DEVELOPMENT OF A NEW INDEX FOR METHANE DRAINAGEABILITY OF A COAL SEAM USING THE FUZZY ROCK ENGINEERING SYSTEM

Ugljeni plin jedan je od najvažnijih izvora energije iz nekonvencionalnih plinskih ležišta. Prepoznavanje varijabli koji utječu na propusnost metana važno je za sve buduće projekte iskorištavanja takvih ležišta. K od crpenja takvih metanskih ležišta efikasnost je određena prirodnim i operacijskim čimbenicima. Prikazan je novi metanski indeks crpenja (MIC, engl. skr. CMDI) kao vrijednost za uporabu u rudarskim zahvatima. Razmatrano je 17 glavnih parametara koji utječu na crpenje metana iz ugljena, svrstanih u matricu kreiranu na temeljima neizravne logike stijenskoga sustava. Zatim je analiziran odnos parametara koji utječu na crpenje. Budući da odnosi u neizravnim logičkim modelima nisu jedinstveni, takav sustav pažljivo je prilagođen kako bi minimizirao subjektivnost u određivanju težinskih faktora pojedinačnih parametara. Primjer uporabe modela prikazan je za rudnik ugljena Tabas u Iranu. Na uzorcima iz sloja C1 toga prostora primijenjen je izračun indeksa crpenja. Rezultati su pokazali kako takav indeks može vrlo uspješno predvidjeti moguću proizvodnju metana te biti uporabljen kao varijabla za donošenje odluka i smanjenje rizika negativnih događaja u takvim projektima.Coal seam gas is one of the most significant energy resources in unconventional gas fields. The identification of influencing parameters and methane drainage assessment are, thus, a prime geotechnical focus for all potential methane drainage projects. In methane drainage operations of coal seams, many factors, such as natural factors and operational factors affect the drainage efficiency. In this paper, a new coal seam methane drainageability index (CMDI) is introduced for pre-drainage techniques in a working mine. In this approach, seventeen parameters are considered as the main factors affecting the methane drainage form coal seam, and the interaction matrix based on the fuzzy rock engineering system (FRES), which analyzes the interrelationship between the parameters affecting methane drainage activities, are used to study coal seam methane drainageability. Since the value of interaction in the RES method is not unique, the fuzzy system is used to minimize subjectivity of the weights which are computed in the RES method. The Tabas coal mine (Iran) was selected as a case study and the proposed index was used to rank the C1 seam in this mine. It was observed that the methane drainageability index could suitably predict the potential of the methane drainage of coal seam. The newly proposed index can be used as a basis for decision-making when uncertainties about the evaluation of the parameters affect the methane drainage of a coal seam and reduce the risk of methane drainage projects