validation of lateral fluid flow in an overpressured sand shale sequence during development of azeri chirag gunashli oil field and shah deniz gas field south caspian basin azerbaijan abstract data collected over the past 15 years from exploration appraisal and production in the offshore south caspian sea validates the previously developed model of lateral fluid flow from the overpressured basin center to the basin margins within the sandstone aquifers of the pliocene productive series specifically new data confirm the predictions that 1 although both sandstones and shales are overpressured sandstones are generally less overpressured than shales 2 there is a lateral regional gradient in sandstone overpressure decreasing from the basin center to the basin margin and 3 the impact on the pressure field from local features such as mud volcanoes or local faults is limited additional pressure data combined with regional seismic mapping suggests variations in lateral fluid flow in different stratigraphic intervals these data show that the less continuous sandstones of the upper and lower productive series are closer to the surrounding shale pressures as they are less well connected to the basin margin outlet whereas continuous sandstones in the middle productive series show the highest amount of lateral pressure transfer from the basin center and are therefore at lower pressures than the surrounding shales pressure data from development wells at the azer chirag gunashli oil field and the shah deniz gas condensate field reveal local variations in sandstone and shale overpressure resulting from the lateral pressure transfer affect traugott and heppard 1994 traugott 1996 swarbrick and osborne 1998 yardley and swarbrick 2000 across large high relief structures well connected sandstones transmit fluid pressures from the adjacent deep overpressured synclines into the shallower crest of the structure pressures in sandstones decrease updip along a hydrostatic gradient 0 433 psi ft the pressure gradient in the shales however will change according to the shale overpressure gradient in the south caspian basin the overpressure gradient in the shales varies between 0 6 and 0 9 psi ft therefore the relative overpressure between the sandstones and shales varies along structural dip there are a number of important implications to exploration appraisal and development because of large scale lateral fluid flow lateral fluid flow has consequences for the sealing capacity of sandstone reservoirs and the variable position of hydrocarbon to water contacts around a structural accumulation this requires each sandstone shale couplet be considered separately for pore pressure prediction basin scale 3d models were constructed to better understand the implications of basin scale fluid flow within and between individual reservoirs at each structure

the solid solution aqueous solution system sr ba ra so4 h2o a combined experimental and theoretical study of phase equilibria at sr rich compositions abstract solid solution formation between raso4 and other isostructural sulfates has been known for a long time as a process potentially controlling ra concentrations in aquifers here we measured the ra uptake in the sr rich corner of the ternary sr ba ra so4 solid solution aqueous solution ss as system by equilibrating srso4 baso4 and mixed sr ba so4 solids with ra bearing aqueous solutions for up to 1302 days at 90 c at a solid liquid ratio of 5 g l the recrystallization experiments were combined with electron microscopy studies of the solids the evolution of the solid and aqueous phases was interpreted based on thermodynamic modelling applying a recently revised thermodynamic dataset for the sr ba ra so4 h2o system the recrystallization process involved several metastable phases starting from the least soluble ba and ra rich precipitates and ending with sr rich solids whose compositions approached the predicted equilibrium states the composition and the time evolution of metastable phases were correlated with changes in the computed supersaturation functions particularly the formation of ra ba and sr rich rims on primary barite grains in the experiment with the mechanical mixture of 99 of celestine and 1 of barite has been explained by combining calculated supersaturation conditions with considerations of structural misfit a key result was the observed final raaq concentration which is about one order of magnitude lower compared to the initial concentration implying an efficient uptake into the newly formed solid phases these concentrations appeared to be just slightly lower than those predicted by the thermodynamic calculations implying that the complete ss as equilibrium was close to be reached in sr rich systems in the recrystallization experiments lasting for about 3 5 years

mud volcano growth by radial expansion examples from onshore azerbaijan abstract we investigated the mode of growth of flat topped mud volcanoes through the study of three active edifices onshore azerbaijan they are the bozdag guzdek the ayazakhtarma and the akhtarma pashaly mud volcanoes the three edifices are up to 80 m high and 3 km wide and have eruptions with recurrent times from a few months to a few years surface changes during and between eruptions were documented by a combination of mapping from satellite pictures repeated direct observation over five years and structural analysis in addition resistivity profiles and microgravity measurements were used to decipher their subsurface geometries we interpret the flat topped character of the mud volcanoes as the result of rapid isostatic readjustment of a brittle surface crust

classification of mud volcanoes in the south caspian basin offshore azerbaijan abstract a 2d seismic grid in the south caspian basin offshore azerbaijan is used to define the areal distribution of mud volcanoes and to make a classification of the mud volcanoes based on characteristic seismic features a high concentration of mud volcanoes is observed at the southern part of the study area that coincides with the distribution of subsurface structures within the basin mud volcanoes with low relief several tens of meters are concentrated primarily in the northeastern portion of the study area mud volcanoes with large vertical relief greater than 200 m are clustered in the southwest part of the basin mud volcano development in the south caspian basin is generally linked to faults which in some instances are detached at the basement level the seismic database allows us to determine the relative timing of mud flows and gives us valuable information about mechanisms of mud volcanism within the south caspian basin the cycles of mud volcano activity coincides with time of high sedimentation rates regional contraction episode and a major stage for hydrocarbon generation mud volcano formation within the south caspian basin is primarily controlled by compressional tectonic forces and overpressured sediments mud volcano activity may not always be related to the maykop organic rich shale succession late oligocene lower miocene but may also occur at shallower stratigraphic zones

triggering and dynamic evolution of the lusi mud volcano indonesia abstract mud volcanoes are geologically important manifestations of vertical fluid flow and mud eruption in sedimentary basins worldwide their formation is predominantly ascribed to release of overpressure from clay and organic rich sediments leading to impressive build up of mud mountains in submarine and subaerial settings here we report on a newly born mud volcano appearing close to an active magmatic complex in a backarc sedimentary basin in indonesia the location of the mud volcano close to magmatic volcanoes results in a high background temperature gradient that triggers mineralogical transformations and geochemical reactions at shallow depth the eruption of 100 c mud and gas that started the 29th of may 2006 flooded a large area within the sidoarjo village in northeast java thousands of people have so far been evacuated due to the mud flood hazards from the eruption since the initial eruption the flow rate escalated from 5000 to 120 000 m 3 d during the first eleven weeks then the erupted volume started to pulsate between almost zero and 120 000 m 3 d in the period august 14 to september 10 whereas it increased dramatically following swarms of earthquakes in september before reaching almost 180 000 m 3 d in december 2006 sampling and observations were completed during two fieldwork campaigns on the site the eruption of boiling water is accompanied by mud aqueous vapour co 2 and ch 4 based on geochemical and field results we propose a mechanism where the eruptions started following the 27th of may earthquake due to fracturing and accompanied depressurization of 100 c pore fluids from 1700 m depth this resulted in the formation of a quasi hydrothermal system with a geyser like surface expression and with an activity influenced by the regional seismicity

the structure and geomorphology of the dashgil mud volcano azerbaijan the large scale and small scale 10 m structure and geomorphology of the active dashgil mud volcano in central azerbaijan have been studied through historical records it is known that this mud volcano has major eruptions every 6 32 years the activity observed during two field trips in 1995 consisted of low energy venting and debouching of mud water oil and gas from three mud pools salses and about 20 individual cones gryphons located on the summit plateau of the mud volcano besides the bubbling mud pools ranging from 30 to 75 m across and the cones ranging from 0 8 to 3 m height a 200 m long string of about 10 sinter mounds was found on the summit plateau the internal structure of the mud volcano and the processes responsible for the observed dashgil geomorphology are discussed assuming the dashgil mud volcano to be continuously active with an average methane production similar to that observed in 1995 between the rare major eruptions we have conservatively estimated the dashgil mud volcano to produce an annual amount of at least 800 sm3 standard cubic metres of gas mainly methane which is emitted directly into the atmosphere this estimate indicates that the natural contribution of atmospheric greenhouse radiatively active gases from the world s terrestrial and submarine mud volcanoes is highly significant

