Hydrocarbon Potential of the Middle–Late Jurassic Series of Northwestern Iraq: A Case Study in the Shaikhan Oil Field

The Middle–Late Jurassic Sargelu, Naokelekan, and Barsarin formations of northwestern Iraq have been investigated in the Shaikhan oilfield (well Shaikhan-8) to assess their potential for hydrocarbon generation.The results of total organic carbon analysis and rock-eval pyrolysis revealed a good-to-excellent hydrocarbon content and suggest that the depositional conditions were suitable for the production and preservation of organic matter. The thermal maturity proxy indicates that the studied formations were at the start of the hydrocarbon generation period. Most of the samples from the Sargelu and Barsarin formations belong to kerogen type II, whereas those of the Naokelekan Formation belong to kerogen type II/III. The Pr/Ph, Pr/n-C17, and Ph/n-C18 ratios of the extracted bitumen indicated that the organic matter originated from marine sources under reducing conditions. The stable carbon isotope composition of the saturated and aromatic hydrocarbon fractions ranged from –28.3 to –27.7 ‰ and –28.0 to –27.7 ‰, respectively. The biomarker results show a high contribution of marine organic matter that was preserved under relatively anoxic conditions. The profiles of the burial and thermal maturity history show that the simulated generation zones, based on the calculated vitrinite reflectance, indicate immature (0.44%–0.6%)-to-early oil generating (0.6%–0.75%) source rock. The low thermal maturity of the studied formations relative to the depth may be attributed to the low geothermal gradient and heat flow.

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Using aromatic biological markers as a tool for assessing thermal maturity of source rocks in the Campano-Maastrichtian Mamu Formation, southeastern Nigeria

Earth Sciences Research Journal ◽

10.15446/esrj.v18n1.34799 ◽

2014 ◽

Vol 18 (1) ◽

pp. 51-62 ◽

Cited By ~ 4

Author(s):

Jude E. Ogala ◽

Mike I. Akaegbobi

Keyword(s):

Organic Matter ◽

Aromatic Hydrocarbons ◽

Mixed Type ◽

Higher Plants ◽

Vitrinite Reflectance ◽

Source Rocks ◽

Hydrocarbon Generation ◽

Type Ii ◽

Thermal Maturity ◽

Southeastern Nigeria

The concentration and distribution of aromatic biomarkers in coals and shales from five boreholes penetrating the Maastrichtian Mamu Formation of the Anambra Basin, southeastern Nigeria, were investigated by gas chromatography-mass spectrometryto assess the thermal maturity and organic matter input. The study focused on the variations of the relative abundances of naphthalenes, phenanthrenes, and monaromatic and triaromatic steroids identified on the mass fragmentograms. Trimethylnaphthalene(TMN) is the most abundant member of the naphthalene family while methylphenanthrene (MP) is the most abundant phenanthrene family member. The total of phenanthrenes and their isomers was greater than that of naphthalenes. The distribution of these aromatic hydrocarbons and their akyl derivatives was strongly controlled by a selective expulsion mechanism and thermal maturation of organic matter. The low dibenzothiophene/phenanthrene (DBT/PHEN) ratios (0.01-0.06), as well as the enhanced concentrations of 1,2,5-TMN relative to 1,2,7- TMN,indicates organic matter derived mainly from higher plants,and the extract ternary plot of C27, C28 and C29 monoaromatic steroids suggests a Type III and mixed Type II/III kerogen. The calculated mean vitrinite reflectance (%Rm), determined from the distributions of the isomers of methyldibenzothiophene ratio (MDR) in the rock extracts, ranged from 0.51 to 1.43. These maturity values indicate that the coal and shale extracts are marginally mature for hydrocarbon generation. ResumenLa concentración y distribución de biomarcadores aromáticos en carbones y esquistos de cinco perforaciones en la formación Maastrichtian Mamu de la cuenca de Anambra, en el sureste de Nigeria, fueron analizados a través de un estudio de espectometría cromatográfico y de masa del gas para medir la madurez termal y la entrada de material orgánico. El estudio está enfocado en las variaciones de la abundancia relativa de naftalinas y fenantrenos, y en los esteroides monoaromáticos y triaromáticos identificados en los fragmentogramas de masas. La trimetinaftalina (TMN) es la más abundante de la familia de las naftalinas mientras el metilfenantreno (MP) es el más abundante de los fenantrenos. El tota de los fenantrenos y sus isómeros fue mayor que el de las naftalinas. La distribución de estos hidrocarbones aromáticos y sus alquilos derivados fue controlada ampliamente por un mecanismo de expulsión selectiva y de la maduración térmica de material orgánico. La baja proporción dibenziotofeno/fenantreno (DBT/ PHEN) (0.01-0.06), al igual que las concentraciones mejoradas de 1,2,5-TMN relativas de 1,2,7-TMN indican que la materia orgánica se deriva principalmente de plantas mayores, y del diagrama terniario de los esteroides monoaromáticos C27, C28 y C29 sugiere un tipo III mezclado con tipos II/III de querógenos. El valor calculado de la reflectancia de vitrinita (%Rm) determinado de la proporción de isómeros de metildibenziotofeno (MDR) en los extractos rocosos oscila de 0.51 a 1.43. Estos valores de madurez indican que los extractos de carbones y esquistos son marginalmente maduros para la generación de hidrocarbono.

