Use of petrological and organic geochemical data in determining hydrocarbon generation potential of coals:miocene coals of Malatya Basin(Eastern Anatolia-Turkey)

With this study,the hydrocarbon generation potential of Miocene aged coals around Arguvan-Parçikan in the northern district of Malatya province was evaluated with the aid of petrological and organic geochemical data.According to organic petrography,coal quality data,and low thermal maturity,the Arguvan-Parçikan coals are of high-ash,high-sulfur subbituminous B/C rank.The organic fraction of the coals is mostly comprised of humic group macerals,with small percentages derived from the inertinite and liptinite groups.The mineral matter of the coals is comprised mainly of calcite and clay minerals.The total organic carbon(TOC,wt%)values of the shale and coal samples are between 2.61 wt%and 43.02 wt%,and the hydrogen index values are between 73 and 229 mg HC/g TOC.Pyrolysis(T_(max),PI),huminite/vitrinite reflectance(R_(o),%),and biomarker ratios CPI,Pr/Ph ratio,Ts/(Ts+Tm)ratio,C_(32) homohopane ratio(22S/22S+22R)and C_(29)ββ/(ββ+ααsterane ratio)indicate that the organic matter of the studied coals is thermally immature.When all these data are taken together,Miocene aged coals around Arguvan are suitable for hydrocarbon generation,especially gas,in terms of organic matter type(Type III and Type II/III mixed),organic matter amount(>10 wt%TOC),however,low liptinitic macerals(<15%–20%),low hydrogen index(<200 mg HC/g TOC)and low thermal maturity values inhibit the hyrocarbon generation.