Thermogravimetry-differential thermal analysis coupled with chromatography as a thermal simulation experimental method and its application to gaseous hydrocarbons from different source rocks

In this paper a thermogravimetry-differential thermal analysis method coupled with chromatography (TG-DTA-GC) has been adopted to simulate the generation of gaseous hydrocarbons from different hydrocarbon source rocks such as coals, mudstones, and carbonate rocks with different maturities. The temperature programming for thermal simulation experiment is 20℃/min from ambient temperature to 700℃. As viewed from the quantities and composition of generated gaseous hydrocarbons at different temperatures, it is shown that low-mature coal has experienced the strongest exothermic reaction and the highest loss of weight in which the first exothermic peak is relatively low. Low-mature coal samples have stronger capability of generating gaseous hydrocarbons than high-mature samples. The amounts and composition of gaseous hydrocarbons generated are closely related not only to the abundance of organic carbon in source rocks, but also to the type of kerogen in the source rocks, and their thermal maturity. In the present highly mature and over-mature rock samples organic carbon, probably, has already been exhausted, so the production of gaseous hydrocarbons in large amounts is impossible. The contents of heavy components in gaseous hydrocarbons from the source rocks containing type-Ⅰand -Ⅱ kerogens are generally high; those of light components such as methane and ethane in gaseous hydrocarbons from the source rocks with Ⅲ-type kerogens are high as well. In the course of thermal simulation of carbonate rock samples, large amounts of gaseous hydrocarbons were produced in a high temperature range.

Interaction between source rock and evaporite:A case study of natural gas generation in the northern Dongying Depression

It is well known that oil generated from source rocks of saline-lake facies is characteristic of low Pr/Ph ratio and high contents of gammacerane.The authors found that gas generated from the same source rocks was high in benzene and cyclohexane contents and had light carbon isotope compositions.In this study,a series of thermal simulations of gas generations on source rock with/without evaporites(such as carbonate,gypsum,and sodium chlorite,respectively),were conducted.It was found that the gypsum played an important role on the catalyzsis of gas generation in the thermal simulations.Compositions of the gaseous hydrocarbons generated from source rocks with evaporites are very similar to those of natural gases discovered from northern Dongying Depression.Meanwhile,in the thermal simulations,it was found that the carbon isotopic compositions of gaseous hydrocarbons generated from source rocks with evaporites are lighter than those of the gases from source rocks without evaporites.Therefore,it is concluded that natural gases discovered from northern Dongying Depression are the product of interaction between source rocks and evaporites(especially gypsum) of the saline facies.

试论天然气水合物成藏系统

针对天然气水合物理论预测和实际产出的不一致性、各种标志或异常未与天然气水合物建立起严格的对应关系、世界范围内已知或由BSR等间接指标所指示的天然气水合物在垂直方向和水平方向上分布的不确定性,如何更好地从地质系统论角度研究天然气水合物成藏过程和分布规律,尝试提出天然气水合物成藏系统概念,分别从烃类生成体系、流体运移体系、成藏富集体系对天然气水合物成藏过程进行了初步探讨;同时运用此思路对世界上调查研究程度较高的分布区开展了天然气水合物成藏系统初步分析。

不同类型烃源岩气态烃的生成特征研究——来自差热—色谱联机热模拟实验方法的证据

运用差热—色谱联机分析仪对不同煤阶的标准煤样及泥岩和碳酸盐岩烃源岩的热模拟研究表明，低成熟的煤具有更强的放热反应和较大的失重量，其放热反应第一峰温度和失重温度相对较低。低煤阶煤在热模拟过程中比高煤阶煤具有更强的生烃能力。烃源岩气态烃的生成量和特征不仅受控于烃源岩中有机质的丰度而且与其岩石类型、干酪根类型、成熟度等存在着密切关系。成熟度较高的烃源岩属耗尽了的烃源岩，其生烃能力相对较弱。含Ⅰ、Ⅱ型干酪根烃源岩生成的气态烃中重组分含量普遍较高，含Ⅲ型干酪根烃源岩生成的气态烃中甲、乙烷等轻组分含量普遍较高。碳酸盐岩烃源岩在热模拟的高温阶段往往能生成比较大量的气态烃。