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Assessment of the hydrocarbon potentiality of the Late Jurassic formations of NW Iraq: A case study based on TOC and Rock-Eval pyrolysis in selected oil-wells

Open Geosciences ◽

10.1515/geo-2019-0071 ◽

2019 ◽

Vol 11 (1) ◽

pp. 918-928

Author(s):

Swar J. Al-Atroshi ◽

Govand H. Sherwani ◽

Srood F. Al-Naqshbandi

Keyword(s):

Organic Matter ◽

Late Jurassic ◽

Immature Stage ◽

Mature Stage ◽

Organic Carbon Content ◽

Hydrocarbon Generation ◽

Type Ii ◽

Kerogen Type ◽

Two Samples ◽

Rock Eval

Abstract The Late Jurassic Naokelekan and Barsarin formations of northwestern Iraq have been investigated in three wells to assess their potentiality for hydrocarbon generation. The results of Total Organic Carbon content (TOC) and Rock-Eval Pyrolysis reveal fair to excellent content of hydrocarbon and suggest that the depositional conditions were suitable for the production and preservation of organic matter. The Thermal Maturity Proxy indicates that the studied formations were mature stage of hydrocarbon generation, with an exception of three samples from the Naokelekan Formation in Shaikhan-8 well, and two samples from the Barsarin Formation in Atrush-1 and Shaikhan-8 wells were at an immature stage. The S1 and TOC relationship shows that all the samples are indigenous in nature. Most of samples from the Naokelekan Formation belong to kerogen Type II/III, and that in the Barsarin Formation belongs to kerogen Type II is dominant. The Pr/Ph, Pr/n-C17 and Ph/n-C18 ratios for the extracted bitumen of both the formations indicate that they were originated from marine organic matter under reducing conditions. The δ13CSat and δ13CAro range from −28.7 to −27.7‰ and −28.8 to −27.7‰ respectively. These biomarkers show high contribution of marine organic matters preserved under relatively anoxic conditions in the studied formations.

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Liquid hydrocarbon characterization of the lacustrine Yanchang Formation, Ordos Basin, China: Organic-matter source variation and thermal maturity

Interpretation ◽

10.1190/int-2016-0114.1 ◽

2017 ◽

Vol 5 (2) ◽

pp. SF225-SF242 ◽

Cited By ~ 2

Author(s):

Xun Sun ◽

Quansheng Liang ◽

Chengfu Jiang ◽

Daniel Enriquez ◽

Tongwei Zhang ◽

...

Keyword(s):

