Shallow seismic reflection survey for imaging deep-seated coal layer - Case study from Muara Enim coal

Indonesia has a great potential for deep-seated coal resources. To assist and support the deep-seated coal exploration, a shallow seismic reflection method is applicable for this purpose. This study has conducted a shallow seismic reflection method in Musi Banyuasin Regency, South Sumatera Province. The Muara Enim coal target varies from 100 to 500 meters from the surface. The thickness of the coal layer varies from 2 to 10.65 meters. This study uses 48 channels with 14 Hz single geophone and MiniSosie as the energy source. The receiver and source interval is 15 meters. This study uses a fixed receiver and moving source configuration. From the interpreted seismic section, this study identified a deep-seated coal layer target. These layers are Mangus, Burung, Benuang, Kebon and Benakat layers. A simple interpretation is analyzed by combining the seismic amplitude characteristics and the thickness of the coal layer from the borehole data. From the interpreted seismic section, deep-seated coal layer targets have strong amplitude characteristics and are continuous from southwest to the northeast with a down-dip of around 20-30°. This study helps to inform the operator companies who develop the utilization of deep-seated coal (coalbed methane, underground coal gasification and underground coal mining) about the effective and proper geophysical method for imaging deep-seated coal layer.

Features of Borehole Degassing of the Outburst-prone Coal Seams

The conditions and features are given concerning the degassing of outburst-prone coal seams by wells drilled from the underground workings in the plane of the mined seam. Technological schemes for the location of wells in the mining areas during the preparation and development of the coal seams prone to sudden outbursts of coal and gas were substantiated taking into account the coal strength determined using the method of M.M. Protodyakonov. The scheme of coal seams degassing by wells oriented to the working face line is recommended with a coal strength factor f ≥ 1.3, the degassing scheme with crossed wells — at f < 1.3. The wells are drilled parallel to the working face line and oriented to it. The schemes are implemented in the shallow mines of Karaganda (Kazakhstan), Ukraine and China. Degassing of coal seams not unloaded from the rock pressure by crossing wells ensured an increase in methane production from 1 ton of coal by 0.4–4.8 m3 in the conditions of seams with different coal strength. The highest indicators were achieved in the powerful outburst-prone seams with a coal strength factor of f = 0.3–0.8 in the conditions of the mines of Karaganda Basin, where the volumes of methane extraction by crossing wells were 5.0–5.6 m3 per ton of the degassed coal reserves in the working areas. In the conditions of the outburst-prone shallow seams of Ukraine, the volumes of methane extraction from 1 ton of the degassed coal reserves on the medium density seams amounted to 2.5–4.4 m3 with a coal strength factor of f = 0.6–1.1. 2-2.3 m3 of methane was removed from 1 ton of coal at the Dziulishan mine (China) at a strongly crushed coal layer II1 with a strength factor f = 0.3–0.6. The use of degassing schemes for gas-bearing and outburst-prone coal seams ensures an increase in the productivity of working faces and, as a result, high economic indicators.

ASSESSMENT OF MAIN ROOF CA VING INCREMENTS IN WORKING FACE PROCESSING OF TOLMACHEVSKY COAL LAYER WITHIN THE DIP-WORKING PANEL 18-2

This work reviews the study aimed to assess the actual increments of the main roof caving which appear in the course of working face processing of ‘Tolmachevsky ' coal layer in ‘Polysayevskaya' coal mine as the main parameter defining the degree of abutment pressure influence on mine tunnels adjacent to working face.

On the paleobotanical characteristic of the mospino formation (middle carboniferous, Donets Basin)

Formulation of the problem. Deposits of the Mospino Formation (Upper Bashkirian) are poorly characterized by plants remains. Any new data supplementing the paleobotanical characterization of the Carboniferous deposits of the Donets Basin are, undoubtedly, of interest. The aims of the article are to find out the systematic composition of plant remains from two localities and to determine the conditions of growth and burial of plants. The history of the study of Carboniferous flora of the Donets Basin dates back almost two centuries. During this long period, a rich fossil macroflora was investigated from the Carboniferous sediments. Material and research methods. This article is based on the results of a study of fossil flora from two sites – Makedonovka and Volnuhino (Lutuginsky district of the Luhansk region). Statement of the main material. Of the sediments with the coal layer g12 (Makedonovka), 32 taxa were identified: 20 species and 12 forms defined in the open nomenclature. The composition of the plant complex is as follows: Bothrodendron minutifolium, Cyperites bicarinatus, Halonia sp., Lepidodendron lycopodioides, Lepidophloios laricinus, Lepidostrobophyllum sp., Syringodendron sp. 2, Stigmaria ficoides, Asterophyllites grandis, Asterophyllites longifolius, Calamites carinatus, Calamites undulatus, Calamites cistii, Calamites sp., Pinnularia capillacea, Sphenophyllum cuneifolium, Sphenophyllum sp., Alethopteris sp. 2, Dictyoxylon sp., Eusphenopteris cf. obtusiloba, Eusphenopteris sp., Karinopteris acuta, Karinopteris sp., Neuralethopteris rectinervis, Neuralethopteris schlehanii, Lyginopteris hoeninghausi, Paripteris gigantea, Trigonocarpus parkinsonii, ?Trigonocarpus sp., Cordaicarpus cordai, Cordaites principalis, Cordaites sp. From the roof of the coal layer g3 (Volnuhino), 36 plant taxa were determined: 21 species and 15 forms defined in the open nomenclature. Among them: Asolanus camptotaenia, Bothrodendron minutifolium, Cyperites bicarinatus, Knorria sp., Lepidodendron obovatum, Lepidodendron aculeatum, Lepidophloios laricinus, Lepidostrobophyllum majus, Syringodendron sp. 1, Stigmaria ficoides, Asterophyllites charaeformis, Asterophyllites grandis, Calamites carinatus, Calamites undulatus, Calamites cf. sachsei, Calamites sp., Calamostachys sp., Sphenophyllum cuneifolium, Alethopteris davreuxi, Alethopteris sp.1, Aulacopteris sp., Cardioneura amadoca, Cyclopteris sp., Karinopteris acuta, Karinopteris beneckei, Karinopteris cf. dernoncourti, Mariopteris cf. nervosa, Mariopteris sp., Lyginopteris hoeninghausi, Neuropteris cf. obliqua, Neuropteris sp., Palmatopteris furcata, Tetragonocarpus palibinii, Artisia approximata, Cordaites sp., Samaropsis sp. A detailed morphological comparison of the following group of species is necessary: Cardioneura amadoca, Neuropteris bulupalganensis, Neurocardiopteris asiatica, as well as species of the genus Neurocardiopteris Lutz. It is possible that Neuropteris bulupalganensis and Neurocardiopteris asiatica, having close age and morphology, will turn out to be synonyms. Hygrophilic and meso-hygrophilic plant communities were the initial plant communities for Volnukhino phytoorictocenosis. The deposits of the Mospino Formation belong to the zone of joint distribution Neuralethopteris spp. – Lyginopteris hoeninghausii (NL) schemes by O.P. Fisunenko or macrofloristic subzone Alethopteris decurrens of the Lyginopteris hoeninghausi zone of the scheme of N.I. Boyarina. Conclusions. Fossil site Volnuhino is the richest locality of the flora remains of the Mospino Formation. The deposits are sediments of a freshwater lake, peat, lagoon, delta, and coastal accumulative plain. Volnuhino’s locality deserves to be granted the status of a conservation object – a paleontological geosite.