塔里木盆地北部深层烃气垂向微运移特征

VERTICAL MICRO-MIGRATION CHARACTERISTICS OF DEEP HYDROCARBON GAS IN THE NORTH PART OF TALIMU BASIN

烃气的垂向微运移是指油气组分中轻烃成分的运移，它运移距离较远，常对油气藏起破坏作用。对塔里木盆地北部地区近表层和烃源层的轻烃组分和图谱特征、甲烷碳同位素值等的对比分析结果表明，该区超深油气藏中的烃气可以运移至地表，具备开展地表油气化探的前提条件。根据井中垂向游离烃气、吸附烃气的分布变化规律，结合地史演化过程中重大地质事件的发生与发展情况，研究发现：烃气垂向微运移通量的高峰与构造运动具有一定的吻合性，在时间上也表现出旋回性。在塔北地区烃气垂向运移过程中，运移通量总体上具有向上阶梯状分段的递减现象，并具垂向微运移的“梯状”形态特征。

The vertical micro migration of hydrocarbon gas means the migration of light hydrocarbon constituent in petroleum composition,its migration distance is relatively far,which often plays a destructive role in oil and gas reservoir.Through contrasting and analyzing the constituent and pattern property as well as methane carbon isotope value,etc.,of the light hydrocarbon in near surface and hydrocarbon source strata in the north part of Talimu Basin,it is shown that in this region,the hydrocarbon gas in ultra deep oil & gas reservoir can migrate to the surface,thus possessing a prerequisite for carrying out surface geochemical exploration for oil and gas.Based on the distribution rule of the vertical free and absorbed hydrocarbon gases in the well and in combination with the occurrence and expansion of significant geological events in the process of geohistory evolution,it is found that the peaks of vertical micro migration flux of the hydrocarbon gas are coincidental with tectonic movements to a certain degree,showing a cyclic property in terms of time.In the north part of Talimu Basin,in the process of vertical migration of hydrocarbon gas,the migration flux has an upward cascade type segmentation decline phenomenon in general and is of a“stepped”shape property of vertical micro migration.