鄂尔多斯盆地东南部奥陶系烃源岩评价

中煤科工集团西安研究院有限公司 地质研究所,陕西 西安 710054

鄂尔多斯盆地; 东南部地区; 奥陶系; 烃源岩

Evaluation to ordovician hydrocarbon source rocks in the southeast of the Ordos Basin
LI Xin

(Geological Research Institute,Xi'an Research Institute of China Coal Technology & Engineering Group Corp,Xi'an 710054,China)

Ordos Basin; Southeast area; ordovician; source rocks

DOI: 10.13800/j.cnki.xakjdxxb.2015.0110

备注

鄂尔多斯盆地东南部奥陶系地层烃源岩厚度大,类型多种多样,成熟度高,为了客观认识鄂尔多斯盆地东南部奥陶系地层烃源岩有机质丰度和生烃潜力,通过有机岩石学和有机地球化学相互结合综合分析的方法开展对鄂尔多斯盆地东南部地区奥陶系烃源岩评价研究。结果 表明:鄂尔多斯盆地东南部奥陶系发育泥质烃源岩和碳酸盐岩烃源岩,其主要分布在南缘古坳陷和陕北古坳陷; 烃源岩残余有机碳平均值0.30%~3.12%; 有机质类型主要为Ⅰ-Ⅱ1型; 烃源岩热演化程度达到高成熟-过成熟阶段; 奥陶系烃源岩在三叠系末(T3y末)进入生气高峰,至侏罗系末(J末)属持续埋藏生气阶段,从晚白垩世开始抬升隆起,生气强度逐渐降低。综合区域地质分析认为,渭北隆起北部与伊陕斜坡南部过渡带在晚古生代沉积后,奥陶系烃源岩埋深一般大于2 500 m,生气时间长,有利于天然气形成,是有利的勘探目标区。

The hydrocarbon source rocks of Ordovician strata in the southeast of Ordos Basin are thickness with various types and high maturity.In order to have a more comprehensive understanding of abundance about organic matter and hydrocarbon potential.Ordovician hydrocarbon source rocks in the southeast Ordos Basin.By the comprehensive analysis method which combines organic petrology and organic geochemistry,evaluation study is carried out on Ordovician hydrocarbon source rock in the southeastern region of Ordos Basin.The results show that: the shale source rocks and carbonate source rocks are widely distributed in the southeast Ordos Basin,Mainly distributed in the southern-margin paleo-depression and Shanbei paleo-depression.The average content of remaining organic carbon of source rocks is 0.30 to 3.12%.The organic matter of the source are mainly typeⅠand type Ⅱ1.Thermal evolution of source rocks reach es high maturity-over mature stage.The source rocks of Ordovician was thought to be the phase of gas generation peak at later Triassic Yanchang period,to the end of the Jurassic(J)case of a continuing uplift buried stage.The strata uplift from the Cretaceous sedimentary,with the gas-generation intensity gradually reducding.Comprehensive regional geological analysis indicates,in the norther part of the Weibei uplift and the southern part of the Yishan solpe of the Ordos basin at late Paleozoic,the burial depth of the Ordovician generally exceeds 2 500 m,and the time for gas,generation was long,which are conducive to the formation of natural gas; so the two areas are favorable exploration target.