radiogenic helium concentration and isotope variations in crustal gas pools from sichuan basin china abstract helium is an exhaustible natural resource and the main commercial helium was separated from helium rich natural gas the helium in the sedimentary basin is mainly the radiogenic origin of crustal rocks with high level of uranium and thorium data from 242 natural gas samples were used to investigate the distribution and formation mechanism of helium rich gases in the sichuan basin of china all gas samples show remarkably low 3he 4he ratios with ranging from 0 002 to 0 05 ra which represent typical crustal helium the weiyuan gas pool in the southern sichuan basin possesses high levels of helium 1500 18770 ppm average 2785 7 ppm in precambrian and cambrian strata a positive relationship were observed in the helium and nitrogen contents increased with reservoir layer age for all weiyuan gas samples presinian granite was considered as the main helium source for the weiyuan gas pool gaoshiti moxi and weiyuan gas pools belonged to the same ancient gas pool before the late cretaceous but the helium abundance of gaoshiti moxi gas pool is relatively low 200 891 ppm the change of pressure and fracture system caused by the uplift of weiyuan structure in the himalayan orogenesis led to the helium accumulation and enrichment of weiyuan gas pool the shale of the silurian longmaxi formation has high contents of uranium and thorium and generated a large amount of helium while forming large quantities of hydrocarbon gases generally the helium abundance of shale gases and conventional gases generated from the longmaxi formation ranges from 63 to 1500 ppm and some of the gas pool are sufficient for commercial helium resource exploitation therefore the relative quantities of helium and hydrocarbon gases are act as a key factor influencing the formation of helium rich natural gas reservoirs

origin of the unusually high dibenzothiophene oils in tazhong 4 oilfield of tarim basin and its implication in deep petroleum exploration abstract unusually high dibenzothiophene dbt concentrations are present in the oils from the tazhong 4 oilfield in the tazhong uplift tarim basin positive ion electrospray ionization fourier transform ion cyclotron resonance mass spectrometry ft icr ms was used in combination with conventional geochemical approaches to unravel the enrichment mechanisms significant amounts of s1 species with relatively low dbe values 0 8 i e sulfur ethers mercaptans thiophenes and benzothiophenes were detected in three lower ordovician oils with high thermal maturity which were suggested to be the products of thermochemical sulfate reduction tsr in the reservoir the occurrence of tsr was also supported by the coexistence of thiadiamondoids and abundant h2s in the gases associated with the oils obviously low concentrations of the dbe 9 s1 species mainly equivalent to c0 c35 dbts compared to its homologues were observed for the three oils which were probably altered by tsr indicating that no positive relationship existed between tsr and dbts in this study the sulfur compounds in the tazhong 4 oils are quite similar to those in the majority of lower ordovician oils characterized by high concentrations of dbts and dominant dbe 9 s1 species with only small amounts of sulfur compounds with low thermal stability dbe 0 8 suggesting only a small proportion of sulfur compounds were derived from tsr it is thermal maturity rather than tsr that has caused the unusually high dbt concentrations in most of the lower ordovician oils we suggest that the unusually high dbt oils in the tazhong 4 oilfield are caused by oil mixing from the later charged lower ordovician or perhaps even deeper with high dbt abundances from the earlier less mature oils which was supported by our oil mixing experiments and previous relevant investigations as well as abundant authigenic pyrite of hydrothermal origin we believe that tsr should have occurred in the tazhong uplift based on our ft icr ms results however normal sulfur compounds were detected in most oils and no increase of 13c2h6 13c4h10 was observed for the gas hydrocarbons suggesting only a slight alteration of the oils by tsr currently and or recently we suspect that the abnormal sulfur compounds in the lower ordovician oils might also be a result of deep oil mixing which might imply a deeper petroliferous horizon i e cambrian with a high petroleum potential this study is important to further deep petroleum exploration in the area

annual record of particle fluxes geochemistry and diatoms in effingham inlet british columbia canada and the impact of the 1999 la nina event abstract sediment traps were deployed inside the anoxic inner basin of effingham inlet and at the oxygenated mouth of the inlet from may 1999 to september 2000 in a pilot study to determine the annual depositional cycle and impact of the 1999 la nina event within a western canadian inlet facing the open pacific ocean total mass flux geochemical parameters carbon nitrogen opal major and minor element contents and stable isotope ratios and diatom assemblages were determined and compared with meteorological and oceanographic data deposition was seasonal with coarser grained terrestrial components and benthic diatoms settling in the autumn and winter coincident with the rainy season marine sedimentary components and abundant pelagic diatoms were coincident with coastal upwelling in the spring and summer despite the seasonal differences in deposition the typical temperate zone thalassiosira skeletonema chaetoceros bloom succession was muted a july 1999 total mass flux peak and an increase in biogenous components coincided with a rare bottom water oxygen renewal event in the inlet likewise there were cooler than average sea surface temperatures ssts just outside the inlet and unusually high abundances of a previously undescribed cool water marine diatom fragilariopsis pacifica sp nov within the inlet each of these occurrences likely reflects a response to the strong la nina that followed the year after the strongest ever recorded el nino event of 1997 1998 by the autumn of 1999 ssts had returned to average and f pacifica had all but disappeared from the remaining trap record indicating that oceanographic conditions had returned to normal oxygenation events were not witnessed in the inlet in the years before or after 1999 suggesting that a rare oceanographic and climatic event was captured by this sediment trap time series the data from this record can therefore be used as a benchmark for identifying anomalous environmental conditions on this coast

living diatom assemblages from north pacific and bering sea surface waters during summer 1999 diatom assemblages collected during july august 1999 along an e w transect comprising sixty two north pacific and bering sea surface water samples were identified and enumerated absolute abundance profiles of centric and raphid pennate diatoms show that the former group dominates in shallow coastal waters and through island passes whilst the latter group though less numerous dominates the oceanic regions this pattern is interpreted as nutrient related with centric diatoms especially chaetoceros section hyalochaete minidiscus and thalassiosira spp preferring eutrophic and upwelling conditions and raphid pennate diatoms especially nitzschioid genera like fragilariopsis neodenticula and pseudo nitzschia preferring oligotrophic pelagic conditions the absolute abundances of the two sections of chaetoceros chaetoceros ex phaeoceros and hyalochaete and some species belonging to the thalassiosirales and bacillariaceae show distribution patterns that can be interpreted as preferences for shallow or oceanic waters subtropical or subarctic waters or ice related arctic conditions r 2005 elsevier ltd all rights reserved

