Material Composition and Petrogenetic Features of Coals of the Vasyugan Formation in Tomsk Oblast
Abstract Generated abstract
This paper presents petrographic study of coal interbeds from the Kvartovaya, Nizhne-Tabaganskaya, and Kalinovaya areas of Tomsk Oblast, mainly within the Vasyugan Formation, with one sample from the Bazhenov Formation. Using polished and thin polished sections, microcomponent counts, and the GOST 9414-60 nomenclature, the author characterizes the proportions of vitrinite, semivitrinite, fusinite, liptinite, and mineral inclusions. The Kvartovaya and Kalinovaya coals are interpreted as clarain or clarain-like coals formed in stagnant forest bogs with high groundwater levels, while the Nizhne-Tabaganskaya coal is assigned to a dureno-clarain type associated with a forest bog with weak groundwater flow. The study provides an initial petrographic classification and facies interpretation for these deeply buried coal interbeds.
Full Text
MATERIAL COMPOSITION AND PETROGENETIC FEATURES OF COALS OF THE VASYUGAN FORMATION IN TOMSK OBLAST
O. A. Dulzon
(Presented by the scientific seminar of the Department of Fossil Fuels)
The Kvartovoe, Nizhne-Tabaganskoe, and Kalinovoe oil fields are located in Tomsk Oblast. Geologically, these fields are situated in the West Siberian Lowland, filled with Meso-Cenozoic sedimentary deposits.
The present work sets out the results of macro- and microscopic studies of the coal substance, the petrogenetic types, and the facies of coal formation.
The first coal sample was taken in the Kvartovaya area from well No. 3 at a depth of 2606–2612.7 m, from the Vasyugan Formation.
The second sample was collected in the Nizhne-Tabaganskaya area from well No. 5 at a depth of 2618–2622 m, from the Vasyugan Formation.
The third sample was taken in the Kalinovaya area from well No. 3 at a depth of 2547.6–2551.6 m, from the Bazhenov Formation.
Petrographic studies of coal from the Vasyugan and Bazhenov formations have not yet been carried out by coal petrographers.
In the course of the work, we used the method of distinguishing facial-genetic types of coals, based on a thorough study of changes in the material composition of coals. A detailed petrographic description of the material composition of the coals of the Kvartovaya, Nizhne-Tabaganskaya, and Kalinovaya areas was carried out by the author according to the new terminology established by GOST 9414—60. The composition of the microcomponents is given in Table 1.
The study of the material composition of the coal-forming plants of the coal interbeds of the listed areas was carried out in polished sections and thin polished sections. In addition, the percentage content of microcomponents was calculated, and the data were compiled in Table 2. The counting of microcomponents is carried out on an ISA-type integration stage. Recalculation of the microcomponents in polished sections into the content of microcomponents in the coal interbed was carried out according to the method of Z. V. Ergolskaya [3].
Kvartovaya area
According to GOST 9414—60, the coal interbed of the Kvartovaya area is composed predominantly of microcomponents of the following five groups: vitrinite, semivitrinite, fusinite, liptinite, and mineral impurities.
Table 1
Nomenclature of microcomponents of hard coals established by GOST 9414—60
| Groups: Name | Groups: Designation | Microcomponents: Name | Microcomponents: Designation |
|---|---|---|---|
| Vitrinite | Vt | Telinite Collinite |
Vt₂ Vt₁ |
| Semivitrinite | Sv | Semitelinite Semicollinite Micstinite |
Sv₂ Sv₁ Sv₃ |
| Fusinite | F | Semifusinite Fusinite Micrinite Sclerotinite |
F₁ F₃ F₂ F₄ |
| Leiptinite | L | Sporinite Cutinite Suberinite Resinite |
L₁ L₂ L₄ L₃ |
| Alginite | Alg | Algotelinite Algocollinite |
Alg₁ Alg₂ |
| Mineral inclusions | Ml | Clay matter Iron sulfides Carbonates Other |
Ml₁ Ml₂ Ml₃ Ml₄ |
Table 2
Microcomponent composition of coal interbeds
| No. | Area, borehole no., sample-collection interval in meters | Vt₁ | Vt₂ | Sv₁ + Sv₂ | F | L | ML |
|---|---|---|---|---|---|---|---|
| 1 | Kvartovaya, No. 3, 2606.0—2612.7 |
90,76 | 4,58 | 0,15 | 0,15 | 3,31 | 1,05 |
| 2 | Nizhne-Tabaganskaya, No. 5 2618.0—2622.0 |
73,86 | 8,56 | 12,67 | 1,25 | 0,47 | 3,17 |
| 3 | Kalinovaya, No. 3, 2547.6—2551.6 |
95,62 | — | — | — | 0,84 | 3,54 |
Vitrinite group — Vt
The vitrinite group comprises two components: structureless collinite and structured telinite, which in transmitted light have a reddish-brown color.