some practical guidance for petroleum migration modeling abstract petroleum migration modeling is widely used to assess petroleum charge and fluid phase risk in exploration and appraisal there are three principal migration methods darcy flow invasion percolation and flowpath or ray tracing each method relies on different assumptions and yields different outcomes this paper analyzes the strengths and weaknesses of these methods as they are implemented in petromod providing a practical guide as to how and when to apply each migration method flowpath is the most simplistic and computationally fastest method and should only be applied when a quick screening is required invasion percolation delivers satisfactory results for most geological settings from structurally and stratigraphically simple to complex but does not consider expulsion from the source rock properly darcy flow is the preferred method for unconventional resource assessments and supports maximum downward migration a traditional modeling approach is to use two methods applying darcy flow to tight rocks and flowpath to highly permeable rocks another combined method can be used in such a way that darcy flow is applied to the source rock and invasion percolation to the carrier and reservoir beds the latter seems to deliver best results in most geological settings while also providing more realistic results of secondary migration losses

the nature and hydrogeologic significance of mud diapirs and diatremes for accretionary systems in accretionary wedges often morphologically similar sedimentary intrusions when observed by remote geophysical means may have one of two quite different driving mechanisms and a highly variable significance for the regional hydrogeologic picture for example mud diapirs are driven by buoyancy forces that arise from bulk density contrasts in them mud and pore fluid upwell en masse and fluid migration is a related sometimes important but generally subsidiary process in contrast diatremes contain sediments fluidized during rapid fluid advection and are forcibly and directly driven by the hydrogeologic system the nature of fluid input from local and exotic source regions can therefore strongly affect sedimentary intrusive processes and vice versa this complicates the process of defining the main features of the hydrogeological systems operating in accretionary wedges focused vertical advection through steep sided piercement mud diapirs requires conduit systems otherwise flow will be diffuse and directed more horizontally out of the low permeability mud mass however where the permeability of the overburden is less than that of the diapir the whole diapir may act as a conduit apart from this special case conduits will be associated with highly anisotropic scaly fabrics that can sometimes develop in the marginal shear zone of diapirs scaly fabrics form during deformation and compaction of a mud matrix under conditions of constant or increasing effective stress however the effective stress path can be complex as it is both controlled by the relative rates of upward intrusion and burial by sedimentation and or structural thickening and the hydrogeologic system due to this it appears likely that even in a geographically related group of diapirs effective stress histories will vary widely between intrusions so that some can form advective pathways for fluids and some cannot mixed systems of behavior may also be present with local diatremes developing within diapirs above the terminations of conduit systems and rapidly expanding methane gas pockets the potentially heterogeneous near surface behavior may be why the surface manifestations of sedimentary intrusions are so variable when observed in the field diatremes can also form separately as large primary features above any structural or stratigraphic conduit that rapidly expels water or gas into the base of an unlithified sediment column when active large diatremes require enormous quantities of fluid water or gas to drive them particularly if they are long lived features and hence are a direct indication of at least an episodically vigorous hydrogeologic system

lateral fluid flow in a compacting sand shale sequence south caspian basin the article lateral fluid flow in a compacting sand shale sequence south caspian basin by john d bredehoeft rashid d djevanshir and kenneth r belitz aapg bulletin v 72 no 4 april 1988 p 416 424 needs the following corrections there are several typographical errors that were the author s error equation 2 should be equation 2 equation 3 should be equation 3 although the equations were incorrect in the article the associated discussion and equations 4 and 5 are based upon the correct expressions as shown above table 3 the calculated regional sand permeabilities is also incorrect the hydraulic conductivity which in our case has the units of meters per second was incorrectly converted to millidarcys values in meters per second were multiplied by the standard conversion 1 m sec equals 1 04 108 md in retrospect this conversion was a conceptual error table 3 should read table 3 calculated regional sand permeabilities acknowledgment we appreciate the comments of stan lohman who brought our attention to these errors end of article last page 1525

mud volcanism by repeated roof collapse 3d architecture and evolution of a mud volcano cluster offshore nigeria abstract using 3d seismic data we document the subsurface architecture of a cluster of 3 mud volcanoes located on the upper continental slope offshore nigeria in a background of gently dipping stratified sediments the subsurface of the cluster contains 8 seismic sequences made of one subcircular syncline 1 3 km in diameter and adjoining unstratified units synclines flatten out upward through intercalation of unstratified concave up lenses between stratified units and are eventually filled by a convex up unstratified lens onlapped by background sediments the lower boundary of each sequence is a 0 5 1 5 km deep bowl shaped unconformity across which high dip strata rest above truncated low dip series we interpret each seismic sequence as a mud volcano system mvs sourced from a connected region and evolving through episodes of roof collapse three are associated with the surface mud volcanoes and another 4 to fossil ones mud volcano systems are dynamic features that record the evolution of 1 the material extruded from one single connected source region depletion zone as it grows downwards and stepwise becomes depleted 2 the basal unconformity which joins strata originally separated by material evacuated in the remobilization process by analogy with salt tectonics we propose to call it a mud weld 3 the conduits and 4 the successive collapsed roofs of the depletion zone the evolution of each mud volcano system in this interpretation records progressive growth of the depletion zone by downbuilding punctuated by episodes of roof collapse and extrusion the geometry and evolution of this type of mvs can be interpreted in the light of analogue models of magmatic caldera development in early stages the thin roof experiences downsagging while remobilized material is extruded through an axial pipe like conduit in later stages the thickened roof undergoes piston like subsidence and mud extrusion occurs along the peripheral fault

clay diapiric structures within the strike slip margin of the southern leg of the barbados prism abstract the study area is situated 200 km to the east of trinidad in the southern sector of the barbados accretionary wedge analysis of seismic profiles and seabeam bathymetric data permit the identification of an important dextral wrench fault system oriented n95 e which induced morphostructural elements characteristic of this type of kinematics in a thick sedimentary cover separated from its basement by a decollement level this decollement level is due to the presence of miocene clay beds supersaturated with water which under the effect of stresses trigger clay diapiric processes in this transtensional sector we shall demonstrate that the boundary between the caribbean plate and the south american plate continues as far as 250 km to the east of trinidad

mud volcanoes the most important pathway for degassing deeply buried sediments abstract this paper discusses the nature of the phenomenon of mud volcanism with respect to degassing of deeply buried sediments mud volcanoes are defined as geological structures and their main elements are described based on the nature of activity mud volcanoes are grouped in to three main types and the relationship between each type and corresponding morphological expression is discussed the presented up to date data of the world geographical distribution of mud volcanoes show that they approximate to 1800 individuals a detail overview of geological environments in which they occur helps to deduce some necessary conditions for mud volcano formation the basic mechanisms of mud volcano formation are discussed specifically the fluid pressure hypothesis and some triggering events are identified the most common investigation approach and some criteria for recognizing of a submarine mud volcano on side scan sonar records and seismic sections are given mud volcanism in the mediterranean ridge an accretionary complex and black sea abyssal plane a back ark basin with tectonic regime of extension are described as case studies to show variety in morphology and common factors in development of mud volcanoes the manifestation of continuous gas migration through mud volcanoes is clarified and the attempt made to quantify the gas release shows that mud volcanoes are one of the significant natural sources of atmospheric methane emitting a total amount of about 10 3 to 12 6 tg annually

