Thermal Maturity Assessment Research Articles

Characteristics of carbazole compounds in ultra-deep marine oil from Fuman oilfield, Tarim Basin: Significance for thermal maturity assessment of crude oil

Characteristics of carbazole compounds in ultra-deep marine oil from Fuman oilfield, Tarim Basin: Significance for thermal maturity assessment of crude oil

Geochemical characteristics of crude oils and source rocks in the Malaysia-Thailand Joint Development Area (MTJDA), North Malay Basin

Geochemical characteristics of crude oils and source rocks in the Malaysia-Thailand Joint Development Area (MTJDA), North Malay Basin

Facies distribution, paleoenvironment and hydrocarbon potential of Kanawa Member of Pindiga Formation, Gongola Basin, Northern Benue Trough, Nigeria

The Gongola sub-basin is a frontier inland sedimentary basin consisting of Cretaceous to Tertiary sediments, believed to have been deposited in continental to coastal shallow marine complex. The Kanawa Member of Pindiga Formation is a sequence of limestone and shale. Sedimentology, facies analysis, biostratigraphy, thermal maturity assessment and kerogen typing were conducted on these strata to determine the facies, facies associations, facies successions, paleoenvironment, age, and hydrocarbon generation potential. The studied sequences are of Turonian–Santonian age, deposited due to a major transgression of the basal part of the Pindiga Formation. The shale-limestone series of the Kanawa Member is interpreted as lagoon-to-shallow marine deposits of a carbonate ramp depositional system. The sediments consist of mainly wackestone and packstone facies and shallow marine foraminiferal, suggesting that the Kanawa Member was deposited under low-energy condition. The presence of Ammobaculites subcretacea, Haplophragmoides bauchensis, Haplophragmoides pindigensis, Haplophragmoides excavata, Ammobaulites pindigensis, Ammobaculites bauchensis, Ammobaculites gombensis, Ammobaculites benuensis Ammoastuta nigeriana, Reophax guineana and Miliammina pindigensis foraminiferal assemblages, indicating Late Cretaceous age. Hydrocarbon potential is interpreted to be gas prone although, minor oil could be expected. These correspond to temperature range (TAI values) of 60 to 75 indicating thermally matured for both oil and gas generation.

Petrological evaluation of changes occurring in organic matter sourced from Patala-Chichali sequence, Upper Indus Basin

This study focuses on the determination of organic matter (OM) concentration, thermal maturity assessment, and source rock quality of the samples from the Chichali and Patala formations. The TOC in the Chichali and Patala formations sediment samples ranged from 0.8% to 2.1% and 2.3% to 3.8% respectively, showing the sediments with different level of organic richness. The genetic potential varied from 2.4 to 17.1 mg/g, and 25.2 to 31.1 mg/g indicating the likely source rock quality. The Tmax, ranging from 306 °C to 432 °C, 413 °C and 430 °C indicating immature to mature OM. The HI values varied from 113 to 257 mg/g, 353 to 431 mg/g, OI ranged from 7 to 33 mg/g, 9 to 19 mg/g, revealing OM richness. PI assess the potential productivity of source rocks, ranged from 0.5 to 0.7, 0.6 of Chichali and Patala formations, respectively. The various geochemical properties of the Chichali and Patala formations exhibited their varying geological potential. These findings add to a better knowledge of the geological properties of the Upper Indus Basin and provide significant recommendations for hydrocarbon exploration and resource estimation.