Collinite constitutes the bulk of the coal and has reached the complete stage of coaling of the plant tissues of the coal-forming plants without preservation of the cellular structure; it is distinguished only by faintly traceable outlines of plant components. The color of the main mass is reddish-brown; the structure is xylovitrainic.
Telinites—Vt₂, combining plant fragments with xylene and xylovitrainic structure, have a reddish-brown color in transmitted light. In this coal band, a single fragment with xylovitrainic structure measuring 1.0 × 6.0 mm is observed.
Semivitrinite group—Sv
The microcomponents of this group are subdivided by the color and structure of the fragments into structureless semicollinite and structured semitelinite. In the coal, a single fragment of semitelinite with xylovitrainic structure and dark-brown color, measuring 0.8 × 6.0 mm, is observed.
Fusinite group—F
The microcomponents of the fusinite group are characterized by black color and a distinct cellular structure. Of the fusinite group, only two microcomponents are observed—semifusinite and micrinite.
Semifusinite—F₁ consists of plant fragments having a dark-brown, almost black color. For this coal band, the presence of semifusinite with xylovitrainic structure is characteristic.
Micrinite—F₂ is a structureless black microcomponent measuring 0.1 × 0.2 mm. The shape of the fragments is acute-angled. It is observed in the coal as small isolated inclusions scattered in the main mass.
Liptinite group—L
The liptinite group of this coal is represented by three microcomponents: sporinite, cutinite, and resinite.
Sporinite—L₁ consists of small yellow inclusions in the form of commas and strokes. Sporinite occurs as exine of microspores 0.03–0.04 mm in size and as a single accumulation measuring 0.04 × 0.12 mm. Microsporinite is evenly scattered in the collinite mass.
Cutinite—L₂ occurs in only one variety: thin cutinite of yellow and yellow-orange color. It has the form of elongated strips without a serrated structure; their lengths are 1.30 and 1.70 mm. Cutinite is scattered throughout the entire coal mass.
Resinite—L₃ occurs in the coal in insignificant quantity as oval inclusions of yellowish-orange color. In this coal it is represented by isolated inclusions in the main mass. Resinite is characterized by a fine-mesh fracture pattern, and their dimensions do not exceed 0.04 × 0.08 mm.
Mineral inclusions—M1
Mineral inclusions are observed as isolated concretions of light-gray spherosiderite, 0.10 mm in diameter.
The coal band of Quartz Square is composed of hard coal; in petrographic composition it is fairly uniform and is represented by clare—
new type of coal. This type of coal is formed under conditions of a stagnant forest bog with a high groundwater level.
Nizhne-Tabaganskaya Area
According to GOST 9414–60, the coal interbed of the Nizhne-Tabaganskaya area is composed of microcomponents of the following four groups: vitrinite, semivitrinite, fusinite, leiptinite, and mineral impurities.
The coal interbed of this area is characterized by a content of telinites of 8.56% and of the semivitrinite group of 12.67%. In comparison with the coal of the Kvartovaya area, microcomponents of the telinite subgroup are twice as abundant, and a fairly significant amount of semivitrinite fragments is observed, as is clearly seen from the data in Table 2.
The coal interbed of the Nizhne-Tabaganskaya area is composed of hard coal; in petrographic composition it is very rich in microcomponents of all five groups of Table 1. In most plant fragments, the process of fusenization is superimposed on telified plant remains. This coal may be assigned to the dureno-clarain type of coal. It is characterized by the facies of a forest bog with weak groundwater flow.
Kalinovaya Area
According to GOST 9414–60, the coal interbed of the Kalinovaya area is composed of microcomponents of three groups: vitrinite, leiptinite, and mineral impurities.
The coal interbed of this area is characterized by a content of components of the vitrinite group of 95.62% and of leiptinite of 0.84%.
This coal interbed is composed of hard coal; in petrographic composition it contains microcomponents of collinites and telinites with a high degree of gelification of plant fragments. According to the calculated data of Table 2, this coal may be called clarain. It is characterized by the facies of a stagnant forest bog with a high groundwater level.
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