THE SUPPRESSION OF VITRINITE REFLECTANCE IN SOME NORTH WEST SHELF WELLS: BARROW-1, JUPITER-1 AND FLAMINGO-1

1992 ◽  
Vol 32 (1) ◽  
pp. 300 ◽  
Author(s):  
R.W.T. Wilkins ◽  
J.R. Wilmshurst ◽  
G. Hladky ◽  
M.V. Ellacott ◽  
C.P. Buckingham
Keyword(s):  
Organic Matter ◽  
Vitrinite Reflectance ◽  
Accurate Determination ◽  
Petroleum Exploration ◽  
Thermal Maturity ◽  
North West ◽  
The North ◽  
The Individual ◽  
Reflectance Data

The sediments of the North West Shelf pose several problems for the accurate determination of thermal maturity by vitrinite reflectance. There are some serious discrepancies between the results of different workers; in some wells there is a surprisingly small increase of reflectance with depth, and it is sometimes difficult to honour these data in thermal maturity modelling. There appear to be two major sources of error in the reflectance data. These are firstly, the effect known as 'suppression' of vitrinite reflectance, and secondly, the difficulty of identifying the vitrinite population in dispersed organic matter.These problems may be addressed by the fluorescence alteration technique which is closely related to vitrinite reflectance but has two special advantages. Firstly, it depends on an analysis of the fluorescence alteration response of a small representative population of organic matter in which the individual macerals need not be identified. Secondly, anomalous vitrinites with suppressed vitrinite reflectance are readily characterized, and the corrected equivalent reflectances determined.The technique has been tested on three North West Shelf petroleum exploration wells, Barrow-1, Jupiter-1 and Flamingo-1. Major discrepancies between measured and equivalent vitrinite reflectance appear to originate in part from the difficulty of identifying the vitrinite population in dispersed organic matter from marine sediments. There is also evidence of suppression of vitrinite reflectance in most samples from Barrow-1, in the Flamingo Group and Plover Formation of Flamingo-1, and in the upper part of the Mungaroo Formation of Jupiter-1.A model is proposed to facilitate the assessment of measured vitrinite reflectance data from Carnarvon or Bonaparte Basin wells. Suppression effects are likely to have influenced measured vitrinite reflectance results from wells for which the strongest data are obtained from the Lower Cretaceous fluvio-deltaic Barrow Group sediments or their equivalents.

THE CURRENT STATUS OF THE FAMM THERMAL MATURITY TECHNIQUE FOR PETROLEUM EXPLORATION IN AUSTRALIA

1998 ◽  
Vol 38 (1) ◽  
pp. 421 ◽  
Author(s):  
R.W.T. Wilkins ◽  
C.P. Buckingham ◽  
N. Sherwood ◽  
N.J. Russell ◽  
M. Faiz ◽  
...  
Keyword(s):  
Organic Matter ◽  
Vitrinite Reflectance ◽  
Petroleum Exploration ◽  
Current Status ◽  
Thermal Maturity ◽  
North West ◽  
Intensity Measurements ◽  
Organic Matter Oxidation ◽  
Working Set

The fluorescence alteration of multiple macerals (FAMM™) technique was developed in 1989-91 to overcome problems encountered by existing techniques applied to the thermal maturity determination of North West Shelf organic matter. Subsequently it has been widely used in Australia, SE Asia and elsewhere. This paper reviews the present status of the FAMM technique.Since its inception, the methodology of the FAMM technique has undergone some changes. The most important is a closer integration with vitrinite reflectance (VR) resulting in expansion of the capacity of the technique to solve complex maturity problems. The accumulated data indicate that shales and mudstones are most suitable for FAMM analysis for the reason that more porous lithologies are potentially more susceptible to organic matter oxidation. There is extensive evidence that organic matter in cores and well-protected cuttings samples of shales remain unaffected by oxidation during decades of storage because clay is extremely effective in limiting access of oxygen. Adhering to sampling guidelines can greatly reduce the risk of errors from this source. Of the two recently described thermal maturity techniques based on combining VR with fluorescence intensity measurements (Quick, 1994; Newman, 1997), FAMM is more closely related to Quick's method. As the fluorescence alteration ratio which acts as the thermal maturity indicator in the FAMM method is independent of VR, it is possible to cross check results for consistency using suppression iso-correction curves-a possiblity which does not exist with the other thermal maturity techniques based on fluorescence. A working set of suppression iso-correction curves has been determined specifically for Australian Jurassic vitrinite. Whether from coal or dispersed organic matter (DOM), Australian Jurassic vitrinites are commonly perhydrous and this should be borne in mind when modelling thermal histories of North West Shelf sequences.

