乍得Bongor盆地北部斜坡带原油地球化学特征与成因
Geochemical Characteristics and Origins of Crude Oil in the North Slope,Bongor Basin,Chad
陈清瑶 1王文强 2程顶胜 3肖洪 2冉子超2
作者信息
- 1. 中国石化江苏油田分公司勘探开发研究院,江苏扬州 225009
- 2. 中国石油大学(北京)地球科学学院,油气资源与探测国家重点实验室,北京 102249
- 3. 中国石油勘探开发研究院,北京 100083
- 折叠
摘要
[目的]中非裂谷系乍得Bongor盆地北部斜坡带原油的物性与地球化学特征均存在明显差异.探讨其差异性特征及主控因素,并可为Bongor盆地及周边地区石油勘探工作中原油性质的预测提供部分思路与依据.[方法]利用原油族组分分离、气相色谱及色谱—质谱等方法,对北部斜坡带41件原油样品的物性及分子标志化合物组成进行了系统分析.[结果与结论]不同级别的生物降解作用是导致Bongor盆地原油物性与地球化学性质差异的主要原因.根据正构烷烃、无环类异戊二烯烃的相对丰度与分布特征及色谱基线特征,将原油划分为未降解原油、轻微降解原油与严重降解原油.埋深是影响原油降解强度的首要因素,当埋深小于800 m时,绝大部分原油遭受了严重的生物降解;当埋深大于1 300 m时,原油基本未遭受降解;当埋深介于800～1 300 m时,降解程度受距深大断裂的距离、上覆盖层的厚度与圈闭类型共同控制.
Abstract
[Objective]The physical properties and geochemical characteristics of oil found in the Northern slope,Bongor Basin,Chad,are clearly different.This paper aims to determine their differences and the influences on their properties and provide practical guidance for the assessment and prediction of oil quality in future oil exploration in this region.[Methods]The physical properties and molecular marker compounds of 41 crude oil samples from the northern slope belt were analyzed by oil family separation,gas chromatography,gas chromatography-mass spectrometry.[Results and Conclusions]It was found that the degree of biodegradation is responsible for the differences.Non-,slightly-or heavily degraded oils were classified according to the relative content and distribution pattern of normal alkanes and acyclic isoprenoids,as well as the baseline characteristics of gas chromatograms.Burial depth is evident-ly the most important factor constraining the degree of biodegradation.No biodegraded oil was found deeper than 1 300 m;the most heavily biodegraded oil occurs shallower than 800 m.In reservoirs between these depths,the degree of biodegradation is associated with distance from main faults,thickness of local caprock and type of trap.
关键词
Bongor盆地/白垩系/地球化学特征/原油/生物降解Key words
Bongor Basin/Cretaceous/geochemical characteristics/crude oils/biodegradation引用本文复制引用
基金项目
国家科技重大专项(2016ZX05029)
出版年
2024
国家科技期刊平台
NSTL
万方数据