On the Methodology for Processing Hydrogeological Observations in Mine Fields and Mines

P. A. Udodov

In the course of the geological study of mine fields, a large body of factual material accumulates from hydrogeological observations in exploratory boreholes and in mine workings. These data, presented in most cases in the form of tables, are highly illustrative, and therefore are not always used with sufficient completeness.

Without dwelling on the methodology of hydrogeological observations in mine fields, which has been covered in a number of articles and special instructions, we shall give only a description of the resulting graphs that make it possible to express the data of hydrogeological observations obtained during the drilling of core exploratory boreholes and in mine workings. We have usually used these graphs in processing the results of hydrogeological observations in the territory of the Kuzbass mine fields. As an illustration of the data expressed by these graphs, we shall give only one example of the processing of hydrogeological observations for the Anzhero-Sudzhensk district.

Hydrogeological observations in exploratory boreholes at this mine were carried out, as is evident from Figure 1, with varying completeness. It was very difficult to compare such data. The most complete observations provided for determining the discharge of groundwater, the static and dynamic levels of groundwater, the loss of flushing water during drilling, the position of pipes during the drilling of boreholes, the percentage of core recovery, the lithological composition of the rocks, and the process of recovery of the groundwater level. All these data for each borehole are given in conventional symbols in Figure 1 (for 70 core boreholes). The depth of individual boreholes reached 350 meters.

These data chiefly characterize the central unit of the Balakhonka Series. It includes a group of closely spaced coal seams of workable thickness, from the Koksovyi seam (below) to the Dvoinoi seam (above), which are worked by all the mines of the Anzhero-Sudzhensk district.

The factual data shown in Fig. 1 make it possible to conclude that, for the central unit, the discharge from boreholes varies over wide limits—the change in specific discharge ranges from one or more liters per second down to hundredths and even thousandths of a liter per second.

The greatest discharge in deep boreholes is associated with zones of tectonic disturbances. This is clearly seen in the figure under consideration, which shows that a specific discharge of more than one liter per second is observed mainly in boreholes that encountered disturbances. In the Andreevsky sector, for example, the specific discharge of the borehole

905 in the disturbance zone at a depth of 231 m was 1.5 l/sec. A specific yield above 1.5 l/sec at a depth of more than 150 m was observed in wells 564, 546, 549 (Fig. 1).

The increased water-bearing capacity of the disturbance zones is explained by the fact that they serve as drainage channels for groundwater. Hydrogeological sections of the area show that the piezometric surface drops noticeably in the direction of the disturbance zones.

From the graph described we also see that fissure–stratal waters are confined predominantly to coal and sandstone beds. This is confirmed by the data of the hydrogeological survey, in the course of which scattered discharges of groundwater from outcropping coal and sandstone beds were found along the right bank of the Mazalovskii Kitat River near the “Nadezhda” mine. In addition, springs with discharges from 0.5 to 1.3 l/sec are observed here. These data are fully consistent with the results of hydrogeological observations in mines, where it is also noted that the greatest water content is usually encountered in coal and sandstone beds.

The most persistent horizon of fissure–stratal waters is observed in the sandstone occurring in the roof of the Andreevskii coal seam. Most exploratory wells, when encountering this sandstone, especially in the Andreevskii sector, are characterized by significant water-bearing capacity.

From the data presented in the figure, it may be concluded that fissure–stratal waters and waters of disturbance zones are distributed not only in the central sequence, but also in the Chelinskaya and Alchedatskaya sequences. Because of the complex tectonics and facies variability of the rocks, these types of waters are not strictly persistent along strike, but occur as small water-bearing horizons, often cut by fractures of disturbances.

The water-bearing capacity of the Alchedatskaya sequence, as can be seen in Figure 1, has been studied only in its lower horizons. This part of the sequence is characterized by the predominance of sandstones over siltstones. The most complete data on the lower horizons of this sequence are available for the Andreevskii sector. Here wells 464, 507, 469, 879, 943 (Fig. 1) show a specific yield from 0.5 to 5.0 l/sec.

In the roof of the Eleventh coal seam, a thick sandstone horizon is watered over the entire area, regardless of the depth at which it is encountered. In this sequence, as in the others, the greatest water content of the rocks is also confined to zones of tectonic disturbances.

Consideration of the factual material from hydrogeological observations in exploratory wells makes it possible to conclude that the greatest water content of the rocks is observed in the upper zone, to a depth of approximately 100 m. This is also confirmed by hydrogeological observations in mine workings. Such a vertical distribution of rock water content is due to the presence of strong fissuring in the upper part of the bedrock as a result of a deep weathering zone.

By comparing the hydrogeological observation data for individual exploratory wells (Fig. 1), it is possible to address the question of the sources and areas of recharge, as well as the formation of the chemical composition of various types of groundwater. On the basis of these data it was established that groundwater recharge occurs from both local and distant areas. Local recharge is effected mainly by stratal–pore waters of the loose sequence, represented in individual areas by sandy varieties. Through these sandy lenses atmospheric precipitation infiltrates into the disintegrated bedrock. In addition,

Fig. 1. Lithologic-stratigraphic column of the central formation of the Balakhonka series with characteristic water yield.