A complex case of thermal maturity assessment in a terrigenous sedimentary system: The Northwestern Black Sea basin

A complex case of thermal maturity assessment in a terrigenous sedimentary system: The Northwestern Black Sea basin

Thermal maturity evaluation on mildly artificially oxidised sporomorphs: A comprehensive calibration of palynomorph darkness index (PDI) with vitrinite reflectance

Thermal maturity evaluation on mildly artificially oxidised sporomorphs: A comprehensive calibration of palynomorph darkness index (PDI) with vitrinite reflectance

GEOCHEMICAL CHARACTERISTICS AND THERMAL MATURITY OF THE UPPER DEVONIAN ROCKS (DNIEPER-DONETS BASIN) ACCORDING TO ROCK-EVAL PYROLYSIS DATA (EXPLORATION DRILLING)

Background. In the Dnieper-Donets Basin (DDB), Devonian deposits are a very interesting object of hydrocarbon system research – from the initial stage of hydrocarbon generation to the stage of formation of oil and gas deposits. The presence of sedimentary layers enriched with scattered organic matter determines the oil and gas generation potential of the deposits. The article presents the results of laboratory studies of Upper Devonian rocks performed on the Rock-Eval pyrolytic tool in order to assess their thermal maturity and degree of hydrocarbon generation. Methods. Laboratory studies were carried out by the method of pyrolysis of rock samples (Rock-Eval) with the determination of a number of parameters that allow for the assessment of thermal maturity, the type of organic matter (kerogen) and the coefficient of organic matter transformation. Data processing was performed using the methods of mathematical statistics. Results. An important result of the research is the established regularity that shales and limestones with an increased content of organic carbon (TOC) of the Famennian layer from between-salt strata in this part of the DDB are already in the active phase of oil generation and belong to oil-source rocks. Precisely in this part of the Dnieper-Donets depression the main explored reserves of liquid hydrocarbons in the Eastern region are concentrated. Conclusions. Generalized conclusion based on the results of the above studies: most samples of shales (argillites) and limestones have quite high concentrations of organic carbon; the thermal maturity of the rocks for 63 % of the samples corresponds to the "oil window"; all four types of kerogen are present in the rocks; the best oil-generating properties are characteristic of shales from between-salt strata; also, these shales have the maximum degree of realization of the generating potential TRI – more than 0.3 at depths of 4,700 m. The results of the above studies indicate that the shales and limestones of the Frasnian and Famennian layers from the studied deposits can be considered as potential oil-source rocks.

Assessment of thermal maturity in Lower Cambrian organic-rich shale in south China using integrated optical reflectance and Raman spectroscopy of pyrobitumen

Assessment of thermal maturity in Lower Cambrian organic-rich shale in south China using integrated optical reflectance and Raman spectroscopy of pyrobitumen

Relationship between fluorescence and IR parameters of oil inclusions and crude oils in the Dongpu Depression (Bohai Bay Basin, China)

The Dongpu Depression is an important petroliferous basin in China with abundance of hydrocarbons. The fluorescence characteristics of inclusion oils and their relationship with the present-day produced crude oils have never been systematically studied in the basin scale. This knowledge can further clarify ambiguities in petroleum system modeling and support exploration efforts in the area. To this end, core samples and crude oils were collected from the Shahejie Formation (Paleogene) in the Dongpu Depression to perform fluorescence and infrared spectroscopy from the source rock and the reservoir. Results show that the fluorescence characteristics of oil inclusions in the source rocks are consistent with oil inclusions in the reservoirs in the northern part of the depression, showing blue, green, yellow and orange fluorescence colors; whereas orange fluorescence is absent in the southern part in inclusions. Moreover, lack of a robust relationship between λmax and QF-535 suggests crude oils have gone through secondary alterations towards becoming heavy oil. Herein, comparison between the IR (CH2/CH3) and fluorescence parameters (λmax and QF-535) illustrates that CH2/CH3, although is suitable for organic matter thermal maturity assessment, cannot be directly applied to the expelled oils. Moreover, the occurrence of orange fluorescing oils in the horsts can be accounted for a higher hydrocarbon potential in these areas. Additionally, establishing a clear relationship between fluorescence and IR parameters failed in certain strata or structural unit, proving a complex tectonic setting of the depression. Overall, this study reveals the geologic nature of the Dongpu Depression is very complicated, which means additional analytical studies to resolve the oil-source correlation problem, in particular, would be necessary.

