摘要
乌里雅斯太凹陷与二连盆地中其他富油凹陷相比在构造特征、烃源岩类型和原油物性方面独具特色,主要体现在凹陷地层厚度大(大于4 500m)、烃源岩类型较差(主体为D/E相)、原油密度轻的特点。烃源岩体精细分析表明凹陷主体发育D/E相烃源岩,初始氢指数(I_(Ho))为200~400mg/g_(TOC),烃源岩有机显微组分主要为腐泥组、壳质组和镜质组混合型。D/E相烃源岩形成于高沉积速率和高陆源有机质输入的超补偿沉积环境,这种偏氧化环境也可解释凹陷中不发育二连盆地其他凹陷普遍可见的以云质泥岩为主的特殊岩性段现象。凹陷D/E相烃源岩主要发育在K_1bt_1和K_1ba,层序上主要位于最大湖泛面上下,烃源岩生烃门限深度为1 900~2 000m;镜质体反射率R_O值主体介于0.5%~1.0%之间,并且K_1ba烃源岩成熟度较K_1bt_1高。D/E相烃源岩与典型C相烃源岩(以层状藻类和结构藻类为主,I_(Ho)值在400~800mg/g_(TOC)之间)在生烃特征方面具有明显不同,D/E相烃源岩生烃门限温度较高,且排出的烃类主要以轻质油为主。目前乌里雅斯太凹陷已发现的原油API主体介于35°~45°之间,为轻质油,并且与二连盆地其他凹陷相比具有高蜡低硫的特点,乌里雅斯太凹陷已发现油气物理性质与D/E相烃源岩在现阶段生成油气特征相符。
Wuliyasitai Sag is unique in terms of tectonic features,type of source rocks and oil properties compared to other hydrocarbon-rich sags in Erlian Basin,which is mainly characterized by thick strata（more than 4 500 m）,relatively poor type of source rocks（dominated by organic facies D/E）and light oil.Refined source rocks analysis indicated that the sag is dominated by organic facies D/E,which has an original hydrogen index（IHo）about 200-400 mg/gTOC,and the majority of organic macerals are sapropelinite,exinite and vitrinite.This type of source rock is developed in an extra-compensation environment with high deposition rate and high input of terrigenous organic matter,and oxidation environment can explain the phenomenon that the sag is lack of the special lithologic section which is mainly composed of dolomitic mudstone and generally appears in other sags in Erlian Basin.The source rocks of the sag mainly developed in the K1bt1 and K1ba,they also located above or below the maximum lake flooding surface when considering the sequence,the threshold depth of hydrocarbon generation is from 1 900 to 2 000 m;the RO data of two source rocks mainly range from 0.5% to 1.0%,and the maturity of K1ba source rock is higher than that of K1bt1.There are significantly different hydrocarbon generation features between organic facies D/E source rock and typical organic facies C source rock（dominated by laminated and texture algae,with an original hydrogen index about 400 to 800 mg/gTOC）,organic facies D/E source rock has a high hydrocarbon generation temperature,and the expelled oil is light.The API data of oil have been found to range from 35° to 45°,classified as light oil,meanwhile the oil is characterized by high wax and low sulfur content compared to other sags in Erlian Basin,the physical properties of discovered oil correspond to the theoretical characteristic of expelled oil from organic facies D/E source rock at this stage.
作者
程志强
王飞宇
师玉雷
冯伟平
谢佩宇
任利兵
吴子强
江涛
赵志刚
Cheng Zhi-qiang;Wang Fei-yu;Shi Yu-lei;Feng Wei-ping;Xie Pei-yu;Ren Li-bing;Wu Zi-qiang;Jiang Tao;Zhao Zhi-gang(College of Geosciences in China University of Petroleum ,Beijing 102249,China;Research Institute of Exploration and Development ,PetroChina Huabei Oilfi＇eld Company ,Renqiu 062552 ,China)
出处
《天然气地球科学》
EI
CAS
CSCD
北大核心
2018年第5期696-707,共12页
Natural Gas Geoscience
基金
国家科技重大专项(编号:2016ZX05007001-003)
中国石油华北油田科技项目(编号:HBYT-YJY-2017-JS-152)联合资助
关键词
乌里雅斯太凹陷
烃源灶
有机相
生烃特征
湖相烃源岩
Wuliyasitai Sag
Source kitchen
Organic facies
Hydrocarbon characteristics
Lacustrine source rock