Organic Matter ◽

Source Rock ◽

Ordos Basin ◽

Depositional Environments ◽

Source Rocks ◽

Type I ◽

Hydrocarbon Generation ◽

Type Ii ◽

Thermal Maturity ◽

Yanchang Formation

Source-rock samples from the Upper Triassic Yanchang Formation in the Ordos Basin of China were geochemically characterized to determine variations in depositional environments, organic-matter (OM) source, and thermal maturity. Total organic carbon (TOC) content varies from 4 wt% to 10 wt% in the Chang 7, Chang 8, and Chang 9 members — the three OM-rich shale intervals. The Chang 7 has the highest TOC and hydrogen index values, and it is considered the best source rock in the formation. Geochemical evidence indicates that the main sources of OM in the Yanchang Formation are freshwater lacustrine phytoplanktons, aquatic macrophytes, aquatic organisms, and land plants deposited under a weakly reducing to suboxic depositional environment. The elevated [Formula: see text] sterane concentration and depleted [Formula: see text] values of OM in the middle of the Chang 7 may indicate the presence of freshwater cyanobacteria blooms that corresponds to a period of maximum lake expansion. The OM deposited in deeper parts of the lake is dominated by oil-prone type I or type II kerogen or a mixture of both. The OM deposited in shallower settings is characterized by increased terrestrial input with a mixture of types II and III kerogen. These source rocks are in the oil window, with maturity increasing with burial depth. The measured solid-bitumen reflectance and calculated vitrinite reflectance from the temperature at maximum release of hydrocarbons occurs during Rock-Eval pyrolysis ([Formula: see text]) and the methylphenanthrene index (MPI-1) chemical maturity parameters range from 0.8 to [Formula: see text]. Because the thermal labilities of OM are associated with the kerogen type, the required thermal stress for oil generation from types I and II mixed kerogen has a higher and narrower range of temperature for hydrocarbon generation than that of OM dominated by type II kerogen or types II and III mixed kerogen deposited in the prodelta and delta front.

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Integration of the outcrop and subsurface geochemical data: implications for the hydrocarbon source rock evaluation in the Lower Indus Basin, Pakistan

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-018-0569-6 ◽

2018 ◽

Vol 9 (2) ◽

pp. 937-951 ◽

Cited By ~ 1

Author(s):

Sajjad Ahmad ◽

Faizan Ahmad ◽

Abd Ullah ◽

Muhammad Eisa ◽

Farman Ullah ◽

...

Keyword(s):

Organic Matter ◽

Source Rock ◽

Vitrinite Reflectance ◽

Indus Basin ◽

Hydrocarbon Generation ◽

Type Ii ◽

Hydrocarbon Source Rock ◽

Hydrocarbon Generation Potential ◽

Well Data

Abstract The present study details the hydrocarbon source rock geochemistry and organic petrography of the outcrop and subsurface samples of the Middle Jurassic Chiltan Formation and the Lower Cretaceous Sembar Formation from the Sann #1 well Central and Southern Indus Basin, Pakistan. The total organic carbon (TOC), Rock–Eval pyrolysis, vitrinite reflectance (Ro) % and Maceral analysis techniques were used and various geochemical plots were constructed to know the quality of source rock, type of kerogen, level of maturity and migration history of the hydrocarbons. The outcrop and Sann #1 well data on the Sembar Formation reveals poor, fair, good and very good quality of the TOC, type II–III kerogen, immature–mature organic matter and an indigenous hydrocarbon generation potential. The outcrop and Sann #1 well data on the Chiltan Formation show a poor–good quality of TOC, type II–III kerogen, immature–mature source rock quality and having an indigenous hydrocarbon generation potential. The vitrinite reflectance [Ro (%)] values and Maceral types [fluorescent amorphous organic matter, exinite, alginite and inertnite] demonstrate that maturity in both Sembar and the Chiltan formation at surface and subsurface fall in the oil and gas generation zone to cracking of oil to gas condensate zone. Recurrence of organic rich and poor intervals within the Sembar and Chiltan formation are controlled by the Late Jurassic thermal uplift preceding the Indo-Madagascar separation from the Afro-Arabian Plate and Early Cretaceous local transgressive–regressive cycles. From the current study, it is concluded that both Sembar and Chiltan formation can act as a potential hydrocarbon source rock in the study area.

