Thesis (Ph.D.)--University of Western Sydney, 2007. / "A thesis submitted in partial fulfilment of the requirements for the award of the degree of Doctor of Philosophy from University of Western Sydney, College of Arts, Centre for Cultural Research." Includes bibliography.

M.Tech. (Extraction Metallurgy) / Please refer to full text to view abstract

Abstract The mineralogy and geochemistry of the fine and clay fractions of till in different moraine types and in different bedrock areas in northern Finland have been studied. A total of 250 till samples from 140 test pits were studied mineralogically and geochemically. X-ray diffraction, differential thermal and thermogravimetric analyses, transmission electron microscopy, X-ray fluorescence and atomic absorption spectrometry were used as analytical methods. In the clay fraction of till quartz, plagioclase, microcline and amphibole are the primary minerals occurring. The clay minerals proper include vermiculite, chlorite, illite, swelling-lattice vermiculite and mixed-layer clay minerals. Kaolinite occurs most abundantly in the clay fractions of till in the Kittilä, Jerisjärvi, Kaaresuvanto and Pulju areas. In the clay fraction of Kittilä and Jerisjärvi illite is dioctahedral type, but in their of other study areas both di- and trioctahedral types occur. Kaolinite and dioctahedral illite are evidence of the mixing of the weathered bedrock material into the till matrix. In the fine fraction of till most abundant minerals are primary minerals and clayminerals are in a minor role. In the clay fraction of till the content of primary minerals are at higher and secondary minerals are at lower level in the Granitic and Archaean gneiss areas than in the Greenstone Belt, Svecokarelian schists and gneiss and Granulite areas. Amphibole, microcline and plagioclase occur in very low amounts or are totally destroyed by chemical weathering in the clay fraction of the till in the Kittilä area. The mineral composition of fine and clay fractions in the tills of northern Inari gives an indication that there occur much more mafic volcanites than is known today. The mineralogical compositions of fine fraction of the tills correlates quite well with the underlying bedrock in all study areas, but clay fraction does not. Geochemical results are in accordance with the mineralogical composition of both fractions. In the fine fraction of the till Si, Ca and Na contents are higher than in the clay fraction. Clay fraction is enriched in Al, Fe, Mg, K and trace elements as compared to the fine fraction. Present study material points out that the distribution of chemical elements in the clay fraction of the till does not correlate with the composition of the underlying bedrock, but fine fraction does so with a few exceptions. The chemical composition of till in Kaaresuvanto and Inari does not fully correspond to the composition of the underlying bedrock as known today. In northern Inari and Kittilä the results give an indication that there are more mafic volcanites and/or sulphide mineralizations occurring in these areas than is known at the present time. The most important factors controlling the mineralogical and geochemical composition of the fine and clay fractions of the tills in northern Finland are the composition of the bedrock and the possible occurrence of an old weathering crust. The final grain size composition of the tills and consequently the quantitative proportions of the different minerals are often related to the last glacial quarrying and sorting processes; therefore the mineralogical composition of the tills is to a certain extent bound also to the respective moraine type.

>Magister Scientiae - MSc / Clay diagenesis phenomenon and their effects on some petrophysical properties of lower cretaceous silliciclastic sandstones, offshore Orange basin have been established. Previous studies on Orange basin revealed that chlorite and quartz cements have significantly compromised the reservoir quality in this basin but it is expected that the reservoirs shows better improvement basinward, an analogy of this is displayed by tertiary sandstones deposit, offshore Angola. The main goal of this thesis is to perform reservoir quality evaluation by intergrating geological, geochemical and geophysical tools to substantiate the effects of clay minerals distribution and its subsequent diagenesis on the intrinsic properties (porosity, permeability and saturation) of reservoir intervals encountered within three wells in block 3A (deeper waters), offshore Orange basin. Five lithofacies were identified based on detailed core description from wells KF-1, KH-1 and AU-1 in this block. The facies were grouped based on colour and grain sizes, they are named : A1 (shale), A2 (sandstone), A3 (siltstone), A4 (dark coloured sandstone) and A5 (conglomerates).Depositional environment is predominantly marine, specifically, marine delta front detached bars and deepwater turbiditic sandstone deposit. Geophysical wire line logs of gamma ray, resistivity logs combo and porosity logs were interpreted, parameters and properties such as VCL, porosity, permeability and saturation were estimated from these logs and the values obtained were compared with values from conventional core analysis data, the values agreed well with each other. Detailed petrographic studies (SEM, XRD and thinsection) plus geochemical studies (CEC, EDS, pH, Ec) were carried out on twenty two core samples to establish if these clay minerals and other cements have pervasive effects on the reservoir quality or otherwise.

>Magister Scientiae - MSc / With the latest advancements in the Pletmos Basin it is imperative to understand and study how sandstone reservoirs are affected by clay minerals. Clay minerals are an influential component in sandstone reservoirs worldwide and thus have an impact on the reservoir quality and petrophysical properties. The present research was aimed at assessing the effects of clay minerals on the petrophysical properties of sandstone reservoirs from the Offshore Pletmos Basin. This was done by integrating geological (wireline logs and core analysis), geochemical (XRD and pore water chemistry) and petrographical (QEMSCAN and thin section petrography) analysis to highlight the effects of clay minerals on the intrinsic properties (porosity, permeability and fluid saturation) on reservoirs encountered within the two wells (Ga- Q1 and Ga – S1). The results highlight pervasive quartz cementation as well as the presence of clay minerals: Glauconite (Illite group), Kaolinite (Kaolinite group), Clinochlore (Chlorite group) as the dominant clay minerals and Calcite as the dominant cement in both well Ga – Q1 and well Ga – S1. The most abundant clay mineral in both wells is Glauconite. This clay mineral had a more profound effect on the petrophysical parameters compared to the other clay minerals. The clay minerals occur as pore–filling Kaolinite and pore–bridging Glauconite and pore–lining Clinochlore. As a result, the clay minerals affected the pore connectivity (permeability) more than the pore spaces (porosity). This is confirmed by the petrophysical analysis where both wells have extremely low permeability and good porosity values. The study concludes that the presence of Glauconite, Kaolinite, Clinochlore and Calcite in both wells (Ga-Q1 and Ga-S1) had an adverse effect on the permeability more compared to the porosity in sandstone reservoirs. Due to the high volume of clay and high clay mineral content in well Ga-Q1, the petrophysical parameters were more adversely affected compared to well Ga-S1. As a result, we see better petrophysical properties (porosity and permeability) in the sandstone reservoir from well Ga-S1 due to intense bioturbation. The reservoir quality of well Ga-S1 is much better compared to well Ga – Q1 because water saturation averages at 42% and gas saturation averages at 58%, has decent porosity averages at 12% but low permeability ranges of 0, 1 – 4mD. / 2021-09-30

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