COAL AS A SOURCE OF OIL AND GAS: A CASE STUDY FROM THE BASS BASIN, AUSTRALIA

2003 ◽  
Vol 43 (1) ◽  
pp. 117 ◽  
Author(s):  
C.J. Boreham ◽  
J.E. Blevin ◽  
A.P. Radlinski ◽  
K.R. Trigg
Keyword(s):  
Organic Matter ◽  
Oil And Gas ◽  
Middle Eocene ◽  
Vitrinite Reflectance ◽  
Mineral Resources ◽  
Sedimentary Basins ◽  
Source Rocks ◽  
Gas Generation ◽  
Australian Context ◽  
Effective Source

Only a few published geochemical studies have demonstrated that coals have sourced significant volumes of oil, while none have clearly implicated coals in the Australian context. As part of a broader collaborative project with Mineral Resources Tasmania on the petroleum prospectivity of the Bass Basin, this geochemical study has yielded strong evidence that Paleocene–Eocene coals have sourced the oil and gas in the Yolla, Pelican and Cormorant accumulations in the Bass Basin.Potential oil-prone source rocks in the Bass Basin have Hydrogen Indices (HIs) greater than 300 mg HC/g TOC. The coals within the Early–Middle Eocene succession commonly have HIs up to 500 mg HC/g TOC, and are associated with disseminated organic matter in claystones that are more gas-prone with HIs generally less than 300 mg HC/g TOC. Maturity of the coals is sufficient for oil and gas generation, with vitrinite reflectance (VR) up to 1.8 % at the base of Pelican–5. Igneous intrusions, mainly within Paleocene, Oligocene and Miocene sediments, produced locally elevated maturity levels with VR up to 5%.The key events in the process of petroleum generation and migration from the effective coaly source rocks in the Bass Basin are:the onset of oil generation at a VR of 0.65% (e.g. 2,450 m in Pelican–5);the onset of oil expulsion (primary migration) at a VR of 0.75% (e.g. 2,700–3,200 m in the Bass Basin; 2,850 m in Pelican–5);the main oil window between VR of 0.75 and 0.95% (e.g. 2,850–3,300 m in Pelican–5); and;the main gas window at VR >1.2% (e.g. >3,650 m in Pelican–5).Oils in the Bass Basin form a single oil population, although biodegradation of the Cormorant oil has resulted in its statistical placement in a separate oil family from that of the Pelican and Yolla crudes. Oil-to-source correlations show that the Paleocene–Early Eocene coals are effective source rocks in the Bass Basin, in contrast to previous work, which favoured disseminated organic matter in claystone as the sole potential source kerogen. This result represents the first demonstrated case of significant oil from coal in the Australian context. Natural gases at White Ibis–1 and Yolla–2 are associated with the liquid hydrocarbons in their respective fields, although the former gas is generated from a more mature source rock.The application of the methodologies used in this study to other Australian sedimentary basins where commercial oil is thought to be sourced from coaly kerogens (e.g. Bowen, Cooper and Gippsland basins) may further implicate coal as an effective source rock for oil.

ORIGIN OF GILMORE GAS AND OIL, ADAVALE BASIN, CENTRAL QUEENSLAND

1998 ◽  
Vol 38 (1) ◽  
pp. 399 ◽  
Author(s):  
C.J. Boreham ◽  
R.A. de Boer
Keyword(s):  
Oil And Gas ◽  
Isotope Composition ◽  
Vitrinite Reflectance ◽  
Sedimentary Basins ◽  
Source Rocks ◽  
Gas Generation ◽  
Migration Pathway ◽  
Wet Gas ◽  
Modelling Studies ◽  
High Maturity

