The Occurrence of Bedding-Parallel Fibrous Calcite Veins in Permian Siliciclastic and Carbonate Rocks in Central Thailand

Bedding-parallel fibrous calcite veins crop out at two Permian carbonate localities in the Phetchabun area, central Thailand, within the Nam Duk and Khao Khwang Formations. Samples are studied to determine their petrographic, geochemical and isotopic character, depositional and diagenetic associations and controls on the formation of fibrous calcite across the region. Biomarker and non-biomarker parameters are used to interpret organic matter sources in the vein-hosting units, the depositional environment and levels of source rock maturation in order to evaluate source rock potential in the two Formations. Carbon and oxygen isotope values of the veins and the host are determined to discuss the source of carbonates and diagenetic conditions. The petroleum assessment from the Khao Khwang and Nam Duk Formations suggests that both Formations are a petroleum potential source rock with type II/III kerogen deposited in an estuarine environment or a shallow marine environment and a slope-to-basin marine environment or an open marine environment, respectively. The bedding-parallel fibrous calcite veins from the Khao Khwang and Nam Duk Formations are divided into two types: 1) beef and, 2) cone-in-cone veins. The carbon and oxygen isotope compositions from the fibrous calcite veins suggest that the calcite veins could be precipitated from a carbon source generated in the microbial methanogenic zone. The results in this study provide a better understanding of the interrelationship between the bedding-parallel fibrous calcite veins and petroleum source rock potential.

Biomarkers in Source Rocks from Barreirinha Formation (Devonian): Distribution and Paleoenvironment Significance

The Barreirinha Formation-Upper Devonian, is the main petroleum source rock of the Amazon Basin, deposited during the great Devonian Transgression, contributing to significant accumulations of organic matter (OM) in anoxic conditions, which allowed its preservation. The present work had the objective of characterizing the molecular composition of biomarkers in outcrops samples of the Barreirinha Formation, aiming to evaluate the paleoenvironment, thermal evolution, and the preservation of OM total organic carbon (TOC) and Rock-Eval pyrolysis indicate considerable amounts of immature OM deposited in a low oxygenation environment. Gas chromatographymass spectrometry (GC-MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS) data corroborate that the OM was deposited in a suboxic to the oxic environment and low salinity (absence or low relative abundance of β-carotane and gammacerane). 24-N-Propyl-cholestane was detected and identified by synthetic pattern co-injection. High concentrations of tetracyclic polyprenoids (TPPs) in ascending order from base to top, high hopane/sterane ratios, to suggest that the samples had a high molecular weight n-alkanes, C29 steranes, low thermal evolution, and anoxic depositional paleoenvironment.

Ogilvie Platform Composite Tectono-Sedimentary Element

The Ogilvie Platform Composite Tectono-Sedimentary Element occupies an area of about 68,000 square kilometers in the northern part of the Yukon Territory of Canada and includes all Paleozoic- and Triassic-aged strata between a base of Cambrian unconformity and a base of Jurassic and Cretaceous unconformity. This cratonic platform is composed of two lithologically distinct sedimentary successions; a lower suite of peritidal, to shallow subtidal, carbonate-dominated, Cambrian- to Middle Devonian-aged units, and an upper succession of siliciclastic-dominated alluvial fan, shelf delta, nearshore, slope and basinal strata of Middle Devonian to Late Permian and Triassic age. The lower succession is composed of a syn-rift tectono-sedimentary element (TSE) and an overlying passive continental margin TSE. The upper succession is composed of an Ellesmerian orogenic foreland TSE and a syn-epeirogenic TSE. The total discovered oil reserve within the Ogilvie Platform is estimated to be 1.757 × 106 m3 (11.05 million barrels, or MMbbl) and the total discovered gas reserve is estimated to be 2.376 × 109 m3 (83.7 Bcf) in four oil and gas pools. A variety of stratigraphic and structural trap types have been assessed to contain additional conventional hydrocarbon reserves, with a total mean potential of 33.4 × 106 m3 (210.1 MMbbls) of oil and 33.4 × 109 m3 (2.63 Tcf) of gas. The organic-rich shale and siltstone-dominated petroleum source rock units, such as within the Road River Group, Canol and Ford Lake formations, and organic-rich strata within the Hart River and Blackie formations are also prospective for large reserves of unconventional oil and gas and have yet to be formally assessed.

The Lithofacies of Pandua Formation Shale in the Andowia Area, North Konawe, Southeast Sulawesi and Its potential as Petroleum source rock

Research on the Late Miocene of Pandua Formation shale in Andowia area, Southeast Sulawesi is fundamental because it is considered to have the potential as a source rock in Manui Basin. This study aimed to determine the lithofacies and its potential as petroleum source rock using megascopic, petrographic, and total organic carbon analyses in Pandua Formation shale. Based on the megascopic and petrographic analysis of outcrops, the shale can be subdivided into 11 lithofacies consists of clayey shale, massive claystone, clastic detritus-rich claystone, massive mudstone, mica-rich mudstone, iron oxide-rich mudstone, low-angle laminated mudstone, massive siltstone, carbon-rich massive siltstone, laminated siltstone, and carbon-rich laminated siltstone. The results of the analysis of 19 samples of shale showed that the total organic carbon (TOC) content was classified as poor to excellent (<0.5%- >4%). The lithofacies with a high concentration of TOC are carbon-rich massive siltstone and carbon-rich laminated siltstone. Both lithofacies were categorized as potentially excellent source rock which the TOC value content is 5.78% and 5.74%.The result implies the better understanding of the depositional environment and hydrocarbon accumulation potential of the Manui basin for future exploration.