when mud volcanoes sleep insight from seep geochemistry at the dashgil mud volcano azerbaijan the worlds 1500 mud volcanoes are normally in a dormant stage due to the short duration of eruptions their dormant stage activity is often characterized by vigorous seepage of water gas and petroleum however the source of the fluids and the fluid rock interactions within the mud volcano conduit remain poorly understood in order to investigate this type of activity we have combined satellite images with fieldwork and extensive sampling of water and gas at seeping gryphons pools and salsa lakes at the dashgil mud volcano in azerbaijan we find that caldera collapse faults and e w oriented faults determine the location of the seeps the seeping gas is dominated by methane 94 9 99 6 with a 13c v pdb in the 43 9 to 40 4 range consistent throughout the 12 analysed seeps ethane and carbon dioxide occur in minor amounts seventeen samples of seeping water show a wide range in solute content and isotopic composition pools and salsa lakes have the highest salinities up to 101 043 ppm cl and the lowest 18o v smow values 1 4 the mud rich gryphons have low salinities 18 000 ppm cl and are enriched in 18o 18o 4 6 the gas geochemistry suggests that the gases migrate to the surface from continuously leaking deep seated reservoirs underneath the mud volcano with minimal oxidation during migration however variations in gas wetness can be ascribed to molecular fractionation during the gas rise in contrast the water shows seasonal variations in isotopic composition and surface evaporation is proposed as a mechanism to explain high water salinities in salsa lakes by contrast gryphons have geochemical signals suggesting a deep seated water source these results demonstrate that the plumbing system of dormant mud volcanoes is continuously recharged from deeper sedimentary reservoirs and that a branched system of conduits exists in the shallow subsurface while the gas composition is consistently similar throughout the crater the large assortment of water present reflects the type of seep i e gryphons versus pools and salsa lakes and their location within the volcano our data highlight the importance of a carefully planned sampling strategy when the target is water geochemistry whereas the methane content and isotopic composition is relatively independent of the particular seep morphology

cyclic activity of mud volcanoes evidences from trinidad se caribbean fluid and solid transfer in mud volcanoes show different cyclic phases of activity including catastrophic events and periods of relative quiescence characterized by moderate activity this is notably well shown by the compilation of historical data onshore trinidad it appears that each eruptive mud volcano has its own period of catastrophic activity and this period is variable from one volcano to another the frequency of the eruptions seems essentially controlled by local pressure regime within the sedimentary pile the dynamics of expulsion of the mud volcanoes during the quiescent phases has been studied with the help of temperature measurements within the mud conduits the mud temperature in these conduits is notably concurrently controlled by the gas flux endothermic gas depressurizing induces a cooling effect and by the mud flux mud is a vector for convective heat transfer complex temperature distribution was observed in large conduits and pools especially in the bigger pools the temperature distribution characterizes convective cells with an upward displacement of mud above the deep outlet and ring shaped rolls associated with the burial of the mud on the flanks of the pools in tube like shaped narrow conduits the temperature is more regular but we observed different types of profiles with either downward increasing or decreasing temperatures near constant to even negative gradients compared to the general temperature gradient are typical for very dynamic fluid systems the temperature profiles varied from one place to another as well as over time the temperatures measured within the conduits and their base show that the fluid flow is not constant but highly variable through short time periods we observed locally a significant daily change of the temperature of the expelled mud which shows also that the mud flux is changing very rapidly due to the migration dynamics of the mud in fracture systems we also observed very short time period cyclic variations with a frequency of several minutes these high frequencies temperature changes could be related to the dynamics of two phase flows gas and mud through the mud volcano conduits

influence of paleo trade winds on facies patterns of the cambrian shanganning carbonate platform north china abstract the shanganning carbonate platform scp of the north china craton ncc was located in the trade winds belt during the cambrian which influenced its facies development in recent years numerous drillcores have been recovered from these units but the depositional environments and facies architecture of this large 2 0 105 km2 carbonate platform system have not yet been reported in detail in this study we integrate sedimentological and magnetic fabric data collected from outcrops and drillcores in order to document variation in microfacies and facies associations within the scp to infer paleowind directions and constrain the paleogeographic location of the scp and to evaluate eolian controls on platform development this analysis documented numerous carbonate microfacies belonging to six fabric types mudstone wackestone packstone grainstone framestone and dolostone along with rarer siliciclastic sediments these microfacies belong to facies associations representing tidal flat open platform platform margin slope and deep basinal depositional environments anisotropy of magnetic susceptibility ams measurements yielded mean paleocurrent directions for the early middle and late cambrian of 114 63 and 83 30 from paleo north respectively that were relatively consistent for 12 out of 13 platform margin sites all vectors being corrected for a post cambrian 150 clockwise rotation of the ncc these wind orientations are consistent with the scp shifting from south of the paleo equator in the early cambrian to north of it by the middle cambrian paleo trade winds influenced facies patterns across the platform producing a distinct windward leeward zonation the windward margin is characterized by well sorted oolitic grainstone as well as favositids coral and dasycladacean algal sponge framestone and the leeward margin by poorly sorted oolitic wackestone grainstone and fine bioclastic sediments the present study is innovative in 1 integrating microfacies and ams analyses in order to establish paleowind patterns and influences on an ancient carbonate platform 2 documenting windward leeward variation in quantifiable sediment properties across the scp and 3 constraining the paleo hemispheric location of the ncc during the cambrian

sedimentation and shale tectonics of the northwestern niger delta front abstract the modern day slope and outer shelf of the niger delta are characterized by fault bounded sedimentary depocentres and intervening shale structures some of which are diapiric using two dimensional seismic reflection data and stratigraphic information from five wells the neogene history of a 70 30 km portion of the northwestern niger delta shelf and slope has been examined the shale structures were established by late miocene time probably in response to lateral shale withdrawal from beneath the advancing deltaic load combined with compressional uplift and folding of pro delta strata during pliocene and pleistocene time these structures were buried by the prograding delta and extensional growth faulting commenced stacked onlap relationships and stacked erosional channels indicate that the shale structures continued to influence sedimentation patterns throughout this period throughout the pliocene extension and subsidence were concentrated in a graben like depocentre bounded by both regional and counter regional growth faults during the early pleistocene subsidence on the regional growth fault ceased and growth was transferred to the counter regional growth fault set the geometry and history of the depocentre is analogous to salt related depocentres typical of the northern gulf of mexico and atlantic margins of brazil and angola to explain the history of the niger delta study area a model is proposed in which the miocene pleistocene sedimentary package has slid basinward breaking up during extension thereby creating seaward stepping depocentres examples from analogue modelling studies are used to suggest possible origins for the large counter regional growth faults

significance of mud volcanism 1 mud volcanism and diapirism have puzzled geoscientists for 2 centuries they have been described onshore and offshore in many places on earth and although they occur in various tectonic settings the majority of the features known to date are located in compressional tectonic scenarios this paper summarizes the main thrusts in mud volcano research as well as the various regions in which mud volcanism has been described mud volcanoes show variable geometry up to tens of kilometers in diameter and several hundred meters in height and a great diversity regarding the origin of the fluid and solid phases gas predominantly methane water and mud may be mobilized at subbottom depth of only a few meters but in places can originate from several kilometers depth with minor crustal or mantle input the possible contribution of mud extrusion to global budgets both from quiescent fluid emission and from the extrusive processes themselves is important in regions where mud volcanoes are abundant such as the collision zones between africa and eurasia fluid flux through mud extrusion exceeds the compaction driven pore fluid expulsion of the accretionary wedge also quiescent degassing of mud volcanoes may contribute significantly to volatile budgets and hence to greenhouse climate