Basin-wide unconventional potential of the Doig Formation, Triassic of the Western Canada Sedimentary Basin

Basin-wide unconventional potential of the Doig Formation, Triassic of the Western Canada Sedimentary Basin

Application of light hydrocarbons for classification and geochemistry characterization of condensates from the Gavbendi High, southwest Iran

Application of light hydrocarbons for classification and geochemistry characterization of condensates from the Gavbendi High, southwest Iran

Automatic organofacies identification by means of Machine Learning on Raman spectra

Automatic organofacies identification by means of Machine Learning on Raman spectra

Thermal maturity calibration of extremely high-mature pre-Devonian strata: A case study from the Lower Cambrian Qiongzhusi Formation in the Sichuan Basin, South China

Thermal maturity calibration of extremely high-mature pre-Devonian strata: A case study from the Lower Cambrian Qiongzhusi Formation in the Sichuan Basin, South China

Paleoenvironmental, paleoclimatic, and organic matter assessment of the hybrid Kharita Formation (Albian) in the Abu Gharadig Basin, Egypt: Integration between palynology, organic petrography, and organic geochemistry

Paleoenvironmental, paleoclimatic, and organic matter assessment of the hybrid Kharita Formation (Albian) in the Abu Gharadig Basin, Egypt: Integration between palynology, organic petrography, and organic geochemistry

Source and thermal maturity assessment of the Paleozoic-Mesozoic organic matter in the Risha gas field, Jordan

Source and thermal maturity assessment of the Paleozoic-Mesozoic organic matter in the Risha gas field, Jordan

Thermal maturity assessment of marine source rocks integrating Raman spectroscopy, organic geochemistry and petroleum systems modeling

A core sample set, comprising twenty-eight carbonaceous mudrocks from ten exploration wells was analysed by standard organic geochemical methods (programmed pyrolysis, elemental analysis) and a novel Raman spectroscopic technique. The kerogen of the studied rocks is classified as amorphous marine, sulfur-rich, oil-prone organic matter with predominantly algal precursor material. The sample set covers a wide range of thermal maturation form premature to late mature. Hydrogen index, T max and atomic H/C ratios vary from 52 to 708 mg HC/g rock, from 426 to 488 °C, and from 0.58 to 1.35, respectively. Raman spectral features, expressed as Raman band separation (RBS), correlate with geochemical maturity parameters and with results from basin modeling. The combined use of independent maturity parameters, like programmed pyrolysis, elemental analysis and Raman spectroscopy, improves the calibration of a regional basin model in the Eastern Arabian Basin, where direct maturity measurements from vitrinite reflectance are deficient. • Comprehensive case study on Middle to Upper Jurassic source rock from 10 wells. • Broad maturity distribution ranging from 0.5 to 1.2%VRE. • Good agreement between pyrolysis, elemental analysis and organic petrology. • Review and comparison of kinetic algorithms to model thermal stress. • Validation of Raman spectroscopy to calibrate basin scale maturity models.

Assessment of hydrocarbon generation potential and thermal maturity of the deep offshore Lamu Basin, Kenya