Dry gas in the Gilmore Field of the Adavale Basin has been sourced from both wet gas associated with oil generation, together with methane from a deep, overmature source. The latter gas input is further characterised by a high nitrogen content co-generated with isotopically heavy methane and carbon dioxide. The eastern margin of the Lissoy Sandstone principal reservoir unit contains the higher content of overmature dry gas supporting reservoir compiirtmenmlisalion and a more favourable migration pathway to this region. The combination of a molecular and multi-element isotopic approach is an effective tool for the recognition of an overmature, dry gas source. This deep source represents a play concept that previously has been undervalued and may be more widespread within Australian sedimentary basins.The maturity level of the wet gas and associated oil are identical, having reached an equivalent vitrinite reflectance of 1.4−1.6 per cent. Modelling studies support the concept of local Devonian source rocks for the wet gas and oil. Reservoir filling from late stage, high maturity oil and gas generation and expulsion, was a result of reactivation of petroleum generation from Devonian source rocks during the Early Cretaceous. The large input of dry gas from a deeper and highly overmature source is a more recent event. This gas can fractionally displace condensable C2+ liquids already in the reservoir possibly allowing tertiary migration into younger reservoirs, or adjacent structures.Oil recovered from Gilmore-2 has been sourced from Devonian marine organic matter, deposited under mildly evaporitic, restricted marine conditions. The most likely source rocks in the Adavale Basin are the basal marine shale of the Log Creek Formation, algal shales at the top of the Lissoy Sandstone, and the Cooladdi Dolomite. Source-sensitive biomarkers and carbon isotope composition of the Gilmore-2 oil have much in common with other Devonian-sourced oils from the Bonaparte and Canning basins. The chemical link between western and eastern Australian Devonian oils may suggest diachronous development of source rocks over a wide extent. This implies that the source element of the Devonian Petroleum Supersystem may be present in other sedimentary basins.

PETROLEUM SOURCE ROCKS IN THE ROPER GROUP OF THE MCARTHUR BASIN: SOURCE CHARACTERISATION AND MATURITY DETERMINATIONS USING PHYSICAL AND CHEMICAL METHODS

1994 ◽  
Vol 34 (1) ◽  
pp. 279 ◽  
Author(s):  
Dennis Taylor ◽  
Aleksai E. Kontorovich ◽  
Andrei I. Larichev ◽  
Miryam Glikson
Keyword(s):  
Organic Matter ◽  
Chemical Evolution ◽  
Oil And Gas ◽  
Source Rocks ◽  
Type I ◽  
Peak Oil ◽  
Gas Generation ◽  
Oil Generation ◽  
Physical And Chemical ◽  
Extractable Organic Matter

Organic rich shale units ranging up to 350 m in thickness with total organic carbon (TOC) values generally between one and ten per cent are present at several stratigraphic levels in the upper part of the Carpentarian Roper Group. Considerable variation in depositional environment is suggested by large differences in carbon:sulphur ratios and trace metal contents at different stratigraphic levels, but all of the preserved organic matter appears to be algal-sourced and hydrogen-rich. Conventional Rock-Eval pyrolysis indicates that a type I-II kerogen is present throughout.The elemental chemistry of this kerogen, shows a unique chemical evolution pathway on the ternary C:H:ONS diagram which differs from standard pathways followed by younger kerogens, suggesting that the maturation histories of Proterozoic basins may differ significantly from those of younger oil and gas producing basins. Extractable organic matter (EOM) from Roper Group source rocks shows a chemical evolution from polar rich to saturate rich with increasing maturity. Alginite reflectance increases in stepwise fashion through the zone of oil and gas generation, and then increases rapidly at higher levels of maturation. The increase in alginite reflectance with depth or proximity to sill contacts is lognormal.The area explored by Pacific Oil and Gas includes a northern area where the Velkerri Formation is within the zone of peak oil generation and the Kyalla Member is immature, and a southern area, the Beetaloo sub-basin, where the zone of peak oil generation is within the Kyalla Member. Most oil generation within the basin followed significant folding and faulting of the Roper Group.

