Comparisons of pyrolysis parameters between source rocks and their clay-sized fractions: Implication for source material of hydrocarbon generation

2022 ◽  
pp. 1-42
Author(s):  
Xiaojun Zhu ◽  
Jingong Cai ◽  
Feng Liu ◽  
Qisheng Zhou ◽  
Yue Zhao ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Source Material ◽  
Source Rocks ◽  
Natural Environments ◽  
Hydrocarbon Generation ◽  
Petroleum Systems ◽  
Organic Mineral ◽  
Organic Clay ◽  
Organo Clay ◽  
Rock Eval

In natural environments, organic-clay interactions are strong and cause organo-clay composites (a combination between organic matter [OM] and clay minerals) to be one of the predominant forms for OM occurrence, and their interactions greatly influence the hydrocarbon (HC) generation of OM within source rocks. However, despite occurring in nature, dominating the OM occurrence, and having unique HC generation ways, organo-clay composites have rarely been investigated as stand-alone petroleum precursors. To improve this understanding, we have compared the Rock-Eval pyrolysis parameters derived from more than 100 source rocks and their corresponding <2 μm clay-sized fractions (representing organo-clay composites). The results show that all of the Rock-Eval pyrolysis parameters in bulk rocks are closely positively correlated with those in their clay-sized fractions, but in clay-sized fractions the quality of OM for HC generation is poorer, in that the pyrolysable organic carbon levels and hydrogen index values are lower, whereas the residual organic carbon levels are higher than those in bulk rocks. Being integrated with the effects of organic-clay interactions on OM occurrence and HC generation, our results suggest that organo-clay composites are stand-alone petroleum precursors for HC generation occurring in source rocks, even if the source rocks exist in great varieties in their attributes. Our source material for HC generation comprehensively integrates the original OM occurrence and HC generation behavior in natural environments, which differs from kerogen and is much closer to the actual source material of HC generation in source rocks, and it calls for further focus on organic-mineral interactions in studies of petroleum systems.

Evolution of organic-mineral interactions and implications for organic carbon occurrence and transformation in shale

2019 ◽  
Vol 132 (3-4) ◽  
pp. 784-792 ◽  
Author(s):  
Xiaojun Zhu ◽  
Jingong Cai ◽  
Yongshi Wang ◽  
Huimin Liu ◽  
Shoupeng Zhang
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Burial Depth ◽  
Hydrocarbon Generation ◽  
Petroleum Systems ◽  
Fine Grained ◽  
Sedimentary Environments ◽  
Organic Mineral ◽  
Organic Fractions ◽  
Sequential Treatments

Abstract Organic-mineral interactions are pervasive in sedimentary environments; however, the extent of these interactions is not constant and has a significant impact on organic carbon (OC) occurrence and transformation. To understand the evolution of organic-mineral interactions and the implications for OC occurrence and transformation in fine-grained sediments, several shale samples were selected and subjected to physical and chemical sequential treatments. The samples were subjected to pyrolysis, Fourier transform infrared spectrophotometry (FTIR), and adsorption measurements to determine the organic parameters and the mineral surface area (MSA) of the shale samples. The results show that the organic fractions derived from sequential treatments have varying pyrolysis and FTIR characteristics. The correlation between the total OC content and MSA is positive, but it is split according to organic fractions with different attributes. Correlations between the different organic fractions and MSA indicate that the organic matter in shale is mainly adsorbed on mineral surfaces, while a certain portion of organic matter occurs in the pores and is adsorbed on the organic-mineral aggregates, suggesting variable interactions between the organic fractions with different attributes and minerals. From the pyrolysis and FTIR analysis, the organic fractions of different occurrence sites vary in their OC proportion, proclivity to form organic functional groups, and hydrocarbon generation potential. With increasing burial depth, the MSA and hydrogen index as well as OC loading per unit MSA are reduced, and the OC proportions of organic fractions with different attributes have regular trends. These observations indicate that the extent of organic-mineral interactions that can stabilize organic matter gradually decreases, resulting in transformation of the tightly mineral-combined OC into free OC. Our work reveals the heterogeneity in organic matter occurrence and the effect of the evolution of the organic-mineral interactions on OC occurrence and transformation, which is significant in the global carbon cycle and in petroleum systems.