trinidad mud volcanoes where do the expelled fluids come from abstract in order to establish the origin of fluids expelled from mud volcanoes in trinidad we analyzed their major element trace element and isotopic h o sr compositions the mineralogical chemical and sr isotope compositions of associated expelled muds were also determined on the basis of their chemical and sr isotope compositions the fluids were divided into two groups those southwest and northeast of a major right lateral wrench fault the los bajos fault that both controls the chemical quality of the fluids and acts as a drain strontium isotopes were derived via mixing between a radiogenic source 0 71135 and a nonradiogenic source 0 70671 for both southwest and northeast groups however the nonradiogenic source possibly feeding the northeast group showed a lower sr concentration than that of the southwest group h and o isotope data show that the fluids became enriched in 18 o through interaction with wall rocks the fluids were originally oceanic but their properties were subsequently modified by diagenesis as evidenced by chemical data and mixing between fluids issued from two deep seated reservoirs and surface aquifer end members the gas phase expelled with the mud and the fluid through the mud volcanoes is composed mainly of methane with minor carbon dioxide the amount of expelled gas seems the same in samples from both sides of the los bajos fault the almost unique methane content of the gas phase and the large positive 18 o shifts of the reservoir end member as well as b li and ba contents reveal that the fluids from the deep seated reservoirs inherited their chemical compositions at high temperature fluid rock interactions estimates of equilibrium temperatures of the two deep seated reservoirs suggest that to acquire the estimated higher temperature 150 c the mud volcanoes must have been fed partly by a reservoir located at a depth of more than 3 km this depth corresponds to previous geologic information which located the deep seated reservoir in miocene sediments at such a comparable depth the mixing of the original fluids with a less deep seated reservoir and meteoric waters on the ascending path suggests the presence of a recharge mechanism and contributes to the dynamics of the expulsion itself

sedimentation in a discharge dominated fluvial lacustrine system the neogene productive series of the south caspian basin azerbaijan abstract the largely lower pliocene productive series and its regional equivalents contain the major hydrocarbon reservoirs of the south caspian basin examination of outcrops in the apsheron region azerbaijan has resulted in re interpretation of the depositional environments of the productive series the lower part of the productive series consists of sandstones and mudstones interpreted as channelised and sheetflood fluvial deposits intercalated with mudstones that represent short lived lacustrine transgressions of a regional caspian lake the upper productive series pereriva and younger suites comprises sandstone prone intervals interpreted as deposition during periods of increased fluvial discharge and sediment supply and mudstone prone intervals interpreted as deposition during periods of decreased discharge and therefore coarse grained sediment starvation sand prone reservoir intervals in the pereriva and overlying balakhany suites mainly comprise amalgamated low sinuosity braided fluvial sheet sandstones mudstone rich intervals form inter and intra suite seals comprising alluvial plain and lacustrine facies the succession displays an overall fining up trend which is controlled by long term climatic cooling decreased fluvial discharge and reduced coarse clastic input the modern volga caspian system is a partial analogue for the lower productive series in the apsheron region where fluvial and lacustrine conditions alternate on a low gradient ramp without evidence for a shelf break lake eyre australia may be a modern analogue for the upper productive series where there are fewer lacustrine influences discernible in the sedimentology and the overall setting resembles a dryland river terminal fan

methane emission from the mud volcanoes of sicily italy 1 mud volcanoes represent the largest expression of natural methane release into the atmosphere however the gas flux has never been investigated in detail methane output from vents and diffuse soil degassing is herewith reported for the first time measurements were carried out at 5 mud volcano fields around sicily italy each mud volcano is characterized by tens of vents and bubbling pools in the quiescent phase methane emission from single vents ranges between 0 01 and 6 8 kg day diffuse soil leakage around the vents is in the order of 102 104 mg m 2 d 1 an exceptional flux of 106 mg m 2 d 1 was recorded close to an everlasting fire soil ch4 flux is positive even at large distances from the mud volcano fields suggesting a diffuse microseepage over wider areas a total of at least 400 tons ch4 per year can be estimated over the area investigated alone 1 5 km2

active mud volcanoes on and offshore eastern makran pakistan to study the activity source and driving force of the venting of fluidized mud in the coastal makran we carried out reconnaissance surveys of two active onshore mud volcano fields chandragup and jebel u ghurab and of a newly born march 1999 offshore mud volcano malan island all studied on and offshore mud volcanoes line up along one southwest northeast trending structural lineament the axis of the dhak anticline isotopic data point to a bacterial origin of the gas mainly methane mixed benthic foraminiferal faunas and calcareous nannofloras suggest that the source level of the extruded mud is at a sub surface depth of 2 3 km observed mud discharge varied between 0 and 1 4 m3 h 1 and gas discharge rates between negligible amounts to 1 m3 s 1 mud temperatures in the crater lake of chandragup i are near ambient temperatures they rise slightly 1 5 c during episodes of modest mud outflow an area of 160 000 m3 of soft mud was vigorously extruded from the sea floor at a water depth of 10 m within days after 15 march 1999 forming malan island the island was destroyed within a few months after its birth by deep reaching wave action during the sw monsoon this was possibly aided by local subsidence of the mud volcano structure due to the volume loss following rapid degassing and mud extrusion

seismic indicators of focused fluid flow and cross evaporitic seepage in the eastern mediterranean abstract we present for the first time a synthesis of the evidence of focused fluid flow in the eastern mediterranean providing an updated record that includes recent and past occurrences through the last ca 6 my of evolution of the basin we do this by adding the interpretation of a previously unpublished regional 2d seismic dataset to the existing occurrences of focused fluid flow reported in the literature our interpretation shows a high number 141 of focused fluid flow features which span the stratigraphic interval from late miocene to recent of these features 82 are at the seabed and 59 are buried the previous published record is more difficult to quantify but in comparison shows an overwhelming majority of seabed features with only rare examples of buried features the spectrum of the buried and seabed features covers pockmarks pipes mud volcanoes clastic intrusions and collapse structures clustering of the fluid flow features is observed at different times in specific areas including the nile cone and the levant herodotus cyprus and latakia basins with the buried record we are able to highlight the evolution of the leakage points through time focused fluid flow venting has been occurring since the onset of the messinian salinity crisis and the start of basinwide deposition of evaporites we focus in particular on seismic indicators of leakage through evaporites and of sub evaporitic source for fluids and remobilised sediments we also discuss the role of the evaporites as a seal to ascending fluids and in which circumstances they can be breached fluids and associated remobilised sediments are sourced from different intervals from the sub and supra evaporitic section and possibly within the evaporites only a minor proportion of the fluid flow features are certainly sourced from below the messinian evaporites and most of them are located in the nile levant eratosthenes areas the few examples of pathways that are able to cross thick undeformed and well preserved evaporites are typically correlated to overpressure release and hydrofracturing this confirms that the evaporites do act regionally as a very good seal as expected while fluids are able to cross the evaporites only in their most extreme expression i e in near lithostathic overpressure conditions this is confirmed by our observations made in the eastern mediterranean where in the presence of relatively undisturbed evaporites cross evaporite vertical fluid pathways are only observed at the high end of the flux pressure range and involve sediment remobilisation maps combining these different elements can be used to detect areas potentially more prone to breaching