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Burial history, thermal history and hydrocarbon generation modelling of the Jurassic source rocks in the basement of the Polish Carpathian Foredeep and Outer Carpathians (SE Poland)

Geologica Carpathica ◽

10.2478/v10096-012-0026-2 ◽

2012 ◽

Vol 63 (4) ◽

pp. 335-342 ◽

Cited By ~ 3

Author(s):

Paweł Kosakowski ◽

Magdalena Wróbel

Keyword(s):

Organic Matter ◽

Thermal History ◽

Vitrinite Reflectance ◽

Source Rocks ◽

Hydrocarbon Generation ◽

Thermal Maturity ◽

Burial History ◽

Se Poland ◽

Carpathian Foredeep ◽

Outer Carpathians

Burial history, thermal history and hydrocarbon generation modelling of the Jurassic source rocks in the basement of the Polish Carpathian Foredeep and Outer Carpathians (SE Poland)Burial history, thermal maturity, and timing of hydrocarbon generation were modelled for the Jurassic source rocks in the basement of the Carpathian Foredeep and marginal part of the Outer Carpathians. The area of investigation was bounded to the west by Kraków, to the east by Rzeszów. The modelling was carried out in profiles of wells: Będzienica 2, Dębica 10K, Góra Ropczycka 1K, Goleszów 5, Nawsie 1, Pławowice E1 and Pilzno 40. The organic matter, containing gas-prone Type III kerogen with an admixture of Type II kerogen, is immature or at most, early mature to 0.7 % in the vitrinite reflectance scale. The highest thermal maturity is recorded in the south-eastern part of the study area, where the Jurassic strata are buried deeper. The thermal modelling showed that the obtained organic matter maturity in the initial phase of the "oil window" is connected with the stage of the Carpathian overthrusting. The numerical modelling indicated that the onset of hydrocarbon generation from the Middle Jurassic source rocks was also connected with the Carpathian thrust belt. The peak of hydrocarbon generation took place in the orogenic stage of the overthrusting. The amount of generated hydrocarbons is generally small, which is a consequence of the low maturity and low transformation degree of kerogen. The generated hydrocarbons were not expelled from their source rock. An analysis of maturity distribution and transformation degree of the Jurassic organic matter shows that the best conditions for hydrocarbon generation occurred most probably in areas deeply buried under the Outer Carpathians. It is most probable that the "generation kitchen" should be searched for there.

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Geochemistry and petrology of selected sediments from Bukit Song, Miri, Sarawak, Malaysia, with emphasis on organic matter characterization

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-021-01275-2 ◽

2021 ◽

Vol 11 (10) ◽

pp. 3663-3688

Author(s):

Amin Tavakoli

Keyword(s):

Organic Matter ◽

Depositional Environment ◽

Vitrinite Reflectance ◽

Xrd Analysis ◽

Source Rocks ◽

Hydrocarbon Generation ◽

Thermal Maturity ◽

Petroleum Potential ◽

Type Iv ◽

Two Samples

AbstractThe aim of this study is to provide a better understanding of the type of source input, quality, quantity, the condition of depositional environment and thermal maturity of the organic matter from Bukit Song, Sarawak, which has not been extensively studied for hydrocarbon generation potential. Petrological and geochemical analyses were performed on 13 outcrop samples of the study location. Two samples, having type III and mixed kerogen, showed very-good-to-excellent petroleum potential based on bitumen extraction and data from Rock–Eval analysis. The rest of the samples are inert—kerogen type IV. In terms of thermal maturity based on vitrinite reflectance, the results of this paper are akin to previous studies done in the nearby region reported as either immature or early mature. Ph/n-C18 versus Pr/n-C17 data showed that the major concentration of samples is within peat coal environment, whilst two samples were associated with anoxic marine depositional environment, confirmed by maceral content as well. Macerals mainly indicated terrestrial precursors and, overall, a dominance of vitrinite. Quality of the source rock based on TOC parameter indicated above 2 wt. % content for the majority of samples. However, consideration of TOC and S2 together showed only two samples to have better source rocks. Existence of cutinite, sporinite and greenish fluorescing resinite macerals corroborated with the immaturity of the analysed coaly samples. Varying degrees of the bitumen staining existed in a few samples. Kaolinite and illite were the major clays based on XRD analysis, which potentially indicate low porosity. This study revealed that hydrocarbon-generating potential of Bukit Song in Sarawak is low.