GEOLOGY, SOURCE ROCKS AND HYDROCARBON GENERATION IN THE CLARENCE-MORETON BASIN

1982 ◽  
Vol 22 (1) ◽  
pp. 5
Author(s):  
A. R. Martin ◽  
J. D. Saxby
Keyword(s):  
Vitrinite Reflectance ◽  
Source Rocks ◽  
Geochemical Data ◽  
Hydrocarbon Potential ◽  
Hydrocarbon Generation ◽  
Tectonic Events ◽  
History Of ◽  
Rock Eval ◽  
Coal Measures ◽  
Migration Pathways

The geology and exploration history of the Triassic-Cretaceous Clarence-Moreton Basin are reviewed. Consideration of new geochemical data ('Rock-Eval', vitrinite reflectance, gas chromatography of extracts, organic carbon and elemental analysis of coals and kerogens) gives further insights into the hydrocarbon potential of the basin. Although organic-rich rocks are relatively abundant, most source rocks that have achieved the levels of maturation necessary for hydrocarbon generation are gas-prone. The exinite-rich oil-prone Walloon Coal Measures are in most parts relatively immature. Some restraints on migration pathways are evident and igneous and tectonic events may have disturbed potentially well-sealed traps. Further exploration is warranted, even though the basin appears gas-prone and the overall prospects for hydrocarbons are only fair. The most promising areas seem to be west of Toowoomba for oil and the Clarence Syncline for gas.

scholarly journals A New Evaluation Method of Total Organic Carbon for Shale Source Rock Based on the Effective Medium Conductivity Theory

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Jian Fu ◽  
Xuesong Li ◽  
Yonghe Sun ◽  
Qiuli Huo ◽  
Ting Gao ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Clay Minerals ◽  
Pore Water ◽  
Effective Medium ◽  
Source Rocks ◽  
Model Parameters ◽  
Hydrocarbon Generation ◽  
Tight Sandstone

In the evaluation of source rocks, the total organic carbon (TOC) is an important indicator to evaluate the hydrocarbon generation potential of source rocks. At present, the commonly used methods for assessing TOC include △ log R and neural network method. However, practice shows that these methods have limitations in the application of unconventional intervals of sand-shale interbeds, and they cannot sufficiently reflect the variation of TOC in the vertical direction. Therefore, a total organic carbon (TOC) evaluation model suitable for shale and tight sandstone was established based on the effective medium symmetrical conduction theory. The model consists of four components: nonconductive matrix particles, clay minerals, organic components (solid organic matter and hydrocarbons), and pore water. The conductive phase in the model includes clay minerals and pore water, and other components are treated as nonconductive phases. When describing the conductivity of rock, each component in the model is completely symmetrical, and anisotropic characteristics of each component are considered. The model parameters are determined through the optimization method, and the bisection iteration method is used to solve the model equation. Compared with the classic TOC calculation method, the new model can evaluate the abundance of organic matter in shale and tight sandstone, which provides a new option to assess the TOC of rocks based on logging methods.

scholarly journals Rhenium–osmium (Re–Os) geochronology of crude oil from lacustrine source rocks of the Hailar Basin, NE China

2020 ◽  
Author(s):  
Qi-An Meng ◽  
Xue Wang ◽  
Qiu-Li Huo ◽  
Zhong-Liang Dong ◽  
Zhen Li ◽  
...  
Keyword(s):  
Crude Oil ◽  
Source Rocks ◽  
Radiometric Dating ◽  
Age Dating ◽  
Hydrocarbon Generation ◽  
Ne China ◽  
Petroleum Systems ◽  
Younger Age ◽  
Hailar Basin ◽  
Age Trends

