sedimentary record of mesozoic deformation and inception of the turpan hami basin northwest china the turpan hami basin is a major physiographic and geologic feature of northwest china yet considerable uncertainty exists as to the timing of its inception its late paleozoic and mesozoic tectonic history and the relationship of its petroleum systems to those of the nearby junggar basin to address these issues we examined the late paleozoic and mesozoic sedimentary record in the turpan hami basin through a series of outcrop and subsurface studies mesozoic sedimentary facies regional unconformities sediment dispersal patterns and sediment compositions within the turpan hami and southern junggar basins suggest that these basins were initially separated between early triassic and early jurassic time prior to separation upper permian profundal lacustrine and fan delta facies and triassic coarse grained braided fluvial alluvial facies were deposited across a contiguous junggar turpan hami basin permian through triassic facies were derived mainly from the tian shan to the south as indicated by northward directed paleocurrent directions this is consistent with the sedimentary provenance of triassic sandstone mean qm29f29lt42 qp23lvm49lsm28 and qm51p25k24 and conglomerate 32 granitic clasts in the northern turpan hami basin we interpret a relative increase in quartz and feldspar concentration and a relative decrease in volcanic lithic grains in the northern turpan hami basin to reflect unroofing in the tian shan and exposure of late paleozoic granitoid rocks in addition two basinwide unconformities of late permian early triassic and early triassic middle late triassic age attest to deformation within the turpan hami basin and associated continued uplift and erosion of the tian shan

organic geochemical characteristics and generating potential of source rocks from the lower middle jurassic coal bearing strata in the east junggar basin nw china abstract the junggar basin located in nw china is a large intracontinental superimposed basin samples were collected from the lower middle jurassic coal bearing strata of the eastern junggar basin and include mudstones carbargilites and coal the origin of organic matter thermal maturity paleoenvironment of sediment deposition and hydrocarbon potential of drill core samples was investigated organic geochemical analysis performed on 65 source rock samples indicates a wide range of toc values from 0 81 wt to 81 06 wt this study combined sedimentology biomarker organic petrography and stable carbon isotopic composition of kerogen and extracts analysis demonstrating the organic matter of the source rocks is derived from terrestrial higher plants with a minor contribution of aquatic algae and microbes rock eval data elemental composition of kerogen and odd over even normal alkane distribution reveal immaturity to low maturity with a humic type organic matter the source rocks were deposited in a freshwater oxic to sub oxic environment indicated by high pr ph ratios a predominance of c29 steranes low tricyclic terpanes and a low gammacerane index high dia regular c29 sterane ratios and moderate to high c29 c30 hopane ratios found in most samples are related to the presence of clay minerals based on the following parameters h c vs o c toc s1 s2 hydrogen index saturated hydrocarbons aromatic hydrocarbons and chloroform a we concluded that the samples collected from organic rich coal bearing strata may yield not only gas but also have the capability to generate and release liquid hydrocarbons

stress directions in eastern north america determined to 4 5 km from borehole elongation measurements stress directions have been determined to depths of 4 5 km in eastern north america from borehole elongation measured by dipmeter calipers in 47 wells the average maximum horizontal stress directions are eastern canada n54 e 7 appalachian basin n58 e 8 and the illinois basin n89 w 5 stress directions determined for the illinois and appalachian basins are in agreement with published interpretations from hydraulic fractures and earthquake fault plane solutions new results from eastern canada and the appalachian basin show that stress directions are everywhere consistent with the midcontinent stress province these data suggest that the maximum horizontal stress does not rotate from the ene midcontinent trend to nw near the atlantic coast a directional analysis of hydraulic fractures petal centerline fractures and natural fractures from the appalachian basin shows that borehole elongation is systematically aligned perpendicular to the directions of hydraulic fractures centerline fractures and northeast striking natural fractures but is not systematically aligned with northwest striking natural fractures these observations indicate that borehole elongations provide reliable stress orientations

fracture cleat analysis of coals from zonguldak basin northwestern turkey relative to the potential of coalbed methane production abstract in this study the fracture structure of three coals sulu k 1 acilik k 2 and cay dogu ayak from two different seams in the zonguldak basin located on the black sea coast of turkey have been analyzed in relation to coalbed methane recovery x ray computerized tomography ct light microscopy image analysis and scanning electron microscopy sem analysis have been performed on mine coal samples to have a better understanding of distribution of minerals fracture morphology and apertures and matrix fracture interactions via examination of fracture surfaces results show that the acilik and sulu coals seem to be structurally more prone to be commercially productive these coals show a high degree of fracturing and cleat development as evidenced by x ray ct and light microscopy examination of polished surfaces although the cay dogu ayak coal shows a high fracture density the cleat surface morphology and smaller fracture apertures may make this coal unfavorable for gas flow

revised models for hydrocarbon generation migration and accumulation in jurassic coal measures of the turpan basin nw china abstract whether or not the lower middle jurassic coal measures in the turpan basin of nw china have generated commercial quantities of liquid petroleums is a problem of considerable importance that remains contentious as it has not yet been resolved unequivocally this study provides evidence against the jurassic humic coals as the only major source for the oils discovered in the taibei depression of this basin and suggests additional significant contributions from the upper permian and middle lower jurassic lacustrine source rocks the carboniferous permian marine source rocks may have been important also in limited locations along the major basement faults molecular and petrographic data indicate that the majority of the middle jurassic strata are currently immature or marginally mature with respect to hydrocarbon generation within the major depocenters the middle lower jurassic coal bearing strata of the baodaowan and xishanyao formations has reached the conventional oil window i e with vitrinite reflectance 0 7 ro pre jurassic upper permian in particular derived hydrocarbons appear to be widespread in extracts of fractured jurassic coal and fine grained rocks large differences have been observed in the absolute concentrations of biomarker compounds in rock extracts of various source intervals thus coaly biomarker signatures of the oils most likely resulted from mixing and migration contamination when hydrocarbons derived from mature source rocks migrated up through highly fractured coal seams along deep seated faults in addition to conventional exploration targets revised petroleum generation and accumulation models predict that the focus in the turpan basin should also include deep structures within the carboniferous permian strata and subtle low magnitude anticlines and stratigraphic traps within the triassic jurassic sections crown copyright

controls of oil family distribution and composition in nonmarine petroleum systems a case study from the turpan hami basin northwestern china controls on oil family distribution in tectonically complicated nonmarine petroliferous basins are commonly difficult to isolate because of the varying ages of potential source rocks the complex assemblage of organic rich sedimentary facies and the geographic variability of burial histories the turpan hami basin of northwestern china is an oil bearing intermontane basin where stratigraphic sedimentologic and geochemical controls are sufficient to address each of these issues independently and to determine how they influence the current distribution and composition of liquid hydrocarbons source rock age is one of three major statistically significant discriminators affecting oil family composition both lower middle lower or middle jurassic and upper permian rocks are important source rocks for the basin a newly developed diterpane biomarker parameter can distinguish permian rocks and their correlative oils from jurassic coals and mudrocks and their derivative oils source facies is a second key control on petroleum occurrence and character a variety of biomarker parameters that reflect source rock depositional conditions are indexed to rock samples from interpreted depositional environments by erecting rock to oil correlation models the biomarker parameters separate oil families into end member groups group 1 oils lower middle jurassic peatland swamp facies high land plant input less reducing conditions group 2 oils lower middle jurassic profundal lacustrine facies high algal input more reducing conditions and group 3 oils upper permian lacustrine facies high algal stratified anoxic conditions burial history exercises a third major control on petroleum distribution source rock maturation modeling can demonstrate that relatively uninterrupted burial in the asymmetrically subsiding northern turpan hami area taibei depression exhausted upper permian sourced rocks by the late cretaceous which led to southward migration of upper permiansourced oils group 3 into triassic reservoirs of southern and southwestern turpan hami tainan and tokesun depressions subsequent to uplift of the central basin thrust that currently partitions taibei from tainan lower middle jurassicsourced oils were expelled in the taibei depression by paleoceneeocene time which locally charged jurassic and cretaceous reservoirs groups 1 and 2 forming turpan hami s largest oil accumulations in the basin

