Artificial maturation of a high volatile bituminous coal from Asturias (NW Spain) in a confined pyrolysis system Part II. Gas production during pyrolysis and numerical simulation

摘要

The objective of this work is to estimate the hydrocarbon production in the Central Asturian Coal Basin (NW Spain) by using the results of artificial maturation and the numeric maturation modeling taking into account the thermal evolution of the maceral composition, the vitrinite reflectance, the T_(max), and the gas production. A confined pyrolysis was carried out inside gold cells under a pressure of 700 bar at several temperatures (330, 360 and 400℃) and duration (24, 120 and 720 h). The kinetic model METAGAZ-1D was used to simulate hydrocarbon production. Methane production begins at %R_r = 0.7 and increases with reflectance. Vitrinite reflectance, and T_(max) were calculated from the model by describing the kerogen transformation under the action of typical temperature of burial. From the spatial distribution of the vitrinite reflectance, and after the depth, the importance of the hydrocarbon production was estimated by the simulation and artificial maturation and compared with the gas quantities adsorbed by coal. Two mechanistic pathways relating to CH_4 production and CH_4 adsorption from coal were built to estimate the real exploitable gas proportion as function of depth and the geographical location of the coal seams in the basin.