Characteristics of the Overpressure Resulted from Hydrocarbon Generation

2013 ◽  
Vol 295-298 ◽  
pp. 2707-2710
Author(s):  
Hai Yan Hu ◽  
Hui Wang
Keyword(s):  
Organic Matter ◽  
Oil And Gas ◽  
Vitrinite Reflectance ◽  
Junggar Basin ◽  
Hydrocarbon Generation ◽  
Sonic Velocity ◽  
Gas Generation

Overpressure is often encountered in the Jurassic tight sandstones in the central Junggar Basin. In this studt, a new mechanism of overpressure formation related to gas generation is proposed. Organic-rich mudstones have sonic velocity well-line reserves but their densities continue to increase in the over-compacted mudstone system resulting in the overpressure development during the conversion of the organic matter to oil and gas. The top of the overpressure zone correlates with the depth required for a large quantity of gas generation in which the vitrinite reflectance (Ro) is about 0.7%, showing that the overpressure in organic-rich mudstones is closely associated with gas generation.

PETROLEUM GEOCHEMISTRY OF THE MURTA MEMBER, MOOGA FORMATION, AND ASSOCIATED OILS, EROMANGA BASIN

1989 ◽  
Vol 29 (1) ◽  
pp. 114 ◽  
Author(s):  
T.G. Powell ◽  
C.J. Boreham ◽  
D.M. McKirdy ◽  
B.H. Michaelsen ◽  
R.E. Summons
Keyword(s):  
Organic Matter ◽  
Vitrinite Reflectance ◽  
Hydrocarbon Composition ◽  
Source Rocks ◽  
Marine Oils ◽  
Algal Organic Matter ◽  
Conventional Oil ◽  
Effective Source ◽  
Eromanga Basin ◽  
Chemical Evidence

An investigation has been made of the source potential, degree of maturation and hydrocarbon composition of selected oils and sediments in the Murta Member in ATP 267P and the Moomba and Napacoongee- Murteree Blocks (PEL 5 and 6), Eromanga Basin. Shales in the Murta Member contain low amounts (up to 2.5% TOC) of terrestrial oil- prone organic matter (Types II–III) which consists predominantly of sporinite, lipto- detrinite and inertinite with lower amounts of vitrinite, although some samples contain relatively abundant telalginite. Extractable hydrocarbon yields demonstrate that parts of the Murta Member are effective source rocks at present maturation levels, which are at the threshold of the conventional oil window (vitrinite reflectance = 0.5- 0.6% Ro).Oils from Murta reservoirs in ATP 267P (Kihee, Nockatunga and Thungo) all show the characteristics found by previous analyses of many Murta oils, namely paraffinic, low wax, and high pristane- to- phytane ratios. In contrast Murta oils from Limestone Creek and Biala are waxy. All oils show chemical evidence of generation at relatively low maturation levels. Gas chromatograms of the saturate fractions from the best source facies show the same characteristics noted for the low- wax oils. Samples with lower source potential in contrast contain relatively abundant waxy n- alkanes. Methylphenan- threne Indices and biomarker maturation indicators obtained from the oils show the same values as were measured on sediment samples from the Murta. Hence the oils could not have been derived from deeper, more mature source rocks. The distribution of biomarkers in the low- wax oils is also consistent with an origin from the Murta Member. A corresponding source facies for the high- wax oils has not yet been located. However, chemical maturation indices also suggest a source in the Murta Member or in immediately adjacent strata.The unusual circumstances represented by the Murta oils (low maturity, low- wax terrestrial oils) provide evidence for bacterial contribution to the source material for non- marine oils. Both the low- wax oils and the best source facies contain abundant hydrocarbons derived from bacterial precursors. This bacterial organic matter appears to yield hydrocarbons at an earlier stage of maturation than the predominantly terrestrial plant and algal organic matter with which it is associated. In the case of the Murta Member there are sufficient hydrocarbons generated at relatively low maturity to allow migration to occur. Chemical evidence suggests a low contribution from algal organic matter to the generated hydrocarbons.