Abstract Re–Os radiometric dating of crude oil can be used to constrain the timing of hydrocarbon generation, migration or charge. This approach has been successfully applied to marine petroleum systems; however, this study reports on its application to lacustrine-sourced natural crude oils. Oil samples from multiple wells producing from the Cretaceous Nantun Formation in the Wuerxun-Beier depression of the Hailar Basin in NE China were analysed. Subsets of the Re–Os data are compatible with a Cretaceous hydrocarbon generation event (131.1 ± 8.4 Ma) occurring within 10 Myr of deposition of the Nantun Formation source rocks. In addition, two younger age trends of 54 ± 12 Ma and 1.28 ± 0.69 Ma can be regressed from the Re–Os data, which may reflect the timing of subsequent hydrocarbon generation events. The Re–Os geochronometer, when combined with complementary age dating techniques, can provide direct temporal constraints on the evolution of petroleum system in a terrestrial basin.

scholarly journals Geochemical characterization and possible hydrocarbon contribution of the Carboniferous interval natively developed in the Chepaizi Uplift of Junggar Basin, northwestern China

2019 ◽  
Vol 38 (3) ◽  
pp. 654-681 ◽  
Author(s):  
Lixin Mao ◽  
Xiangchun Chang ◽  
Youde Xu ◽  
Bingbing Shi ◽  
Dengkuan Gao
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Junggar Basin ◽  
Source Rocks ◽  
Hydrocarbon Generation ◽  
Exploration Process ◽  
Potential Source ◽  
Hydrocarbon Generation Potential ◽  
Northwestern Region ◽  
Effective Source

Previous studies on Chepaizi Uplift mainly focused on its reservoirs, and the potential source rocks natively occurred was ignored. During the exploration process, dark mudstones and tuffaceous mudstones were found in the Carboniferous interval. These possible source rocks have caused great concern about whether they have hydrocarbon generation potential and can contribute to the reservoirs of the Chepaizi Uplift. In this paper, the potential source rocks are not only evaluated by the organic richness, type, maturity, and depositional environment, but also divided into different kinetics groups. The Carboniferous mudstones dominated by Type III kerogen were evolved into the stage of mature. Biomarkers indicate that the source rocks were deposited in a marine environment under weakly reducing conditions and received mixed aquatic and terrigenous organic matter, with the latter being predominant. The effective source rocks are characterized by the total organic carbon values >0.5 wt.% and the buried depth >1500 m. The tuffaceous mudstone shows a greater potential for its lower active energy and longer hydrocarbon generation time. Considering the hydrocarbon generation potential, base limits of the total organic carbon and positive correlation of oil–source rock together, the native Carboniferous mudstones and tuffaceous mudstones might contribute to the Chepaizi Uplift reservoirs of the northwestern region of the Junggar Basin, especially the deeper effective source rocks should be paid enough attention to.

scholarly journals Source rock potential of the Late Miocene Metochia formation of Gavdos Island, Greece

2017 ◽  
Vol 47 (2) ◽  
pp. 871
Author(s):  
I. Pyliotis ◽  
A. Zelilidis ◽  
N. Pasadakis ◽  
G. Panagopoulos ◽  
E. Manoutsoglou
Keyword(s):  
Organic Matter ◽  
Source Rock ◽  
Late Miocene ◽  
Source Rocks ◽  
Hydrocarbon Generation ◽  
Low Oxygen ◽  
Crete Island ◽  
Good Potential ◽  
The Rich ◽  
Rock Eval

Rock-Eval method was used to analyze 53 samples from late Miocene Metochia Formation of Gavdos Island (south of Crete Island) in order to characterize the contained organic matter and to evaluate its potential as source rock. The samples were collected from Metochia Section which consists of about 100 m thick marlssapropels alternations. Organic matter analysis showed that the studied succession could be subdivided into two parts. The lower one, which is generally rich in organic matter and the upper one, which is poor. In the lower part the rich horizons in organic matter are characterized by Kerogen type II, III and IV, with low oxygen content, and with fair to very good potential for gas and/or oil hydrocarbon generation. Additionally, the studied samples are thermally immature. Taking into account that the studied area has never been buried in such a depth to reach conditions of maturation, as well as, that the studied section in Gavdos is connected with Messara basin located in the northeastern and, finally, that the main part of Gavdos basin, which is situated between Gavdos and Crete islands, has continuously encountered subsidence, we could conclude that sediments of Metochia Formation could act as source rocks but in the more deep central part of the Gavdos basin.