Loran-C Chains: Determination of Extent of Cover

1988 ◽  
Vol 41 (02) ◽  
pp. 149-173 ◽  
Author(s):  
K. F. Woodman ◽  
J. Juleff ◽  
R. A. Allen
Keyword(s):  
Field Strength ◽  
North Sea ◽  
Western Europe ◽  
Accurate Determination ◽  
Propagation Path ◽  
North West ◽  
The North ◽  
The North Sea ◽  
Geometric Effects

A mainly theoretical study has been undertaken to demonstrate how the extent of cover from a hyperbolic navigation system chain can be evaluated. The impetus for the study was the need to assess how Loran-C could be extended over Western Europe, particularly in the South western Approaches, North Sea, English Channel and Bay of Biscay sea areas.The technique described in this article leads to an accurate determination of the electric field strength at a distance from each transmitting site and takes into account the complexities of the ground-wave propagation path. This field-strength contour is combined with the geometric effects of station siting (expansion factors) to yield a constant S/N contour (–10 dB) which defines the ¼n.m. error and hence the limit of cover for the hyperbolic chain under study.In order to exercise the analytical methods a hypothetical Loran-C chain was studied comprising a master station at Lessay (France), with secondary stations at Soustons (also in France), at Sylt (dual rated; off the North Sea coast of Germany, near the Danish border) and at a fourth station located in north-west Britain on the Hebridean island of Barra. The study indicated that such a hypothetical chain would significantly improve Loran-C cover over much of western Europe.

Thermal imprints along conjugated continental margins in response to the opening of the northern North Atlantic - case studies from eastern North Greenland and western Svalbard

2021 ◽  
Author(s):  
Katrin Meier ◽  
Paul O'Sullivan ◽  
Malte Jochmann ◽  
Patrick Monien ◽  
Karsten Piepjohn ◽  
...  
Keyword(s):  
Heat Flow ◽  
North Atlantic ◽  
Thermal History ◽  
Vitrinite Reflectance ◽  
Continental Margins ◽  
Thermal Maturity ◽  
Quartz Veins ◽  
The North ◽  
Reflectance Data ◽  
North Greenland

