Landslide susceptibility prediction(LSP)is significantly affected by the uncertainty issue of landslide related conditioning factor selection.However,most of literature only performs comparative studies on a certain c...Landslide susceptibility prediction(LSP)is significantly affected by the uncertainty issue of landslide related conditioning factor selection.However,most of literature only performs comparative studies on a certain conditioning factor selection method rather than systematically study this uncertainty issue.Targeted,this study aims to systematically explore the influence rules of various commonly used conditioning factor selection methods on LSP,and on this basis to innovatively propose a principle with universal application for optimal selection of conditioning factors.An'yuan County in southern China is taken as example considering 431 landslides and 29 types of conditioning factors.Five commonly used factor selection methods,namely,the correlation analysis(CA),linear regression(LR),principal component analysis(PCA),rough set(RS)and artificial neural network(ANN),are applied to select the optimal factor combinations from the original 29 conditioning factors.The factor selection results are then used as inputs of four types of common machine learning models to construct 20 types of combined models,such as CA-multilayer perceptron,CA-random forest.Additionally,multifactor-based multilayer perceptron random forest models that selecting conditioning factors based on the proposed principle of“accurate data,rich types,clear significance,feasible operation and avoiding duplication”are constructed for comparisons.Finally,the LSP uncertainties are evaluated by the accuracy,susceptibility index distribution,etc.Results show that:(1)multifactor-based models have generally higher LSP performance and lower uncertainties than those of factors selection-based models;(2)Influence degree of different machine learning on LSP accuracy is greater than that of different factor selection methods.Conclusively,the above commonly used conditioning factor selection methods are not ideal for improving LSP performance and may complicate the LSP processes.In contrast,a satisfied combination of conditioning factors can be constructed according to the proposed principle.展开更多
Hydrocarbons are one of the important fluids within the Earth's crust,and different biotic and abitoic processes can generate hydrocarbon during geological periods.Tracing the sources and sinks of hydrocarbons can...Hydrocarbons are one of the important fluids within the Earth's crust,and different biotic and abitoic processes can generate hydrocarbon during geological periods.Tracing the sources and sinks of hydrocarbons can help us better understand the carbon cycle of the earth.In this study,an improved approach of adsorbed hydrocarbons extraction from sediments was established.The improved thermal desorption approach,compound-specific isotope analysis and position-specific isotope analysis were integrated to investigate the molecular and intramolecular isotope fractionation between trace hydrocarbon gases within sediments and geological hydrocarbon deposits.The isotopic compositions of the terminal position carbon of propane(δ^(13)C_(terminal))serves as a correlation indicator between trace hydrocarbon gases within sediments and geological hydrocarbon deposits.The tight sandstone gas from the Turpan-Hami Basin is a first case study for the application of this novel method to trace hydrocarbon origins.The results showed that the hydrocarbons in the tight sandstone gases in the study area most likely originated from humic organic matter(typeⅢkerogen)at an early mature stage.δ^(13)C_(terminal)values of the thermally desorbed propane gases from different source rocks were distinguishable and the values of the tight sandstone gases significantly overlap with those of the Lower Jurassic Sangonghe source rocks,suggesting their genetic relationship.Overall,the results provided novel position-specific carbon isotopic constraints on origins of hydrocarbons.展开更多
Overpressure prediction for exploratory drilling has become robust in most basins with increasing well control,high-quality seismic datasets,and proactive real-time overpressure monitoring while drilling.However,accur...Overpressure prediction for exploratory drilling has become robust in most basins with increasing well control,high-quality seismic datasets,and proactive real-time overpressure monitoring while drilling.However,accurate overpressure prediction remains challenging in offshore Northwest Borneo despite several decades of drilling experience.This paper focuses on two exploration wells drilled by Brunei Shell Petroleum 40 years apart that faced similar challenges with overpressure prediction and well control.An integrated lookback study is attempted using seismic and well-log data to explore the causes of the unsatisfactory Pore Pressure Prediction(PPP)outcome in pre-drill and real-time operation settings for thesewells.Our study indicates that the misprediction of overpressures is due to real differences