controls on coal cleat spacing this study was undertaken to determine the relationship between cleat spacing cleat height and coal banding texture for queensland permian age coals of different rank four of which are presented here whereas relationships between cleat frequency and rank and with coal type or grade have been reported in the past relationships between the spacing and height among the different kinds of cleats are not quantitatively established for other layered sedimentary rocks joint or fracture spacing relates directly to both bed thickness and rock strength coal is similar to other layered rocks four major classes of cleats were distinguished which were separate data populations when cleat spacing was plotted against cleat height master cleats single vitrain layer cleats multiple vitrain layer package cleats and durain dull coal cleats understanding the relationship between cleat height and spacing for specific coals and the specific kinds of cleats within those coals will lead to more accurate predictions of cleat density and hence coal permeability this can improve modelling and prediction of methane gas deliverability in coal seams in the australian permian coals studied narrowly spaced cleats exist at all ranks but the distribution of cleat spacing with cleat height is what varies for specific cleat classes cleat spacing was found to be directly proportional to cleat height in most cases

joint sets that enhance production from middle and upper devonian gas shales of the appalachian basin the marine middle and upper devonian section of the appalachian basin includes several black shale units that carry two regional joint sets j1 and j2 sets as observed in outcrop core and borehole images these joints formed close to or at peak burial depth as natural hydraulic fractures induced by abnormal fluid pressures generated during thermal maturation of organic matter when present together earlier j1 joints are crosscut by later j2 joints in outcrops of black shale on the foreland northwest side of the appalachian basin the east northeast trending j1 set is more closely spaced than the northwest striking j2 set however j2 joints are far more pervasive throughout the exposed devonian marine clastic section on both sides of the basin by geological coincidence the j1 set is nearly parallel the maximum compressive normal stress of the contemporary tectonic stress field shmax because the contemporary tectonic stress field favors the propagation of hydraulic fracture completions to the east northeast fracture stimulation from vertical wells intersects and drains j2 joints horizontal drilling and subsequent stimulation benefit from both joint sets by drilling in the north northwest south southeast directions horizontal wells cross and drain j1 joints whenever present then staged hydraulic fracture stimulations if necessary run east northeast i e parallel to the j1 set under the influence of the contemporary tectonic stress field thereby crosscutting and draining j2 joints

guidelines for assessing the petroleum potential of coaly source rocks using rock eval pyrolysis abstract coaly source rocks are sufficiently different from marine and lacustrine source rocks in their organic matter characteristics to warrant separate guidelines for their assessment using rock eval pyrolysis the rank threshold for oil generation is indicated by the increase in bi s1 toc at rank sr 9 10 tmax 420 430 c ro 0 55 0 6 and the threshold for oil expulsion is indicated by the peak in qi s1 s2 toc at rank sr 11 12 5 tmax 430 440 c ro 0 65 0 85 the pronounced rank related increase in hi s2 toc prior to oil expulsion renders the use of immature samples inappropriate for source rock characterisation a more realistic indication of the petroleum generative potential and oil expulsion efficiency of coaly source rocks can be gained from samples near the onset of expulsion alternatively effective hi values i e his near the onset of expulsion can be estimated by translating the measured his of immature samples along the maturation pathway defined by the new zealand or other defined coal band coaly source rocks comprise a continuum of coaly lithologies including coals shaly coals and coaly mudstones determination of the total genetic potential of coaly source rock sequences is best made using lithology based samples near the onset of expulsion

combining palynofacies and petrography in the study of sub bituminous tropical coals a case history from lower tertiary coals in colombia abstract colombia contains large coal reserves of late cretaceous to cenozoic age in various sedimentary basins but little is known about their potential to generate hydrocarbons in western venezuela coals are known to be potential source rocks for oil and the vicinity of these coals with coal bearing basins in colombia has prompted new studies in colombian tropical coals to develop concepts about their hydrocarbon generating potential the paleogene amaga formation studied here although of limited geographical extension is an ideal field laboratory which contains low rank coal seams in which the transformation and preservation state of organic matter permits the assessment of environment and vegetation types existing at the time of peat formation several seams up to 1 m thick have been analyzed using both bulk seam samples and ply or lithotype samples it is demonstrated that bulk seam samples are not representative for a proper evaluation of the hydrocarbon generation potential of seams one needs to evaluate all lithotype assemblages within a seam proximate analysis and rock eval pyrolysis provide a rapid and cheap way to assess the generation potential of each lithotype the potentially interesting lithotypes can be further analyzed through the combination of petrographic and palynological observations these methods permit the comparison of coal macerals with the equivalent palynofacies constituents provided that a preparation technique especially designed for tropical sub bituminous tertiary coals is used the palynofacies technique has proved to be more accurate than petrography in determining the relative proportion of the potentially oil prone constituents macerals which can be hidden or difficult to identify in petrographic polished section moreover the comparison between resinite oil observed in petrography and resins identified in palynofacies may yield indications of early hydrocarbon generation this methodology provides a fully detailed inventory of coal properties with respect to hydrocarbon generation potential the use of palynofacies is an additional tool to apprehend the floral composition and paleoenvironment of coals thereby increasing the geological and geochemical database needed to evaluate their potential such a methodology may prove very important to assess the petroleum potential of thicker coal deposits in prospective petroleum provinces such as the cerrejon coals in northern colombia

geochemical and petrological evidence for tertiary terrestrial and cretaceous marine potential petroleum source rocks in the western kamchatka coastal margin russia abstract rock eval pyrolysis and microscopic analyses of palaeogene terrestrial strata from the western kamchatka coastal margin russia indicate that good oil prone source rocks are present in both coals and shales hydrogen indices hi of up to 493 mg hc g toc are present in low maturity 0 45 r o vitrinite shale samples from the irgirninvayam river delta region whereas coals with 0 37 0 75 r o and hi of 270 310 mg hc g toc comprise potential oil gas and oil prone source rocks in the kvachincha bay tigel coastal and rassoshina napanskaya river areas the shales and coals with the highest petroleum potential were deposited in a freshwater paleo setting and consist of gelovitrinite cutinite suberinite sporinite resinite and matrix bituminite molecular geochemistry was also used to group genetically related oil samples and to postulate the likely petroleum systems in this area while the preliminary data confirm the origin of two families of oils from the palaeogene deltaic to marginal lacustrine source rocks the chemical composition of oils in two other families suggests the possible presence of marine source rocks in not yet penetrated upper cretaceous paleocene sequences of the basin

comparison of three series of organic matter of continental origin abstract three series of sediments containing land plant derived organic matter were studied they include wells from mahakam delta indonesia miocene douala basin cameroon upper cretaceous and eastern paris basin france paleozoic all of the kerogens and coals isolated from these series can be related to type iii in a van krevelen diagram however they obviously differ in terms of chemical structure as reflected by their pyrolysis gc patterns and by their bitumen composition these observations indicate the variations in the nature of land plant derived sedimentary organic matter and thus differences in quantity and composition of the hydrocarbons which are are released upon maturation based on hydrocarbons potential of the insoluble organic matter and on pyrolysis gc there is no reason to disregard coals and to favor shales as potential source rocks in these two deltaic sequences moreover we assume that the bitumen depletion in coal samples is a reflection of loss by migration which is favored in coals when compared to shales the gc patterns of the residual saturates compared to the pyrolysis gc patterns of the related insoluble coals suggest that migration of hydrocarbons proceeds in these coals without any significant alteration of their distribution at least in the c15 range

