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Drainage wells as an integral part of a deep dewatering system in Szczerców field in the Bełchatów Lignite Mine

Gasiński J., Macuda J., Szewczyk S.

AGH Drilling, Oil, Gas

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2017

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Vol. 34, no. 2

455--463

EN

The open-pit extraction of lignite in the Bełchatów Lignite Mine can be conducted after prior deep dewatering of the rock mass, realized with large-diameter dewatering wells distributed in the form of outer and inner barriers. This type of dewatering system allows for safe extraction of lignite, however residual waters in the overburden may locally create hazard. These are rain waters infiltrating into the rock mass, and which, due to the complicated geological structure of the deposit and disturbed system of layers, were not intaken by wells belonging to the primary dewatering system. They are removed through the existing and newly drilled exploration wells, which are converted into drainage wells. Such wells are used for removing waters suspended in permeable overburden and gravitationally moved to the lower absorbing layers, from where they are directed to the primary dewatering system wells and then to the surface water courses. The applied enhancement of the dewatering system used in the lignite deposit significantly improves the safety of mining works conducted in this place. Technical and technological aspects of drilling dewatering wells in Bełchatów Lignite Mine are discussed in this paper and followed by the evaluation of efficiency of dewatering of the overburden.

2

Percussion-rotary method of drilling large-diameter dewatering wells in ‘Bełchatów’ liginte mine

Gasiński J., Macuda J., Kaczmarek T.

AGH Drilling, Oil, Gas

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2016

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Vol. 33, no. 3

571--577

EN

Lignite opencast extraction can be performed after prior dewatering of the rock mass. Most frequently it is realized with large-diameter dewatering wells which have been mostly drilled with the invert mud rotary method and airlift. This method allows for quick drilling in lithologically diversifi ed aquifers, minimizing the negative impact of mud on the near-well zone. When drilling in dewatered carbonate rocks with the stone runs or well developed karst the effi ciency of this method considerably decreases. The technical and technological aspects of use of downhole hammers for drilling large-diameter dewatering wells in diffi cult geological conditions are discussed in the paper. Thanksto the use of this method for drilling wells in ‘Bełchatów’ Lignite Mine the drilling rate could be increased and the number of complications and drilling failures lowered.

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Efficiency of drilling large diameter wells with cutter bits on Szczerców opencast

Macuda J.

AGH Drilling, Oil, Gas

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2015

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Vol. 32, no. 2

405--413

EN

Drilling of large diameter wells to be used for dewatering of lignite deposits is inefficient due to the presence of large packages of loose Quaternary and Tertiary strata. Moreover, considerable dewatering of the rock mass favors serious complications and drilling break-downs connected with the sliding of wellbore walls. Accordingly, new technical and technological solutions, which enable faster drilling, are searched for. In this way the time of operation of drilling mud on the near-wellbore zone can be shortened and the safety of drilling works increased. For the sake of obtaining higher rates of drilling in large diameter dewatering wellbores a new cutter bit 0.96 m of diameter was designed. Drillability tests in industrial conditions followed. These tests were performed in separated, loose and low-compaction, macroscopically homogeneous rocks of similar drillability. The tests were performed on selected sections 0.3 to 1.0 m long, and each of the sections was drilled at constant rotational velocity and weight on bit. Prior to these tests there were established limitations regarding weight on bit and rotational velocity of the bit, in reference to the technical characteristic of the rig, strength of the string and the cutter bit. Two different regression models were considered to find a dependence of mechanical drilling rate on weight on bit and rotational velocity of the bit for selected macroscopically homogeneous strata. The most favorable results were obtained for a power model representing impact of axial stress and rotational velocity of the bit on the drilling rate. They have been confirmed by calculated regression coefficients and statistical parameters. Industrial tests were performed to assess the efficiency of drilling large diameter dewatering wells with a cutter bit of 0.96 m diameter on the basis of the presented model of average drilling rate. The results for the average drilling rate turned out to be much higher than the ones obtained so far.

4

Analysis of efficiency of drilling of large-diameter wells with a profiled wing bit

Macuda J.

Archives of Mining Sciences

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2012

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Vol. 57, no. 2

363--373

EN

In Poland all lignite mines are dewatered with the use of large-diameter wells. Drilling of such wells is inefficient owing to the presence of loose Quaternary and Tertiary material and considerable dewatering of rock mass within the open pit area. Difficult geological conditions significantly elongate the time in which large-diameter dewatering wells are drilled, and various drilling complications and break-downs related to the caving may occur. Obtaining higher drilling rates in large-diameter wells can be achieved only when new cutter bits designs are worked out and rock drillability tests performed for optimum mechanical parameters of drilling technology. Those tests were performed for a bit ø 1.16 m in separated macroscopically homogeneous layers of similar drillability. Depending on the designed thickness of the drilled layer, there were determined measurement sections from 0.2 to 1.0 m long, and each of the sections was drilled at constant rotary speed and weight on bit values. For finding the dependence of the rate of penetration on weight on bit and rotary speed of bit various regression models have been analyzed. The most satisfactory results were obtained for the exponential model illustrating the influence of weight on bit and rotary speed of bit on drilling rate. The regression coefficients and statistical parameters prove the good fit of the model to measurement data, presented in tables 4-6. Industrial tests were performed for assessing the efficiency of drilling of large-diameter wells with a cutter bit having profiled wings ø 1.16 m according to elaborated model of average rate of drilling. The obtained values of average rate of drilling during industrial tests ranged from 8.33×10-4 to 1.94×10-3 m/s and were higher than the ones obtained so far, i.e. from 181.21 to 262.11%.