in shale pressure(basis of pre-drill work and monitoring)and sand pressure(source of drill kick and well control chal-lenges)due to large-scale vertical leak or expulsion of deep-seated fluids into pre-compacted normally pressured overlying sediments in several regions through a mix of shear and tensile failure mechanisms.Such migrated fluids inflate the sand pressure in the normally compacted shallower sequences with the shale pressure remaining low.A predictive framework for upward fluid expulsion was attempted but found impracticable due to complex spatial and temporal variations in the horizontal stress field responsible for such leakage.As such,it is proposed that these migratory overpressures are essentially'unpredictable'from conventional PPP workflows viewed in the broad bucket of compaction disequi-librium(undercompaction)and fluid expansion(unloading)mechanisms.Further study is recommended to understand if such migrated overpressures in the sand can produce a discernible and predictable geophysical or petrophysical signature in the abutting normally compacted shales.The study highlights the possibility of large lateral variability in the sand overpressure within the same stratigraphic unit in regions with complex tectonostratigraphic evolution like Northwest Borneo.展开更多
An integrated study on source rock characterization and hydrocarbon generation potential modeling was conducted for the selected Dingo Claystone,Barrow Sub-basin,Australia.In this study,data were collected solely from...An integrated study on source rock characterization and hydrocarbon generation potential modeling was conducted for the selected Dingo Claystone,Barrow Sub-basin,Australia.In this study,data were collected solely from two wells represented by the Bambra-1 and Bambra-2 wells.The collected data include those from bulk geochemical analyses of cuttings and sidewall cores sampled from the Late Jurassic Dingo Claystone.Geochemical data obtained from Rock-Eval pyrolysis and gas chromatography(GC)of extracted organic matter were integrated for source rock characterization and the construction of burial history and hydrocarbon generation in the Dingo Claystone.To improve the accuracy of thermal maturity estimations,only samples with S2 greater than 1 were considered due to potential issues with peak integration and uncertainties of Tmax determination in samples with lower S2 values.Furthermore,Rock-Eval data from the Bambra wells may be unreliable due to the contamination of cuttings and sidewall core(SWC)samples by drilling mud additives and natural hydrocarbons,which could impact the reliability of the data for determining thermal maturity.This study reveals that the Dingo Claystone Formation has total organic carbon(TOC)contents ranging from 0.66%to 8.31%.A poor to good hydrocarbon generation potential is indicated,with a production yield(PY=S_(1)+S_(2))ranging from 1.37 to 10.44 mg HC/g rock.Hydrogen index values vary between 42 and 226 mg HC/g TOC,confirming that the Dingo Claystone is dominantly kerogen TypeⅢ,with minor contributions from typesⅡ/ⅢandⅣ.Thermal maturity ranges from immature to late mature and is mostly in the oil window.This is indicated by T_(max)values of 398-462℃and vitrinite reflectance(Ro,%)of 0.47-1.99.Some samples show suppressed T_(max)and a higher production index,which is typical for samples affected by drilling fluids during drilling operations.Additionally,gas chromatography(GC)analyses are used to interpret the paleodepositional environment showing mixed input between marine and terrestrial origins of the source rocks.One-dimensional basin modeling for the Bambra-1 and Bambra-2 wells was carried out to evaluate the burial and thermal history of the formation.The transformation ratio suggests that hydrocarbon generation has not reached its peak and is still in an ongoing phase.An indication of hydrocarbon migration can be observed in this formation based on the transformation ratio.The effects of contamination warrant further investigation,as it could significantly impact maturity estimates and data reliability.展开更多
0 INTRODUTION The Kuqa Depression,situated along the northern margin of the Tarim Basin,holds substantial geological significance due to its intricate sedimentary burial history,tectonic history,and the evolution of h...0 INTRODUTION The Kuqa Depression,situated along the northern margin of the Tarim Basin,holds substantial geological significance due to its intricate sedimentary burial history,tectonic history,and the evolution of hydrocarbon source rocks(Jiang et al.,2024;Zhang et al.,2023;Huang et al.,2019;Yang et al.,2017;Jia et al.,2003;Hendrix,2000).展开更多