petrology of ultrahigh pressure eclogites from the zk703 drillhole in the donghai eastern china abstract the 558 m deep zk703 drillhole located near donghai in the southern part of the sulu ultrahigh pressure metamorphic belt eastern china penetrates alternating layers of eclogites gneisses jadeite quartzites garnet peridotites phengite quartz schists and kyanite quartzites the preservation of ultrahigh pressure metamorphic minerals and their relics together with the contact relationship and protolith types of the various rocks indicates that these are metamorphic supracrustal rocks and mafic ultramafic rock assemblages that have experienced in situ ultrahigh pressure metamorphism the eclogites can be divided into five types based on accessory minerals rutile eclogite phengite eclogite kyanite phengite eclogite quartz eclogite and common eclogite with rare minor minerals rutile eclogite forms a thick layer in the drillhole that contains sufficient rutile for potential mining two retrograde assemblages are observed in the eclogites the first stage is characterized by the formation of sodic plagioclase amphibole symplectite or symplectitic coronas after omphacite and garnet plagioclase biotite after garnet or phengite and plagioclase coronas after kyanite the second stage involved total replacement of omphacite and garnet by amphibole albite epidote quartz peak metamorphic p t conditions of the eclogites were around 32 to 40 kbar and 720 c to 880 c the retrograde p t path of the eclogites is characterized by rapidly decreasing pressure with slightly decreasing temperature micro textures and compositional variations in symplectitic minerals suggest that the decompression breakdown of ultrahigh pressure minerals is a domainal equilibrium reaction or disequilibrium reaction the composition of the original minerals and the diffusion rate of elements involved in these reactions controlled the symplectitic mineral compositions

the complexity secondary geochemical process genetic mechanism and distribution prediction of deep marine oil and gas in the tarim basin china abstract most paleozoic marine craton basins in china are rich in natural gas except the tarim basin where both oil and gas are prolific various hydrocarbon types have been found in this basin including deep ultra heavy oil heavy oil normal oil volatile oil condensate and natural gas petroleums with diverse types even coexist within a single reservoir generally the ordovician and cambrian reservoirs are deeply buried 5500 8000 m and intensively altered after initial oil and gas accumulations bringing challenges to physical property prediction before drilling and evaluation of exploration targets based on recent exploration discoveries and experimental data we systematically analyzed the origin of oil and gas demonstrated the mechanisms and processes of secondary geochemical alteration e g biodegradation gas washing fractionation tsr and high temperature cracking moreover the preservation mechanism of ultra deep normal oil was also clarified and the distribution patterns of oil and gas were predicted tarim basin has been uplifted and shallowly buried in the early accumulation stage then rapidly and deeply buried in the late stage resulting in various geochemical alteration processes at different burial stages through the reconstruction of complex deep strata oil and gas accumulation histories the spatial distribution of deep petroleum types were predicted this review has provided detailed assessment with case studies in the tarim basin and shed light on the preservation mechanisms and the alteration processes of deep liquid petroleums in addition to massive gas accumulations liquid oils still have great exploration potential in strata deeper than 8000 m in the tarim basin

geochemical characteristics of natural gases related to late paleozoic coal measures in china abstract by 2013 more than 20 gas fields related to late paleozoic coal measures have been discovered in china primarily distributed in the bohai bay ordos sichuan and junggar basins the total proven reserve in these gas fields is more than 3200 109 m3 accounting for 30 1 of the proven gas reserves in china after analyzing the molecular compositions stable carbon isotopes and helium isotopes of 375 gas samples genetic types and origins of the natural gas as well as the secondary alterations it experienced are discussed in this study most of the natural gas related to the late paleozoic coal measures are coal type gas with some of the gases from the sichuan basin and the jingbian gas field in the ordos basin being oil type gases generated from marine mudstones in the permian longtan formation and marine carbonates in the ordovician majiagou formation respectively the equivalent vitrinite reflectance values based on stable carbon isotopes of natural gases vary from 0 8 to 2 5 indicating the mature to over mature stage positive carbon isotope series 13c ch4 13c c2h6 and 13c ch4 13c c3h8 the form of 13c ch4 13c c2h6 is primarily resulted from the mixing of oil type gases of different maturities while the form of 13c ch4 13c c3h8 is primarily resulted from the mixing of coal type gases of different maturities high concentrations of hydrogen sulfide in natural gas from the sichuan basin and the chenghai gas field in the bohai bay basin are resulted from thermochemical sulfate reduction tsr which causes to some extent the fractionation of carbon isotopes by contrast the fractionation of methane carbon isotopes resulting from the tsr effect is not clear carbon dioxide from the bohai bay and junggar basins is primarily biogenic generated via the thermal decomposition of organic matter while that from the ordos basin sichuan basin and chenghai gas field is generated via the thermal decomposition of carbonates carbon dioxide related to the tsr effect has also contributed to the sichuan basin and chenghai gas field

influence of the pacific decadal oscillation el nino southern oscillation and solar forcing on climate and primary productivity changes in the northeast pacific evidence of 11 year schwabe solar sunspot cycles el nino southern oscillation enso and the pacific decadal oscillation pdo were detected in an annual record of diatomaceous laminated sediments from anoxic effingham inlet vancouver island british columbia radiometric dating and counting of annual varves dates the sediments from ad 1947e1993 intact sediment slabs were x rayed for sediment structure lamina thickness and composition based on gray scale and subsamples were examined for diatom abundances and for grain size wavelet analysis reveals the presence of w2e3 w4 5 w 7a ndw9e12 year cycles in the diatom record and an w11e13 year record in the sedimentary varve thickness record these cycle lengths suggest that both enso and the sunspot cycle had an influence on primary productivity and sedimentation patterns sediment grain size could not be correlated to the sunspot cycle although a peak in the grain size data centered around the mid1970s may be related to the 1976e1977 pacific climate shift which occurred when the pdo index shifted from negative cool conditions to positive warm conditions additional evidence of the pdo regime shift is found in wavelet and cross wavelet results for skeletonema costatum a weakly silicified variant of s costatum annual precipitation and april to june precipitation higher spring april may values of the north pacific high pressure index during sunspot minima suggest that during this time increased cloud cover and concomitant suppression of the aleutian low al pressure system led to strengthened coastal upwelling and enhanced diatom production earlier in the year these results suggest that the 11 year solar cycle amplified by cloud cover and upwelling changes as well as enso exert significant influence on marine primary productivity in the northeast pacific the expression of these cyclic phenomena in the sedimentary record were in turn modulated by the phase of pdo as indicated by the change in period of enso and suppression of the solar signal in the record after the 1976e1977 regime shift