Wanganui and East Coast Basins - Two of New Zealand's Little Explored Sedimentary Basins

1988 ◽  
Vol 6 (3) ◽  
pp. 281-297 ◽  
Author(s):  
H.R. Katz
Keyword(s):  
Oil And Gas ◽  
East Coast ◽  
Sedimentary Basins ◽  
Gas Production ◽  
Source Rocks ◽  
Gas Generation ◽  
Offshore Oil And Gas ◽  
Multiple Deformation ◽  
Shale Diapirism ◽  
Offshore Oil

Of the 5 largest basins, with over 20,000 km and 4 km plus of sediments, only one (Taranaki) has seen more than reconnaissance exploration. The other basins have barely been scratched, with results that in all cases remain inconclusive. There is a wide potential still untested in New Zealand. Two examples are presented: The Wanganui Basin, where the older part of the sequence has never been drilled. Wells were located on buried hills with older sediments onlapping along flanks. There are extensive updip wedgeouts and potential for structural-stratigraphic trap combinations. Aspects of source rock and flushing, while initially thought of as downgrading prospects, may look more favourable upon proper evaluation. East Coast Basin. With very thick. Cretaceous-Tertiary sediments, multiple deformation, local unconformities and facies changes, this is one of the more exiting basins, measuring 40,000-50,000 km2 on and offshore. Oil and gas generation is widespread, source rocks being of Paleocene and Cretaceous age. Potential reservoirs are Cretaceous and Miocene sandstones and Oligocene and Pliocene limestones, the latter of excellent qualities. Lower Tertiary, undercompacted and gas-charged mudstones may be an additional target for gas production. Shale diapirism has contributed widely to structural trap formation. Since 1960, only 14 wells have been drilled, of which I offshore. This amounts to 0.3 wells per 1,000 km2, or 0.6 m/km2.

scholarly journals Evaluation of Shale Source Rocks and Clay Mineral Diagenesis in the Permian Basin, USA: Inferences on Basin Thermal Maturity and Source Rock Potential

Geosciences ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 381
Author(s):  
Hunter Green ◽  
Branimir Šegvić ◽  
Giovanni Zanoni ◽  
Silvia Omodeo-Salé ◽  
Thierry Adatte
Keyword(s):  
Organic Matter ◽  
Clay Mineral ◽  
Vitrinite Reflectance ◽  
Sedimentary Basins ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Peak Oil ◽  
Permian Basin ◽  
Thermal Indices ◽  
Rock Eval

The use of mineral diagenetic indices and organic matter maturity is useful for reconstructing the evolution of sedimentary basins and critical assessments for potential source rocks for petroleum exploration. In this study, the relationship of clay mineral diagenesis and organic matter thermal indices (Rock-Eval Tmax) and calculated vitrinite reflectance (%Ro) were used to constrain the maximum burial depths and temperatures of three distinct intervals within the northern Permian Basin, USA. X-ray diffraction of clay fractions (<2 µm) consists of illite, chlorite, and illite-smectite intermediates. Primary clay mineral diagenetic changes progressively increase in ordering from R0 to R1 I-S between 2359.5 and 2485.9 m and the appearance of chlorite at 2338.7 m. Rock-Eval pyrolysis data show 0 to 14 wt% TOC, HI values of 40 to 520 mgHC/g TOC, and S2 values of 0 to 62 mg HC/g, with primarily type II kerogen with calculated %Ro within the early to peak oil maturation window. Evaluation of the potential for oil generation is relatively good throughout the Tonya 401 and JP Chilton wells. Organic maturation indices (Tmax, %Ro) and peak burial temperatures correlate well with clay mineral diagenesis (R0–R1 I-S), indicating that maximum burial depths and temperatures were between 2.5 and 4 km and <100 °C and 140 °C, respectively. Additionally, the use of clay mineral-derived temperatures provides insight into discrepancies between several calculated %Ro equations and thus should be further investigated for use in the Permian Basin. Accordingly, these findings show that clay mineral diagenesis, combined with other paleothermal proxies, can considerably improve the understanding of the complex burial history of the Permian Basin in the context of the evolution of the southern margin of Laurentia.

