鄂尔多斯盆地西峰油田原油含氮化合物分布特征与油气运移

为了给鄂尔多斯盆地西峰油田进一步勘探决策提供油气运移方面的依据，根据对该油田延长组原油的中性含氮化合物研究探讨油气运移问题。结果表明，原油的中性含氮化合物在平面和剖面方向均存在着明显的运移分馏效应．但是长。油层组原油中咔唑类化合物的绝对丰度和异构体参数值变化较小，说明该油层组油气经历了短距离运移。根据含氮化合物的运移分馏特征认为，平面上长s油层组油气主要从北东方向注入并向南西运移，部分原油从南部西33井地区注入并向北部运移；纵向上长s油层组油气由上向下运移，研究区西部长8、长3和延8油层组油气则自下而上从长。油层组向延s油层组方向运移。这种油气运移方向与研究区流体压力的指向一致。依据油气运移途径推断，该区油气主要来自长7段油源层。图5表2参10

Distribution of nitrogen compounds and migration of the oils in the Xifeng Oilfield, Ordos Basin, NW China

The Xifeng Oilfield is the largest new-discovered one in the Ordos Basin, NW China. Distribution of the nitrogen compounds in crude oils of the oilfield shows that the migration fractionation of neutral nitrogen compounds in the crude oils are present in the lateral and vertical directions of the oilfield. However, the small variance in the absolute concentration and isomer parameter values of neutral nitrogen compounds in oils from the subsection of Chang-8 oil layer of the Yanchang Formation indicates the short migration distance of the oils. The migration fractionation features of neutral nitrogen compounds in the oils show that the charging direction of crude oil is mainly from the northeast of the oilfield to the southwest and partially from the south to the north for oils from the subsection of the Chang-8 of the Yanchang Formation. It is also observed by means of the migration fractionation of neutral nitrogen compounds in the oils that vertical migration direction of crude oil is downward for Chang-8 oil leg and upward for Chang-3 oil leg and Yan-8 oil leg. This oil migration direction of Xifeng Oilfield is consistent with the distribution of subsurface fluid pressure of the studied area. These oil migration pathways suggest that the oils of Xifeng Oilfield are mainly derived from the subsection of Chang-7 of the Yanchang Formation.