高邮凹陷韦庄地区原油吡咯类含氮化合物运移分馏效应

高邮凹陷韦庄地区具有正常和轻微生物降解2类原油, 对油气运移方向一直存在争议.根据2类原油中含氮化合物浓度、屏蔽型含氮化合物的相对含量与反映原油生物降解的地化参数C₂₁-/C₂₂+、Pr/nC₁₇等nC₁₇物降解作用对该区原油中含氮化合物的相对含量及其分布影响不明显, 运移作用仍然是造成含氮化合物分馏的主要因素.自东向西、东北向西南方向, 韦X11井、韦6 - 2井、韦5 - 19井、韦8井原油中屏蔽型咔唑的相对含量依次增大, 分别为11.6 2 %, 10.6 6 %, 12.70 %, 13.88%;暴露型咔唑的相对含量则表现出相反的变化趋势, 分别为30.6 0 %, 2 8.5 6 %, 2 6.4 3%, 2 4.6 2 %.由此明确了本区油气自东、东北方向向西、西南方向注入, 深凹带和车逻鞍槽提供了主要油源. 

Migration Fractionation Effects of Pyrrolic Nitrogen Compounds of Crude Oil in Weizhuang Area, Gaoyou Sag

The fractionation of pyrrolic nitrogen compounds has been applied widely on studying secondary hydrocarbon migration. As for a biodegraded crude oil, the effect of biodegradation on pyrrolic nitrogen compounds should be studied. The normal crude oil occurs in the reservoirs of Wei 2, Wei 9 and Wei 11 in Weizhuang area of Gaoyou sag, but the oil with little biodegradation occurs in reservoirs of Wei 5, Wei 6 and Wei 8. By comparison among concentration of nitrogen compounds, relative contents of pyrrolic N-H shielded carbazoles and parameters of C_(21)~-/C_(22)~+, Pr/nC_(17), the results show that slight biodegradation has little effects on the relative contents and distribution of pyrrolic nitrogen compounds, but has certain effect on its concentration. Hence, variation of relative contents of pyrrolic nitrogen compounds would imply the secondary migration direction of hydrocarbon. The results indicate that hydrocarbon originated from the deep depression zone and Cheluo saddle and injected westward and southwestward in Weizhuang area.