The Natural Gas Resource Potential Assessment Of Xujiahe Formation In Puguang Area

Puguang area which located in northeastern Sichuan basin, is also between faultand fold lines in front of Dabashan thrust nappe structures and gradual fold lines ofmiddle Sichuan basin. Puguang area mainly developed in three hydrocarbon sourcerocks-T3x1-T3x2, T3x3-T3x4, and T3x5-T3x6, and by now clear progress has been madein this area. However，characteristics of source bed like distribution characteristics,evolution and hydrocarbon generation and expulsion characteristics and the naturalgas resource potential need in-depth research,especially hydrocarbon generation andexpulsion stage and scale of the source bed.Based on systematic research in sedimentation and tectonic background of thearea as well as the seismic and well data, tectonic phases were divided since UpperTriassic and the characteristics and experiences at difference phases along with effectsthey caused to hydrocarbon accumulations were analysed. Denudation thicknessof sedimentary discontinuity was also recovered. And then investigated the sourcerocks geochemical characteristics of Xujiahe formation in Puguang area by using ofparametric analysis of the pyrolysis and kerogen microscopy analysis. Through settingthe parameters used in basin simulation from experimental data and literature data ofPuguang area, hydrocarbon generation and expulsion stage and scale simulationwere done with the basin model software Petromod. Results showed that seen fromtime of expulsion, the scale of hydrocarbon generation of middle Jurassic, lateJurassic, early Cretaceous and late Cretaceous accounted for31.1%,22.2%,23.5%and23.2%its total amount respectively. Seen from strata separately, the scale ofhydrocarbon generation of T3x1-T3x2,T3x3-T3x4,T3x5-T3x6and coal bed were21093.78×108m3,44978.43×108m3,33728.60×108m3and22902.11×108m3,occupying17.2%,36.7%,27.5%and18.6%of the total amount in Xujiahe Formation.