Maturity of light oil and its significance in indicating oil source in Hetianhe gas field, Tarim Basin

Cui Jingwei; Wang Tieguan; Hu Jian; Li Meijun

doi:10.11743/ogg20130104

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Maturity of light oil and its significance in indicating oil source in Hetianhe gas field, Tarim Basin
Vol. 34, Issue 1, Pages: 27-36(2013)
Online First：28 February 2013，

Published：2013
DOI： 10.11743/ogg20130104
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DOI：

Cui Jingwei, Wang Tieguan, Hu Jian, et al. Maturity of light oil and its significance in indicating oil source in Hetianhe gas field, Tarim Basin[J]. 2013, 34(1): 27-36. DOI： 10.11743/ogg20130104.

摘要

为评价和田河气田轻质原油的成熟度

利用气相色谱与气相色谱-质谱联用仪

对和田河气田4个轻质原油中具有成熟度信息的化合物进行分析。轻烃庚烷值与异庚烷值、甲基双金刚烷参数、甲基菲参数、甲基二苯并噻吩参数和Ts/(Ts+Tm)成熟度参数显示和田河轻质油处于高成熟阶段(凝析油阶段)

烷基萘类成熟度参数、C

甾烷20S/(20S+20R)和C

甾烷ββ/(αα+ββ)显示尚未进入生烃高峰期。轻烃等参数显示原油高成熟与原油密度等物理性质一致

烷基萘类成熟度参数成熟度偏低可能与原油存在轻微生物降解有关

甾烷成熟度参数偏低是演化达到平衡终点后翻转所致。综合成熟度参数认为

和田河气田轻质原油处于成熟末期-高成熟阶段。与该地区典型的烃源岩样品成熟度对比

推断轻质原油与天然气同源

主要来自寒武系烃源岩。甾萜类生物标志物油-源对比分析支持该结论。

Abstract

GC and GC-MS analysis was performed on compounds possibly containing information on maturity in four light oil samples selected in Hetianhe gas field.Maturity indexes including heptane index

isoheptane index

methyldiamantane index

MPI

methyldibenzothiophene(MDBTs)and Ts/(Ts+Tm) indicate that the light oil in Hetianhe gas field is at high maturation stage(gas condensate).In contrast

methylnaphthalene

sterane 20S/(20S+20R) and C

sterane ββ/(αα+ββ) suggest that the source rocks have not entered peak oil generation stage.Indexes such as light hydrocarbon show that high maturity of the light oil is consistent with its physical properties.The anomalies of naphthalenes may be the result of weak biodegradation

while the low sterane indexes may be the result of overturning at the end of evolutionary balance.Comprehensive analyses of the maturity indexes reveal that the light oil is at the end of maturation-high maturation stage.Furthermore

comparison with the typical local source rocks indicates that both the light oil and natural gas are generated by the Cambrian source rocks

a conclusion supported by oil-source correlation based on sterane and terpane.