structure and emplacement of mud volcano systems in the south caspian basin the term mud volcano system is coined to describe the set of structures associated with a constructional edifice mud volcano and feeder complex that connects the volcano to its source stratigraphic unit three dimensional 3 d seismic data from the south caspian basin are used to investigate the structural elements and evolution of these systems mud volcano systems initiate via early kilometer scale biconic edifices termed pioneer cones these are fed by fluidization pipes tens of meters in width subsequent kilometer scale mud volcanoes grew via persistent extrusion fed by numerous additional fluidization pipes injected in the country rock this subvolcanic intrusion complex creates a densely intruded cylindrical zone similar in cross section to gryphon swarms observed at an outcrop onshore wall rock erosion and compaction of the intruded zone leads to the collapse of a downward tapering cone enveloping the cylindrical zone capped by ring faults that define a kilometer scale caldera that downthrows the overlying mud volcano mud volcanoes get buried during basin subsidence and can look like intrusive laccoliths at first glance on seismic data reactivation of mud flow through a conduit system generates a stack of superimposed mud volcanoes through time large volcanoes continue to dewater during burial and may locally remobilize this model of mud volcano evolution has similarities with igneous and salt tectonic systems to reduce drilling and geologic uncertainty mud volcano system extent and impacts on a reservoir can be assessed on 3 d seismic data simon stewart received his ph d from the imperial college london in 1992 in 1992 2000 he was seismic interpreter at amerada hess in support of exploration and appraisal drilling in the north sea in 2000 he moved to bp and has since worked on structural geology and well planning in the americas middle east and the former soviet union his special interest is in the integration of structural geology and seismic interpretation richard davies received his ph d from the university of edinburgh in 1995 in 1995 2003 he was with mobil and exxonmobil working on field development and exploration the north sea the west of shetlands and the west niger delta deep water slope in 2003 2005 he was a senior lecturer in earth sciences at cardiff university united kingdom currently he is professor and director of cerees center for research into earth energy systems durham university united kingdom his special interest is in seismic scale expression of fluid migration and diagenesis

mud volcanoes in deepwater nigeria abstract detailed study of 3d seismic data from deepwater nigeria has revealed the presence of features interpreted to be mud volcanoes they occur in an upper slope environment seen as 1 2 km circular features at the seabed seabed cores from the mud volcanoes contain oil gas and sand shale clast content richer than the seabed background pliocene fossils have been identified in the cores demonstrating transport of material from depth the features show a high seabed seismic amplitude above a chimney of chaotic seismic reflections and data wipe out the mud volcanoes in the study area shows two distinct clusters located over deeper structural culminations four active mud volcanoes area 1 are located above a rollover anticline in the central part of the area cuspate listric faults reach the seabed on the up slope side of these mud volcanoes four abandoned mud volcanoes have also been identified with progressively older ages towards the crest of the underlying structure these abandoned features are associated with an extremely chaotic seismic signature a combination of over pressured carrier beds and low integrity top seals are believed to be responsible for the formation of these mud volcanoes it is further believed that gas expansion subsequent to seal failure was the main driving force for what must have been violent eruptions the long lived mud volcano activity over the deep structural closure suggests a plumbing system that focuses on escaping compaction water and hydrocarbons through time in the south west of the study area another cluster of five mud volcanoes is located above a shale diapir the seabed expression of the members of this cluster is more varied some show a positive relief at the seabed while others show circular depressions the largest feature represents an assemblage of many smaller mud volcanoes with a common root system their seismic expression is also different from that of area 1 with a well defined sediment wedge at surface and a shallower root system these features are believed to represent a less violent type of mud volcano characterised by ductile flow tectonic stress due to growth of the underlying diapir is thought to have played an important role during eruption in addition to focused methane escape and the low mechanical strength of the overburden

composition and flux of explosive gas release at lusi mud volcano east java indonesia the lusi mud volcano has been erupting since may 2006 in the densely populated sidoarjo regency east java indonesia forcing the evacuation of 40 000 people and destroying industry farmland and over 10 000 homes mud extrusion rates of 180 000 m 3 d 1 were measured in the first few months of the eruption decreasing to a loosely documented 4000 m for methane and approximately 600 m for carbon dioxide however the mass fractions of these gases are insufficient to explain the observed dynamics rather the primary driver of the cyclic bubble bursting activity is decompressional boiling of water which initiates a few tens of meters below the surface setting up slug flow in the upper conduit our measured gas flux and conceptual model lead to a corresponding upper bound estimate for the mud water mass flux of 10 5 m 3 d 1

reservoir microfacies analysis exploiting microscopic image processing and classification algorithms applied to carbonate and sandstone reservoirs abstract two case studies are presented that apply a new quantitative micro facies analysis method to multiple thin section photographs from the carbonate and sandstone reservoirs of two giant fields 1 the permo triassic carbonate reservoir formation from the south pars gas condensate field offshore iran and 2 the fasila sand reservoir of middle pliocene age from the shah deniz field offshore azerbaijan an essential part of comprehensive microfacies analysis of reservoir rocks is to reliably identify characterize and quantify microscopic features including matrix components mineral grains rock fabrics porosity fossil contents and the products of diagenesis this can be achieved by a combination of image processing techniques to assist in distinguishing paleoenvironments and depositional settings of porous and permeable formations these techniques applied to the case studies are shown to effectively improve reservoir characterization for both carbonate and clastic reservoirs image processing algorithms have to overcome several hurdles to achieve consistent and repeatable microfacies analysis and this is best conducted by exploiting several algorithms focus on specific recognition tasks initially a histogram equalization algorithm is applied to adjust the quality of thin section images to make them consistently comparable with reference photographs microfacies analysis is then conducted on the adjusted images in steps to distinguish matrix texture grain and pore space boundaries and micro fossil components this is achieved by applying multiple functional image processing algorithms and sensitivity analysis sequentially targeting specific microfacies characterization objectives accurate grain size is quantified by a customized graphical user interface gui algorithm pore detection and quantified two dimensional porosity volumes are calculated for multiple thin section images with a k means clustering of two measurements extracted from color image space analysis color image data is also used to specifically distinguish the different minerals constituting the rock matrix cement and the form of the pore space in two dimensions this enables these features to be consistently visualized and displayed in scatter plots that determine the precise microfacies to which each thin section belongs applying these techniques to the two case studies demonstrates how they can objectively and quantitatively provide microfacies analysis for carbonate and silicate reservoirs

mud diapirism and subcretion in the barbados ridge accretionary complex the role of fluids in accretionary processes mud diapirism has recently been recognized in several modern accretionary wedges it provides an important means of dewatering accretionary wedges and should be regarded as an important process for producing the melanges found in both modern and ancient accretionary terranes mud diapirism affects a large area of the barbados ridge accretionary complex the distribution of the mud diapirs appears to be primarily controlled by the presence of underconsolidated terrigenous submarine fan deposits that are being accreted to the complex the frequency of diapir occurrence decreases northward as the fan becomes thinner mud diapirs are absent from the very eastern most part of the complex formed from sediments accreted at its toe with the exception of a few mud volcanoes on the ocean floor in front of the complex the initiation of diapirism appears to be spatially coincident with the onset of subcretion or underplating of sediment to the base of the complex at a ramp between two levels of decollement it is proposed that the release of mud and pore water from the subcreted sediments is a direct or indirect cause of most of the mud diapirism in the accretionary complex there is a range of diapiric form dependent on the viscosity of the mud from mud volcanoes fed by low viscosity mud to higher viscosity mud ridges the diapirs in the eastern areas of the complex are generally mud volcanoes with narrow conduits feeding a surface mound mud ridges are prominent in the western parts of the complex this is interpreted as reflecting a general westward decrease in the fluid content of the accretionary complex bottom simulating seismic reflectors formed by gas hydrate are commonly developed in the areas of mud volcano occurrences the presence of the hydrate indicates that large volumes of methane are being generated at depth in these regions the generation of methane may be contributing to zones of overpressuring in the wedge methane may also be partly responsible for driving the diapiric material to the surface to form mud volcanoes ridges in the subducting oceanic crust beneath the accretionary complex locally enhance diapirism above their crests and southern flanks faults formed later in the development of the complex are more commonly associated with diapirism than those resulting from accretion at the toe of the wedge these later faults play an important role in controlling the sites of individual mud volcanoes chains of mud volcanoes and mud ridges