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Albian-Cenomanian Palynology, Paleoecology and Organic Thermal Maturity of Well DK-B in the Dukhan Oil Field of Western Qatar

GeoArabia ◽

10.2113/geoarabia0504483 ◽

2000 ◽

Vol 5 (4) ◽

pp. 483-508 ◽

Cited By ~ 2

Author(s):

Mohamed I.A. Ibrahim ◽

Hind H.A. Al-Hitmi ◽

Suzan E. Kholeif

Keyword(s):

Climatic Conditions ◽

Oil Field ◽

South American ◽

Type Ii ◽

Thermal Maturity ◽

Dinoflagellate Cysts ◽

Short Term ◽

Kerogen Type ◽

System Tracts ◽

Angiosperm Pollen

ABSTRACT A palynological investigation of the Nahr Umr, Mauddud and Ahmadi formations of the middle Cretaceous Wasia Group in Well DK-B in the Dukhan oil field of Qatar, yielded 30 species of dinoflagellate cysts, 18 of pteridophytic spores, 14 of gymnosperm pollen, and 16 of angiosperm pollen. Based on the investigation, the age of the Nahr Umr Formation is middle to late Albian. The basal part of the Formation was deposited in a marine prodelta or shallow shelf environment, whereas sedimentation of the upper part took place in normal marine conditions of an inner to middle shelf at depths of 10 to 80 meters. The carbonates of the Mauddud Formation are of late Albian (Vraconian) to early Cenomanian age and were deposited in an inner-middle shelf environment (20–100 meters). The shales and limestones of the Ahmadi Formation are of early to middle Cenomanian age and accumulated in open-marine conditions within an outer-shelf environment (100–200 meters). Two regressive pulses or lowstand system tracts can be detected in the lower and middle parts of the Ahmadi Formation that are consistent with published short-term global eustatic curves. Rocks of the Wasia Group studied in Well DK-B are in general enriched in kerogen type II (oil-prone material) except for the lower part of the Nahr Umr Formation that can be attributed to kerogen type III (gas-prone material). The thermal alteration index range of 2, 2+ to 3− suggests that the sediments of the Ahmadi Formation are immature whereas those of the Mauddud and Nahr Umr formations are slightly mature. The Albian-Cenomanian palyno-assemblage of western Qatar is referable to the African-South American Phytogeoprovince as shown by the presence of Crybelosporites pannuceus, ephedroid pollen, elater-bearing pollen, Afropollis, Stellatopollis, Reyrea and Cretacaeiporites species. Arid to semi-arid (tropical to subtropical) climatic conditions prevailed in the African-South American province at this time. Dinoflagellate cysts suggest a Tethyan connection.

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Geochemical and organic petrographic characteristics of high bituminous shales from Gurha mine in Rajasthan, NW India

Scientific Reports ◽

10.1038/s41598-020-78906-x ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Alok K. Singh ◽

Mohammed Hail Hakimi ◽

Alok Kumar ◽

Adeeb Ahmed ◽

Nor Syazwani Zainal Abidin ◽

...

Keyword(s):

Organic Matter ◽

Vitrinite Reflectance ◽

Immature Stage ◽

Type Ii ◽

High Hydrogen ◽

Reducing Conditions ◽

Kerogen Type ◽

Oil Generation ◽

Bituminous Shale ◽

Index Value

AbstractA high bituminous shale horizon from the Gurha mine in the Bikaner sub-basin of the Rajasthan District, NW India, was studied using a collection of geochemical and petrological techniques. This study investigated the nature and environmental conditions of the organic matter and its relation to the unconventional oil-shale resources of the bituminous shale. The analyzed shales have high total organic carbon and total sulfur contents, suggesting that these shale sediments were deposited in a paralic environment under reducing conditions. The dominant presence of organic matter derived from phytoplankton algae suggests warm climatic marine environment, with little connection to freshwater enhancing the growth of algae and other microorganisms. The analyzed bituminous shales have high aquatic-derived alginite organic matters, with low Pr/Ph, Pr/n-C17, and Ph/n-C18 ratios. It is classified as Type II oil-prone kerogen, consistent with high hydrogen index value. Considering the maturity indicators of geochemical Tmax (< 430 °C) and vitrinite reflectance values less than 0.40%VRo, the analyzed bituminous shale sediments are in an immature stage of the oil window. Therefore, the oil-prone kerogen Type II in the analyzed bituminous shales has not been cracked by thermal alteration to release oil; thus, unconventional heating is recommended for commercial oil generation.

