鄂尔多斯盆地南缘古坳陷奥陶系烃源岩与天然气勘探潜力研究  

Ordovician source rocks and natural gas potential in the southern Ordos basin marginal paleo-depression

作　　者：左智峰[1] 李荣西[2] 

机构地区：[1]成都理工大学沉积地质研究院 [2]长安大学西部矿产资源与地质工程教育部重点实验室,陕西西安710054

出　　处：《中国地质》2008年第2期279-285,共7页Geology in China

基　　金：国家重点基础研究发展规划项目(2003CB214606)资助

摘　　要：鄂尔多斯盆地南缘古坳陷奥陶系分布广,沉积厚度大,其中泥岩烃源岩厚度10～58 m,泥质碳酸盐岩烃源岩厚度20～285 m.有机质丰度高,有机碳(TOC)含量主要在0.15%～0.25%,烃源岩有机质类型主要为Ⅰ型和Ⅱ_1型。在晚三叠世(相当于延长组沉积期)早期开始生气.在晚三叠世末期进入生气高峰阶段,之后从侏罗纪开始强烈抬升。南缘古坳陷现今所在的鄂尔多斯盆地渭北隆起南部山区天然气保存条件差.没有勘探潜力。而渭北隆起北部地区及与伊陕斜坡南部过渡带地区奥陶系埋深一般超过3000 m.生气时间长.具有良好的成藏条件.是构造气藏和构造-岩性气藏有利的勘探目标区。Ordovician source rocks are widespread and very thick in the southern Ordos basin marginal paleodepression. Of these rocks, mudstone and muddy carbonate source rocks are 10-57.6 m and 19.5-285 m thick respectively. They have a high organic abundance with the total organic content （TOC） clustering at 0.15%- 0.20%. Organic matter of the source rocks are mainly of type Ⅰ and type Ⅲ. The Ordovician source rocks began to generate gas in the early part of the Late Triassic （which is equivalent to the period of deposition of the Yanchang Formation） and gas generation reached the peak stage at the end of the Late Triassic. Later, the rocks stopped generating gas because the study area began strong uplift from the Jurassic on. There is no gas potential in the mountainous area in the southern part of the Weibie uplift at the southern margin of the Ordos Basin because of poor conditions of gas preservation. However, in the northern part of the Weibie uplift and the southern part of the Yishan slope of the Ordos basin, the burial depth of the Ordovician generally exceeds 3000 m, the time for gas generation was long and there are good conditions for forming a good gas accumulation; so the two area are favourable exploration targets for exploring for the structural gas accumulation and structural-lithologic gas accumulation.

关 键 词：鄂尔多斯盆地 南缘古坳陷 奥陶系 烃源岩 天然气勘探 

分 类 号：P618.13[天文地球—矿床学]