Diagram headings: Series; Formation; Coal seams; Thickness in m; Columns: stratigraphic, generalized lithological; Specific yield of wells, in l/sec.: < 1.0; 1.0–0.1; 0.1–0.01; 0.01–0.001; > 0.001.

Visible stratigraphic and seam labels: Balakhonka series; Alchedat formation; Ostróg formation; Chernogorsk formation. Coal seams: Alchedat II; Alchedat I; Naddesyatyi; Desyatyi; Andreevsky; Dvoinik; Petrovsky and Tonkii; Sputnik; Maksimovsky; Lebedyansky; Chelyabinsk I; Chelyabinsk II; Chelyabinsk III.

Note in the diagram: Low-thickness sandstones in the roof of the Andreevsky seam increase sharply in thickness southward.

1. Loose sequence.
2. Clayey sandstone.
3. Sandstone.
4. Aleurolite.
5. Argillite.
6. Carbonaceous argillite.
7. Coal.
8. Sandy-clayey sequence with frequent alternation of beds.
9. Sandy-clayey sequence with thick sandstone beds.
10. Designations of hydrogeological observations in exploratory wells: 967 — well number, 2 — number of yield determinations in wells, O — pumping, H — injection, C — artesian flow, K — determination of yield from data on loss of flushing water and by analogy.
11. Designations of hydrogeological observations in exploratory wells by analogy.
12. Cased with pipes.
13. Tested zone.
14. Tectonic disturbance.

Moreover, it is noted that Lower Carboniferous and Middle Devonian limestones, which yield their water by lateral filtration, play a considerable role in feeding the productive strata.

The chemical composition of groundwater should also be shown on the lithologic-stratigraphic section. On this section it is necessary to mark areas with the presence of various mineralization zones. Thus, for example, in Anzhero-Sudzhensk, considerable pyritization is observed in some coal and argillite beds. The groundwater of these beds is usually characterized by an increased content of the sulfate ion. The accompanying figure does not show mineralization zones, analyses of aqueous and hydrochloric extracts of rocks, or spectral analyses of characteristic lithologic-stratigraphic horizons; therefore we shall not dwell on the question of the formation of the chemical composition of the various types of natural waters in the area under consideration.

In addition to hydrogeological observations in exploration boreholes, we also carried out hydrogeological observations in mines. For one of the mines of the area (“Fizkulturnik”), located, apparently, outside the influence of the drainage zone of neighboring mine workings, we were able to collect more complete data on its water abundance and, as a result, to construct a genetic graph of water inflow for this mine (Fig. 2). On the basis of the genetic graph, the quantitative aspect of the dynamic and static water resources of the mine is clarified. In addition, the main factors composing the static reserves have been identified. The figure shows that the inflow to the mine increases sharply when water-bearing tectonic zones are encountered,

Fig. 2. Genetic graph of water inflow into the “Fizkulturnik” mine.
I — static reserves; 1 — when water-bearing tectonic zones are encountered, 2 — when water-bearing sand lenses are encountered, 3 — after the setting of longwall faces, 4 — during the driving of main mine workings. II — dynamic resources.

water-bearing sand lenses, during the setting of longwall faces, and during the driving of main mine workings. Taking into account the separate components of the inflow, it is possible to plan specific measures for eliminating unexpected catastrophic water inflows into the mine. For these purposes, first of all, the use of the method of preliminary drainage of workings should be recommended. It is widely used in the practice of the Donbass and in the Moscow Basin, but in the Kuzbass we so far have only isolated cases of its application (the “Kapitalnaya” mine of the Kiselevsk district and the “Pioner” mine in Kemerovo).

Further, this figure shows that a systematic increase in inflow into the mine is observed during the period from 1943 to 1945. This is explained by the fact that the “Fizkulturnik” mine is located outside the drainage zone of the mines of the area, and therefore the inflow into it grows with the growth of the area opened up by mine workings. Unfortunately, we do not have a mine-surveying plan of this mine with the boundaries of the mine workings plotted for 1943, 1944, and 1945.

Given these data, it would be possible to determine the inflow of water into the mine per unit area of mine workings.

Thus, having a genetic graph of water inflow into mines, one can, by analogy, also solve the question of water inflow into newly designed mines of the region.

Fig. 2 does not reflect the increased inflow of water into the mine in the spring period, which is usually observed in old mines. This is due to the fact that in the mine field there were almost no subsidence funnels, which form when longwalls settle. Through these funnels, surface runoff sometimes enters the mine workings. In addition, for most mines located near various bodies of water, a periodic increase in water inflow into the mine workings is sometimes observed depending on the regime of these bodies of water. An example is the Baikoim mine of the Leninsk-Kuznetskii district of Kuzbass, which is located partly in the valley of the Inya River. The genetic graph of inflow for the Fizkulturnik mine does not show sharp peaks of inflow during periods of hydrological maxima of the rivers of the region, since the mine field is located on a watershed.

From the description of the figures we see that they clearly illustrate all the results of hydrogeological observations in mine fields and operating mines. Therefore, we consider it possible to recommend presenting the obtained results of hydrogeological observations by means of these graphs.

Tomsk Polytechnic Institute
named after S. M. Kirov