the solubility of nickel ni in crude oil at 150 200 and 250 c and its application to ore genesis abstract the very low solubility of ni in saline brines and the correspondingly high concentration of ni in some crude oils raise the possibility that liquid hydrocarbons may be the ore fluids for black shale hosted ni deposits to test the feasibility of this hypothesis ni wires were reacted with three crude oils of differing composition at 150 200 and 250 c for up to 30 days and the concentration of ni in the oil determined at 150 c ni concentrations in the three oils remained relatively low above 200 c however ni concentrations were elevated and correlated positively with the thiol content of the oil our most thiol rich oil dissolved 217 40 4 ppm ni after 30 days at 250 c x ray photoelectron spectroscopic xps analyses performed on the residual oil coating the ni wires after reaction independently corroborate the conclusion that ni has a strong chemical affinity for thiols in crude oil in crude oils with no thiols the ni reacted with other sulfur compounds potentially sulfonic acids to form thiols significantly our xps analyses show that iron fe from the oil was embedded in the ni wire synchronously with the attachment of thiols this suggests that fe has an affinity for ni and that the thiolation of ni by crude oil may depend on the availability of fe in the oil in addition to thiols porphyrins also likely play an important role in the dissolution of ni as shown by the fact that the oil in which ni was most soluble has a high nitrogen content whereas in the other oil which is characterized by a high thiol content the ni solubility was relatively low and the nitrogen content of this oil was below the detection limit immature biodegraded oils that are sourced from carbonate rocks generally tend to be enriched in asphaltenes ni and sulfur nevertheless some mature oils acquire anomalously large thiol contents through thermochemical sulfate reduction tsr a high temperature 100 to 140 c reaction occurring commonly in carbonate reservoirs which involves the abiotic reduction of sulfate minerals at the expense of oil or bitumen thus given the affinity of ni for thiols large volumes of ni poor oil can potentially be altered by tsr to produce smaller volumes of residual oil enriched in thiols and ni

compound specific radiocarbon dating of the varved holocene sedimentary record of saanich inlet canada 1 the radiocarbon contents of various biomarkers extracted from the varve counted sediments of saanich inlet canada were determined to assess their applicability for dating purposes calibrated ages obtained from the marine planktonic archaeal biomarker crenarchaeol compared favorably with varve count ages the same conclusion could be drawn for a more general archaeal biomarker gdgt 0 although this biomarker proved to be less reliable due to its less specific origin the results also lend support to earlier indications that marine crenarchaeota use dissolved inorganic carbon dic as their carbon source the average reservoir age offset r of 430 years determined using the crenarchaeol radiocarbon ages varied by 110 years this may be caused by natural variations in ocean atmosphere mixing or upwelling at the ne pacific coast but variability may also be due to an inconsistency in the marine calibration curve when used at sites with high reservoir ages

review and update of the applications of organic petrology part 1 geological applications abstract organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry coal petrology was then considered a branch of coal science later with the development of specialized nomenclature classification of coal components and the standardization and improvement of analytical microscopical methods this discipline expanded in interests and name becoming organic petrology organic petrology carries a broader context being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources at present organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences throughout the 20th century several important monographs have been published on the discipline of organic petrology including stach s textbook of coal petrology 1st edition 1935 2nd 1975 3rd 1982 updated as the more general organic petrology by taylor et al 1998 more recently the text applied coal petrology the role of petrology in coal utilization was published by suarez ruiz and crelling 2008 this review is the first in a two part review series that describes and updates the role of organic petrology in geosciences a second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow

relationships between hydrocarbon evolution and the geochemistry of solid bitumen in the guanwushan formation nw sichuan basin abstract recently the devonian guanwushan formation in the northwestern sichuan basin gained industrial attention when solid bitumen was discovered in reservoirs and outcrops this discovery initiated the exploration and development of the devonian natural gas devonian in the northwestern sichuan basin is a new stratum for the exploration and development of paleozoic marine natural gas in sichuan basin however the unclear recognition on the genesis the sources and the hydrocarbon evolution history of solid bitumen and natural gas seriously restricted further exploration and development based on the solid bitumen reflectance carbon isotopes saturated hydrocarbon chromatography and solvent extract bitumen biomarkers combined with the component and carbon isotopes of natural gas comprehensive analyses have been performed on the origin of the solid bitumen and the accumulation and evolution of the natural gases the results showed that the outcrop solid bitumen is derived from biodegraded oil from the lower cambrian source rocks and is characterised by low bitumen reflectance low saturated aromatic hydrocarbon ratios seriously damaged normal alkanes and severe migration of the gas chromatographic baseline the reservoir bitumen formed through thermal cracking of oil from lower cambrian and lower permian source rocks and is characterised by high bitumen reflectance high saturated aromatic hydrocarbons and complete normal alkanes the differences of tectonic evolution take control of the two different genesis bitumen the longmen mountain strata in the northwestern sichuan basin were uplifted sharply after the jurassic and the early generated crude oil was biodegraded during uplifting and formed the outcrop bitumen however strata in well shuangtan 3 st3 continued to subside and the paleo reservoir thermal cracked during deep burial into dry gas and heavy components gathered to form reservoir bitumen revealing the devonian hydrocarbon evolution in sichuan basin is of highly significance and is meaningful to guide further researches on the gas source correlation of natural from paleo strata it is of great significance to reveal the devonian hydrocarbon evolution in sichuan basin and to guide further researches on the gas source correlation of natural gas from paleo strata

carbon isotope fractionation during methane dominated tsr in east sichuan basin gasfields china a review thermochemical sulfate reduction is considered to result in h2s 10 and high dryness coefficient values in the lower triassic and upper permian carbonate reservoirs in the ne sichuan basin the gases pro duced from gasewater transition and water intervals were measured to have h2s higher than 30 and are calculated to have significantly higher h2s and co2 contents than a gas produced from a gas interval and thus are not used to reflect tsr extents methane and ethane were shown to shift positively in carbon isotopes as a result of tsr however the fractionation has not quantitatively described a loga rithmic relationship is found to give the best fit for methane d 13 c 1 and 1 h2s