oil source bed recognition and crude oil correlation trinidad west indies abstract potential source rocks capable of generating hydrocarbons in trinidad were identified using routine geochemical parameters tertiary formations have a poor oil source rating due to low organic carbon contents toc produced oils were classified into genetic types on the basis of gas chromatography and gas chromatography mass spectrometry fingerprinting only one genetic oil type sourced from predominantly marine organic matter was recognised biodegradation is evident in several oils analysed chromatographic characteristics and gross geochemical properties of produced oils correlate best with rock extracts from the naparima hill and gautier formations indicating a probable genetic association

a new hydrothermal scenario for the 2006 lusi eruption indonesia insights from gas geochemistry abstract the 29th of may 2006 gas and mud eruptions suddenly appeared along the watukosek fault in the north east of java indonesia within a few weeks several villages were submerged by boiling mud the most prominent eruption site was named lusi to date november 2011 lusi is still active and a 7 km2 area is covered by the burst mud breccia the mechanisms responsible for this devastating eruption remain elusive while there is consensus about the origin of the erupted mud the source of water is uncertain the origin of the gas is unknown and the trigger of the eruption is still debated in order to shed light on these unknowns we acquired a wide set of data of molecular and isotopic composition of gas sampled in several lusi vents in the surrounding mud volcanoes in the closest natural gas field wunut and in the hydrothermal vents at the neighbouring volcanic complex in the period 2006 2011 the boiling fluids erupted in the crater zone are apparently co2 dominated while colder ch4 dominated and c2 c3 bearing fluids are identified at several sites around the crater zone gas genetic diagrams maturity plots and gas generation modelling suggest that the hydrocarbons are thermogenic 13c1 up to 35 13c2 up to 20 deriving from marine kerogen with maturity of at least 1 5 ro for instance in the 4400 m deep ngimbang source rocks co2 released from the crater and surrounding seeps is also thermogenic 13c from 15 to 24 related to kerogen decarboxylation or thermal ch4 oxidation in deep rocks although three vents just outside the crater showed an apparent inorganic signature 7 5 4000 m magmatic intrusions and hydrothermal fluids responsible for the enhanced heat that altered source rocks and or gas reservoirs the neighbouring magmatic arjuno complex and its fluid pressure system combined with high seismic activity could have played a key role in the lusi genesis and evolution within this new model framework lusi is better understood as a sediment hosted hydrothermal system rather than a mud volcano

implications of outcrop geology for reservoirs in the neogene productive series apsheron peninsula azerbaijan the neogene sediments of eastern azerbaijan and western turkmenistan contain significant hydrocarbon reserves in deltaic reservoirs sedimentary logging of these reservoirs at outcrop in azerbaijan has outlined four facies associations that encompass a range of paleoenvironments from alluvial braided river sandstones and conglomerates to delta front siltstones and mudstones the facies associations suggest a river dominated braid delta and are arranged into an architecture controlled by base level changes parasequences parasequence sets and sequence boundaries are key elements the facies associations and stratigraphic architecture together with outcrop observations of cementation and faulting are summarized in terms of four idealized reservoir models fluvial delta plain proximal delta front and distal delta front each reservoir model has distinctive grain size and shale distributions comparison of nearby oil fields with the studied outcrops suggests that the outcrops form good analogs from which to model reservoir architecture barriers and baffles to fluid flow reservoir heterogeneity and reservoir quality variations

sector collapse of mud volcanoes azerbaijan abstract field data collected from mud volcanoes in azerbaijan are used to describe a process in mud volcano development that involves portions of the constructional edifices collapsing outwards in thin skinned9 slides these events create kilometre scale scarps that are tens of metres in height arcuate in plan view elongate and facing downdip similar morphological features occur on igneous volcanoes and have been described as sector collapse9 structures the largest sector collapses in igneous volcanoes involve some 10 12 tons of mobilized material equivalent structures in mud volcanoes are several orders of magnitude smaller we employ a shape parameter that can be utilized in field and satellite based mapping to distinguish between slope failure and eruptive deposits three mud volcanoes with kilometre scale sector collapses are described and controlling mechanisms are reviewed the updip domains of these collapses are characterized by fluid escape showing that there is also linkage to deeper mud volcano structure the observations are reconciled in a model consisting of a deflating mud chamber that triggers thin skinned sector collapse the updip domain of the sector collapse is localized above a deep seated zone of volume loss and the downdip domain of the collapse runs down the edifice flank onto the surrounding plain

on the effect of aqueous strontium on magnesite growth abstract strontium was found to be a growth promoting additive during the precipitation of calcite from aqueous solution this raises the question of whether growth of the isostructural magnesite is promoted by aqueous strontium ions as well for this the influence of sr2 on magnesite growth was investigated by macroscopic mixed flow reactor experiments and hydrothermal atomic force microscopy at 100 c it was found that neither growth rates nor molecular step morphologies are affected by the presence of strontium the partition coefficient of strontium between magnesite and aqueous solution k d sr mgs x sr x mg m sr m mg was determined to be 50 m and mg sr ratios 60 strontianite precipitation limited sr incorporation into growing magnesite to 0 5 mol similar amounts of sr incorporation into calcite were reported in literature although the partition coefficient of sr between calcite and solution is lower than between magnesite and solution the slow growth rates of magnesite however imply the use of high solution supersaturations these conditions inevitably promote strontianite precipitation depleting the solution of sr in the case of calcite fast growth rates can be achieved at low supersaturations such solutions are permissive of high sr concentrations without strontianite precipitation the magnesite growth rates measured here complete the literature data now spanning a range of supersaturation states of more than one order of magnitude 20 240 the completed data allow for a refinement of the kinetic constants of magnesite precipitation the fit of all rates to the function r k 1 n yielded the reaction order n 1 76 0 03 and the growth rate constant k 0 015 0 002 nmol m 2 s 1

hydrodynamics and hydrocarbon trapping concepts pitfalls and insights from case studies abstract tilted contacts are observed in many oil and gas fields they are generally attributed to the effect of hydrodynamics hydrodynamic flow exists in almost all geological basin types of the wilson cycle from passive margins to foreland basins to mountain chains there are various geological processes driving regional hydrodynamics flow is regulated by permeability variations which are given by the geological framework the role of faults as partial permeability barriers may be a significant regulator for flow hydrodynamics is best recognized by using the principles of hydraulic head however hydraulic data must be carefully interpreted to avoid pitfalls such as transition zones where variable oil saturation may be falsely interpreted as tilted contacts in sedimentary basins we distinguish two different hydrodynamic settings where flow is either mainly gravity driven or centripetal or mainly compaction driven or centrifugal in both cases hydrodynamics can enhance hydrocarbon trapping gravity driven processes are particularly important in the arabian shield and north africa centrifugal and centripetal phenomena can co exist in the same basin e g mahakam delta or douala basin turbidites occur typically in centrifugal settings hydrodynamic concepts applied to petroleum exploration are not frequently used in industry despite being known for a long time they may however become increasingly important in conventional exploration as static plays are rapidly being drilled up and the remaining exploration potential of sedimentary basins is increasingly affected by stratigraphic and hydrodynamic trapping components

the tectonic fabric of the barbados ridge accretionary complex abstract a map showing near surface structure and other surficial geological features on the barbados ridge accretionary complex has been constructed from gloria long range side scan sonographs detailed bathymetric surveys using seabeam and single and multichannel seismic reflection sections the map shows major variations in the size orientation and style of structures across the accretionary complex that are principally related to the increasing thickness of the complex and the sediment drape upon it and variations along the complex that derive from the northward thinning of sediment accreted from the ocean floor and the effects of ridges in the oceanic basement the development of crossfaulting is mainly associated with basement ridges mud diapirism is abundant in the southern part of the complex and is characteristic of that part of the complex into which turbidites from the orinoco submarine fan are accreted slumping on a variety of scales is another feature of the complex the map is presented at a scale of 1 1063415 4 inches per degree of longitude and also shows bathymetry at 200 m contour intervals