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Use of petrological and organic geochemical data in determining hydrocarbon generation potential of coals: miocene coals of Malatya Basin (Eastern Anatolia-Turkey)

International Journal of Coal Science & Technology ◽

10.1007/s40789-020-00376-3 ◽

2020 ◽

Author(s):

Nazan Yalcin Erik ◽

Faruk Ay

Keyword(s):

Organic Matter ◽

Vitrinite Reflectance ◽

Hydrogen Index ◽

Quality Data ◽

Geochemical Data ◽

Mineral Matter ◽

Hydrocarbon Generation ◽

Thermal Maturity ◽

Hydrocarbon Generation Potential ◽

Northern District

AbstractWith this study, the hydrocarbon generation potential of Miocene aged coals around Arguvan-Parçikan in the northern district of Malatya province was evaluated with the aid of petrological and organic geochemical data. According to organic petrography, coal quality data, and low thermal maturity, the Arguvan-Parçikan coals are of high-ash, high-sulfur subbituminous B/C rank. The organic fraction of the coals is mostly comprised of humic group macerals, with small percentages derived from the inertinite and liptinite groups. The mineral matter of the coals is comprised mainly of calcite and clay minerals. The total organic carbon (TOC, wt%) values of the shale and coal samples are between 2.61 wt% and 43.02 wt%, and the hydrogen index values are between 73 and 229 mg HC/g TOC. Pyrolysis (Tmax, PI), huminite/vitrinite reflectance (Ro, %), and biomarker ratios (CPI, Pr/Ph ratio, Ts/(Ts + Tm) ratio, C32 homohopane ratio (22S/22S + 22R) and C29ββ/(ββ + αα sterane ratio) indicate that the organic matter of the studied coals is thermally immature. When all these data are taken together, Miocene aged coals around Arguvan are suitable for hydrocarbon generation, especially gas, in terms of organic matter type (Type III and Type II/III mixed), organic matter amount (> 10 wt% TOC), however, low liptinitic macerals (< 15%–20%), low hydrogen index (< 200 mg HC/g TOC) and low thermal maturity values inhibit the hyrocarbon generation.

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Characterization of organic matter from a stratigraphic sequence intercepted by the Nemo-1X well, Mozambique: Potential for hydrocarbon generation

Energy Exploration & Exploitation ◽

10.1177/0144598717753920 ◽

2018 ◽

Vol 36 (5) ◽

pp. 1157-1171

Author(s):

Agostinho Mussa ◽

Deolinda Flores ◽

Joana Ribeiro ◽

Ana MP Mizusaki ◽

Mónica Chamussa ◽

...

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Total Organic Carbon ◽

Hydrocarbon Exploration ◽

Published Data ◽

Organic Carbon Content ◽

Hydrocarbon Generation ◽

Offshore Area ◽

Type Iii ◽

Kerogen Type

The Mozambique Basin, which occurs onshore and offshore in the central and southern parts of Mozambique, contains a thick sequence of volcanic and sedimentary rocks that range in age from the Jurassic to Cenozoic. This basin, along with the Rovuma basin to the north, has been the main target for hydrocarbon exploration; however, published data on hydrocarbon occurrences do not exist. In this context, the present study aims to contribute to the understanding of the nature of the organic matter of a sedimentary sequence intercepted by the Nemo-1X exploration well located in the offshore area of the Mozambique Basin. The well reached a depth of 4127 m, and 33 samples were collected from a depth of 2219–3676 m ranging in age from early to Late Cretaceous. In this study, petrographic and geochemical analytical methods were applied to assess the level of vitrinite reflectance and the organic matter type as well as the total organic carbon, total sulfur, and CaCO3 contents. The results show that the total organic carbon content ranges from 0.41 to 1.34 wt%, with the highest values determined in the samples from the Lower Domo Shale and Sena Formations, which may be related to the presence of the solid bitumens that occur in the carbonate fraction of those samples. The vitrinite random reflectances range from 0.65 to 0.86%Rrandom, suggesting that the organic matter in all of the samples is in the peak phase of the “oil generation window” (0.65–0.9%Rrandom). The organic matter is mainly composed of vitrinite and inertinite macerals, with a minor contribution of sporinite from the liptinite group, which is typical of kerogen type III. Although all of the samples have vitrinite reflectances corresponding to the oil window, the formation of liquid hydrocarbons is rather limited because the organic matter is dominated by gas-prone kerogen type III.

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