palaeo flux records from electron microscope studies of holocene laminated sediments saanich inlet british columbia holocene varved sediments recovered from saanich inlet odp leg 169s have been analysed using high resolution scanning electron microscope techniques the individual centimetre scale varves form couplets comprising diatom ooze diatomaceous mud deposited during spring to autumn and silty clay deposited during winter each individual varve may contain up to 19 laminae recording sub seasonal to seasonal scale processes these intra annual laminae contain a range of components including pelagic faecal pellets and aggregates of diatomaceous material the combination of these individual components in varying proportions with a heterogeneous sediment leads to a range of laminae fabrics these include intact monospecific skeletonema costatum and thalassiosira pacifica diatom oozes and highly fragmented aggregate and faecal pellet dominated diatom oozes which are typically chaetoceros spp dominated additional laminae fabrics include diatomaceous mud stringer type diatomaceous mud which contains discrete diatom aggregates homogeneous and pelleted silty clay the varved diatom succession typically commences in early spring with thalassiosira spp chaetoceros spp followed by chaetoceros spp in late spring during late spring early summer blooms of s costatum may be recorded and summer to autumn production is characterised by one to several chaetoceros spp dominated blooms inter annual variability in diatom flux typically comprises the presence absence of thalassiosira spp and s costatum in addition resting spores of chaetoceros spp thalassiosira nordenskioeldii and leptocylindricus danicus are intermittently recorded there is a major change in varve thickness from thinner varves prior to approximately 2100 yr bp to thicker varves after this date which is attributed to increased terrigenous input throughout the varve the identification of laminae fabrics diatom successions and a unique massive interval has enabled an inter site correlation between sites 1033b and 1034b

geochemistry of palaeozoic marine petroleum from the tarim basin nw china part 3 thermal cracking of liquid hydrocarbons and gas washing as the major mechanisms for deep gas condensate accumulations abstract the lunnan lower uplift in the tarim basin nw china contains a composite petroleum system with mainly biodegraded heavy oil in the west normal oil in the center and gas condensate in the east twenty three gas samples and 37 oil samples taken from three major hydrocarbon bearing intervals in the lunnan lower bulge were analyzed for their stable carbon isotopes and molecular biomarkers on the basis of their isotopic compositions biomarkers especially diamondoids and integrating the physical properties of the hydrocarbons including densities gor and pvt relationships it has been concluded that the recently discovered deep 6500 m eastern lungu giant ordovician gas condensate pool with an estimated reserve of 723 million bbl oil equivalent is a secondary hydrocarbon accumulation derived from the mixing of an early formed oil and a late formed gas the extremely dry gases with a gas dryness of 0 98 were derived from thermal cracking of crude oils and charged to an existing oil reservoir causing extensive gas washing and secondary alteration compared with most of the hydrocarbons in the lunnan area the gas from the eastern lungu gas condensate pool has a heavier carbon isotopic composition higher dryness and a higher maturity level the unique physical chemical and isotopic compositions of the gas condensate are believed to be a direct result of gas flushing of an early formed eastern lungu oil pool by a late formed dry gas from oil cracking the eastern lungu gas condensate pool is presently characterized by containing dry gas heavy oil abundant aromatics and high wax

chemical and petrographic evidence for thermal cracking and thermochemical sulfate reduction of paleo oil accumulations in the ne sichuan basin china significant extents of heterogeneity are observed in the optical properties reflectance values and s c atomic ratio values of solid bitumens in the carbonate reservoirs of the lower triassic feixianguan and changxing formations in the puguang gas field the largest in marine carbonates in china the chemical and stable carbon isotope compositions of the gaseous alkanes in the produced gases also depend on field location with no clear correlation with the hydrogen sulfate content these data indicate that the gas reservoirs are highly compartmentalized this manuscript describes an integrated chemical and petrographic approach for distinguishing solid bitumens formed by thermal cracking and by thermochemical sulfate reduction tsr the fact that most reservoir bitumens have only been partially affected by tsr suggests that sulfate supply appears to be a major limiting factor for the tsr reactions involving gaseous alkanes

evidence for multiple stages of oil cracking and thermochemical sulfate reduction in the puguang gas field sichuan basin china the puguang gas field is the largest gas field found in marine carbonates in china marine carbonate reservoirs in this field were buried to a depth of about 7000 m 22 966 ft and experienced maximum temperature up to 220c before uplift to the present day depth of 5000 5500 m 16 404 18 045 ft with present day thermal maturity between 2 0 and 3 0 equivalent vitrinite reflectance ro sulfur rich pyrobitumens with reflectance up to 3 5 are widespread in the reservoirs and resulted from thermal cracking of crude oils most likely generated from upper permian source rocks and thermochemical sulfate reduction tsr natural gases in the puguang gas field have wide variations in nonhydrocarbon gas contents with h2s contents between 5 1 and 58 3 and co2 contents between 7 9 and 18 0 the hydrocarbon gases originated mainly from thermal cracking of accumulated oil but were altered by tsr thermochemical sulfate reduction in the study area exerted different effects on the isotope compositions of different hydrocarbon gas components at different tsr stages the differential increase of 13c values for different gas components reflects transformation from a heavy hydrocarbon gas dominated tsr stage to a methane dominated tsr stage this caused a decrease of 13cmethane13cethane values and a corresponding conversion from reversed to normal isotope distributions thermochemical sulfate reduction in the study area appears to have been limited by sulfate concentrations in the reservoirs a successive three stage tsr series namely liquid hydrocarbon involved tsr heavy hydrocarbon gas dominated tsr and methane dominated tsr occurred in reservoirs with sufficient sulfate concentration methane can be the dominant organic reactant for tsr but only at elevated temperature and after most c2 hydrocarbons are exhausted