GEOCHEMICAL TOOLS FOR EVALUATING PETROLEUM GENERATION IN MIDDLE PROTEROZOIC SEDIMENTS OF THE McARTHUR BASIN, NORTHERN TERRITORY, AUSTRALIA

1994 ◽  
Vol 34 (1) ◽  
pp. 692 ◽  
Author(s):  
Roger E. Summons ◽  
Dennis Taylor ◽  
Christopher J. Boreham
Keyword(s):  
Vitrinite Reflectance ◽  
Land Plant ◽  
Source Rocks ◽  
Hydrocarbon Generation ◽  
Strongly Correlated ◽  
Petroleum Potential ◽  
Petroleum Generation ◽  
Early Palaeozoic ◽  
Geochemical Analyses ◽  
Rock Eval

Maturation parameters based on aromatic hydrocarbons, and particularly the methyl-phenanthrene index (MPI-1), are powerful indicators which can be used to define the oil window in Proterozoic and Early Palaeozoic petroleum source rocks and to compare maturities and detect migration in very old oils . The conventional vitrinite reflectance yardstick for maturity is not readily translated to these ancient sediments because they predate the evolution of the land plant precursors to vitrinite. While whole-rock geochemical tools such as Rock-Eval and TOC are useful for evaluation of petroleum potential, they can be imprecise when applied to maturity assessments.In this study, we carried out a range of detailed geochemical analyses on McArthur Basin boreholes penetrating the Roper Group source rocks. We determined the depth profiles for hydrocarbon generation based on Rock-Eval analysis of whole-rock, solvent-extracted rock, kerogen elemental H/C ratio and pyrolysis GC. Although we found that Hydrogen Index (HI) and the Tmax parameter were strongly correlated with other maturation indicators, they were not sufficiently sensitive nor were they universally applicable. Maturation measurements based on saturated biomarkers were not useful either because of the low abundance of these compounds in most Roper Group bitumens and oils.

scholarly journals The geochemical and organic petrological characteristics of coal measures of the Xujiahe formation in the Sichuan Basin, China

2019 ◽  
Vol 37 (3) ◽  
pp. 889-906 ◽  
Author(s):  
Guoxiao Zhou ◽  
Guoqi Wei ◽  
Guoyi Hu
Keyword(s):  
Gas Chromatography ◽  
Organic Carbon ◽  
Sichuan Basin ◽  
Sea Water ◽  
Source Rocks ◽  
Gas Chromatography Mass Spectrometry ◽  
Organic Carbon Content ◽  
Hydrocarbon Generation ◽  
Adsorption Effect ◽  
Xujiahe Formation

Upper Triassic coaly and lacustrine source rocks complicate efforts to determine the source of hydrocarbons in Sichuan Basin. Total organic carbon analyses, pyrolysis experiments, petrological examinations, and gas chromatography and gas chromatography–mass spectrometry determinations were conducted on coals, carbonaceous mudstones and mudstones collected from two outcrop sections and cores of nine wells. Results revealed that the abundant organic carbon content will prolong the hydrocarbon generation cycle for coals and then the hydrocarbon generating capacity of coals will be enhanced by salinization, thereby contributing bacteria and algae microorganisms into humic coal of the Xujiahe Formation. Compared with mudstone, coal with the same maturity has a stronger adsorption effect on free hydrocarbons. When Ro is greater than 1.35, coal still has a strong hydrocarbon generation ability. The stable water column stratification and euxinic bottom water conditions are evidenced from the lower Pr/Ph and the higher gammacerane indices. The mixing of sea water has been proven by the existence of 4α,23,24,-trimethylcholestanes.

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