<p>Prior to break up of Greenland and Svalbard, the Wandel sea basin with Carboniferous to Cenozoic deposits formed in eastern North Greenland. These deposits were affected by the last major period of Arctic tectonism, the Eocene Eurekan deformation. Vitrinite reflectance data from late Cretaceous rocks long the east coast of North Greenland indicate unusual high thermal maturity in association with a swarm of quartz veins, which exceeds the thermal maturity associated with the Eurekan deformation further inland. This pattern is also observed in Cenozoic sediments further to the north as well as along the conjugated North Atlantic margin, in western Svalbard. However, cause and origin of the elevated heat flow indicated by thermal maturity values are not known so far and the timing is not well constrained. We test the hypothesis whether this pattern was established coevally along both margins of the North Atlantic and marks a post-Eurekan thermal event. Vitrinite reflectance data indicate temperatures high enough to reset low temperature chronometers, therefore we used apatite fission track (AFT) and (U-Th-Sm)/He (AHe) thermochronology to determine the age of the high thermal maturation and associated quartz veins formation.</p><p>Our data reveals a more complex thermal history than hypothesized:<br>For the eastern North Greenland margin thermal history modelling of the combined AFT and AHe ages indicates a pre-Eurekan phase of elevated heat flow between 72 Ma and 66 Ma causing the high vitrinite reflectance and the formation of the quartz veins in the late Cretaceous rocks. Additional petrographic and electron microprobe analysis reveals the growth of feldspar, hematite, amphibole, and tourmaline within the quartz veins. According to most paleogeographic reconstructions, northern Greenland was located to the south of Svalbard close to a volcanic province near Bear Island. Heating may thus be associated with incipient igneous activity of that area, related to initial North Atlantic opening. A second phase of elevated heat flow between 58 Ma and 52 Ma is indicated by thermal history modelling of the AFT and AHe ages from the Cenozoic rocks further north. This frames the timing of the initiation of the dextral displacement between Greenland and Svalbard and might be associated with heat transfer along the transform fault from the active spreading centres in the North Atlantic and the Arctic Ocean.<br>Contrasting to the results of North Greenland, thermal history modelling of AFT and AHe ages from the Cenozoic rocks of western Svalbard reveals heating throughout the Eocene and onset of cooling only during the early Oligocene for the Svalbard margin. Thus, even though we cannot exclude a similar thermal history during the Paleocene to early Eocene, the eastern North Greenland and western Svalbard margins are characterized by a differential thermal evolution during the ~middle Eocene to Oligocene.</p><p>In conclusion, our data show that the thermal history of the conjugated continental margins along the northern North Atlantic is characterized by episodic heat flow variations predominantly controlled by oceanic plate tectonic processes.</p>

VITRINITE REFLECTANCE SUPPRESSION IN COAL DUE TO A MARINE TRANSGRESSION: CASE STUDY OF THE ORGANIC GEOCHEMISTRY OF THE GRETA SEAM, SYDNEY BASIN

1994 ◽  
Vol 34 (1) ◽  
pp. 241 ◽  
Author(s):  
S. C. George ◽  
J. W. Smith ◽  
D. R. Jardine
Keyword(s):  
Organic Geochemistry ◽  
Vitrinite Reflectance ◽  
Bimodal Distribution ◽  
Atomic Ratio ◽  
Petroleum Exploration ◽  
North West ◽  
The North ◽  
Geochemical Parameters ◽  
Marine Influence ◽  
Geochemical Investigation

Vitrinite reflectance suppression in marine sequences is a major problem facing some petroleum exploration companies. It leads to considerable difficulties in determining thermal maturity in exploration provinces like the North West Shelf of Australia. The Permian Greta seam, northern Sydney Basin, is a classical example of a marine-influenced coal which displays a vitrinite reflectance suppression of 0.25 per cent R0. It is an ideal candidate for detailed organic geochemical investigation of this problem. The amount and composition of extractable hydrocarbons in the coal appear to be only partially related to vitrinite reflectance, so it is unlikely that suppression is directly caused by the adsorption of hydrocarbons into the vitrinite matrix. Vitrinite reflectance is inversely proportional to the H/C atomic ratio, suggesting that the observed suppression is caused by the more perhydrous nature of vitrinite in marine-influenced coals. At the molecular level the marine influence can clearly be distinguished in the top metre of the seam by depleted amounts of n-alkanes with a lower carbon preference index and a slightly bimodal distribution, a lower pristane/phytane ratio and considerably more hopanes and diasteranes. In addition to the peat-derived humic compounds prevalent throughout the seam, these geochemical parameters indicate bacterial re-working of the newly deposited peat and a direct contribution of marinederived lipids at the top of the seam. Fluctuations in n-alkane and isoprenoid distributions and abundances elsewhere in the seam indicate that the depositional environment changed periodically.

scholarly journals Visualizing the Bohr effect in hemoglobin: neutron structure of equine cyanomethemoglobin in the R state and comparison with human deoxyhemoglobin in the T state

2016 ◽  
Vol 72 (7) ◽  
pp. 892-903 ◽  
Author(s):  
Steven Dajnowicz ◽  
Sean Seaver ◽  
B. Leif Hanson ◽  
S. Zoë Fisher ◽  
Paul Langan ◽  
...  
Keyword(s):  
Structural Changes ◽  
Accurate Determination ◽  
Bohr Effect ◽  
Salt Bridges ◽  
Histidine Residues ◽  
Regions Of Stability ◽  
The Individual ◽  
T State