In this study, the secondary well data for Cretaceous to Miocene cutting samples in four deep offshore exploration wells, i.e., Pomboo-1 in the north, Kubwa-1 in the central, Simba-1 and Kiboko-1 in the south of the deep offshore Lamu Basin were assessed for identifying source rock presence and examining thermal maturity of the source rocks. The 2D basin modelling was used to analyse the bulk gas transformation in the basin. Total organic carbon (TOC) content values for the wells range from 0.09 wt % to 2.23 wt % with an average of 0.78 wt %. The average organic richness is higher in the Upper Cretaceous (0.83 wt %) than in the Palaeogene (0.65 wt %), Lower Cretaceous (0.28 wt %) and Upper Jurassic (0.30 wt %). The S 1 averages for the Upper Cretaceous are 3.76 mg HC/g rock in Pomboo-1 and 0.31mg HC/g rock in Kubwa-1. The S 2 averages for the Upper Cretaceous are 5.00 mg HC/g rock in Pomboo-1 and 0.72 mg HC/g rock in Kubwa-1. Hydrogen index (HI) values vary between 4 and 512 mg HC/g TOC with an average of 157.09 mg HC/g TOC. Organic matters were identified as mixed types of II-III (oil and gas prone) and III-IV (gas prone) kerogen in the potential source rocks. The HI and S 2 yield values are exceptionally high for the observed TOC values in Pomboo-1. The vitrinite reflectance and T max values of deep offshore Lamu Basin range from 0.38% to 0.72% and 360–441 °C, respectively. It suggests the existence of both immature and mature source rocks. Vitrinite reflectance maturity favours near coastal region in the Upper Cretaceous. These results explain why Pomboo-1, Kubwa-1, Simba-1 and Kiboko-1 wells were dry. The temperatures are still cool for hydrocarbon generation in deep offshore. The critical risk for deep offshore Lamu Basin is charge, primarily source presence, and a lack of definitive evidence of a deep-water marine source rock being present. The four wells penetrate good quality reservoir and seal rocks, but source rock presence and maturity remain the critical play risk in the deep offshore Lamu Basin. • Samples from four wells in the deep offshore Lamu Basin were studied. • R o and T max values suggest the existence of immature and mature source rocks. • The critical risk for deep offshore Lamu Basin is charge and primarily source presence. • No definitive evidence of a deep-water marine source rock is present in the Basin.

Use of palynology and thermal maturity in deformed geological units: A case study from the Permian succession in the Monte Leoni area (Middle Tuscan Ridge, inner Northern Apennines, Italy)

The reconstruction of the upper Palaeozoic sedimentary evolution of Western Mediterranean area is suffering for scarce age documentation of its stratigraphic units. This is also the consequence of the metamorphism and deformation they experienced during the Alpine tectonic events. Based on palynology and thermal maturity assessment, we contribute to this issue reporting biostratigraphic and sedimentological results in key-outcrops of the upper Palaeozoic successions of southern Tuscany (Italy), thus offering new data for the Palaeozoic units of the inner Northern Apennines, as well as for their palaeogeographic and palaeotectonic evolution predating the opening of the Alpine Neo-Tethys. This study is focused on the Falsacqua Formation mainly consisting of quartzitic phyllite, sandstone and carbonate, representing the basal succession of two tectonic units exposed in the Middle Tuscan Ridge, and which age attribution was strongly debated in literature and referred either to late Carboniferous-early Permian or Devonian. Palynological data document the first finding of a microflora of middle-late Permian age adding key chronological constraints. This age assignment permits to correlate the Falsacqua Formation with the coeval deposits of southern Tuscany (i.e., Farma and Poggio al Carpino formations) and Elba Island (Rio Marina Formation) that are all characterized by a similar microfloral content. Optical thermal maturity index as Spore Colour Index is around 9 to 10 and suggests a T peak of about 300–350 °C while the Raman spectroscopy on carbonaceous material indicates a T peak around 375 °C for both tectonic units. These data provide new constraints for the maximum T values occurred during syn -collisional metamorphism developed in this sector of the Northern Apennines. • Chronostratigraphic constraints based on the microfloristic content • Stratigraphic correlation with coeval successions of the Northern Apennines • Thermal maturity analysis by different optical and geochemical approach • Permian palaeogeography of Tuscany

Paradigms of biomarker and PAH distributions in lower Gondwana bituminous coal lithotypes