coal as a source rock for oil a review the geological debate about whether and to what extent humic coals have sourced oil is likely to continue for some time despite some important advances in our knowledge of the processes involved it is clear that not only liptinites but also perhydrous vitrinites have the potential to generate hydrocarbon liquids in the course of natural coalification some liptinites especially alginite cutinite and suberinite contain a higher proportion of aliphatic moieties in their structure than other liptinites such as sporinite and resinite and are therefore more oil prone it is of potential value to be able to predict the several environments of deposition in which coals with high liptinite contents or containing perhydrous vitrinites may have been formed review of the distribution of oil prone coals in time and space reveals that most are jurassic tertiary with key examples from australia new zealand and indonesia methods based both on experimental simulations and the examination of naturally matured samples have been used to determine the order of generation of hydrocarbons from different macerals results are not entirely consistent among the different approaches and there is much overlap in the ranges of degradation but it seems probable that in the natural environment vitrinites begin to generate early followed by labile liptinites such as suberinite then cutinite sporinite and finally alginite petroleum potential may be determined by experimental simulation of natural coalification or inferred through various micro techniques especially fluorescence and infrared ir spectroscopy or bulk techniques such as elemental analysis and 13c nmr spectroscopy the latter three techniques enable a measure of the polymethylene component of the coal which now appears to be one of the best available approaches for determining petroleum potential no method of experimental simulation of petroleum generation from coals is without criticism and comparative results are highly variable however hydrous pyrolysis confined pyrolysis and forms of open system hydrous pyrolysis approach acceptable simulations whether and to what degree generated liquid hydrocarbons are expelled has long been the central problem in oil from coal studies the structure of vitrinite was believed until recently to contain an interconnected microporous network in which generated oil would be contained until an expulsion threshold was attained recent studies show the pores are not interconnected combined with a dynamic model of pore generation it now seems that expulsion of hydrocarbons is best explained by activated diffusion of molecules to maceral boundaries and ultimately by cleats and fractures to coal seam boundaries the main reason for poor expulsion is the adsorption of oil on the organic macromolecule which may be overcome 1 if coals are thin and interbedded with clastic sediments or 2 if the coals are very hydrogen rich and generate large quantities of oil the existence of oil in vitrinite is attested to by solvent extractions fluorescence properties and by microscopic observations of oil and bitumen experimental simulation of expulsion of oil from coals has only recently been attempted the relative timing of release of generated co2 and ch4 could have considerable importance in promoting the expulsion of liquid hydrocarbons but the mechanism is unclear as it is universally agreed that dispersed organic matter dom in some shales readily generates and expels petroleum it is curious that few consistent geochemical differences have been found between coal macerals and dom in interbedded shales unambiguous evidence of expulsion from coals is limited and in particular only a few commercial oil discoveries can be confidently correlated to coals these include upper cretaceous fruitland formation coals in the usa from which oil is produced new zealand tertiary coals and middle jurassic coals from the danish north sea it is likely that coals have at least contributed to significant oil discoveries in the gippsland basin australia in the turpan basin china and in the kutei and ardjuna basins in indonesia but this remains unproven early reports that early jurassic coals in mid norway were a major source of the reservoired oils have been shown to be inaccurate none of the proposed rules of thumb for generation or expulsion of petroleum from coals seem particularly robust decisions on whether a particular coal is likely to have been an active source for oil should consider all available geological and geochemical information the assumptions made in computational models should be well understood as it is likely with new understandings of processes involved that some of these assumptions will be difficult to sustain

characteristics and origins of coal cleat a review abstract cleats are natural opening mode fractures in coal beds they account for most of the permeability and much of the porosity of coalbed gas reservoirs and can have a significant effect on the success of engineering procedures such as cavity stimulations because permeability and stimulation success are commonly limiting factors in gas well performance knowledge of cleat characteristics and origins is essential for successful exploration and production although the coal cleat literature spans at least 160 years mining issues have been the principal focus and quantitative data are almost exclusively limited to orientation and spacing information few data are available on apertures heights lengths connectivity and the relation of cleat formation to diagenesis characteristics that are critical to permeability moreover recent studies of cleat orientation patterns and fracture style suggest that new investigations of even these well studied parameters can yield insight into coal permeability more effective predictions of cleat patterns will come from advances in understanding cleat origins although cleat formation has been speculatively attributed to diagenetic and or tectonic processes a viable mechanical process for creating cleats has yet to be demonstrated progress in this area may come from recent developments in fracture mechanics and in coal geochemistry

generation and expulsion of oils from permian coals of the sydney basin australia abstract organic geochemical and petrological assessment of coals coaly shales and fine grained sediments coupled with organic geochemical analyses of oil samples all from permo triassic sections of the southern sydney basin australia have enabled identification of the source for the widely distributed oil shows and oil seeps in this region the permian coals have higher hydrogen indices higher liptinite contents and much higher total organic matter extract yields than the fine grained sediments a variety of source specific parameters obtained from n alkanes regular isoprenoids terpanes steranes and diasteranes indicate that the oil shows and seeps were generated and expelled predominantly from higher plant derived organic matter deposited in oxic environments the source and maturity related biomarkers and aromatic hydrocarbon distributions of the oils are similar to those of the coals the oil coal relationship also is demonstrated by similarities in the carbon isotopic composition of the total oils coal extracts and their individual n alkanes extracts from the permo triassic fine grained sediments on the other hand have organic geochemical signatures indicative of mixed terrestrial and prokaryotic organic matter deposited in suboxic environments which are significantly different from both the oils and coal extracts the molecular signatures indicating the presence of prokaryotic organic matter in some of the coal extracts and oils may be due to thin sections of possibly calcareous lithologies interbedded within the coal measures the genetic relationship between the oils and coals provides new evidence for the generation and expulsion of oils from the permian coals and raises the possibility for commercial oil accumulations in the permian and early triassic sandstones potentially in the deeper offshore part of the sydney basin

fracture model of the upper freeport coal marshall county west virginia pilot ecbmr and co2 sequestration site a model discrete fracture or cleat network was developed for the pennsylvanian upper freeport coal seam at a carbon sequestration pilot site in southeastern marshall co west virginia u s a the model reservoir cleat network was developed using 3d seismic post stack processing and interpretation workflows combined with observations of fracture systems in the surrounding region the upper freeport coal is unminable in this area and served as a test for the feasibility of combined enhanced coalbed methane recovery ecbmr operations with co2 storage in unminable coals well log derived subsurface structure maps were used to calibrate 3d seismic time to depth conversion post stack processing was used to enhance and identify subtle discontinuities in the seismic data that could be related to field scale faults fracture zones or stratigraphic heterogeneity the cleat model was developed using power law fracture length and aperture distributions spatial variations of cleat intensity in the model were controlled using measures of localized structural discontinuity extracted from 3d seismic attribute workflows the cleat model identifies a permeable fracture facies within the reservoir most likely to be impacted by co2 injection and migration areas of concentrated seismic discontinuity bear some spatial association to areas of positive vertical deformation observed in a tiltmeter survey of the site and attributed to co2 injection the model could help focus time lapse processing and interpretation in regions estimated to have higher permeability and porosity and higher probability for change of acoustic properties in response to co2 injection and methane production the approach developed here has general applicability to identification of fracture facies and development of unconventional naturally fractured reservoirs in other lithologies and basins