PL

W Polsce wszystkie odkrywkowe kopalnie węgla brunatnego odwadniane są za pomocą studni wielkośrednicowych. Ich wiercenie jest mało efektywne ze względu na występowanie w profilu luźnych utworów czwarto i trzeciorzędowych oraz znaczne odwodnienie górotworu, które jest jedną z głównych przyczyn obwałów ściany otworów i tym samym powstawania trudnych do usunięcia awarii wiertniczych. W celu uzyskania większych prędkości wiercenia wielkośrednicowych studni odwadniających opracowano nową konstrukcję świdra skrawającego i wykonano w warunkach przemysłowych testy zwiercalności. Testy te wykonano dla świdra o średnicy 1,16 m w wydzielonych warstwach makroskopowo jednorodnych, charakteryzujących się zbliżoną zwieralnością. W zależności od projektowanej miąższości przewiercanej warstwy, wyznaczano odcinki pomiarowe o długości od 0,2 do 1,0 m, a każdy odcinek pomiarowy był wiercony przy stałych wartościach prędkości obrotowej i nacisku osiowego na świder. Dla znalezienia zależności mechanicznej prędkości wiercenia od nacisku osiowego i prędkości obrotowej świdra dla wydzielonych warstw makroskopowo jednorodnych, przeanalizowano różne modele regresyjne. Najbardziej zadawalające wyniki uzyskano dla potęgowego modelu wpływu nacisku osiowego i prędkości obrotowej świdra na prędkość wiercenia. Współczynniki regresji i parametry statystyczne potwierdzające bardzo dobre dopasowanie modelu do danych pomiarowych przedstawiono w tabelach 4-6. Dla dokonania oceny efektywności wiercenia wielkośrednicowych studni odwadniających świdrem skrawającym z profilowanymi skrzydłami o średnicy 1,16 według opracowanego modelu średniej prędkości wiercenia wykonano próby przemysłowe. Uzyskane wartości średniej prędkości wiercenia zawierały się w przedziale od 8,33×10-4 do 1,94×10-3 m/s i były wyższe od dotychczas uzyskiwanych od 181,21 do 262,11%.

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Zagrożenie stateczności szybu na odcinku warstw nadkładu wynikające ze zmiany warunków geotechnicznych

Chudek M., Kleta H.

Zeszyty Naukowe. Górnictwo / Politechnika Śląska

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2008

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z. 286

97-105

PL

W artykule przedstawiono wyniki badań przyczyn wystąpienia zagrożenia stateczności szybu na odcinku warstw nadkładu. Na podstawie przeprowadzonej analizy stwierdzono, że drenaż horyzontów wodnych spowodował stopniowe obniżenie się ciśnienia hydrostatycznego, doprowadzając do powolnego osiadania warstw nadkładu i nierównomiernego przemieszczenia się lunety wentylacyjnej jednostronnie podpartej na obudowie szybu. Najprawdopodobniej długotrwała sufozją chemiczna i koloidalna wraz z procesami odwadniania górotworu i osiadania warstw doprowadziły do spękania obudowy lunety wentylacyjnej, a w efekcie do przedarcia się zawodnionych piasków z warstw przypowierzchniowych przez lunetę wentylacyjną do szybu. Dla opisu stanu deformacji, który doprowadził do spękania obudowy lunety wentylacyjnej i wypływu zawodnionych piasków z warstw przypowierzchniowych przez lunetę wentylacyjną do szybu, przedstawiono wyniki obliczeń numerycznych dla początkowego etapu osiadania gruntu przy szybie.

EN

The results from the investigations of reasons of menace to the shaft stability on the segment of overlay stratums have been presented in this paper. On the basis of analysis, it was found that drainage of water layers caused gradually decrease of hydrostatic pressure and generated slow subsidence of overlay stratums and non-uniform displacements of ventilation pipe one-sided supported on the shaft lining. The most probably longtime chemical and colloidal suffusion and process of dewatering and subsidence of rock layers have caused fractures of the ventilation pipe lining. Presented results of numerical calculation carried out for initial stage of ground subsidence near of shaft fully describing state of deformation, which caused fractures of ventilation pipe lining and outflow of watered sands from near surface layers by the ventilation pipe to shaft.