CAJ | 학술논문

柴达木盆地石炭系暗色泥岩、灰岩、煤及炭质泥岩均较发育.大量区域地质调查结合露头和井下样品的地球化学分析表明,石炭系烃源岩主要为暗色泥岩和灰岩.暗色泥岩有机碳含量介于0.13%～3.25%,平均1.14%,有机质类型以Ⅲ型为主,局部见II型,为中-好的烃源岩;灰岩有机碳含量介于0.02%～0.88%,平均0.23%,有机质类型以Ⅱ型为主,为差-中等的烃源岩.依据镜质体反射率、岩石最大热解温度和生物标志物分析,认为石炭系烃源岩总体处于成熟-过成熟阶段.靠近山前的莲花山、都兰等地区因构造作用造成烃源岩动力变质,热演化程度较高,处于生干气阶段;盆内石灰沟、城墙沟、旺尕秀和扎布萨尕秀等地区烃源岩镜质体反射率和岩石最大热解温度中等,正处于成熟阶段的生、排烃高峰期.石炭系烃源岩的总体评价表明具有良好的油气勘探前景,有可能是继第四系、古近纪-新近纪、侏罗纪之后的第四大含油气系统.特别是德令哈断陷的石灰沟位于可鲁克构造内,圈闭完整,为油气运移的优势指向区,可作为下一步勘探的目标.
시체목분지석탄계암색니암、회암、매급탄질니암균교발육.대량구역지질조사결합로두화정하양품적지구화학분석표명,석탄계경원암주요위암색니암화회암.암색니암유궤탄함량개우0.13%～3.25%,평균1.14%,유궤질류형이Ⅲ형위주,국부견II형,위중-호적경원암;회암유궤탄함량개우0.02%～0.88%,평균0.23%,유궤질류형이Ⅱ형위주,위차-중등적경원암.의거경질체반사솔、암석최대열해온도화생물표지물분석,인위석탄계경원암총체처우성숙-과성숙계단.고근산전적연화산、도란등지구인구조작용조성경원암동력변질,열연화정도교고,처우생간기계단;분내석회구、성장구、왕소수화찰포살소수등지구경원암경질체반사솔화암석최대열해온도중등,정처우성숙계단적생、배경고봉기.석탄계경원암적총체평개표명구유량호적유기감탐전경,유가능시계제사계、고근기-신근기、주라기지후적제사대함유기계통.특별시덕령합단함적석회구위우가로극구조내,권폐완정,위유기운이적우세지향구,가작위하일보감탐적목표.
Carboniferous dark mudstone,limestone,coal and carbonaceous mudstone are well developed in Qaidam Basin.Based on the substantial regional geological surveys,studies of the outcrops and geochemical analysis of the organic matter,it indicates that Carboniferous source rocks are mainly dominated by dark mudstone and limestone.The total organic carbon content(TOC) of dark mudstone is between 0.13% and 3.25%,and averagely 1.14%.The organic matter of dark mudstone is mainly of Ⅲ type,and partly II type,which belongs to middle-good source rocks.The TOC content of limestone is between 0.02% and 0.88%,and averagely 0.23%.The organic matter of limestone is mainly of Ⅱtype,which belongs to poor-middle source rocks.Carboniferous source rocks are totally in the maturity and over-maturity stages according to the analyses about vitrinite reflectance(Ro),maximum pyrolysis temperature and biomarkers.In the areas that near the piedmont such as Lianhua Mt.and Dulan,etc,the source rocks occur dynamic metamorphism and have higher thermal evolution stage because of the regional tectonism,and source rocks are in the stage of dry gas generation.However,the vitrinite reflectance(Ro) and maximum pyrolysis temperature of source rocks is medium in the intra-basin areas such as Shihuigou,Chengqianggou,wanggaxiu and Zabusagaxiu,etc,and source rocks are in a peak time of hydrocarbon generation and expulsion.The organic matter source of limestone in the south margin is marine lower hydrobiont.The overall evaluations of carboniferous source rocks show that carboniferous in the area has good prospect for petroleum exploration.Probably,it is the fourth-largest petroleum system following the Eogene period,Jurassic period and Cretaceous period.Especially the Shihuigou area of Delingha Fault-Depression,which is in the Keluke structure,trap is complete,and the area locates in the dominant directional zone of hydrocarbon migration so that it can become the main target for further exploration in Qaidam Basin.