同源不同成熟度天然气的混合对天然气碳同位素的影响

对胜利油田临南洼陷一块未成熟Ⅱ型烃源岩的干酪根样品进行了封闭体系下高温高压热模拟实验,获取了不同热演化阶段天然气组分和碳同位素值,通过混合配比计算,研究了同源不同成熟度天然气的混合对天然气组分和碳同位素的影响。结果表明,同源不同成熟度天然气的混合改变天然气的组分与碳同位素特征,其变化规律受端元气的成熟度及混合系数的影响,并且端元气体的成熟度差别越大,混合气组分与碳同位素值随混合系数的变化越明显。本研究中,在热模拟实验的成熟度范围内(Easy Ro:0.72%~3.0%),不同混合模型中天然气的δ^(13)C_1与δ^(13)C_2不存在倒转;只有当过成熟天然气和低成熟天然气混合,并且以过成熟天然气为主时,才可能导致δ^(13)C_2与δ^(13)C_3不同程度倒转,但这种混合模型在实际地质条件下很难形成,因此认为只是同源不同成熟度混合作用一般不会造成天然气碳同位素的倒转。本研究对于深刻认识含油气盆地天然气的气源及其碳同位素特征提供了理论依据。

准噶尔盆地南缘侏罗系煤岩生烃动力学研究

应用金管-高压釜装置对采自准噶尔盆地南缘西部煤样JC25和东部煤样JC41进行生烃动力学模拟实验,获取生油、生气量和生烃动力学参数。升温速率分别为2℃/h和20℃/h,实验压力为50 MPa。实验得到两个煤样JC25和JC41最大生油量(以下单位mg/g均表示每克有机碳的生成量)分别为126 mg/g和68.5 mg/g,计算的排油量分别为88.8 mg/g和29.5 mg/g,表明侏罗系煤岩在南缘西部四棵树凹陷较其他区域具有较大的生油潜力。两个煤样最大生气量(∑C1–5)分别为121.6mg/g和112mg/g,差异相对较小。煤样JC25和JC41的H/C原子比值分别为0.85和0.77,类脂组含量分别约为8%和6%,岩石热解(Rock-Eval)参数氢指数(IH)分别为155 mg/g和156 mg/g。实验结果表明, H/C原子比值、类脂组含量比IH能更好地反映煤岩的初始生油、生气潜力。依据生烃动力学参数模拟了地质条件下(升温速率5℃/Ma)的生油和生气过程。煤样主要生、排油阶段的Ro, Easy介于0.80%~1.20%之间。在半开放条件下(发生排油),两个煤样的生气速率比较接近。在Ro, Easy=1.50%时生气转化率分别为23%和18%,煤岩主要生气过程发生在高过成熟阶段(Ro,Easy>1.50%)。侏罗系烃源岩在霍玛吐背斜带中部成熟度较高,较其他区域具有更大的天然气勘探潜力。

郑州大气及颗粒物中多环芳烃的分布特征与来源解析

对2012年郑州市大气中气态和颗粒态多环芳烃（PAHs）的分布特征与来源进行了分析。结果表明，ρ（∑PAHs）（包括气相与颗粒相）为23．27～194．61ng／m^3，气相中∑，PAHs高于颗粒相，四环以下的PAHs大都存在于气态中；在夏、春2季，较小分子质量（≤178）的PAHs占比较高，冬季，较大分子质量（≥252）的PAHs占比明显较高；各功能区ρ（PAHs）排序为工业区〉交通密集区〉医疗、文化、行政混合区。郑州大气和颗粒物中PAHs可能主要来自煤和液体燃料（汽油柴油）的燃烧。

南方海相层系不同类型烃源(岩)生烃模拟实验及其产物同位素演化规律

利用常规高压釜热压模拟仪和仿真地层热压生排烃模拟仪对南方海相不同类型烃源进行生烃模拟实验,研究发现不同类型原油烃气产率最高,分散可溶有机质烃气产率次之,产率最低的为不同类型干酪根。不同类型烃源烃气产率与烃源的有机碳含量、可溶有机质含量高低、有机质类型有密切关系,与烃源原始成熟度具有较好负相关性。烃源碳同位素组成决定产物甲烷碳同位素组成的演化规律,碳同位素组成较轻的烃源其产物甲烷碳同位素组成总体上要轻于碳同位素组成较重烃源的甲烷碳同位素组成。不同类型烃源产物甲烷碳同位素组成随热模拟温度增高具有先变轻再变重的演化特征,但不会重于其烃源的碳同位素组成。乙烷等碳同位素组成也随着热模拟温度增高逐渐变重,演化至生烃高峰时,碳同位素组成接近于其烃源碳同位素组成,可以示踪烃源。当演化至高过成熟阶段,乙烷等δ13C值大于其烃源碳同位素值,故不能仅用重烃碳同位素组成判断天然气母质类型。不同类型干酪根与可溶有机质CO2组分和同位素组成演化规律具有明显区别,可溶有机质生成的CO2和甲烷之间同位素分馏程度要比不同类型干酪根的大。在不同类型烃源生烃过程中,干酪根和液态烃碳同位素组成主要受母质类型控制,继承效应强,同位素分馏程度较小,具有很好的示踪意义,可以用于油源对比和烃源示踪研究。