Evaluation of Carboniferous Source Rocks in Qaidam Basin

By means of field geological investigation,we speculate the distribution of Carboniferous source rocks.We use the geochemical parameters(i.e.organic matter abundance,kerogen type,thermal maturity) to comprehensive evaluate the hydrocarbon generation potential of source.The Carboniferous source rocks widely developed in most area of Qaidam basin.The maximum thickness of 900m is located in the Oulongbuluke Mountain in the northern margin of basin,the thickness of source rock in the Gerermu-Wutumeiren-Gansen area of the south margin is about 400-500m as zonal shape distribution along the basin margin.The thickness in the northwest and the southeast parts become thin.The Carboniferous source rocks in Qaidam basin are composed of dark mudstone,carbonate rocks and coals.The dark mudstone as III and II kerogen type has an average value of organic carbon content of 1.28;the thermal maturity reach up to mature and high mature.Thus,the dark mudstone belongs to moderate to good source rocks.The carbonate rocks has a low organic carbon content,with average 0.37%,and the organic matter is Ⅱ1-Ⅱ2 type,hydrocarbon generation potential is poor.Coal is the good gas source rocks.So,the Carboniferous source rocks widely exist in the Qaidam basin,associated with the good petroleum exploration prospect.