石油与天然气地质 ›› 2024, Vol. 45 ›› Issue (4): 1007-1017.doi: 10.11743/ogg20240408

• 油气地质 • 上一篇    下一篇

柴达木盆地柴西坳陷古近系-新近系石油地质特征与油气环带状分布模式

刘国勇1,2(), 薛建勤1,2, 吴松涛1,2,3, 伍坤宇1,2, 张博策1,2, 邢浩婷1,2, 张娜1,2, 庞鹏4, 朱超3   

  1. 1.中国石油 青海油田分公司,甘肃 敦煌 736202
    2.青海省高原咸化湖盆油气地质重点实验室,甘肃 敦煌 736202
    3.中国石油 勘探开发研究院,北京 100083
    4.西南石油大学,四川 成都 610500
  • 收稿日期:2024-03-29 修回日期:2024-06-18 出版日期:2024-09-05 发布日期:2024-09-05
  • 第一作者简介:刘国勇(1978—),男,博士、教授级高级工程师,油气地质综合研究与勘探生产管理。E-mail: liuguoyong@petrochina.com.cn
  • 基金项目:
    国家自然科学基金重大项目(42090025);中国石油科技专项国际合作项目(2021DQ-0405)

Petroleum geology and ring-shaped distribution of the Paleogene-Neogene hydrocarbon resources in western Qaidam Depression,Qaidam Basin

Guoyong LIU1,2(), Jianqin XUE1,2, Songtao WU1,2,3, Kunyu WU1,2, Boce ZHANG1,2, Haoting XING1,2, Na ZHANG1,2, Peng PANG4, Chao ZHU3   

  1. 1.Qinghai Oilfield Company,PetroChina,Dunhuang,Gansu 736202,China
    2.Qinghai Provincial Key Laboratory of Plateau Saline-Lacustrine Basinal Oil & Gas Geology,Dunhuang,Gansu 736202,China
    3.Research Institute of Petroleum Exploration & Development,PetroChina,Beijing 100083,China
    4.Southwest Petroleum University,Chengdu,Sichuan 610500,China
  • Received:2024-03-29 Revised:2024-06-18 Online:2024-09-05 Published:2024-09-05

摘要:

柴达木盆地柴西坳陷古近系-新近系石油资源丰富,常规石油与页岩油分别占全盆地常规石油资源的82.4 %和非常规页岩油资源的100 %。通过研究沉积储层与石油地质特征,剖析柴西坳陷古近系-新近系沉积相和油气成藏特征,提出了油气环带状分布模式。研究认为:①柴西坳陷古近系-新近系沉积相带呈“环带状”分布。外环带为三角洲与滩坝相,以碎屑岩沉积为主,碳酸盐岩沉积较少,发育砾岩、含砾粗砂岩和中-粗砂岩储层。中环带以滨浅湖灰云坪、灰泥坪相沉积为主,发育细砂岩、粉砂岩、灰云岩及藻灰岩,藻灰岩是中环带最具特色且孔隙度最高的岩相类型。内环带以半深湖-深湖相细粒混积岩沉积为主,发育深灰、暗灰色细粒沉积岩,是古近系-新近系最主要的烃源岩发育区。②不同沉积相环带内油藏类型不同。外环带距离生烃灶较远,油气经断层输导在砾岩、粗砂岩等碎屑岩中聚集,形成构造油气藏。中环带紧邻主力生烃灶,油气经断层输导在藻灰岩等碳酸盐岩储层中储集,形成构造-岩性油气藏。内环带油气短距离运移或原位滞留在细粒混积岩中源-储一体,形成页岩油。柴西坳陷从源外到源内,构造-岩性油气藏与页岩油纵向上相互叠置,平面上构造油气藏、构造-岩性油气藏与页岩油呈环带状分布。

关键词: 有序聚集, 环带状分布, 全油气系统, 英雄岭页岩油, 柴西坳陷, 柴达木盆地, 青藏高原

Abstract:

The western Qaidam Depression features rich Paleogene-Neogene petroleum systems, with conventional and shale oil accounting for 82.4 % and 100 % of the counterparts of the whole basin, respectively. Based on the investigated sedimentary reservoirs and petroleum geology, we analyze the sedimentary facies and hydrocarbon accumulation characteristics of the Paleogene-Neogene in the western Qaidam Depression and propose a ring-shaped hydrocarbon distribution pattern therein. The results reveal that the Paleogene-Neogene sedimentary facies zones in the depression present a ring-shaped distribution pattern comprising outer, middle, and inner rings. The outer ring, featuring deltaic and beach-bar facies, is dominated by clastic sediment, with the presence of small quantities of carbonate sediment. This ring contains conglomerate, coarse-grained conglomeratic sandstone and medium-grained sandstone reservoirs. The middle ring is dominated by the limy dolomite flat and limy muddy flat microfacies of the shore-shallow lacustrine subfacies, including fine-grained sandstones, siltstones, limy dolomites, and algal limestones. Of these, algal limestones serve as the most distinctive lithofacies with the highest porosity observed in the middle ring. The inner ring is composed of fine-grained diamictites of the semi-deep to deep lacustrine facies, encompassing deep- and dark-gray fine-grained sedimentary rocks. This establishes the middle ring as the key area to source rock development in the Paleogene-Neogene system. Reservoir types differ across the different sedimentary facies rings. In the outer ring, which is distant from hydrocarbon kitchens, hydrocarbons, transported via faults, accumulate in clastics such as conglomerates and coarse-grained sandstones, resulting in structural hydrocarbon reservoirs. The middle ring, immediately adjacent to the major hydrocarbon kitchens, has hydrocarbons migrating through faults and accumulating in carbonate reservoirs like algal limestones, resulting in the structural-lithological hydrocarbon reservoirs. The inner ring sitting on major source rock sequence has hydrocarbons either undergo short-distance migration or reside in situ in fine-grained diamictites, forming shale oil reservoirs. The western Qaidam Depression exhibits overlapped structural-lithological hydrocarbon reservoirs and shale oil reservoirs vertically from external to intra source rocks, and manifests a ring-shaped distribution of structural hydrocarbon, structural-lithological hydrocarbon, and shale oil reservoirs in a plan view.

Key words: ordered hydrocarbon accumulation, ring-shaped distribution, total petroleum system, Yingxiongling shale oil, western Qaidam Depression, Qaidam Basin, Qinghai-Tibet Plateau

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