Fischer-Tropsch synthesis conducted in volcanic reservoir stone, an important factor caused a reversed pattern of carbon isotopic for natural gases developed in deep layers, Songliao Basin north east China

摘要

Two-types of experiments of source rocks pyrolysis with volcanic reservoir rock and without one were conducted under hydrothermal condition and at 200 ℃ in gold tube system. The experiments result shows that there is a higher concentration of hydrocarbon gases generated in the experiment with rhyolite of reservoir stone and water than that with only water. Moreover, the hydrocarbon gases generated by experiments with rhyolite show a full reserved pattern of carbon isotope. This indicated that the FST reaction could happened between source rocks and volcanic reservoir rock at relatively low temperature. The numerical calculation for the carbon isotope of the gases from mixture between the gases from our FTS experiments and the typical organic hydrocarbon gases from deep layers of Songliao basin show that the contamination of a little FTS gas (＜5% ,v/v) could cause the carbon isotope composition of thermal gases great variation. So, Fischer-Tropsch synthesis conducted in volcanic reservoir stone is an un-negligible factor caused the reversed pattern of carbon isotopic for natural gases developed in deep layers, Songliao Basin. This also indicated that the natural gases in deep layers of the basin are organic origin chiefly.