the origin of pyrobitumens in upper devonian leduc formation gas reservoirs alberta canada an optical and eds study of oil to gas transformation pyrobitumens are common within deep basin devonian carbonate gas reservoirs of the western canada sedimentary basin incident light microscopy and sem eds have been used to study the origin of pyrobitumens from upper devonian isolated reefs of the leduc formation west central alberta reflectance properties romax and romin coke microtextures and relative s c ratios are used to classify the pyrobitumens in portions of reservoir units where nso enriched low aromaticity crudes may have been dominant oil to gas transformations produced mainly low reflecting isotropic to fine grained mosaic coke microtextures within the reservoir pyrobitumens type a in contrast where normal crudes were most likely dominant in the reservoir units prior to thermal cracking pyrobitumens with high bireflectance and very anisotropic coarse flow to domain cokes dominate type b oil to gas cracking within some of the reservoir units resulted in overpressuring and is represented by highly deformed pyrobitumens with fibrous coke textures and high bireflectance relative concentrations of type a and b pyrobitumens vary vertically and temporally in some of the reefal buildups the variations in the dominant pyrobitumen types are attributed to crude oil alteration which preceded crude oil to gas transformation e g tar mats in some zones whereas other zones may have been altered contemporaneously with crude oil cracking the later may have resulted from the oxidation and sulphur enrichment of the crude oil during thermochemical sulphate reduction this reaction is prevalent within devonian evaporite carbonate strata of the western canada sedimentary basin generating copious volumes of h2s the interaction between crude oil and sulphur enriched highly alkaline fluids is suggested by the presence of high s c very fine grained late stage calcined needle cokes within brecciated pyrobitumens

a holocene record of diatom and silicoflagellate microfossils in sediments of saanich inlet odp leg 169s odp leg 169s laminated sediment cores provided a unique opportunity to examine changes in the siliceous phytoplankton community of saanich inlet these laminated sediments are rich in diatom and silicoflagellate remains as a result of the inlet s high production and excellent preservation our results suggest that species composition and abundance of diatoms and silicoflagellates in the inlet have changed very little since the inlet s formation carbon and opal data indicate an increase in primary productivity with time which is not apparent in the fossil data however the discrepancy between data sets may be due to changes in grazer activity which could have reduced the number of identifiable fossils individual species were useful for identifying changes in the inlet some planktonic diatoms suggest that nutrient supply was highest in the early mid holocene increases in the abundance of a partially benthic diatom paralia sulcata follow variations in sea level and availability of benthic habitat in the inlet a large peak of the silicoflagellate dictyocha fibula corresponds to a catastrophic flood event in the early holocene which probably washed terrestrial material and low salinity water from the british columbia mainland into saanich inlet fossil data were also analyzed to infer past changes in the environment using a weighted averaging calibration and regression technique these data suggest that only minor variations in sea surface temperature have occurred

a 2100 year bp record of the pacific decadal oscillation el nino southern oscillation and quasi biennial oscillation in marine production and fluvial input from saanich inlet british columbia exceptional varved sediments of 2100 years bp recovered from saanich inlet have been analysed using high resolution scanning electron microscopy and spectral analysis techniques each varve may contain up to 22 well defined individual laminae which can be attributed to seasonal scale processes sediment flux comprises alternating diatom ooze diatomaceous mud deposited during spring through autumn and a silty clay deposited during winter the latter may be sporadically punctuated by clay rich laminae identification of some 2000 individual consecutive laminae based on fabric and diatom assemblage has allowed the construction of time series data for spectral analysis laminae types analysed include early spring thalassiosira spp late spring early summer skeletonema costatum multiple summer autumn chaetoceros spp diatom oozes and sporadically present clay rich winter flood deposits sub decadal periods have been identified and linked to the quasi biennial oscillation qbo and el nino southern oscillation enso and decadal periods to the pacific decadal oscillation pdo comparison of spectral analysis results with modern analogues suggests associations may exist between early spring thalassiosira spp laminae and stronger la nina events late spring early summer s costatum laminae and el nino events summer autumn chaetoceros spp multiple laminae and negative pacific northwest index pni regimes and sporadically present winter clay rich laminae and pni regimes the average period for an enso cycle was 3 6 years qbo 2 5 years and pdo 14 8 years spectral analysis of the more recent pni record shows similar significant periods of 13 2 3 7 and 2 6 years multi decadal periods recorded include 42 2 and 31 3 years which might suggest multiples of pdo

effects of oil cracking on fluorescence color homogenization temperature and trapping pressure reconstruction of oil inclusions from deeply buried reservoirs in the northern dongying depression bohai bay basin china the effects of oil cracking on fluorescence color homogenization temperature tho and trapping pressure pt of oil inclusions from deeply buried reservoirs dbrs 3672 4359 m in the northern dongying depression were determined based on fluorescence spectroscopy and homogenization temperatures of oil inclusions kinetic modeling of crude oil cracking and petroleum inclusion thermodynamics modeling the modeling results demonstrate that fluorescence color tho and predicted pt have strong relationships with the transformation rate via cracking of oil to gas tr and the formation temperature tf that the inclusions experienced the fluorescence color is hardly influenced at all during the initial stages of oil cracking tr 13 tf 160 c but fluorescence color begins to shift toward shorter wavelengths blue shift during progressive oil cracking tr 24 tf 190 c with further oil cracking the fluorescence color may either experience no change or continue its blue shift eventually the fluorescence color will disappear as the aromatic compounds are completely cracked the tho increases at first tr 24 tf 190 c but then decreases or even becomes negative during major oil cracking the reconstructed pt values show a corresponding reverse trend oil inclusions from dbrs and other shallow reservoirs in the dongying depression show an obvious blue shift in fluorescence color at a depth of approximate 4000 m tf 160 c and generally contain solid bitumen below 4000 m supporting the effect of oil cracking on fluorescence variation consistent with the modeling result the tho from dbrs in the minfeng area increases with increasing burial depth tf 190 c which is also consistent with the modeling results however the tho of oil inclusions with blue white fluorescence from dbrs in the shengtuo area did not show such a trend recent trapping high trapping pressure and higher maturity oil may have led to a low degree of oil cracking and thus less modification of tho in the shengtuo area oil cracking results in consistent volume ratios of pyrobitumen to oil inclusions fvpy in the same fluid inclusion assemblage and the fvpy value increases with oil cracking level which can be used to recognize if oil cracking has occurred in oil inclusions and what level of oil cracking they have experienced as the oil cracking model used in this study did not account for the role of pressure it is more applicable for oil inclusions that were trapped under normally pressured conditions oil inclusions trapped under overpressured conditions will be less influenced by oil cracking