Neutron crystallography provides direct visual evidence of the atomic positions of deuterium-exchanged H atoms, enabling the accurate determination of the protonation/deuteration state of hydrated biomolecules. Comparison of two neutron structures of hemoglobins, human deoxyhemoglobin (T state) and equine cyanomethemoglobin (R state), offers a direct observation of histidine residues that are likely to contribute to the Bohr effect. Previous studies have shown that the T-state N-terminal and C-terminal salt bridges appear to have a partial instead of a primary overall contribution. Four conserved histidine residues [αHis72(EF1), αHis103(G10), αHis89(FG1), αHis112(G19) and βHis97(FG4)] can become protonated/deuterated from the R to the T state, while two histidine residues [αHis20(B1) and βHis117(G19)] can lose a proton/deuteron. αHis103(G10), located in the α1:β1dimer interface, appears to be a Bohr group that undergoes structural changes: in the R state it is singly protonated/deuterated and hydrogen-bonded through a water network to βAsn108(G10) and in the T state it is doubly protonated/deuterated with the network uncoupled. The very long-term H/D exchange of the amide protons identifies regions that are accessible to exchange as well as regions that are impermeable to exchange. The liganded relaxed state (R state) has comparable levels of exchange (17.1% non-exchanged) compared with the deoxy tense state (T state; 11.8% non-exchanged). Interestingly, the regions of non-exchanged protons shift from the tetramer interfaces in the T-state interface (α1:β2and α2:β1) to the cores of the individual monomers and to the dimer interfaces (α1:β1and α2:β2) in the R state. The comparison of regions of stability in the two states allows a visualization of the conservation of fold energy necessary for ligand binding and release.

Hydrocarbon Generative Properties and Maturity of Cretaceous and Eocene Sediments in the Middle Kura Depression, Azerbaijan

2021 ◽  
Author(s):  
Shahin Khosrov Akhundov ◽  
Mushfig Farhad Tagiyev ◽  
Arastun Ismail Khuduzade ◽  
Natig Namig Aliyev
Keyword(s):  
Organic Matter ◽  
Brown Coal ◽  
Lower Cretaceous ◽  
Vitrinite Reflectance ◽  
Sedimentary Cover ◽  
Hard Coal ◽  
Marine Origin ◽  
Formation Conditions ◽  
Lesser Caucasus ◽  
Reflectance Data

Abstract Meso-Cenozoic sedimentary cover in the Middle Kura depression located between the Greater and Lesser Caucasus mountain structures contains numerous oil accumulations. According to studies in the Cretaceous and Paleogene strata, sedimentary organic matter is of mixed clastic-marine origin. Moderate amounts of organic matter have been recorded in the Eocene sediments (on average 0.70%), in the Upper and Lower Cretaceous average values made up 0.39% и 0.42%, respectively. Analysis of bitumoid composition suggests that in a number of areas bitumoids have experienced a widespread movement across the sedimentary strata. The results of measurements on isolated samples indicate that the Cretaceous strata have only advanced to the initial hard-coal stage of organic transformation (0.48-0.55%Ro). On vitrinite reflectance data the Eocene deposits in studied areas of the Middle Kura depression have reached initial (brown-coal) stage of catagenetic transformation (±0.48Ro%; est. paleotemperature of 85°C). Nonetheless, analysis of formation conditions of commercial HC accumulations found earlier in the Eocene strata allows considering them the most prospective in the Middle Kura depression.

scholarly journals Thermal maturity of the Upper Triassic–Middle Jurassic Shemshak Group (Alborz Range, Northern Iran) based on organic petrography, geochemistry and basin modelling: implications for source rock evaluation and petroleum exploration

