本文選題：天然氣組分　切入點(diǎn)：同位素　出處：《天然氣地球科學(xué)》2017年09期

【摘要】：基于天然氣組分以及組分同位素分析結(jié)果,結(jié)合凹陷烴源巖有機(jī)地球化學(xué)特征與地質(zhì)背景,對(duì)廊固凹陷天然氣的成因類型及其分布規(guī)律進(jìn)行了研究。結(jié)果表明,廊固凹陷淺層(1 900m)與中深層(1 900m)天然氣的地球化學(xué)特征存在很大的差異,具有不同的成因類型。淺層天然氣藏以次生型生物改造氣藏為主,是熱成因氣的濕氣部分遭受細(xì)菌降解而產(chǎn)生的次生生物氣與殘留熱成因氣(主要為甲烷)混合而成。其主要特征為:氣體干燥系數(shù)大于95%,但重?zé)N氣含量較高(ΣC_(2~+)0.5%);甲烷穩(wěn)定碳同位素組成較輕(δ~(13)C_1值分布在-60‰~-50‰之間);異構(gòu)丁烷含量增加,丙烷含量明顯減少;很多氣樣穩(wěn)定碳同位素序列在丙烷處發(fā)生局部倒轉(zhuǎn)。深層天然氣主要為偏腐殖型熱成因氣,而且大多數(shù)天然氣為干酪根初次裂解氣。深層天然氣以低—中等成熟度(RO值范圍為0.5%~0.8%)為主,主要來(lái)自成熟度相當(dāng)?shù)纳橙聛喍螣N源巖;而曹家務(wù)、固安地區(qū)深度超過(guò)4 000m的4個(gè)氣樣以及別古莊地區(qū)奧陶系潛山氣藏成熟度較大(RO值范圍為1.1%~1.5%),來(lái)自深層的沙四段—孔店組烴源巖。廊固凹陷深層天然氣的分布受控于烴源巖干酪根類型以及熱成熟度,淺層天然氣的分布則主要與溝通深部熱成因油氣的斷裂活動(dòng)強(qiáng)度有關(guān)。固安、柳泉、郎東等地區(qū)淺層是次生型生物改造氣藏的主要分布區(qū)與有利勘探帶,固安—舊州地區(qū)大興斷層深部的礫巖體以及別古莊地區(qū)的潛山是深層熱成因天然氣的有利勘探區(qū)帶。
[Abstract]:Based on the results of natural gas composition and isotopic analysis, combined with the organic geochemical characteristics and geological background of hydrocarbon source rocks in the sag, the genetic types and distribution of natural gas in Langgu sag are studied. The geochemical characteristics of natural gas in Langgu sag are very different from those in middle and deep layers, and have different genetic types. The shallow gas reservoirs are mainly secondary biologically modified gas reservoirs. It is a mixture of secondary biogas and residual thermal gas (mainly methane) produced by bacterial degradation of the humid part of thermal gas. Its main characteristics are as follows: the coefficient of gas drying is greater than 95g, but the content of heavy hydrocarbon gas is high (危 C ~ (2) ~ (0. 5)); The stable carbon isotopic composition of methane is lighter (未 ~ (13) C _ (-1)) distributed in the range of -60 鈥，

本文編號(hào)：1656438