palynological records of red tide producing species in canada past trends and implications for the future abstract increases in red tides and other harmful algal blooms habs during the past 50 yr on both the atlantic and pacific coasts of canada suggest that global scale factors such as climate change and increased international shipping trade are the driving forces because the historical record is too short to understand the long term dynamics of habs the holocene history of harmful phytoplankton species was examined using ultra high resolution studies annual to decadal scale of dinoflagellate cysts as a proxy for red tide production paleoecological transfer functions were then applied to the cyst assemblage data to determine correlations with changes in sea surface temperature and salinity pacific records were obtained from varved marine sediments in saanich inlet british columbia and in the santa barbara basin off california comparison of annual cyst production and historical plankton data provides cyst theca ratios from which the magnitude of past bloom size can be evaluated the 10 500 yr pacific record clearly shows that the largest blooms correspond to cysts of protoceratium reticulatum and gonyaulax spinifera during the early holocene sporadic blooms of potentially toxic alexandrium spp lingulodinium polyedrum and gymnodinium spp also occurred from ca 7000 to 5000 yr bp and more frequently from ca 2000 to 3000 yr bp individual holocene blooms were up to 10 times larger than in the historical record but they almost always occurred sequentially without overlap of red tide species in pre historical times the bloom cycles started and stopped abruptly in 10 yr or less and they persisted for about 100 1000 yr in contrast the variability and near concurrence of species blooms in the modern past 60 yr record is unmatched in the past and suggests disequilibrium of the natural ecosystem structure atlantic records from la have and emerald basins on the scotian shelf are less precise because bioturbation limits time resolution to ca 25 yr however cyst abundances of cf alexandrium protoceratium reticulatum gonyaulax spinifera and lingulodinium polyedrum were also an order of magnitude larger in the early holocene where they correspond to a summer sea surface warming of 2 5 c lesser peaks also appear during the past 2000 yr where they apparently correspond to a slight increase in winter temperature there is no evidence of much lower salinity that would support stronger stratification the similarity of pre industrial age cyst records of red tide histories in the oceanographically different pacific and atlantic regions of canada indicates that climate change including surface temperature and storminess is the main driving force stimulating blooms this implies that habs will reoccur regardless of efforts to limit spreading however reduced pollution may decrease the hab diversity thereby stabilizing the population dynamics and increasing the predictability of bloom occurrences

the silica cycle in a northeast pacific fjord the role of biological resuspension abstract this study is a quantitative assessment of the role fish induced bio resuspension plays in the silica cycle of coastal waters we used new published and archived oceanographic data to construct a comprehensive silica budget for saanich inlet vancouver island canada a highly productive northeast pacific fjord where siliceous diatoms dominate primary productivity anoxia in the deep water of the inlet persists during most of the year precluding animal life whereas abundant groundfish continuously rework and resuspend bottom sediments in the shallower oxygenated margins this resuspension transfers settled biogenic silica fragments from the sediment where they are immersed in porewater that is rich with dissolved silica to the overlying water where the much lower concentrations accelerate their dissolution rate the budget shows that saanich inlet sediments constitute a sink for approximately 250 106 mol si y 1 most of this si enters the inlet in advected siliceous phytoplankton sediment resuspension by groundfish in the oxygenated margins of saanich inlet generates about 50 of the total flux of dissolved silica from the inlet seafloor this resuspension also facilitates a massive transport of biogenic silica from the margins to the anoxic basin where approximately 90 of all the biogenic silica is buried the excess dissolution caused by fish activity reduces the burial efficiency of biogenic silica in the entire inlet sediments by about 20 this case study emphasizes the link between the silica cycle and groundfish activity based on this study and because biological resuspension occurs in most regions of the ocean we recommend that it will be taken into account when budgeting the silica cycle and potentially other geochemical cycles in marine environments

phytoplankton crops bacterial metabolism and oxygen in saanich inlet a fjord in vancouver island british columbia abstract phytoplankton crops in saanich inlet were characterized by their content of photosynthetic pigments and by their taxonomic compositions from early april to mid december 1981 crop sizes were correlated to particle volumes bacterial activities and oxygen concentrations at all depths to test the hypothesis that the degradation of sinking phytoplankton debris by bacterial production results in anoxia particles produced during the spring bloom were rich in chlorophyll a and pheopigments which disappeared as particles sank deeper in the water column the volume of particles with sizes ranging from 2 0 to 40 m was dominated by those with a mean size of about 32 m qualitatively many of the particles were frustules of the two diatom genera thalassiosira and chaetoceros which dominated crops in the euphotic zone no temporal changes in either qualities or quantities of photosynthetic pigments were observed in anoxic sediments a positive correlation between particle volume and bacterial production was observed however no correlation between production and changes in dissolved o2 was seen in the deep water prior to mid june further observations were masked by flushing that occurred in august and may have begun as early as mid june

detrital zircon u th he thermochronometry of the mesozoic daba shan foreland basin central china evidence for timing of post orogenic denudation abstract the timing of the transition of a peripheral foreland basin from underfilled to overfilled provides important insights into the post orogenic dynamics of its coupled orogenic wedge such information is lacking in the mesozoic foreland basins surrounding the qinling orogen central china such as the daba shan foreland basin dsfb the northeastern part of the sichuan basin in an effort to constrain the timing of maximum burial and onset of denudation we report detrital zircon u th he zhe data from four deep boreholes in the dsfb results show that zhe ages from the oldest foreland basin formations upper triassic lower middle jurassic are mostly younger than their depositional age whereas non reset zhe ages characterize younger strata this suggests that the oldest strata attained maximum temperatures between 130 c and 200 c zhe partial retention zone which is consistent with previous independent paleotemperatures organic matter reflectance and illite crystallinity reported in two of the boreholes and another nearby the fully reset ages apparently show the youngest peaks at 80 ma and 100 ma which are interpreted as the minimum constraints on the timing of maximum basinal burial and subsequent denudation considering that the regional deposition has lasted to aptian time it is proposed that the onset of the basin exhumation in the dsfb started at aptian albian time 100 125 ma heralding the termination of regional tectonic shortening in the hinterland southern qinling