palynofacies changes and their reflection on preservation of peat accumulation stages in the late permian coal measures of the bowen basin australia a new system for coal palynofacies characterisation a high resolution study n 66 was conducted on late permian coal measures of the bowen basin australia to observe palynofacies changes during peat accumulation over time palynofacies were determined using polytopic vector analysis pva to derive end members with variable compositions that reflected fine scale environmental changes within and between seams of the kaloola member palynofacies reflect a three stage succession within the palaeo peat forming environments from stable anoxic conditions at the base progressing to variable oxic conditions toward the top of each seam in cases where a seam was capped by tuff rather than siliciclastic sediment anoxic conditions similar to the bottom of each seam occurred the results corroborate previous interpretations of palaeofloral communities and provide a new palynofacies model that integrates environmental progression within the coal seams in the late permian coal measures of the bowen basin a complementary study of palynological assemblages recognised a shift from dulhuntyspora sp to protohaploxypinus sp in the lower kaloola member indicating a change in pollen spore source associations between dispersed palynomorphs and coal phyterals of parent flora remain tenuous beyond class rank due to poor preservation and taxonomic bias inherent within the sample space this is the first such palynofacies study to be conducted in the bowen sydney gunnedah basin complex thus opening the way for future work examining regional changes in palynofacies expressed in both coal and siliciclastic sediments

fracture and 3d seismic interpretations of the fruitland formation and cover strata implications for co2 retention and tracer movement san juan basin pilot test abstract this study presents data on faults and fractures in the fruitland formation and its cover strata at a carbon sequestration pilot site in the high rate fruitland coal fairway in the northeastern san juan basin the study incorporates satellite imagery fracture detection and shear wave anisotropy logs and 3d seismic to identify potential issues that could impact long term reservoir integrity co2 flow and retention the properties of fracture networks within the reservoir and sealing strata are important to understand in carbon sequestration and enhanced recovery efforts fracture networks exert significant control on the ability of a reservoir to retain co2 for long thousand year time frames with minimal leakage local structural complexity at the pilot site resulted in tracer migration patterns that differed from predictions based on regional descriptions of fracture and cleat orientations measured in areas several miles from the site perfluorocarbon pfc tracer breakthrough in the production stream of nearby producing wells for example occurred first in a well to the east in a direction close to the presumed butt cleat trend rather than in a well at equal distance along what had been assumed to be the more permeable face cleat trend the study reveals local tectonic complexity not suggested by well log derived structure maps of the area and suggests that fractures and faults disrupt the local fruitland coal reservoir and the overlying kirtland shale primary seal

analysis of temperature variability and determination of apparent thermal diffusivity in sandy intertidal sediments at the german north sea coast abstract temperature was measured at depths of 1 10 30 75 and 170 cm in fine sandy intertidal sediments by means of specially designed temperature lances the measurements cover a period from february to october 2007 and have a temporal resolution of 5 min stochastic as well as recurrent processes due to the solar cycle and due to tide induces flooding and drying of the sediment surface lead to a complex composition of the time series curves spectral analyses based on fast fourier transformation fft reveal that temperature variability at the sediment water air interface is widely controlled by recurrent processes with period lengths of 4 93 6 1 8 19 12 24 h and 354 h 14 7 days the importance of the higher frequencies decreases with increasing sediment depth at a depth of 30 cm the 24 h and the 14 7 days cycles mainly determine the temperature development over time while at 75 cm sediment depth contour temperature varies only along the 14 7 days cycle as well as within the seasonal cycle using cross correlation analysis the time necessary for a temperature signal at the surface to trigger a response at a sediment depth of 10 30 and 75 cm was calculated as 1 4 7 0 and 73 1 h respectively utilizing an alternate approach fft derived temperature peak to peak amplitude values and phase angles of up to 9 different cycles were used to calculate apparent thermal diffusivity in different sediment depths the thermal diffusivity decreases from approximately 6 9 10 7 m 2 s 1 from the surface down to a sediment depth of 75 cm the specially designed instrumentation has proven to be robust and precise enough to record high resolution time series of sediment temperature in different depths the time series analysis of the data clearly shows that the temperature variability in the intertidal sediments to a high degree can be explained by recurrent solar and or tidal effects so the methods and results presented in this paper can help to answer questions which are related to sediment temperature in tidal flat environments

controls on the oil and gas potential of humic coals abstract humic coals are highly heterogeneous both with respect to maceral content and chemical composition although the oldest known humic coals albeit gas prone are of devonian age the majority of humic coals capable of generating and expelling non volatile oil are of cretaceous and tertiary age from australia new zealand and southeast asia in contrast the middle jurassic humic coals of the sleipner and hugin formations in the south viking graben of the north sea are primarily gasprone but have the capability to expel aliphatic rich volatile oil these coals have toc contents up to 80 and hydrogen indices hi ranging from 200 to 400 they are vitrinite rich with some containing up to 45 inertinite liptinite concentrations are generally around 10 20 chiefly as spores pollen and abundant resinite the main control on the oil potential of humic coals is the concentration of long chain aliphatic hydrocarbons in the coal matrix although the aliphatics have a high h c ratio the inference on hydrogen content from the rock eval pyrolysis hi value can be misleading for hi values below 500 mg hc g oc there is no relation between hi and the potential of the coals to generate non volatile oil consequently the hi is a poor indicator of the non volatile oil potential of humic coals a more robust indicator is the relative amount of c8 aliphatic groups also the bulk measure of liptinite content may also prove misleading when assessing the oil potential of coals high resinite concentrations can lead to an overprediction of the non volatile oil potential as they contribute significantly to the hi value but will generate primarily volatile aromatic rich oils expulsion from the sleipner and hugin coals appears to have occurred in a gaseous phase with preferential release of short chain alkanes

hydrocarbon potential of pennsylvanian coal in bohai gulf basin eastern china as revealed by hydrous pyrolysis abstract a hydrous pyrolysis experiment was performed using pennsylvanian brown coal with a vitrinite reflectance vr 0 of 0 56 from a coal mine at the southwest corner of the bohai gulf basin eastern china to evaluate the hydrocarbon potential of the coal the coal sample is vitrinite rich 74 5 and inertinite poor 16 7 with liptinite content of 8 8 much of the vitrinite in the sample consists of hydrogen rich vitrinite collodetrinite hydrous pyrolysis was performed at 200 c 230 c 260 c 290 c 320 c and 350 c for 72 h separately yields of both total liquid pyrolysates and expelled oil increased with temperature before reaching their maximum production of 17 27 kg t coal and 14 57 kg t coal at the same temperature of 320 c vr 0 1 18 and decreased afterwards gaseous products increased sharply at 320 c and tended to increase even at the highest experimental temperature 350 c vr 0 1 53 results show that the coal has not only a certain oil generation potential but also a large capacity for gas production and a high expulsion efficiency oil potential of the coal is attributed to its depositional environment which was transitional from shallow marine to coastal plain or swamp during middle to late pennsylvanian the coal was protected from oxidation under water after deposition experimental results indicate that this pennsylvanian coal could have contributed to oil gas accumulation in the bohai gulf basin

significance of coniferous rain forests and related organic matter in generating commercial quantities of oil gippsland basin australia contrary to the conventional belief that humic coal generates primarily gas 3 billion bbl of recoverable oil has been discovered in the humic coaly succession of the fluviodeltaic latrobe group upper cretaceous tertiary that serves as both the reservoir and the source for hydrocarbons in the offshore gippsland basin of southeastern australia evidence for generation of liquid hydrocarbons from the coaly succession includes 1 similarity of n alkane distribution in the oil and in the coal extracts 2 high wax content of oil up to 27 by weight 3 high ratio of pristane phytane in oil 5 6 and 4 dominance of c29 steranes in the oil in the gippsland basin coniferous rain forests dominated by kauri vegetation flourished in a raised bog setting present temperate climate and kauri vegetation of new zealand are considered to be the modern analog to the gippsland basin the coniferous vegetation provided large quantities of hydrogen rich exinite macerals such as cutinite and resinite with potential to generate oil high rainfall raised ground water level low oxygen high acidity and low nutrient conditions of a raised bog setting were suitable for preserving organic matter a comparison of gas chromatograms of oils in the gippsland basin with gas chromatograms of oils generated by hydrous pyrolysis in the laboratory from the immature source rocks suggests that the paraffinic fraction of the oil was derived from coal and the naphthenic fraction was derived chiefly from resin

