Every year, coal mines record sudden gas outbursts, volumetric explosions and cases of asphyxiation, resulting in fatalities, extended production stoppages and losses in the millions.
Degassing, methane sensors and early-warning systems control the gas inside the mine, not its source. The tectonics of the coal-bearing formation are not studied in depth before extraction begins, and mine safety services rarely have the instruments or the methodologies required to assess the risk of high-pressure methane entering active workings through tectonic faults.
In addition to the methane originating in the underground workings, Inside Earth detects the methane that migrates under high pressure from deep geological reservoirs (4,920–9,840 ft / 1,500–3,000 m), frequently located beyond the mine boundaries, through tectonic fault systems that act as migration pathways.
Explosions can occur below 5% methane. Heavy hydrocarbons — ethane, propane, butane — travel with the methane and lower the auto-ignition threshold of the mixture.
When the mantle is breached during extraction, large volumes of gas enter the drifts and headings before conventional sensors register the critical condition.
The phenomenon is not adequately addressed in the current regulatory framework, nor in the prospecting protocols customarily applied in the sector.
The same physical principle used to characterize metal deposits and hydrocarbons miles below the surface. The same equipment. A different target fluid.
Carried out without contact with the drifts and headings and without access to the mine. Operations are not interrupted.
Depth, thickness and pressure of the detected fluid are determined for each anomaly.
The routes along which the gas migrates from the deep sources toward the coal zone are delimited.
A deliverable georeferenced in WGS-84 over the concession itself.
Each case demonstrates something different: Zasyadko, predictive accuracy against real drilling data; Anzherskaya-Yuzhnaya, the operational usefulness of a complete model in an active mine.
Predictive accuracy. Four horizons of gas-saturated sandstones were confirmed between 1,755 and 5,932 ft (535 and 1,808 m), in direct comparison against the formation-test data of well ZG-1, under a joint protocol signed by the mine's Geological Exploration sub-directorate.
Studied with a complete gasodynamic model. A migratory tectonic fault running southwest to northeast was identified, together with two gas anomalies at operating depth, two high-risk zones and five recommended degassing drill points.
| Horizon | Depth forecast · ft (m) | Depth drilled · ft (m) | Pressure forecast · psi (atm) | Pressure measured · psi (atm) |
|---|---|---|---|---|
| h₁ | 1,785 – 1,916 (544 – 584) | 1,755 – 1,952 (535 – 595) | 147 – 294 (10 – 20) | 235 (16) |
| h₂ | 3,196 – 3,422 (974 – 1,043) | 2,972 – 3,346 (906 – 1,020) | 220 – 294 (15 – 20) | 1,352 (92) |
| h₃ | 4,173 – 4,321 (1,272 – 1,317) | 4,154 – 4,344 (1,266 – 1,324) | 265 – 294 (18 – 20) | — |
| h₄ | 5,751 – 6,093 (1,753 – 1,857) | 5,886 – 5,932 (1,794 – 1,808) | 2,204 – 2,351 (150 – 160) | 2,410 (164) |
The most significant indicators were obtained at 5,886–5,932 ft (1,794–1,808 m): a pressure of 2,410 psi (164 atm) and a flow of 50,080 cu ft (1,418 m³) of gas per day. The discrepancies in the determination of horizon depths were deemed acceptable for the practical application of remote-sensing equipment.
The southern section is crossed from southwest to northeast by a tectonic fault along which an underground gas flow migrates at 3,840 psi (270 kgf/cm²) from the natural reservoir toward the coal zone, feeding two anomalies at 1,585–1,634 ft (483–498 m) and 1,970–2,000 ft (600–610 m), with pressures of 780–855 and 925–995 psi (55–60 and 65–70 kgf/cm²) respectively.
Two high-risk bands were delimited along the fault boundaries, 660 ft (200 m) wide and 6,560 ft (2,000 m) long. Within them, mining at the depth of the anomalies may trigger instantaneous methane emissions into the active drifts and headings, with auto-ignition of the gaseous mixture and volumetric explosion.
The purpose of the study was to determine and delimit the highest-pressure gas anomalies within the southern section of the Anzherskaya-Yuzhnaya mine (S = 2.7 sq mi / 7.1 km²) by means of geosatellite prospecting methods.
Select any map to view it at full size.
Georeferenced contours in WGS-84 over the concession, with estimated pressure and thickness for each anomaly.
Volumetric reconstruction of the deep sources and of the migration routes toward the coal zone.
Bands within the concession where the depth–pressure combination requires additional measures.
Recommended coordinates and depths to extract the gas before it reaches the drifts and headings.
Where an operation would benefit from a map of the gas sources and the migration routes prior to excavation, with the high-risk zones delimited and the degassing points located, the feasibility of the concession can be assessed by the Inside Earth technical team in a first meeting, without obligation.