methane dominated thermochemical sulphate reduction in the triassic feixianguan formation east sichuan basin china towards prediction of fatal h2s concentrations abstract new sour pools have recently found in the lower triassic feixianguan fm carbonate reservoirs in the east sichuan basin in china with h 2 s up to 17 4 by volume a recent blowout from a well drilled into this formation killed hundreds of people as a result of the percentage concentrations of h 2 s in order to assess the origin of fatal h 2 s as well as the cause of petroleum alteration h 2 s concentrations and the isotopes 34 s and 13 c have been collected and measured in gas samples from reservoirs anhydrite pyrite and elemental sulphur 34 s values have been measured for comparison the high concentrations of h 2 s gas are found to occur at depths 3000 m temperature now at 100 c in evaporated platform facies oolitic dolomite or limestone that contains anhydrite nodule occurrence within the reservoirs where h 2 s concentrations are greater than 10 its 34 s values lie between 12 0 and 13 2 cdt this is within the range of anhydrite 34 s values found within the feixianguan fm 11 0 to 21 7 average 15 5 3 5 cdt thus h 2 s must have been generated by thermochemical sulphate reduction tsr locally within the reservoirs burial history analysis and fluid inclusion data reveal that the temperature at which tsr occurred was greater than about 130 140 c suggesting that the present depth temperature minimum is an artifact of post tsr uplift both methane and ethane were actively involved in tsr since the petroleum became almost totally dry no alkanes except methane and methane 13 c values become significantly heavier as tsr proceeded methane 13 c difference thus reflects the extent of tsr while it is tempting to use a present day depth control 3000 m to predict the distribution of h 2 s in the feixianguan fm this is an invalid approach since tsr occurred when the formation was buried some 1000 2000 m deeper than it is at present the likelihood of differential uplift across the basin means that it is important to develop a basinal understanding of the thermal history of the feixianguan fm so that it is possible to determine which parts of the basin have been hotter than 130 140 c

processes controlling the accumulation of diatoms in sediments a model derived from british columbian fjords the transformation of biocoenosis to taphocoenosis of diatom assemblages was examined using monthly sediment traps over a 3 year period at four sites in the fjords of british columbia the fjords were chosen as a natural laboratory where productivity is high and seasonally variable and where geological rates of sediment accumulation approach the biological rates of production and flux the composition of trap samples from different depths was quantified and compared with the surface sediment recovered by box cores fragmentation caused by zooplankton grazing preferentially destroys 20 50 of the early spring and 50 75 of the late spring and early summer production grazing activity and incorporation into pellets does not otherwise affect preservation differential dissolution occurs during settling through the water column taxa with a high surface to volume ratio are preferentially lost low level lateral advection tends to concentrate heavy robust taxa while strong advection affects all particles equally and has no net biasing effect the interaction of these processes results in a sediment assemblage in which winter and fall taxa are more common than they are in the plankton while the early spring bloom is badly underrepresented multivariate analyses indicate that the sediment is dominated by the early summer bloom but caution must be exercised in this interpretation because the bloom is characterized by a species skeletonema costatum which is common at all seasons of the year and therefore is not a reliable indicator of a single period of production the end result is a decrease in seasonal contrast and at some sites a reordering of seasonal proportion in the sediment while the seasonal composition can still be identified there is also evidence of homogenization of sediment assemblages with some of the original spatial variability obscured taken to an extreme a unique fossil assemblage may be produced which cannot be statistically related to any combination of seasons of production three factors which might affect preservation of deep sea assemblages water depth accumulation rate and degree of bioturbation do not have a measurable effect in fjord environments strong modification of assemblages can occur within the upper 500 m deep sea monitoring programs which do not include this interval may lead to erroneous conclusions concerning production and flux to the sediments

occurrences and origin of reservoir solid bitumen in sinian dengying formation dolomites of the sichuan basin sw china abstract reservoir solid bitumen is pervasive throughout the sinian dengying formation dolomites of the sichuan basin and neighboring areas yet its origin remains controversial optical and scanning electron microscope sem studies of the dengying formation were carried out to elucidate the nature and origin of the solid bitumen solid bitumen in dissolution pores intercrystal pores and stylolites appears to have formed in association with regional hydrocarbon charging processes reservoir solid bitumen displays a variety of morphologies each of which appears to reflect different precursor hydrocarbons massive crust like solid bitumen was probably derived from solid precursors whereas finger like solid bitumen likely evolved from liquid precursors sheet like and thin skinned globular solid bitumen appeared to have precipitated from wet gas precursors analyzed solid bitumen is characterized by high random reflectance average 3 4 and bireflectance values 4 2 6 9 exhibits strong optical anisotropy and displays different coke structures including granular mosaic domain and fibrous the coke textures which appear to reflect the nature of bitumen precursors formed by physical coalescence of mesophase spheres and parallel arrangement of laminated aromatic sheets in association with a rapid heating event the inferred thermal episode which is evidenced by the presence of hydrothermal minerals including saddle dolomite quartz authigenic illite and barite may have been associated with the late permian eruption of the emeishan traps thus widespread solid bitumen in the dengying formation reflects the effects of hydrothermal alteration rather than the impact of normal burial related thermal maturation further the close association of sold bitumen and authigenic kaolinite indicates that natural deasphalting plays a role in the formation of reservoir solid bitumen

distribution of diatom surface sediment assemblages within effingham inlet a temperate fjord on the west coast of vancouver island canada abstract twenty nine surface sediment samples from effingham inlet a small fjord on the west coast of vancouver island british columbia were analyzed for diatoms this fjord has been selected for paleoceanographic investigation due to the presence of laminated sediments resulting from the dysoxic to anoxic bottom water conditions in the inner and outer basins of the inlet distributional patterns of the diatom microflora reflected proximity to littoral regions phytoplankton production and marine influence from outside the fjord principal components and cluster analyses of the microflora established four diatom assemblages with a clear separation between the inner and outer basin diatom floras inner basin stations were characterized by elevated absolute abundance with assemblages dominated by spring early summer bloom taxa including skeletonema costatum thalassiosira nordenskioeldii and thalassiosira pacifica chaetoceros spp resting spores were abundant throughout effingham inlet with the exception of the stations closest to the fjord head stations located in the outer basin and towards the fjord mouth had relatively lower absolute abundance yet showed a higher relative and absolute abundance of thalassionema nitzschioides rhizosolenia setigera coscinodiscus radiatus ditylum brightwellii odontella longicruris and paralia sulcata in relation to the inner basin many of these latter taxa are often associated with late summer and autumn conditions in fjords along coastal british columbia oceanographic data for effingham inlet suggest that increased offshore penetration is more likely to occur from summer to early fall with a more restricted offshore influence in the inner basin diatom surface sediment assemblages in effingham inlet appear to reflect incursions of offshore waters into the fjord absolute abundance estimates and the preservation of lightly silicified taxa suggest excellent preservation of fossil material in the sediments of the predominantly anoxic inner basin preservation in the outer basin is reduced reflecting more frequent recharge by oxygenated waters spilling over the outer sill into the basin our findings suggest the inner basin should be an optimal site for reconstruction of diatom production with records from the outer basin providing more consistent information about offshore influence and coastal upwelling conditions over the holocene estimates of diatom abundance within the inner basin sediment may serve as a good proxy of production although proxy tracers of bottom water conditions and sedimentological analyses must be coupled to the diatom record to ensure depositional conditions were not influencing valve preservation or abundance our results suggest that fjords can serve as good environments for paleoceanographic reconstructions of both inshore and offshore conditions although careful site selection and understanding of processes affecting the microfossil record are essential