lower carboniferous coal deposition environments on spitsbergen svalbard abstract two coal bearing units from the lower carboniferous succession in central spitsbergen svalbard have been investigated using coal petrographic and geochemical techniques the upper member consists mainly of algal cannels dominated by botryococcus type algae the coals from the lower member are a mixture of durite type coals with sporinite and inertinite and coals containing prdominantly vitrinite the rock eval and pyrolysis gc also show a clear distinction in the composition of the organic matter in the two coal bearing units investigated these results together with detailed sedimentological analyses are used to reconstruct the depositional environments for the two coal bearing sequences

immature oil and condensate modification of hydrocarbon generation model for terrestrial organic matter petroleum has been found in canadian frontier basins in reservoirs which have undergone low levels of thermal alteration vitrinite reflectance 0 6 ro paraffin indices stable carbon and hydrogen isotope contents pristane to nc17 ratios and diterpenoid biologic markers have been used to assess the level of maturity of the hydrocarbons in the reservoir independently of the level of maturity of the reservoir itself and of the surrounding shale units in the tertiary of the beaufort mackenzie basin naphthenic oils and condensates have been generated from terrestrially derived organic matter in source rocks juxtaposed with the reservoir at reflectance levels of 0 4 to 0 6 ro however condensates discovered in reservoirs which are th rmally immature on the labrador shelf have undergone extensive vertical migration and can be classed as conventional mature to overmature condensates hydrocarbons discovered in the lower cretaceous of the beaufort mackenzie basin and also those of the scotian shelf are more or less in place in that they are at a level of thermal alteration about equivalent to that of the reservoirs in which they are trapped the source for the early oils and condensates is considered to be resinite occurring dispersed in coal fragments the proportion of resinite liptinite and vitrinite in the organic matter of terrestrial source rocks strongly controls both the level of thermal alteration necessary for the section to function as an effective source rock and the ultimate product gas oil or condensate which will be generated

hydrocarbon generation potential and miocene pliocene paleoenvironments of the kangal basin central anatolia turkey abstract this study deals with the organic geochemical characteristics hydrocarbon generative potential and miocene pliocene paleoenvironments of the kangal coal district which developed in a limnic depositional environment and contains the hamal etyemez and kalburcayiri coal fields in the southern part of the sivas basin central anatolia around kalburcayiri the average thickness of each of the two coal seams approximately 10 m are currently being exploited based on open cast methods the coal from which is used by the nearby lignite fired kangal power station an attempt was made to elucidate depositional conditions through proximate and ultimate analyses coal petrography and the geochemical characteristics of the kangal coals these coals have a huminite reflectance value of rmax 0 40 accordingly from the standpoint of coal rank this is a dull brown coal of the subbituminous c type huminite is the most widespread maceral type while gelinites are the most often encountered macerals relative to liptinites the proportion of inertinites is high on the basis of maceral composition the depositional environment of the kangal coals was determined to be either a forest swamp or a lake bottom the distributions of the c27 and c28 c29 steranes for all these coal samples are very similar c29 c27 c28 tricyclic terpanes have low concentrations in all samples of the kangal coals and are dominated by low molecular weight compounds c20 c24 with a maximum at c23 total organic carbon toc wt values of the kalburcayiri samples are 4 64 30 64 wt in the hamal samples 0 83 2 53 wt and in the etyemez samples 8 91 10 39 wt on the basis of tmax values the samples are in the immature early mature stage according to rock eval pyrolysis data the coals have hydrocarbon source rock potential but the coaly shales and other organic matter rich levels have no hydrocarbon source rock potential the high inertinite levels and high vitrinite inertinite ratios suggest that the kangal coals have more potential for gas generation than oil

petroleum secondary migration and accumulation in the central junggar basin northwest china insights from basin modeling the timing of petroleum generation migration and accumulation in the central junggar basin has been evaluated using basin modeling technology to decipher the processes of petroleum secondary migration and accumulation in the jurassic carrier beds during the yanshan and himalayan orogenies during the early yanshan orogeny j2 j3 crude oils sourced mainly from the permian source rocks migrated laterally from depocenters to adjacent structural high points during the late yanshan orogeny cretaceous eocene the hydrocarbon secondary migration pattern changed significantly specifically in the cretaceous a large scale regional second phase of generation and migration occurred in the western part of the central junggar basin in the eastern part of the central junggar basin crude oils emplaced in the depressions migrated mainly to the eastern uplifts in the early tertiary oils in the source kitchens generally began migrating to the north and mixed with the jurassic generated hydrocarbons during the himalayan orogeny neogene quaternary this migration was strengthened continually the modeled results agree with migration associated geochemical information of the jurassic accumulations integration of the regional geological setting and some petroleum geology data suggest that the jurassic tectonic high points and facies change and unconformity associated subtle traps are of crucial importance for current oil exploration both overpressured bodies in the triassic and permian systems and volcanic rock reservoirs of the carboniferous basement in the uplifts have important implications for future natural oil and gas exploration this work should help reduce exploration risk in this region

natural fractures in the barnett shale and their importance for hydraulic fracture treatments gas production from the barnett shale relies on hydraulic fracture stimulation natural opening mode fractures reactivate during stimulation and enhance efficiency by widening the treatment zone knowledge of both the present day maximum horizontal stress which controls the direction of hydraulic fracture propagation and the geometry of the natural fracture system which we discuss here is therefore necessary for effective hydraulic fracture treatment design we characterized natural fractures in four barnett shale cores in terms of orientation size and sealing properties we measured a mechanical rock property the subcritical crack index which governs fracture pattern development natural fractures are common narrow 0 05 mm 0 002 in sealed with calcite and present in en echelon arrays individual fractures have high length width aspect ratios 1000 1 they are steep 75 and the dominant trend is west northwest other sets trend north south the narrow fractures are sealed and cannot contribute to reservoir storage or enhance permeability but the population may follow a power law size distribution where the largest fractures are open the subcritical crack index for the barnett shale is high indicating fracture clustering and we suggest that large open fractures exist in clusters spaced several hundred feet apart these fracture clusters may enhance permeability locally but they may be problematic for hydraulic fracture treatments the smaller sealed fractures act as planes of weakness and reactivate during hydraulic fracture treatments because the maximum horizontal stress trends northeast southwest and is nearly normal to the dominant natural fractures reactivation widens the treatment zone along multiple strands

organic geochemistry and petrology of coals and carbonaceous shales from western venezuela abstract the aim of this study is to provide geochemical and petrological data to characterize coals and carbonaceous shales from western venezuela in terms of both compositional and thermal maturity parameters the samples collected in outcrop belong to the paleocene marcelina formation the eocene oligocene carbonera formation the paleocene orocue group and the lower miocene cerro pelado formation geochemical results are based on total organic carbon toc content rock eval pyrolysis and proximate analyses whereas petrographic data include vitrinite reflectance rr and maceral composition thermal evolution of all samples is low varying from immature to early mature coals and carbonaceous shales from the marcelina and cerro pelado formations are humic the former having larger amounts of inertinite nevertheless both groups of samples are compositionally homogeneous samples from the carbonera formation and orocue group show a great compositional scatter varying from humic to sapropelic our geochemical profile for marcelina formation coals allowed the detection of the first coalification jump whereas the cerro pelado formation profile shows an abrupt decrease of organic matter content toward the top of the studied interval results shown here confirm data from previous studies relative to the high oil source rock potential of carbonera formation and orocue group coals and carbonaceous shales