2011 ◽  
Vol 149 (1) ◽  
pp. 19-38 ◽  
Author(s):  
ALI SHEKARIFARD ◽  
FRANÇOIS BAUDIN ◽  
KAZEM SEYED-EMAMI ◽  
JOHANN SCHNYDER ◽  
FATIMA LAGGOUN-DEFARGE ◽  
...  
Keyword(s):  
Middle Jurassic ◽  
Vitrinite Reflectance ◽  
Upper Triassic ◽  
Petroleum Exploration ◽  
Thermal Maturity ◽  
Northern Iran ◽  
Carbonaceous Shales ◽  
Petroleum Generation ◽  
Central Eastern ◽  
Alborz Range

AbstractOrganic petrography and geochemical analyses have been carried out on shales, carbonaceous shales and coals of the Shemshak Group (Upper Triassic–Middle Jurassic) from 15 localities along the Alborz Range of Northern Iran. Thermal maturity of organic matter (OM) has been investigated using vitrinite reflectance, Rock-Eval pyrolysis and elemental analysis of kerogen. Reflectance of autochthonous vitrinite varies from 0.6 to 2.2% indicating thermally early-mature to over-mature OM in the Shemshak Group, in agreement with other maturity parameters used. The shales of the Shemshak Group are characterized by poor to high residual organic carbon contents (0.13 to 5.84%) and the presence of hydrogen-depleted OM, predominantly as a consequence of oxidation of OM at the time of deposition and the hydrogen loss during petroleum generation. According to light-reflected microscopy results, vitrinite/vitrinite-like macerals are dominant in the kerogen concentrates from the shaly facies. The coals and carbonaceous shales of the Shemshak Group show a wide range in organic carbon concentration (3.5 to 88.6%) and composition (inertinite- and vitrinite-rich types), and thereby different petroleum potentials. Thermal modelling results suggest that low to moderate palaeo-heat flow, ranging from 47 to 79 mW m−2 (57 mW m−2 on average), affected the Central-Eastern Alborz basin during Tertiary time, the time of maximum burial of the Shemshak Group. The maximum temperature that induced OM maturation of the Shemshak Group seems to be related to its deep burial rather than to a very strong heat flow related to an uppermost Triassic–Liassic rifting. The interval of petroleum generation in the most deeply buried part of the Shemshak Group (i.e. Tazareh section) corresponds to Middle Jurassic–Early Cretaceous times. Exhumation of the Alborz Range during Late Neogene time, especially along the axis of the Central-Eastern Alborz, where maximum vitrinite reflectance values are recorded, probably destroyed possible petroleum accumulations. However, on the northern flank of the Central-Eastern Alborz, preservation of petroleum accumulations may be expected. The northern part of the basin therefore seems the best target for petroleum exploration.

scholarly journals A reflection about the social and technological aspects in flood risk management – the case of the Italian Civil Protection

2010 ◽  
Vol 10 (1) ◽  
pp. 109-119 ◽  
Author(s):  
M. del Carmen Llasat ◽  
F. Siccardi
Keyword(s):  
Land Use Planning ◽  
Warning System ◽  
Modern Society ◽  
Civil Protection ◽  
North West ◽  
The North ◽  
The Social ◽  
Ground Effects ◽  
The Individual ◽  
The Right

Abstract. The right of a person to be protected from natural hazards is a characteristic of the social and economical development of the society. This paper is a contribution to the reflection about the role of Civil Protection organizations in a modern society. The paper is based in the inaugural conference made by the authors on the 9th Plinius Conference on Mediterranean Storms. Two major issues are considered. The first one is sociological; the Civil Protection organizations and the responsible administration of the land use planning should be perceived as reliable as possible, in order to get consensus on the restrictions they pose, temporary or definitely, on the individual free use of the territory as well as in the entire warning system. The second one is technological: in order to be reliable they have to issue timely alert and warning to the population at large, but such alarms should be as "true" as possible. With this aim, the paper summarizes the historical evolution of the risk assessment, starting from the original concept of "hazard", introducing the concepts of "scenario of event" and "scenario of risk" and ending with a discussion about the uncertainties and limits of the most advanced and efficient tools to predict, to forecast and to observe the ground effects affecting people and their properties. The discussion is centred in the case of heavy rains and flood events in the North-West of Mediterranean Region.

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