the fate of co2 derived from thermochemical sulfate reduction tsr and effect of tsr on carbonate porosity and permeability sichuan basin china abstract this article discusses the role of methane in thermochemical sulfate reduction tsr the fate of tsr derived co2 and the effect of tsr on reservoir porosity and permeability and the causes of the anomalously high porosity and permeability in the lower triassic soured carbonate gas reservoirs in the northeast sichuan basin southwest china the lower triassic carbonate reservoirs were buried to a depth of about 7000 m and experienced maximum temperatures up to 220 c before having been uplifted to the present day depths of 4800 to 5500 m but they still possess porosities up to 28 9 and permeabilities up to 3360 md the present day dry gas reservoirs evolved from a paleo oil accumulation and experienced varying degrees of tsr alteration as evidenced from the abundant sulfur rich solid bitumens and varying h2s and co2 concentrations tsr occurred mainly within the oil and condensate wet gas windows with liquid hydrocarbons and wet hydrocarbon gases acting as the dominant reducing agents responsible for sulfate reduction sulfur rich solid bitumen and h2s generation and calcite precipitation methane dominated tsr was a rather late event and had played a less significant role in altering the reservoirs intensive h2s and co2 generation during tsr resulted in calcite cementation rather than carbonate dissolution which implies that the amount of water generated during tsr was volumetrically insignificant 13c depleted co2 derived from hydrocarbon oxidation preferentially reacted with ca2 to form isotopically light calcite cements and the remaining co2 re equilibrated with the 13c enriched water rock systems with its 13c rapidly approaching the values for the host rocks which accounted for the observed heavy and relatively constant co2 13c values the carbonate reservoirs suffered from differential porosity loss by tsr involved solid bitumen generation and tsr induced calcite and pyrite precipitation intensive tsr significantly reduced the porosity and permeability of the intervals expected to have relatively high sulfate contents the evaporative platform dolostones and the platform margin shoal dolostones immediately underlying the evaporative facies early oil charge and limited intensity of tsr alteration together with very low phyllosilicate content and early dolomitization accounted for the preservation of anomalously high porosities in the reservoirs above the paleo oil water contact a closed system seems to have played a special role in preserving the high porosity in the gas zone reservoirs below the paleo oil water contact the closed system which is unfavorable for deep burial carbonate dissolution and secondary porosity generation was favorable for the preservation of early formed porosity in deeply buried carbonates especially sucrosic and vuggy dolostones have a high potential to preserve such porosity

pelagic diatom assemblages are good indicators of mixed water intrusions into saanich inlet a stratified fjord in vancouver island abstract we assessed the potential importance of tidally driven intrusions of autochthonous protistan plankton into saanich inlet a fjord in vancouver island as potential sources of fossils in the fine intra annual sediment laminations of odp cores we determined the structure of protistan assemblages throughout the inlet during july 1995 at times of successive neap and spring tides results were compared to a concurrent physical study of tidal flows and nutrient advection into and out of the inlet which allowed us to identify protistan species indicative of mixed satellite channel and stratified saanich inlet waters these identifications were either confirmed or rejected by temporal analyses of protistan assemblages based on weekly sampling at two fixed positions one in saanich inlet and one in sidney channel from may through october 1997 results of both studies supported the hypothesis that the presence of a suite of diatom species including most chaetoceros spp a large celled variant of skeletonema costatum and thalassiosira rotula indicates the intrusion of water with elevated levels of dissolved inorganic nitrogen into saanich inlet from the strait of georgia this indicator group of species contained additional species but not all were observed in large numbers in 1997 many of these species are important components of the laminated sediments of saanich inlet whose presence is probably indicative of paleo environmental conditions in the southern strait of georgia rather than saanich inlet effects of tidal cycles on dinoflagellate and other flagellated cells exclusive of mastigophorans were inconclusive and additional studies are required to elucidate details of their ecology in waters of the southern strait of georgia

unique chemical and isotopic characteristics and origins of natural gases in the paleozoic marine formations in the sichuan basin sw china isotope fractionation of deep and high mature carbonate reservoir gases abstract large quantities of natural gases have recently been discovered in the marine carbonate formations in the sichuan basin southern china the origins and isotopic compositions of the gases are poorly understood and highly controversial we examined the chemical and isotopic compositions of the carbonate reservoir gases in marine formations from the sinian to lower triassic as well as shale gas from the silurian and cambrian formation in the sichuan basin it is found that the carbon isotopes of the carbonate reservoir gases had been evolved through three stages corresponding to pre rollover rollover and post rollover in the plot of 13c2 versus wetness which is consistent with that found in shale gas by tilley and muehlenbachs 2013 the unique carbon isotopic compositions indicate that both kerogen and oil cracking gas have contributed to the accumulation of the carbonate reservoir gases in the sichuan basin a mixing of two thermogenic gases with different maturities can cause the 13c reversal between methane and ethane which is commonly observed in the carbonate reservoir gases in the carboniferous permian and triassic formations and the shale gas in the silurian and cambrian formations in the sichuan basin we established two mixing models for quantitatively determining the contribution of each type gas for the natural gases in different formations kinetic extrapolation based on thermal history of the anyue gas field demonstrates that ethane cracking indeed occurred in the deep reservoir formations which may explain the disappearance of the 13c reversal for methane and ethane in the carbonate reservoir gases in the post rollover zone it is proposed that organic inorganic interactions may be responsible for the presence of d isotope rollover for methane in carbonate reservoir gases with ultra high maturity the organic inorganic interactions include thermal reactions between water and residual organic matters or carbons and hydrogen isotope exchange between water and methane and their mechanism needs further investigations in future