organic facies as a tool for recording eustatic variations in marine fine grained carbonates example of the berriasian stratotype at berrias ardeche se france abstract sediments of the berriasian stratotype in southeastern france consist of marine fine grained carbonates deposited on an outer shelf at the western edge of the vocontian trough the limestones are monotonous but display some erosional surfaces and a condensed interval they are well dated by ammonites and calpionellids except at the base of the section where the boundary with the tithonian is not clearly established despite their very high carbonate content the limestones yielded enough organic residue to allow a study of palynofacies variations in time organic content consists of two fractions one is made of terrestrial components represented essentially by humic fragments of the inertinite and vitrinite maceral groups and accessorily by pollen and spores the other comprises marine components essentially dinocysts and accessorily foraminiferal linings absence of amorphous organic matter and the oxidized nature of dinocysts observable in uv light indicate that aerobic conditions prevailed throughout the berriasian probably associated with a low sedimentation rate the following qualitative and quantitative criteria indicating distal proximal trends were used to convert palynofacies observations into a tentative palaeoenvironmental curve ratio of continental to marine organic constituents diversity of dinocysts degree of biodegradation affecting humic fragments proportion of blade shaped inertinite and finally size sorting and rounding of equidimensional inertinite particles the palaeoenvironmental curve derived from organic matter shows oscillations between more proximal i e shallower water and more distal i e deeper water conditions these variations combined with biostratigraphic information and the few significant sedimentological data can be interpreted in terms of sequence stratigraphy and compared with the global sea level curve published earlier the fairly good correlation between this global curve and that established from palynofacies demonstrates the influence of relative sea level on the organic facies of the berriasian carbonates and the contribution of palynofacies studies to sequence stratigraphy

heat exchanges in muddy intertidal sediments chichester harbour west sussex england abstract temperature observations made from a lightweight tower assembly in chichester harbour west sussex demonstrate that marked changes in temperature at intertidal mud surfaces occur on a flow tide the magnitude and direction of these changes are dependent on the external atmospheric and marine conditions and on the timing of tidal inundation calculated heat exchange values for the 3h prior to high water fall into four distinct timing zones there is a relationship between thermal stress measured as rate of change of temperature with time and time of high water mud surfaces are net receivers of heat energy from inundating water layers

lignite cleat studies from the first middle polish first lusatian lignite seam in central poland abstract some miocene lignite seams are characterized by the presence of natural discontinuities so called cleats most often they are opening mode fractures consisting of two orthogonal sets face and butt both almost perpendicular to the bedding this paper determines distributions of cleat orientation spacing and aperture from the first group of the middle polish first lusatian lignite seams mpls 1 which has been exploited inter alia in the jo win iib and kazimierz n opencast mines in central poland all observations and measurements were conducted at macroscopic scale the cleats mean orientations are ne sw and nw se dipping at a high angle 75 the first set of fractures refers to the face cleats and the second one to the butt cleats the spacing of face cleats is from 10 0 to 17 2 cm averaging 12 65 cm and the spacing of butt cleats is from 9 3 to 24 3 cm averaging 13 75 cm on the other hand aperture measurements of these cleats range from 0 2 to 1 9 cm averaging 0 68 cm and from 0 1 to 1 5 cm averaging 0 42 cm respectively the obtained results clearly indicate that face cleat orientations nw se are strictly parallel to the elongation of the main tectonic structures in the study area their origin may be explained in at least two ways that is by tectonic folding the maximum principal stress 1 was horizontal or by salt diapirism the maximum principal stress 1 was vertical in both cases the intermediate principal stress 2 was parallel to the face cleat strikes namely nw se although the well developed butt cleats in the context of regional geology provide additional evidence for the creation of an orthogonal system of fractures cleats in the cover of salt structures thus the nw se direction is characteristic of both the extent of the main tectonic units in central poland and the face cleat orientation in mpls 1

paleoenvironments and paleogeography of the lower and lower middle jurassic coal measures in the turpan hami oil prone coal basin northwestern china detailed facies and paleogeographical analyses of extensive borehole and outcrop data from lower and lower middle jurassic oil prone coal bearing sequences in the turpan hami oil producing basin of northwest china have led to the reconstruction of a basinwide depositional model a total of 20 distinct lithofacies have been identified and grouped into braided fluvial plain meandering fluvial plain braided delta meandering channel delta and lacustrine depositional systems coal forming swamps occur in each depositional system but the preferred sites of accumulation are interdelta bay and lower delta plain environments in the braided delta and meandering channel depositional systems and it is in these sites that major oil prone source rocks are located a series of age specific basinwide paleogeographical maps have been constructed leading to a depositional model for the basin results indicate that the basin experienced cyclic flooding to produce swamps and lakes and that these characterize the deposition of the lower and lower middle jurassic coal measures analyses indicate that both the bogda and harlik mountains were uplifted prior to the early jurassic and a lake separated the two mountain regions during the early and early middle jurassic from these results it is interpreted that major oil prone coal sequences are to be found in the western part of the taibei depression of the basin and thus the full economic potential of the basin has yet to be fully realized

hydrocarbon genesis of jurassic coal measures in the turpan basin china abstract a typical case of coal derived oils in china i e the crude oils from the middle lower jurassic coal measure strata in the turpan basin is presented by means of oil source correlation it is confirmed that low maturity crude oil in the shengjinkou oil field is derived from the coal bearing qiketai formation of middle jurassic age a brackish lacustrine sediment mature crude oils in the qiketai oil field and in well taican 1 are sourced from the badaowan formation of lower jurassic age which contains coal seams as thick as 100 m results show that commercial accumulations of liquid crude oils can be generated from coals and coal measure strata containing high volatile coal of bituminous rank despite unfavourable types of source material the total hydrocarbon generating potential can be great due to the unusual abundance of organic matter

temperature fluctuation in muddy intertidal sediments forth estuary scotland abstract temperatures in muddy intertidal sediments exhibit rapid changes which occur principally during tidal inundation observations of sub surface temperature were made from an instrument tower in the forth estuary scotland observed rates of temperature change were compared with theoretical rates which would result from molecular diffusion of heat through the mud the discrepancy between observation and theory was likely to be due to rapid non diffusive heat transfers resulting from the movement of water through non capillary pore spaces created by faunal activity

depositional environment and hydrocarbon source potential of the permian gondwana coals from the barapukuria basin northwest bangladesh article barapukuria coal basin is situated in dinajpur district of the northwestern part of bangladesh a total of eight coal samples have been collected from two different locations of the basin and analyzed using organic geo chemical and organic petrological methods the extracted organic matter of the studied samples is a mixture of type iii and type ii kerogen as evaluated by the source rock analyzer sra and pygc pyrograms the measured total organic carbon toc ranges from 61 to 74 wt and the recovered extractable organic matter eom varies from 27 561 to 41 389 ppm these results suggest that the coals are ranked as good quality source rock the hydrocarbon yield has been calculated which is also high and it ranges from 12 192 to 20 799 ppm the organic matter is thermally mature for hydrocarbon generation considering their tmax and measured mean vitrinite reflec tance values of 431 to 435 c and 0 72 to 0 81 ro respectively the hopane 22s 22s 22r moretane hopane ratio and sterane parameters are also in support of these thermal maturity assessment

