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
Petroleum geology and ring-shaped distribution of the Paleogene-Neogene hydrocarbon resources in western Qaidam Depression,Qaidam Basin
刘国勇 1薛建勤 1吴松涛 2伍坤宇 1张博策 1邢浩婷 1张娜 1庞鹏 3朱超4
作者信息
- 1. 中国石油 青海油田分公司,甘肃 敦煌 736202;青海省高原咸化湖盆油气地质重点实验室,甘肃 敦煌 736202
- 2. 中国石油 青海油田分公司,甘肃 敦煌 736202;青海省高原咸化湖盆油气地质重点实验室,甘肃 敦煌 736202;中国石油勘探开发研究院,北京 100083
- 3. 西南石油大学,四川 成都 610500
- 4. 中国石油勘探开发研究院,北京 100083
- 折叠
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.
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.
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Key words
ordered hydrocarbon accumulation/ring-shaped distribution/total petroleum system/Yingxiongling shale oil/western Qaidam Depression/Qaidam Basin/Qinghai-Tibet Plateau引用本文复制引用
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)
出版年
2024
国家科技期刊平台
NSTL
万方数据