鄂尔多斯盆地地球化学特征与受控因素

通过对鄂尔多斯盆地地球化学背景特征的系统研究,并与我国主要含油气盆地的地球化学特征进行比较,认为该盆地整体上具中高背景、较均匀地化场特征。综合研究表明:鄂尔多斯盆地地球化学背景和异常的形成是各种地质作用和近地表沉积物性质、地形地貌景观条件综合作用的结果,其中油气源是地表化探指标浓度变化和异常形成的物质基础,是地表油气化探异常形成的主控因素,但不同的来源具有不同的组分特征和异常组合特征;构造运动是烃类离开油气源区,向储集层运移和纵向运移的主要动力,不同的圈闭类型对地表化探异常的组合形式或异常模式起着控制作用;而近地表沉积物性质和地形地貌景观条件是影响油气化探异常分布规律和油气化探应用效果的重要因素。 

The characteristics and controlling factors of the surface oil and gas geochemical anomaly in the Ordos Basin

Based on the abundant actual data and the joint mapping of these data,the authors systematically studied the characteristics of the geochemical background of the Ordos Basin,and compared the geochemical background values of this basin with those of the main petroliferous basins in China.The results show that the Ordos Basin is characterized by middle to high geochemical background values,and relatively even geochemical field among the main petroliferous basins in China.Comprehensive research result shows that the formation of the background and the anomaly within the basin is the results of the combined reactions of various underground geological conditions,various near-surface sedimentary features and various landscapes.Of witch,oil and gas source is the material basis for the formation of the changes in the near-surface concentration of the geochemical indicators,and acts as the main controlling factor for the formation of the near-surface oil and gas geochemical anomaly.Oil and gas from different sources have different compositional characteristics and can cause different near-surface anomaly combinations.The study also shows that the tectonic movement is the main drive force for oil and gas to migrate vertically and laterally from the source rocks to the reservoirs,the difference in trap types plays a controlling role in the near-surface anomaly combination form or anomaly pattern,while the near-surface sedimentary characteristics and the landscape conditions play an important role in affecting the anomaly distribution regularity and the application effects in near-surface oil and gas geochemical exploration.