The present study aims to illustrate the paradigms of saturated and aromatic biomarker distributions in the lithotypes of Lower Gondwana bituminous coals (R̄ r = 0.50–0.68%), perhaps for the first time. The coal samples were collected from the Early Permian Barakar Formation of the Rajmahal Basin, India. These coals mostly comprise three lithotypes, i.e., vitrain, durain, and fusain. The durain shows a considerable abundance than the other two bands and represents the bulk coal characteristics. The total organic carbon (TOC), S1, and S2 parameters from the Rock-Eval pyrolysis depict insignificant variations among the lithotypes, unlike the hydrogen index (HI), which peaks in the durain samples. The micropetrography furnishes a significant amount of liptinite macerals (30.6–51.3 vol% on the mineral matter free basis) present in the samples, dominated by the sporinite and cutinite. These hydrogen-rich macerals, being one of the crucial micropetrographic constituents, would have enhanced the HI values of the durain lithotype. The waxy nature of durain is also substantiated by the long chain-length n -alkane (LCLAs) distributions, while the plausible scarcity of wax in the lignocellulosic plant materials would have led to lower abundances of the LCLAs in vitrain (detected only from the 2D-Gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS)). Further, although the saturated diterpenoids are abundant in the durain and vitrain, their extremely low abundances (identified only through the GC × GC-TOFMS) along with the degraded LCLA signature in fusain may hint toward its source from the biomass combustion. Besides, the distributions and interrelations of the 4-, 5-, and 6-ringed polycyclic aromatic hydrocarbons (PAHs; m/z 202, 206, 228, 252, 276, and 278), like fluoranthene, pyrene, chrysene, benzo[ g,h,i ]perylene, benzo[ b ]fluoranthene, benzo[ k ]fluoranthene, benzo[ a ]pyrene, benzo[ e ]pyrene, and the isomers of the dimethylphenanthrene, dibenzanthracene, and benzochrysene further support the pyrogenic origin of the fusain lithotype. Meanwhile, these PAHS would have derived from diagenetic/catagenetic origin to mixed sources (diagenetic/catagenetic maturation of organic matter and combustion origin) in vitrain. The durain shows a mixed to pyrogenic origin of these PAHs and represents the PAH distributions of the bulk coal samples. Besides, the thermal maturity assessment of these lithotypes may suggest that the molecular parameters respond more sensitively to the thermal maturation compared to the bulk organic geochemical proxies. • Variabilities in the biomarker distributions among Lower Gondwana coal lithotypes • Long-chain n -alkanes in durain result from abundant sporinite and cutinite grains. • Vitrain lithotype shows abundances of medium chain n -alkanes from shrubs/herbs. • PAH ratios, depleted diterpenoids and n -alkanes reveal pyrogenic origin of fusain. • Molecular fossils depict higher sensitivity to thermal alteration than bulk kerogen.

The effect of diagenesis and acetolysis on the preservation of morphology and ultrastructural features of pollen

Pollen morphology on its own and in conjunction with other characteristics has elucidated the origin and evolution of various plant groups. Previous studies of fossil pollen rarely discuss the effects of diagenesis and sample preparation on pollen characteristics, i.e., variability in staining, pollen morphology, and pollen wall ultrastructural characteristics. This paper examines the effect of acetolysis on reflectance and spectral epi-fluorescence measurements. Based on empirical studies, different species under similar experimental conditions display different reflectance values, indicating individual species respond differently to similar post-depositional thermal events. The quantitative pollen fluorescence spectra showed significant variability, but there is an overall increase in the mean wavelength of maximum emission with acetolysis. Increases in these spectral parameters are used to infer thermal maturation and diagenetic pathways in fossil pollen. The paper also discusses observations made on fossil pollen of a known thermal maturity using Pearson's Pollen/Spore Color Standard. Assessment of pollen thermal maturity using this color standard can be an indicator of the quality of morphological and ultrastructural information that can be extracted from fossil pollen. Increasing thermal maturity of pollen may have an effect on staining variability. Based on observations, staining for brightfield or electron microscopy in fossil pollen, although useful for improving contrast in the specimen, must be used with caution when interpreting pollen wall structure. Although single fossil pollen investigations are useful, replication of these studies on similar or the same specimens from the same locality or various localities will collectively provide more information for elucidation of the morphology and ultrastructure of the once living pollen, and is helpful in sorting out characteristics that may be artifacts from post-depositional diagenesis. • Effects of diagenesis on the interpretation of pollen characteristics are discussed. • Based on reflectance values species uniquely respond to diagenetic events. • The degree of thermal maturity influences the quality of morphological information. • Staining must be used with caution when interpreting pollen wall ultrastructure. • Replication of single grain studies provide more reliable information on morphology.