolated areas. The oldest rock, which is dominant in Group and apart from it is called the Sungai Perlis bed. this belt, is the meta-sediments that is Carboniferous in age and consists of mainly clastic sedimentary rocks Sedimentology, stratigraphy and geochemistry of the that had undergone low-grade metamorphism [5] . carbonaceous shale in Kg. Ibok, Chukai, Kemaman Figure 2 Study area is located in the black rectangle Geology of Chukai, Kemaman (Sungai Perlis bed) From the bigger perspective, the study area of this The metasediments are composed of meta-quartzite, project will focus over Chukai, Kemaman area. The carbonaceous phyllite and slate. Goh [6] reported whole Terengganu is located at the Eastern Belt. about the volcanic rocks and that volcanic rocks The most dominant rock is the sedimentary rocks include acidic pyroclastics (lapilli tuff and ashy tuff) formation (including the metasediment) which aged and rhyolitic lava flow. The intermediate and basic as Carboniferous and Permian together with granite igneous rocks are found as marginal facies of the formation. granite. The sedimentary rocks of the Kemaman area had Chand [2] introduced the Sungai Perlis bed term to undergone a regional metamorphism of low- grade refer it to the sedimentary rocks observed in the Ulu type producing metamorphic rock unit. The oldest Paka area. The name of this formation is taken from rocks in this area are well exposed at Tanjong the Sungai Perlis as these kind of sedimentary rocks Geliga, Tanjong Mat Amin and Tanjong Berhala. The are exposed along the river. The Sungai Perlis bed is VOLUME TWO APRIL 2018 PLATFORM 17 PLATFORM - A Journal of Engineering defined based on the dominant rock sequences of Petrography analysis the argillite, mostly shale, slate, phyllite, and also The sample that had been taken from the outcrop are schist that comes together with some quartzite, further evaluated using thin sections. The purpose meta-conglomerate and hornfels. of this method is to examine the exact lithology and to check on the mineralogy aspect. The thin Pellite facies and psammite facies is observed to section procedure is conducted to determine the be present in Sg Perlis bed (pelite is and old term mineral composition and texture of a rock sample for a clay-rich, fine-grained clastic sediment or by analyzing them under a polarized microscope. sedimentary while psammite is a term applied to The characteristic of the mineral under polarized or metamorphic rocks derived from an arenaceous cross-polarized light can differentiate the mineral, sedimentary protolith or sometimes used as a rock as well as to estimate the mineral composition of name for metamorphic rocks whose classification the rock. is unclear). Along the way to Kg. Ibok, there is sedimentary sequence which comprises of interbedded sandstones, shales and some granite. In Total organic carbon (TOC) the shale layer, there is a fine flake plant found. TOC or total organic carbon is the amount of carbon found in an organic compound. TOC may also This bed is correctable with the Charu Formation refer to the amount of organic carbon in soil, or in a in Pahang that consists of interbedded sandstones, geological formation, particularly the source rock for a siltstones, and shale, which are believed to be petroleum play. TOC analysis is measured from the total carbon present and the so-called “inorganic carbon” (IC) deposited in the shallow marine area near shore by subtracting the inorganic carbon from the total carbon environment by Lee [3]. The meta-sediments show yield. at least two episodes of folding, which are north- northwest (NNW) or south-southeast (SSE) trend and north-south (NS) direction that are considered X-ray diffraction (XRD) analysis as relatively simple structures such as Bukit Bucu and X-ray diffraction (XRD) is a basic tool in the Pulau Kapas area by Abdullah [7]. mineralogical analysis of shales. It is an analytical technique used on a crystalline material to identify In certain area, such as parts of Chukai and Dungun its phase and can provide information on unit cell areas, they are considered as complicated structures dimensions. It is most widely used for the identification with three generations of folding by Abdullah [7]. of unknown crystalline materials (e.g minerals and inorganic compounds). From minimal area, XRD measures the intensities of a reflected area and from METHODOLOGY the results, the atomic-level spacing of the crystal can be calculated. This helps in understanding the Five outcrops are identified across the 34km road crystal structure for the substance. Determination of of Chukai. Throughout the area of study, field the degree of crystallization can also be calculated observations, strike-dip reading, sample collection using XRD analysis. and sketch mapping are undertaken. The size of the samples is estimated to be in 12 cm length and 8 cm width. Rock samples are required in order to analyze Rock-eval pyrolysis the lithology of the study area.