柴达木盆地西部坳陷古近系全油气系统特征与油气成藏模式  

Characteristics and hydrocarbon accumulation model of Paleogene whole petroleum system in western depression of Qaidam Basin, NW China

作　　者：刘国勇 吴松涛 伍坤宇[1,2] 沈月[3] 雷刚 张斌 邢浩婷 张庆辉[1,2] 李国欣 LIU Guoyong;WU Songtao;WU Kunyu;SHEN Yue;LEI Gang;ZHANG Bin;XING Haoting;ZHANG Qinghui;LI Guoxin(PetroChina Qinghai Oilfield Company,Dunhuang 736202,China;Qinghai Provincial Key Laboratory of Plateau Saline-Lacustrine Basinal Oil&Gas Geology,Dunhuang 736202,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;PetroChina Company Limited,Beijing 610500,China)

机构地区：[1]中国石油青海油田公司,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]中国石油天然气股份有限公司,北京610500

出　　处：《石油勘探与开发》2024年第5期951-961,共11页Petroleum Exploration and Development

基　　金：中国石油科技专项(2021DQ0405,2023ZZ15);国家自然科学基金“陆相页岩油富集主控因素与有利区带评价方法”(42090025)。

摘　　要：基于柴达木盆地西部坳陷油气勘探实践,结合地震、钻井、测井及地球化学等资料,对柴西坳陷古近系全油气系统基本地质条件、油气分布特征、成藏运聚动力与成藏模式开展研究。研究表明:柴西坳陷发育全球独具特色的“巨厚山地式”全油气系统,围绕古近系下干柴沟组上段烃源岩层系,从盆缘向湖盆中心,平面上构造油气藏、岩性油气藏、页岩油与页岩气有序分布、纵向上叠置连片。柴西坳陷古近系全油气系统具有3方面独特性:(1)低有机质丰度烃源岩“低碳富氢”,单位有机碳生烃能力强;(2)咸化湖盆沉积巨厚,坳陷中心沉积以混源为主,岩相与储集空间纵横向变化快;(3)喜马拉雅期走滑挤压强改造,山地式全油气系统油气差异富集。柴西坳陷古近系全油气系统是源储盖与输导体系协调演化的结果,具有低碳富氢烃源岩全过程生烃、巨厚储集体全坳陷沉积、挤压走滑断裂体促进油气全方位调整、常规-非常规油气全系列分布的特征。受控于喜马拉雅期强构造运动影响,柴西坳陷经历了先拗后隆的演化过程,在湖盆中心发育广义页岩油,在超过2 000 m厚度的沉积体系中,油气连续分布于烃源岩层系内的薄层状灰云岩与紧邻生烃灶的藻灰岩中,白云石晶间孔、纹层缝与断溶体是有效储集空间。相关认识可进一步丰富和发展中国陆相湖盆全油气系统理论,并为柴达木盆地油气综合勘探提供理论指导与技术支持。Based on the oil and gas exploration in western depression of the Qaidam Basin,NW China,combined with the geochemical,seismic,logging and drilling data,the basic geological conditions,oil and gas distribution characteristics,reservoir-forming dynamics,and hydrocarbon accumulation model of the Paleogene whole petroleum system(WPS)in the western depression of the Qaidam Basin are systematically studied.A globally unique ultra-thick mountain-style WPS is found in the western depression of the Qaidam Basin.Around the source rocks of the upper member of the Paleogene Lower Ganchaigou Formation,the structural reservoir,lithological reservoir,shale oil and shale gas are laterally distributed in an orderly manner and vertically overlapped from the edge to the central part of the lake basin.The Paleogene WPS in the western depression of the Qaidam Basin is believed unique in three aspects.First,the source rocks with low organic matter abundance are characterized by low carbon and rich hydrogen,showing a strong hydrocarbon generating capacity per unit mass of organic carbon.Second,the saline lake basinal deposits are ultra-thick,with mixed deposits dominating the center of the depression,and strong vertical and lateral heterogeneity of lithofacies and storage spaces.Third,the strong transformation induced by strike-slip compression during the Himalayan resulted in the heterogeneous enrichment of oil and gas in the mountain-style WPS.As a result of the coordinated evolution of source-reservoir-caprock assemblage and conducting system,the Paleogene WPS has the characteristics of“whole process”hydrocarbon generation of source rocks which are low-carbon and hydrogen-rich,“whole depression” ultra-thick reservoir sedimentation, “all direction” hydrocarbon adjustment by strike-slip compressional fault, and “whole succession” distribution of conventional and unconventional oil and gas. Due to the severe Himalayan tectonic movement, the western depression of the Qaidam Basin evolved from depression to uplift. Shale

关 键 词：全油气系统 页岩油 英雄岭凹陷 巨厚山地式 连续型油气聚集 古近系 柴西坳陷 

分 类 号：TE122[石油与天然气工程—油气勘探]