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Geologische Rundschau

, Volume 78, Issue 1, pp 361–373 | Cite as

The micro-scale simulation of maturation: outline of a new technique and its potential applications

  • B. Horsfield
  • U. Disko
  • F. Leistner
Thermal Modeling and Evolution of Organic Matter

Abstract

A micro-analytical technique has been developed for artifically maturing sedimentary organic matter and then quantifying the major components generated during this process in a single analytical step. Such a capability is well-suited for examining the compositional relationships between kerogens and petroleums, determining reaction kinetics and making precursor-product mass balances. According to this technique, simulations are made using sealed glass capillary tubes (heated here for three days at 300 °C, 330 °C and 350 °C). Pyrolysis products are then released directly into a combined thermovaporisation/pyrolysis-GC instrument and the major components of the entire C1 yto C35 range can be quantified in a single step using gas chromatography. Alkene yields are very low and pyrolysates are oil-like. This is exemplified by the fact that then−C9−C19 alkane distribution range of simulated whole petroleum chromatograms, from originally immatureGloeocapsamorpha-typz alginite A, resembles that seen in crude oils generated from this same kerogen type in nature. Sealed tube experiments usingBotryococcus type alginite A generated a »high wax« pyrolysate. The relative abundance ofn-alkanes in the C2−C32 range of many kerogen pyrolysates does not appear to change significantly despite an approximately fifteen-fold difference inn-alkane yield between the 300 °C and 350 °C experiments. Kerogens which are »paraffinic« oil-prone, and whose pyrolysates are very rich inn-alkanes might therefore generate petroleums in nature with a fixed wet gas (C2-C4) to oil (C5+) ratio. Alginite B in a Greenland shale is much more thermally labile than eitherBotryococcus-type alginite A orGloeocapsamorpha-type alginite A. The mass balance capabilities of the technique have been tested using Alum Shale kerogen. Two gas chromatograms were obtained, one for the free compounds generated during simulation, and one for the high temperature pyrolysate of the kerogen residue, for each heating experiment. Precursor-product relationships were qualitatively assessed, and dead carbon formation was quantified in this exercise.

Keywords

Kerogen Sedimentary Organic Matter Kerogen Type Phase Gazeuse Alginite 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Zusammenfassung

Eine mikro-analytische Methode zur künstlichen Reifung sedimentärer organischer Substanz konnte entwickelt werden. Dabei werden die Hauptkomponenten, die während des Vorgangs freigesetzt werden, quantitativ erfaßt. Grundlagen dieser Methode sind Simulationen mit kapillaren Glasröhren, nach welchen die Pyrolyse-Produkte direkt in ein kombiniertes Thermovaporation/Pyrolyse-GC Instrument freigesetzt werden. Mit Hilfe der Gas-Chromatographie können in einem einzigen Schritt die Hauptkomponenten der gesamten C1 bis C35 Spannbreite quantitativ erfaßt werden. Kerogen-Typisierung und Abschätzung des Muttergesteinspotentials werden stark vereinfacht, wenn die Verhältnisse der Vorläufer-Produkte sorgfältig bestimmt und die chemisch-kinetischen Parameter für einzelne Komponenten, Komponentengruppen und/oder Siedepunktbereiche berechnet werden. Diese Anwendung stimmt mit Techniken im Makro-Bereich (z. B. Hydro-Pyrolyse) überein, aber die Vorteile der Annäherung im Mikro-Bereich liegen darin, daß geochemische Informationen schneller und bequemer gewonnen werden können und sehr kleine Probenmengen ausreichen. Ferner kann neben der Möglichkeit der singulären Anwendung die Annäherung im Mikro-Bereich dazu verwendet werden, Proben für detailierte und Labor-intensive Simulationen im Makro-Bereich effizient auszuwählen.

Résumé

Les auteurs présentent une technique micro-analytique qui comporte la maturation artificielle de la matière organique sédimentaire suivie du dosage des composants majeurs ainsi engendrés. Dans le cadre de ce procédé, on réalise des simulations dans des tubes capillaires en verre, après quoi les produits de la pyrolyse sont libérés directement dans un instrument combiné de thermovaporisation/hydrolyse-GC et les composants majeurs de la lignée complète C1 à C35 peuvent être dosés en une seule opération de Chromatographie en phase gazeuse. De cette manière, la caractérisation du kérogène et l'estimation du potentiel de la rochemère sont grandement facilitées dans la mesure où les relations des produits précurseurs sont soigneusement établies et où il est possible de calculer les paramètres chimico-cinétiques pour des composants isolés, pour des groupes de composants et/ou les domaines de température où se situent les points d'ébullition. Ces procedures sont en accord avec celles des techniques macroscopiques (p.ex l'hydro-pyrolyse), mais l'avantage de l'approche microanalytique réside dans le fait que les résultats géochimiques sont obtenus plus rapidement et plus aisément et qu'il est possible de traiter de très petits échantillons. Enfin, nonobstant ses avantages propres, l'approche micro-analytique peut être utilisée à la sélection d'échantillons destinés à des simulations détaillées et laborieuses à l'échelle macroscopique.

Краткое содержание

Попытались разработ ать микроаналитичес кий метод искусственного созр евания органическог о вещества седиментов. При этом у дается провести коли чественное определение основны х компонентов, выделе нных во время этого процес са. Метод моделирован ия основан на пропускан ии продуктов пиролиз а через капиллярные колонки в комбинированный пр ибор термоиспарения и пир олитического газхро матографа. С помощью газхромато графии можно количес твенно определить ведущие к опмоненты от С1 до С35 н а каждом этапе экспери мента. Если соотношен ие соединений-предшевс твенников и химико-кинетически е параметры отдельных компонентов, групп ко мпонентов и/или интервал темпер атуры кипения опреде лить точно, то как классифи кация керогенов, так и оценка потенциала пород-нос ителей значительно у прощается. Эта методика соотвес твует таковой макром етода, напр.: гидропиролизу, н о преимущество метод а микроанализа закиюч ается в том, что геохим ическую информацию можно зде сь получить быстро и л егко на небольших по обьему п робах. Помимо анализа небольших количеств этот микрометод разр ешает сделать выбор проб дл я последующего подро бного и интенсивного макром етода.

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Copyright information

© Ferdinand Enke Verlag Stuttgart 1989

Authors and Affiliations

  • B. Horsfield
    • 1
  • U. Disko
    • 1
  • F. Leistner
    • 1
  1. 1.Institute of Petroleum and Organic Geochemistry at the Nuclear Research Centre (KFA) JülichJü lichFed. Rep. of Germany

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