the 2011 strong fire eruption of shikhzarli mud volcano azerbaijan a case study with implications for methane flux estimation shikhzarli is a typical active mud volcano mv in azerbaijan with extremely high percentages of fire eruptions reaching 74 the strong eruption of shikhzarli mv on 13 march 2011 shamakhi gobustan region central azerbaijan at 40 29 12 5 n 49 02 03 4 e was accompanied by gas ignition with a straight flow vertical gas flare a large 60 m height short living 30 min gas flare and small 1 5 m height gas spouts with longer lifetimes 5 h were simulated in sigmaflow and the model was used to evaluate methane flux and the amount of combusted methane geological and mineralogical data field observations as well as eye witness reports and photographs in mass media were used to choose the boundary conditions for the gas fire simulation this study provides the first quantitative evaluation for methane emission during an mv catastrophic eruption as simulation predicts 14 000 m3 of methane was consumed for the life time 30 min of the main 60 m high flare which is equivalent to nine tons of cold gas at ambient conditions the volume of erupted methane for the 5 h lifetime of a small spout 1 5 m high was 72 6 m3 45 kg of cold ch4 the amount of methane emitted during a single strong flame eruption is commensurate with the annual output of permanently active individual mv vents or may be ten to hundred times as high

morpho acoustic characterization of a shallow water mud volcano offshore scoglio d affrica northern tyrrhenian sea responsible for a violent gas outburst in 2017 abstract a violent gas outburst occurred offshore the scoglio d affrica islet tuscan archipelago northern tyrrhenian sea on march 16th 2017 with local fishermen observing columns of dirty water rising up to 10 m above the sea surface the integration of video footage and dissolved ch4 measurements collected 5 days after the event with high resolution multibeam data collected 4 months later allowed us to characterize the source area of the outburst corresponding to a shallow water mud volcano the mud volcano covers an area of ca 170 000 m2 has a vertical relief of ca 30 m with respect to the surrounding seafloor and an estimated volume of ca 1 106 m3 based on bathymetric reconstruction the elongated nnw sse shape of the mud volcano is compatible with local structural trends indicating a tectonic control for its development the mud volcano is made up of two mounds whose tops are located at a depth of ca 10 m the southern mound was responsible for the 2017 outburst as testified by a 15 20 m wide circular crater on its summit where a large amount of mud breccia and diffuse seepage from small pockmarks were observed in video footage the flanks of the mud volcano are steep and characterized in the upper part by a hummocky morphology and multiple sediment flows on the western flank the characterization of the mud volcano and the deposits associated with the 2017 gas outburst provides insight into seafloor shaping processes linked to fluid seepage in shallow water sectors this is a particularly relevant issue considering both the paucity of studies on shallow water mud volcanoes as well as the hazard associated with violent gas outbursts in such settings as witnessed by the march 16th 2017 event

tectonic diapiric and sedimentary chaotic rocks of the rakhine coast western myanmar abstract the western margin of myanmar is the northern extension the active sunda india eurasia subduction zone coastal regions and offshore islands have remarkable exposures of chaotic rock terranes along wave cut terraces that allow characteristics of tectonic sedimentary and diapiric melanges to be recognized tectonic shear zones tectonic melanges contain fragments of cretaceous ophiolites chrome spinel bearing peridotites and radiolarian cherts that are in contact with thrust packets of eocene turbidite units broken formations the turbidites contain shale rich beds that have been sheared during soft sediment deformation sedimentary broken formations and are sandwiched between undeformed thick sandy beds these are mass transport deposits mtds that most likely formed during deposition of the initial detritus of the himalayan orogenic zone probably trench slope basins on the accretionary prism the ophiolitic and turbiditic thrust slices have been exhumed and are currently being intruded by active mud volcanoes that bring fragments of units up from depth to the surface forming diapiric melanges these diapiric melange bodies contain only small fragments

gas venting and subsurface charge in the green canyon area gulf of mexico continental slope evidence of a deep bacterial methane source abstract questions as to the role of modern carbon in methanogenesis and the maximum depth of methane sources in the gulf of mexico continental slope remain unanswered a research submersible was used to sample mixed bacterial and thermal gas 13 c of methane 62 8 d 176 venting to the water column from the gulf slope in green canyon gc 286 the 14 c value of the methane 998 is consistent with fossil carbon another gas vent on gc 185 is 100 methane 13 c 62 9 d 155 and may be from a bacterial source the 14 c 997 of this bacterial methane is also consistent with fossil carbon fossil bacterial methane and thermal hydrocarbons are present in pliocene to pleistocene reservoirs 3509 4184 m of genesis field gc 205 161 160 oil in these reservoirs is biodegraded but gas is not suggesting that gas charge to reservoirs continues presently at 3 4 km depth mixed thermal and bacterial methane may charge the deep reservoirs and fossil methane from depth may ultimately vent on the sea floor at gc 286 and gc 185 results of this study of green canyon suggest that bacterial methane in gas vents and in reservoirs is from deep fossil sources

retention of 226 ra by barite the role of internal porosity abstract the role of internal macropores and nano scale pores for the uptake of 226 ra into barite was studied via scanning and transmission electron microscopy as well as focused ion beam methods a temporal evolution of the internal microstructure and the ra distribution was observed on samples taken from long term ra uptake experiments the results of this study clearly show a significant impact of the presence of ra leading to a complete reconstruction of the internal barite microstructure whereas the microstructure of ra free reference samples remained unchanged the initial internal barite microstructure contains a connected network of macropores and a layered structure of nano scale pores which in the presence of ra coalesced in favor of larger pores during the experiment a clear relationship between the ra uptake and the internal porosity was observed by high resolution stem edx mappings starting from strongly enhanced ra concentrations in the solid in the vicinity of the pores ra is temporarily inhomogeneously distributed within the barite particles at later stages of the long term experiment the ra distribution becomes homogenous while nano scale and macro scale pores disappear in conclusion the uptake of ra into barite takes place by a special case of dissolution reprecipitation from the inside of the particle to the outside

a three dimensional insight into the mackenzie basin canada implications for the thermal history and hydrocarbon generation potential of tertiary deltaic sequences the stratal architecture of the mackenzie basin was reconstructed based on seismic and well data and used to define a three dimensional model to reconstruct the so far poorly known thermal and maturation history of the basin to correctly account for the complex tectonic history of the mackenzie basin episodes of uplift and erosion were implemented based on interpretations of original depositional surfaces our results indicate that the combined effects of basin inversion and low surface temperatures inhibited maturation from the late miocene forward in all except the most deeply buried parts of the basin this explains why upper eocene and younger deposits are mostly immature despite their burial to more than 5000 m 16 400 ft the specific history of the basin is shown to control the time intervals of potential hydrocarbon generation predictions of transformation ratios using a variety of published kinetics to account for source rock kinetic variability indicate that potential generation from paleocene and older strata occurred mainly before the late oligocene the generation from eocene strata however occurred mainly during the miocene and therefore is interpreted to be a source for oligocene and younger gas rich reservoirs these findings contribute to a better understanding of hydrocarbon systems in the mackenzie basin and are the basis for future studies of hydrocarbon migration and accumulation

multibeam bathymetric survey and high resolution seismic investigations on the barbados ridge complex eastern caribbean a key to the knowledge and interpretation of an accretionary wedge abstract an important problem of active margin processes is the way accretionary wedges form in response to oceanic crust subduction new data have been obtained along the barbados ridge in front of the lesser antilles tertiary island arc they include high resolution multichannel seismic data and accurate sea beam bathymetric maps both have been used to propose a 3 dimensional interpretation of tectonic and sedimentary processes related to subduction such as oceanic off scraping ductile folding relative uplift and subsidence fore arc basin evolution and mud diapirism they all improved our knowledge of the evolution of accretionary prisms and more specifically of the barbados ridge development in plio quaternary time previous tectonic events are deduced from recently published geological data from barbados and the lesser antilles islands