scholarly journals Thermal history and organic matter maturation modeling of the East Siberian Sea sedimentary basins

2017 ◽  
pp. 15-27
Author(s):  
M. D. Lineva ◽  
N. A. Malyshev ◽  
A. M. Nikishin
Keyword(s):  
Organic Matter ◽  
Cross Sections ◽  
Thermal History ◽  
Vitrinite Reflectance ◽  
Sedimentary Basins ◽  
Source Rocks ◽  
Hydrocarbon Generation ◽  
Seismic Line ◽  
East Siberian Sea ◽  
Temperature Maps

2D and 3D thermal history and organic matter maturity modeling of East Siberian Sea sedimentary basinsare performed in this study. We present cross-sections with temperature and vitrinite reflectance distribution along composite seismic line, temperature maps ofmain horizons fordifferent time stages. Vitrinite reflectance maps of source rocks fordifferent time stages and transformation ratio maps of source rocks for present time are also presented. Maturation history and possibilities of hydrocarbon generation were analyzed using modeling results.

scholarly journals Clay Minerals and Organic Matter from Deeply Buried Ordovician-Silurian Shale in Western Iraq: Implications for Maturity and Hydrocarbon Generation

2020 ◽  
pp. 3006-3023
Author(s):  
Ali I. Al-Juboury ◽  
Mohammed A. Al-Haj ◽  
Adrian Hutton ◽  
Brian Jones
Keyword(s):  
Organic Matter ◽  
Clay Minerals ◽  
Mixed Layer ◽  
Oil And Gas ◽  
Vitrinite Reflectance ◽  
Hydrocarbon Generation ◽  
X Ray Diffraction ◽  
Gas Generation ◽  
X Ray ◽  
Organic Mineral

The present work is conducted on the Paleozoic (Ordovician) Khabour and the (Silurian) Akkas shales in the Akkas-1 well of western Iraq. The study is aiming to determine the implications of clay mineral transformation, organic mineral distribution and maturity of hydrocarbon generation, using X-ray diffraction (XRD), scanning electron microscopy (SEM) in addition to organic matter concentrations. In the shale of the Khabour Formation, amorphous organic matter is common and includes various Tasmanite-type organic matter, vitrinite, inertinite, and bituminite. The main clay minerals observed include illite, chlorite, kaolinite, in addition to mixed-layer illite-smectite and rare smectite. In Silurian shale, high content of organic matter is recorded in addition to abundant vitrinite and low content of grainy organic matter (Tasmanites) and pyrite. Illite and kaolinite are commonly found in addition to chlorite and illite-smectite clay minerals. Conversion of smectite to mixed-layer illite-smectite (I-S) and an increase in vitrinite reflectance are commonly observed below 2500 m depth in the studied formations, which coincides with oil and gas generation. These results could be used as an indication of higher maturity and hydrocarbon generation in the deeply buried shale of the Khabour and Akkas formations in western Iraq.

Burial History Reconstruction of the Appalachian Basin in Kentucky, West Virginia, Pennsylvania, and New York, Using 1D Petroleum System Models

2019 ◽  
Vol 56 (4) ◽  
pp. 365-396
Author(s):  
Debra Higley ◽  
Catherine Enomoto
Keyword(s):  
New York ◽  
Vitrinite Reflectance ◽  
Structural Complexity ◽  
Appalachian Basin ◽  
Source Rocks ◽  
Burial History ◽  
Gas Generation ◽  
Deep Basin ◽  
Utica Shale ◽  
Wet Gas