the petroleum generation potential and effective oil window of humic coals related to coal composition and age abstract a worldwide data set of more than 500 humic coals from the major coal forming geological periods has been used to analyse the evolution in the remaining hydrogen index hi and total quality index qi generation potentials with increasing thermal maturity and the effective oil window oil expulsion window all samples describe hi and qi bands that are broad at low maturities and that gradually narrow with increasing maturity the oil generation potential is completely exhausted at a vitrinite reflectance of 2 0 2 2 ro or tmax of 500 510 c the initial large variation in the generation potential is related to the original depositional conditions particularly the degree of marine influence and the formation of hydrogen enriched vitrinite as suggested by increased sulphur and hydrogen contents during initial thermal maturation the hi increases to a maximum value himax similarly qi increases to a maximum value qimax this increase in hi and qi is related to the formation of an additional generation potential in the coal structure the decline in qi with further maturation is indicating onset of initial oil expulsion which precedes efficient expulsion liquid petroleum generation from humic coals is thus a complex three phase process i onset of petroleum generation ii petroleum build up in the coal and iii initial oil expulsion followed by efficient oil expulsion corresponding to the effective oil window efficient oil expulsion is indicated by a decline in the bitumen index bi when plotted against vitrinite reflectance or tmax this means that in humic coals the vitrinite reflectance or tmax values at which onset of petroleum generation occurs cannot be used to establish the start of the effective oil window the start of the effective oil window occurs within the vitrinite reflectance range 0 85 1 05 ro or tmax range 440 455 c and the oil window extends to 1 5 2 0 ro or 470 510 c for general use an effective oil window is proposed to occur from 0 85 to 1 7 ro or from 440 to 490 c specific ranges for himax and the effective oil window can be defined for cenozoic jurassic permian and carboniferous coals cenozoic coals reach the highest himax values 220 370 mg hc g toc and for the most oil prone cenozoic coals the effective oil window may possibly range from 0 65 to 2 0 ro or 430 to 510 c in contrast the most oil prone jurassic permian and carboniferous coals reach the expulsion threshold at a vitrinite reflectance of 0 85 0 9 ro or tmax of 440 445 c

coal cleat domains and domain boundaries in the allegheny plateau of west virginia regional face cleats cutting pennsylvanian and permian coal seams in the allegheny plateau of west virginia can be divided into domains separated by boundaries that are sharply defined along most of their lengths domains and domain boundaries are established based on cleat trends number of regional cleat sets and relative chronology of cleat set development regional cleats of each set show a common trend and abutting relationships between multiple sets within a domain describe a progressive history of changing stress fields and cleat development boundaries dividing the in situ directions of horizontal principal stress are coincident with cleat domain boundaries suggesting a common and persistent controlling factor uniform trends of face cleats within domains and ab upt changes in cleat signature across domain boundaries can be spatially related to regional basement structures and a depositional hinge line within the coal bearing and underlying mississippian rocks in addition fold structures in coal and underlying sedimentary rocks across the allegheny plateau commonly terminate or change trend abruptly at joint domain boundaries in some cases regions of common fold trends in coal bearing rocks are contained within specific domains face cleat trends commonly differ from joint trends in rocks immediately bounding coal seams however one domain boundary in coal can be traced into mississippian rocks through the unconformity at the base of the pennsylvanian section in this case mississippian and pennsylvanian joint trends differ it follows tha joint domain boundaries can extend downward through rocks of different lithologies as well as coincide with conformable and unconformable stratigraphic boundaries

oil generation capacity of coals as a function of coal age and aliphatic structure abstract the relative proportions of aliphatic ch2 ch3 aliphatic hydrogen hali together with the aliphatic chain length in a series of carboniferous permian jurassic and cenozoic humic coals have been analysed using ftir and ruthenium tetroxide catalysed oxidation rtco followed by gc ms analysis of the n monocarboxylic acids esterified to assess their ability to generate oil most of the coals contain 2 11 vol liptinite only coals with almost similar hydrogen indices his were compared as they were considered to possess comparable hydrocarbon generation potentials all contain isolated aromatic hydrogen haro in the coal structure and a considerable proportion of aliphatic chains in the range c16 18 hi values cannot alone explain the proportion of aliphatic ch2 implying that for coals haro contributes to the measured hi cenozoic coals contain the highest proportion of aliphatic ch2 and hali and the content of longer chain aliphatics c18 increases considerably from palaeozoic to cenozoic coals aliphatic chains c18 are absent from or very restricted in the carboniferous coals and most of the permian coals indicate no or a negligible ability to generate oil jurassic coals show a slightly better potential whereas cenozoic coals contain aliphatic chains up to at least c35 demonstrating the greatest capacity to generate oil in addition to significant gas potential multivariate data analysis suggests that the aliphatic chains c24 are related to the collodetrinite liptodetrinite matrix which is a prominent constituent of cenozoic coals with regard to oil potential the coals from the major coal forming periods may be ranked carboniferous permian

evaluation of petroleum generation from resinites by hydrous pyrolysis hydrous pyrolysis experiments are useful in evaluating the composition yield and kinetics of liquid hydrocarbons generated from potential source rocks using this technique on a representative set of resinites revealed that fossil resin does not generate a light naphthenic crude oil gas chromatograms of liquid hydrocarbons generated by resinites are dominated by aromatic peaks and show no resemblance to commercially produced crude oils resinites may make minor contributions to conventionally sourced crude oils but their limited occurrence inhibits their potential as a prolific source of petroleum on a basinal scale data from the natural system and pyrolysis experiments also indicate that resinites do not generate liquid hydrocarbons at abnormally low levels of therm l maturity

compound specific stable carbon isotope analysis as a tool for correlating coal sourced oils and interbedded shale sourced oils in coal measures an example from turpan basin north western china molecular geochemical methods have shown that it is often diacult to diaerentiate between coal and interbedded shale sourced oils even though coals and interbedded shales may exhibit considerable organic influx variation e g land plant vs algal organic matter due to the changes of depositional setting however compound specific stable carbon isotopic compositions are sensitive to the source input variations typically specific molecules are more depleted in 13 c with increasing content of aqueous biota this hypothesis is examined and exemplified by comparing the stable carbon isotopic ratios of n alkanes from source rock extracts and related oils of the turpan basin northwestern china stable carbon isotopic values of n alkanes extracted from coals and interbedded shales show that d 13 c values of n alkanes with less than 20 carbon atoms vary only slightly however there are dramatic changes in the isotopic compositions of higher molecular weight n alkanes furthermore n alkanes from coal extracts are enriched in 13 c relative to that of interbedded shales with excursions up to 2 3 this comparison enables the diaerentiation of coal and interbedded shale sourced oils and provides information useful in assessing the hydrocarbon system of a basin 2000 elsevier science ltd all rights reserved

petroleum potential of oligocene lacustrine mudstones and coals at dong ho vietnam an outcrop analogue to terrestrial source rocks in the greater song hong basin the outcrop of oligocene age at dong ho northern vietnam may constitute an immature analogue to offshore terrestrial source rocks in the greater song hong basin the outcrop includes an interval with two source rocks 1 highly oil prone carbonaceous mudstones containing kerogen types iia and iia i and with toc contents from 6 48 to 16 89 wt and hi values from 472 to 690 and 2 oilprone humic coals kerogen type iii with hi values from 200 to 242 the mudstones were deposited in oxygen deficient lakes which on occasion were subject to marine influence and the coals accumulated in freshwater peat forming mires the coals have broad activation energy ea distributions while the mudstones have ea distributions characterised by a pronounced principal ea during artificial maturation about 16 17 of the organic carbon in the coals and 45 50 of the organic carbon in the mudstones participated in petroleum formation the two source rocks primary generate oil and secondary generate gas however the mudstones realised the majority of their potential over a more narrow temperature range than the coals the excellent generative potential of the terrestrial source rocks at dong ho is encouraging for offshore exploration for reservoirs charged by cenozoic rift lake successions q 2001 elsevier science ltd all rights reserved

characterization of oil generation and expulsion from coals and source rocks using diamond anvil cell pyrolysis abstract a visual technique has been developed using a diamond anvil cell to characterize oil prone vs gas prone coals and source rocks and evaluate their oil expulsion efficiency the experiments conducted using 15 humic or shaly coals two boghead coals and eight source rock samples from taiwan turkey north america and australia show that the technique has potential to distinguish oil prone coals from gas prone coals the oil potential of humic coals was estimated from the amounts of total liquid generated during pyrolysis which show correlations with the hydrogen index hi from rock eval pyrolysis and the gas to oil ratio gor determined by py gc analysis the changes of visual area or volume of neoformed liquid as a function of temperature at four heating rates were used to calculate the extents of kerogen to oil transformation for determining the kinetic parameters the results confirm the kinetic controls on the measured transformations but reveal unusually high apparent activation energies and frequency factors the use of this technique as a quantitative tool to predict oil generation kinetics should be treated with caution until this discrepancy has been resolved in addition this study has demonstrated that the expulsion of oil like liquid from coals is generally more efficient than from shales possibly due to the much higher organic content in coal