liquefied vs stratified sediment mobilization processes insight from the south of the barbados accretionary prism this paper discusses the nature and origin of subsurface sediment mobilization processes in deep marine clay rich environments in the studied area of the southern barbados accretionary prism new geophysical acquisitions have emphasized the spectacular widespread development of mud volcanoes that are well developed along ramp anticlines and along sigmoidal rises with trends that are oblique to the axes of the main folds of the accretionary wedge on some active mud volcanoes heat flow measurements show high positive anomalies related to high fluxes of mud transfer the mobilized solid fraction expelled by the mud volcanoes does not originate from a unique source bed but from various formations pierced by the mud conduits and is driven by the water phase the area studied also exhibits trends of structures corresponding to sub circular massive local uplifts of deformed but well preserved stratified sediments turbidites and hemipelagics no piercing shale diapirs have been encountered in this area some of these local uplift structures are complicated by the development of collapses calderas and superimposed mud volcanoes mud volcanism corresponds fundamentally to fluid displacement water and gas whereas massive sedimentary uplift corresponds to large vertical displacements of stratified solid levels but for which the deep cause could be partly the intrusion of mud plugs both are dynamic phenomena controlled by the development of overpressure at depth contributing to sedimentary mobilizations

morphology and activity of the helgoland mud volcano in the sorokin trough northern black sea abstract morphological change and activity of submarine mud volcanoes mvs are still poorly understood in this study we integrated acoustic subbottom profiles autonomous underwater vehicle auv high resolution bathymetric and backscatter data remotely operated vehicle rov seafloor observations bottom water temperatures bwt and compositions of gas samples collected from three research expeditions to study the morphology and activity of the helgoland mud volcano helgoland mv in the sorokin trough of the black sea based on the micro bathymetric and backscatter maps we conducted a geomorphological analysis which differentiates the helgoland mv into five regions which are the active center the inner crest the inner moat the outer crest and an outer moat special seafloor features such as gas bubble emissions mud breccia and mud pools were observed in different regions by rov observations they indicate a heterogeneous distribution of materials and activities at the helgoland mv active mud extrusion from the center was inferred from bwt elevations up to 1 652 c that showed the same orientation as a major fault nw se at the location methane stable carbon isotopes 58 1 63 6 and molecular compositions of light hydrocarbons c1 c2 2836 ch4 99 545 c2h6 0 033 c3h8 0 002 co2 0 417 suggest a predominance of biogenic hydrocarbons with an admixture of thermogenic gas circular faults surrounding the helgoland mv as observed in the bathymetric and sub bottom profiles are speculated to be formed due to subsidence of the mv caldera and gravity driven sediment movement a conceptual model is proposed to explain the interrelationship between the seafloor morphology and activity of the helgoland mv combining multidisciplinary data especially from the application of rovs and auvs broaden the scope in which the activity and morphology of submarine mud volcanoes can be investigated

hydrothermal changes related to earthquake activity at mud volcano yellowstone national park wyoming the mud volcano hydrothermal area in yellowstone national park is near the intersection of a 20 km long zone of northeast trending normal faults with the eastern resurgent dome within the 600 000 year old yellowstone caldera recent crustal uplift along the northeast trending axis of the caldera is at a maximum 700 mm since 1923 near the mud volcano area from 1973 through april 1978 less than 10 earthquakes largest m 2 4 were located within 3 km of the mud volcano area in may 1978 earthquakes began occurring beneath the hydrothermal area at depths of 1 to 5 km the seismic activity continued until the end of november with intense swarms 100 events per hour occurring on october 23 and november 7 the largest event m 3 1 occurred on november 14 and at least 8 events were m 2 5 or larger in december 1978 heat flux in the mud volcano hydrothermal features began increasing along a 2 km long northeast trending zone existing mud cauldrons became more active new mud cauldrons and fumeroles were formed and vegetation primarily lodgepole pine was killed by increased soil temperature the increase in heat flux continued through july 1979 then gradually declined reaching the early 1978 level by june 1980 the spatial and temporal association of earthquakes and increased hydrothermal activity at mud volcano suggests that the seismic activity expanded preexisting fracture systems premitting increased fluid flow from depths of several kilometers

mud volcanism and fluid geochemistry in the cheleken peninsula western turkmenistan abstract a geological and geochemical study has been carried out to investigate the relationships between major mud volcano structures and deep fluid migration in the cheleken peninsula in the south caspian basin the fluid geochemistry allowed the origin and migration of the saline waters and the hydrocarbons to be deduced along with the regional source and reservoir rocks the emitted waters formed by the mixing of deep highly saline water from the main source rocks of the maykop fm with the caspian like pore water contained in the pliocene reservoirs the water composition is very similar to that emitted by the mud volcanoes in azerbaijan allowing comparisons to be done between the reservoirs in the western and eastern sides of the south caspian basin the associated oil is derived from a mixed type ii iii kerogen deposited in a sub oxic marine environment and generated during the early oil window the oil biomarkers indicate that the source rock is the maykop fm as previously determined for the other areas of the south caspian basin the spontaneous emissions showing different morphologies are mainly aligned along normal and transtensive fault systems which provide effective pathways for rapid fluid ascent from deep reservoirs to the surface

probabilistic longevity estimate for the lusi mud volcano east java abstract a new method for estimating the duration of a mud volcano eruption is applied to the lusi mud volcano in east java the estimate is based upon carbonates at depths in the range 2500 3500 m being the water source with an estimated area of 100 600 km 2 thickness of 0 2 1 0 km porosity of 0 15 0 25 an initial pressure between 13 9 and 17 6 mpa and a separate shallower source of mud c 1200 1800 m depth the resulting 50 percentile for the time it takes for flow to decline to 1 is 26 years by analogy with natural mud volcanoes it can be expected to continue to flow at lower rates for thousands of years assuming subsidence rates of between 1 and 5 cm day 1 land surface subsidence of between c 95 and c 475 m can be expected to develop within the 26 year time period

abstract mud volcanoes of the south caspian basin seismic data and implications for hydrocarbon systems mud volcanoes and their associated hydrocarbon seeps brought the oil business to azerbaijan yet it is only recently that high quality 3d seismic data has been available to integrate with geological data and this document how these features work the data illustrates their regional context and allows us to consider their substantial implications for hydrocarbon systems of the south caspian basin scb

characteristics of mixed sporopollen assemblage from sediments of dushanzi mud volcano in southern junggar basin and indication to the source of mud and debris ejecta in order to search for the source of muddy eruption debris a series of erupted mud samples were collected from a corn of the dushanzi mud volcanoes in southern junggar basin nw china and analyzed for palynological records two palynomorph groups were revealed in the mixed sporopollen assemblage from the erupted sediments according to their colors the light color group accounting for about 95 of the total was dominated by the chenopodiaceae and artemisia and in a color of faint yellow indicating an immature stage of organic matter evolution the dark color group was composed of cyathidites classopollis schizaeoisporites lygodiumsporites and rugubivesiculites in a color of brown yellow indicating a low maturity to maturity stage of organic matter evolution the palynomorph records suggested that most of the muddy debris ejecta of the dushanzi mud volcano might be sourced from the cenozoic deposits mainly the middle late miocene taxihe and dushanzi formations and a small portion likely from the lower cretaceous tugulu group in addition there is also a possibility that a little part of eruption debris is from the upper jurassic qigu formation the dushanzi anticline occurred strong extrusion and thrust faults in the late himalayan period and the oil and gas reservoirs were destroyed and resulted in eruption of the mud volcano in the dushanzi area