Nine 1D burial history models were built across the Appalachian basin to reconstruct the burial, erosional, and thermal maturation histories of contained petroleum source rocks. Models were calibrated to measured downhole temperatures, and to vitrinite reflectance (% Ro) data for Devonian through Pennsylvanian source rocks. The highest levels of thermal maturity in petroleum source rocks are within and proximal to the Rome trough in the deep basin, which are also within the confluence of increased structural complexity and associated faulting, overpressured Devonian shales, and thick intervals of salt in the underlying Silurian Salina Group. Models incorporate minor erosion from 260 to 140 million years ago (Ma) that allows for extended burial and heating of underlying strata. Two modeled times of increased erosion, from 140 to 90 Ma and 23 to 5.3 Ma, are followed by lesser erosion from 5.3 Ma to Present. Absent strata are mainly Permian shales and sandstone; thickness of these removed layers increased from about 6200 ft (1890 m) west of the Rome trough to as much as 9650 ft (2940 m) within the trough. The onset of oil generation based on 0.6% Ro ranges from 387 to 306 Ma for the Utica Shale, and 359 to 282 Ma for Middle Devonian to basal Mississippian shales. The ~1.2% Ro onset of wet gas generation ranges from 360 to 281 Ma in the Utica Shale, and 298 to 150 Ma for Devonian to lowermost Mississippian shales.

Evidence from the Changing Carbon Isotopic of Kerogen, Oil, and Gas during Hydrous Pyrolysis from Pinghu Formation, the Xihu Sag, East China Sea Basin

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8317
Author(s):  
Qiang Cao ◽  
Jiaren Ye ◽  
Yongchao Lu ◽  
Yang Tian ◽  
Jinshui Liu ◽  
...  
Keyword(s):  
Carbon Isotopes ◽  
Oil And Gas ◽  
Thermal Evolution ◽  
Vitrinite Reflectance ◽  
Heating Time ◽  
Source Rocks ◽  
Evolution Process ◽  
Carbon Isotopic ◽  
Hydrous Pyrolysis ◽  
Increasing Temperature

Semi-open hydrous pyrolysis experiments on coal-measure source rocks in the Xihu Sag were conducted to investigate the carbon isotope evolution of kerogen, bitumen, generated expelled oil, and gases with increasing thermal maturity. Seven corresponding experiments were conducted at 335 °C, 360 °C, 400 °C, 455 °C, 480 °C, 525 °C, and 575 °C, while other experimental factors, such as the heating time and rate, lithostatic and hydrodynamic pressures, and columnar original samples were kept the same. The results show that the simulated temperatures were positive for the measured vitrinite reflectance (Ro), with a correlation coefficient (R2) of 0.9861. With increasing temperatures, lower maturity, maturity, higher maturity, and post-maturity stages occurred at simulated temperatures (Ts) of 335–360 °C, 360–400 °C, 400–480 °C, and 480–575 °C, respectively. The increasing gas hydrocarbons with increasing temperature reflected the higher gas potential. Moreover, the carbon isotopes of kerogen, bitumen, expelled oil, and gases were associated with increased temperatures; among gases, methane was the most sensitive to maturity. Ignoring the intermediate reaction process, the thermal evolution process can be summarized as kerogen0(original) + bitumen0(original)→kerogenr (residual kerogen) + expelled oil (generated) + bitumenn+r (generated + residual) + C2+(generated + residual) + CH4(generated). Among these, bitumen, expelled oil, and C2-5 acted as reactants and products, whereas kerogen and methane were the reactants and products, respectively. Furthermore, the order of the carbon isotopes during the thermal evolution process was identified as: δ13C1 < 13C2-5 < δ13Cexpelled oil < δ13Cbitumen < δ13Ckerogen. Thus, the reaction and production mechanisms of carbon isotopes can be obtained based on their changing degree and yields in kerogen, bitumen, expelled oil, and gases. Furthermore, combining the analysis of the geochemical characteristics of the Pinghu Formation coal–oil-type gas in actual strata with these pyrolysis experiments, it was identified that this area also had substantial development potential. Therefore, this study provides theoretical support and guidance for the formation mechanism and exploration of oil and gas based on changing carbon isotopes.

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