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。
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 shortdistance 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.
作者
刘国勇
薛建勤
吴松涛
伍坤宇
张博策
邢浩婷
张娜
庞鹏
朱超
LIU Guoyong;XUE Jianqin;WU Songtao;WU Kunyu;ZHANG Boce;XING Haoting;ZHANG Na;PANG Peng;ZHU Chao(Qinghai Oilfield Company,PetroChina,Dunhuang,Gansu 736202,China;Qinghai Provincial Key Laboratory of Plateau Saline-Lacustrine Basinal Oil&Gas Geology,Dunhuang,Gansu 736202,China;Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China;Southwest Petroleum University,Chengdu,Sichuan 610500,China)
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2024年第4期1007-1017,共11页
Oil & Gas Geology
基金
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)。
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
ordered hydrocarbon accumulation
ring-shaped distribution
total petroleum system
Yingxiongling shale oil
western Qaidam Depression
Qaidam Basin
Qinghai-Tibet Plateau
