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EN
The longwall mining system with fall of the roof is still the most common hard coal extraction system in Polish mining. Its utilization for selective coal seams’ mining results in the development of post-extraction gobs at different depths. Methane desorption phenomena from the coal seams in the stress release zones and migration of gas towards the area of operations, result in methane accumulating also after completion of coal exploitation. Methane which is not exploited from the gobs can migrate directly to the atmosphere e.g. through overlying layers, faults, workings or directly via an operated ventilation grid of an adjacent coal mine – contributing to the Greenhouse Gas effect. One of the methods to capture methane (Abandoned Maine Methane) from abandoned coal mines is to drill vertical wells through several post-extraction gobs from the surface. This paper presents the results of drilling operations at the AGH-Wieczorek-1 well, where first time in Poland, down-the-hole-hammer (DTH) with casing-while-drilling (CwD) technology were used to drill through several post-extraction gobs. The AGH-Wieczorek-1 well with 440.0 m MD was successfully drilled without any complications. Finally, three post-extraction gobs and two coal seams were drilled. Additionally, results from drillability tests, which were performed during drilling operations, are presented.
EN
One of the most important sources of water for communal purposes in the Lublin area are the useful groundwater aquifers intaken with deep drilled wells. Such wells should be highly efficient and localized in a close vicinity of the local water supply network to lower the cost of transport. Large amounts of water can be produced by large diameter wells, where heavy duty pump aggregates can be installed. High rates of penetration cannot be obtained if the profile abounds in hardly drillable carbonate. This elongates the time of drilling and increases negative impact of mud on the near well zone of the aquifer. It also lowers hydraulic parameters of the well. To improve the efficiency of the wells, drillability tests with cogged bits were performed in carbonate rocks to optimize the mechanical parameters of drilling. Measurement sections, each 0.3 to 0.5 m long, were selected for the tests. Each section was drilled at constant rotational speed and weight of bit values. Prior to the drillability tests, the limits on the weight of bit and rotational speed of the bit were established, in line with the technological characteristic of rig Wirth B3A, strength of the string and of the cogged bit.
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