鄂尔多斯盆地古峰庄—王洼子地区长9油层组流体过剩压力与油气运移研究

Fluid Overpressure and Migration of Oil and Gas from Chang 9 Member in Gufengzhuang-Wangwazi Area,Ordos Basin

近几年,在鄂尔多斯盆地上三叠统长9油层组中不断有新的油气发现,因而对长9油层组石油运移的认识对进一步的勘探开发愈发重要。本文通过对古峰庄-王洼子地区延长组长7—长9油层组流体过剩压力的计算,并结合地球化学特征分析,对该地区长9油藏形成时的油气运移的动力特征进行了研究。结果表明,古峰庄—王洼子地区延长组长9油层组石油和长7油层组烃源岩具有相似的地球化学特征,长9原油可能主要来自于其上部长7油层组源岩。长7油层组源岩层具有远远大于长9油层的过剩压力分布,二者之间具有14MPa以上过剩压力差值,成为长7油气向长9油层组储层运移的主要动力。

In recent years, new oil reservoirs have been discovered gradually in Chang 9 member of the upper Trias Yanchang Formation in the Ordos basin. It is important to understand the migration of Chang 9 oil and gas for further exploration and exploitation. By calculation of the fluid overpressure from Chang 7 to Chang 9 members of upper Trias Yanchang Formation and the analysis for the geochemistry of crude oil and resources, migration dynamics of the Chang 9 oil and gas was studied during the formation of Chang 9 oil reservoirs in Gufengzhuang--Hujianshan area. There are similar geochemical characters between Chang 9 crude oils and Chang 7 source rocks in studied area, which reflects that Chang-9 crude oils are likely derived from the upper Chang 7 source rocks. Chang 7 member have a very higher overpressure than Chang 9 member so that a significant overpressure difference （〉14 MPa） has occurred between them. Such an overpressure difference offers energy of migration from Chang 7 oil and gas to Chang 9 reservoir bed.