Abstract: The Permian basin-scale unconformity in the northern truncation zone of Shawan sag of Junggar Basin develops between the Shangwuerhe Formation and the underlying strata, exhibiting an erosional unconformity contact. The Fengcheng Formation, Xiazijie Formation, and Xiawuerhe Formation exhibit good hydrocarbon shows in this region. Recently, a new breakthrough has been made in exploration of Well TT1 in the lowstand system tract conglomerate reservoirs of the Shangwuerhe Formation. To further summarize the Permian hydrocarbon accumulation regularities in Shawan sag, a systematic study on reservoir characteristics, sedimentary facies, and controlling factors was conducted, leading to the following conclusions. (1)The angular unconformity at the bottom of the Shangwuerhe Formation in Shawan sag controls oil and gas enrichment. The Shangwuerhe Formation possesses favorable conditions for large-scale accumulation and serves as the main target for large-scale cost-efficient exploration. (2)The Zhongguai fan provenance is abundant and the scale is large, with the development of effective reservoirs at its distal end. In the Shangwuerhe Formation retrogradational fan delta depositional system, the thin sandstone layer from the Member 2 of Shangwuerhe Formation and the sandstone body from the Member zero of Shangwuerhe Formation constitute the main reservoir bodies. (3)A Permian accumulation model characterized with "unconformity-controlled migration, anticline-controlled enrichment, and overpressure sealing" was established in the northern truncation zone of Shawan sag. The oil-over-gas distribution pattern is the result of the dynamic coupling between petroleum migration and overpressure sealing systems. The discovery of the lowstand system tract conglomerate oil reservoirs in the Shangwuerhe Formation of Well TT1 not only marks a new exploration idea of "prospecting sandstone beneath mud", but also provides valuable insights for expanding exploration fields and optimizing exploration strategies in Shawan sag.

Key words: Shangwuerhe Formation, angular unconformity, Zhongguai fan provenance, accumulation model, exploration breakthrough, Shawan sag

摘要： 准噶尔盆地沙湾凹陷北部超削带二叠系发育盆地级不整合面,上乌尔禾组与下伏地层呈削蚀不整合接触,在风城组、夏子街组和下乌尔禾组中均见良好的油气显示。近期,TT1井在上乌尔禾组低位域砾岩取得勘探新突破。为进一步总结沙湾凹陷二叠系油气的成藏规律,通过系统研究储层特征、沉积相带和控藏要素,获得以下认识:①沙湾凹陷上乌尔禾组底部的角度不整合面控制了油气富集,上乌尔禾组具备大面积成藏条件,是规模效益勘探的主力层系。②中拐扇体物源充足且规模大,其远端仍发育有效储层;在上乌尔禾组的退覆式扇三角洲沉积体系中,上乌尔禾组二段薄砂层和上乌尔禾组零段砂体构成了主要储集体。③建立了沙湾凹陷北部超削带二叠系"不整合控运-鼻隆控富-超压封存"的成藏模式,其中,上油下气分布格局是油气运聚与超压封存系统动态耦合的结果。TT1井在上乌尔禾组低位域发现砾岩油藏,这不仅实现了"泥下找砂"勘探思路的突破,更为沙湾凹陷未来勘探领域的拓展和勘探思路的优化提供了参考。

关键词: 上乌尔禾组, 角度不整合, 中拐扇体物源, 成藏模式, 勘探突破, 沙湾凹陷