adapting palynological preparation methods in subbituminous and bituminous coals from colombia to improve palynofacies and hydrocarbon source rock evaluations abstract apart from their potential as fossil fuel bituminous and subbituminous coals in colombia may prove to be potential source rocks for the generation of hydrocarbons the assessment of such properties requires the combination of petrographic and palynofacies studies the latter correspond to the microscopic investigation in transmitted white and reflected uv lights of sedimentary organic matter insoluble in organic and inorganic solvents to date mineral acid and schulze methods have failed to produce good samples of palynofacies constituents from cenozoic coals in colombia so that the latter method had to be modified the main modifications consist in adapting the kclo 3 to hno 3 ratio in the schulze mixture and introducing two extra phases of oxidation with naoh and nh 4 oh which permit the washing off of humic substances this method yields the full spectrum of palynofacies constituents which are not destroyed or damaged by the alkali treatment neither is their fluorescence colour affected by the initial acid treatment on the contrary the particle fluorescence intensity tends to increase because of the dissolution of humic acids making their identification easier the achievements of the modified method are threefold 1 it permits the correlation between macerals in petrographic polished sections and their equivalent in palynofacies slides making the two methods complementary 2 palynofacies provides a better identification of sporomorphs than petrography resulting in better paleoenvironmental interpretations 3 palynofacies tend to give a more precise quantitative evaluation of the liptinitic constituents and consequently of the coal hydrocarbon generation potential

petrology rank and evidence for petroleum generation upper triassic to middle jurassic coals central alborz region northern iran abstract upper triassic to middle jurassic coals from the alborz region of northern iran were analyzed by reflected light fluorescence microscopy and rock eval 6 pyrolysis to evaluate their regional rank variation degree of hydrothermal alteration and petroleum generative potential the coal ranks in the region range from a low of 0 69 ror in the glanddeh rud area to a high of 1 02 ror in the gajereh area tmax c values rock eval 6 pyrolysis also increase progressively with increasing vitrinite ro values however tmax is suppressed lower than would be expected for each rank ranging from 428 c for the glandeeh coal to 438 c for the gajereh coal tmax suppression may be caused by maceral composition and soluble organics within the coal moderately high hydrogen indices persistent and oily exudations from the coals during uv exposure and traces of hydrocarbon fluid inclusions suggest that liquid petroleum was likely generated within some of the coals

heat transport dynamics at a sandy intertidal zone 1 intertidal zones are spatially complex and temporally dynamic environments coastal groundwater discharge including submarine groundwater discharge may provide stabilizing conditions for intertidal zone permeable sediments in this study we integrated detailed time series temperature observations porewater pressure measurements and two dimensional electrical resistivity tomography profiles to understand the coupled hydraulic thermal regime of a tropical sandy intertidal zone in a fringing coral reef lagoon rarotonga cook islands we found three heating patterns across the 15 m study transect over tidal and diel periods 1 a highly variable thermal regime dominated by swash infiltration and changes in saturation state in the upper foreshore with net heat import into the sediment 2 a groundwater supported underground stable cool region just seaward of the intertidal slope break also importing heat into the subsurface and 3 a zone of seawater recirculation that sustained consistently warm subsurface temperatures that exported heat across the sediment water interface simple calculations suggested thermal conduction as the main heat transport mechanism for the shallow intertidal sediment but deeper and or multidimensional groundwater flow was required to explain temperature patterns beyond 20 cm depth temperature differences between the distinct hydrodynamic zones of the foreshore site resulted in significant thermal gradients that persisted beyond tidal and diel periods the thermal buffering of intertidal zones by coastal groundwater systems both at surface seeps and in the shallow subsurface can be responsible for thermal refugia for some coastal organisms and hotspots for biogeochemical reactions

assessment of hydrocarbon source rock potential of polish bituminous coals and carbonaceous shales abstract we analyzed 40 coal samples and 45 carbonaceous shale samples of varying thermal maturity vitrinite reflectance 0 59 to 4 28 from the upper carboniferous coal bearing strata of the upper silesian lower silesian and lublin basins poland to evaluate their potential for generation and expulsion of gaseous and liquid hydrocarbons we evaluated source rock potential based on rock eval pyrolysis yield elemental composition atomic h c and o c and solvent extraction yields of bitumen an attempt was made to relate maceral composition to these source rock parameters and to composition of the organic matter and likely biological precursors a few carbonaceous shale samples contain sufficient generation potential pyrolysis assay and elemental composition to be considered potential source rocks although the extractable hydrocarbon and bitumen yields are lower than those reported in previous studies for effective type iii source rocks most samples analysed contain insufficient capacity for generation of hydrocarbons to reach thresholds required for expulsion primary migration to occur in view of these findings it is improbable that any of the coals or carbonaceous shales at the sites sampled in our study would be capable of expelling commercial amounts of oil inasmuch as a few samples contained sufficient generation capacity to be considered potential source rocks it is possible that some locations or stratigraphic zones within the coals and shales could have favourable potential but could not be clearly delimited with the number of samples analysed in our study because of their high heteroatomic content and high amount of asphaltenes the bitumens contained in the coals are less capable of generating hydrocarbons even under optimal thermal conditions than their counterpart bitumens in the shales which have a lower heteroatomic content

permeability tensor for discontinuous rock masses rock masses which commonly contain a large number of discontinuities are treated as homogeneous anisotropic porous media to formulate the corresponding permeability tensor this has been successfully achieved by introducing a symmetric tensor crack tensor which depends only on the geometry of the related cracks aperture size and orientation the principal directions associated with the symmetric crack tensor are coaxial with those of the permeability tensor the first invariant of the crack tensor is proportional to the mean permeability while the deviatoric part is related to the anisotropic permeability these results are well supported by numerical experiments on the permeability of cracked media by long remer wilson and witherspoon an actual rock mass moderately jointed granite was studied to see whether the crack tensor can be determined in situ stereology based on geometrical statistics provides a sound basis for determining the crack tensor in situ the crack tensor is obtained by

aspects of generation and migration of hydrocarbons from coal bearing strata of the hitra formation haltenbanken area offshore norway abstract the haltenbanken area situated 150 200 km offshore mid norway is a proven gas condensate and oil producing province with continuing exploration potential in this structurally and stratigraphically complex area with multiple source rock possibilities we have examined the upper triassic lower jurassic hitra formation to determine its possible contribution to the hydrocarbon pools in the area the 400 m thick hitra formation consists of interbedded shales siltstones sandstones and coal seams in this study conventional cores of the hitra formation from depths varying from 2 4 and 4 6 km have been examined with the objective to obtain a better understanding of hydrocarbon generation migration and expulsion processes in these coals as function of variation in facies and maturity in addition to basic geochemical measurements toc rock eval and gc analysis of c15 saturated hydrocarbons microscopic studies normal and uv reflected light were carried out to determine the abundance and initial distribution of hydrogen rich macerals including fluorescent mobile phases such as exsudatinities geochemical and microscopal evidence was obtained suggesting that some of the interbedded sandstones show indications of impregnation by migrated hydrocarbons some bitumen filled micro fractures were observed extending from the coals towards the adjacent sands a preliminary interpretation of these data is that these fractures represent conduits carrying hydrocarbons from the coal seams towards the sandstones the role of the kerogen type variations on the amount of hydrocarbons generated and the mechanism and efficiency of hydrocarbon expulsion from the coals is discussed