The offshore Tanzanian Basin contains numerous igneous intrusions emplaced at various stratigraphic levels.Previous studies indicate these intrusions have impacted petroleum systems,affecting key elements such as sour...The offshore Tanzanian Basin contains numerous igneous intrusions emplaced at various stratigraphic levels.Previous studies indicate these intrusions have impacted petroleum systems,affecting key elements such as source rocks,reservoirs,seals,migration pathways,and trapping mechanisms.However,due to the limited number of wells drilled in the region,there have been few studies reporting the associated thermal effects on source rock maturation and their role in hydrocarbon generation.To gain a comprehensive understanding of the intricate relationship between intrusions and the petroleum system,particularly source rock,an integrated geochemical and resistivity log analysis was carried out.The geochemical results show that the Cretaceous-Cenozoic sediments of the study area have low total organic carbon contents(TOC<1 wt%),kerogen yield(<1 Mg HC/g),and Hydrogen Index(<100 Mg HC/g),primarily composed of TypeⅢ(gas-prone)to TypeⅣ(inert)kerogens.These sediments have undergone varying levels of thermal maturity,ranging from post-mature(within Cretaceous),matured(in Paleocene)to immature(in Eocene)thermal states.The Cretaceous strata located proximal to the intrusions exhibit significant thermal alteration,resulting in a reduction of both organic matter(OM)content and source potential compared to the Eocene and Paleocene samples.This observation is consistent with the estimated paleotemperature(T)and resistivity log(ILD)along the depth profile,which have mapped local thermal alteration increasing from base Paleocene to Cretaceous.These findings have implications for source rock potential and thermal evolution history in the offshore Tanzanian Basin.This study highlights the necessity for thorough subsurface mapping in the area to identify both younger and older intrusive rocks.These intrusions pose a potential risk in petroleum exploration,especially when they intrude into matured source rock intervals.展开更多
Conventional borehole image log interpretation of linear fractures on volcanic rocks,represented as sinusoids on unwrapped cylinder projections,is relatively straight-forward,however,interpreting non-linear rock struc...Conventional borehole image log interpretation of linear fractures on volcanic rocks,represented as sinusoids on unwrapped cylinder projections,is relatively straight-forward,however,interpreting non-linear rock structures and complex facies geometries can be more challenging.To characterize diverse volcanic paleoenvironments related to the formation of the South American continent,this study presents a new methodology based on image logs,petrography,seismic data,and outcrop analogues.The presented methodology used pseudo-boreholes images generated from outcrop photographs with typical igneous rock features worldwide simulating 2D unwrapped cylinder projections of a 31 cm(12.25 in)diameter well.These synthetic images and standard outcrop photographs were used to define morphological patterns of igneous structures and facies for comparison with wireline borehole image logs from subsurface volcanic and subvolcanic units,providing a“visual scale”for geological evaluation of volcanic facies,significantly enhancing the identification efficiency and reliability of complex geological structures.Our analysis focused on various scales of columnar jointing and pillow lava lobes with additional examples including pahoehoe lava,ignimbrite,hyaloclastite,and various intrusive features in Campos,Santos,and Parnaíba basins in Brazil.This approach increases confidence in the interpretation of subvolcanic,subaerial,and subaqueous deposits.The image log interpretation combined with regional geological knowledge has enabled paleoenvironmental insights into the rift magmatism system related to the breakup of Gondwana with associated implications for hydrocarbon exploration.展开更多
Open pit mining operations generate significant spoil dumps that need to be characterised for stability to identify potentially unstable slopes.However,the current subjective practice for spoil characterisation often ...Open pit mining operations generate significant spoil dumps that need to be characterised for stability to identify potentially unstable slopes.However,the current subjective practice for spoil characterisation often involves tedious and risky field work.To this end,this study demonstrated the use of periodically acquired unmanned aerial vehicle(UAV)-based images over a coal mine spoil dump in New South Wales,Australia.A granular approach that captures the variability of each truck offload pile on a dump was adopted through morphology-based segmentation and ensemble algorithm-based classification which consolidates predictions from multiple classifiers.Overall accuracy of over 90% in the material characterisation based on the classification framework was achieved.The two-dimensional classification outcome was then transformed into three-dimensional(3D)block models using a point-based interpolation approach for stability analysis.The factor of safety derived from the granular approach offered improved assessment of failure risk compared to the conventional approaches,which treat the entire dump as a uniform category.This rapid classification and assessment method proposed in this study will help reduce the uncertainty associated with the variability of spoil dumps in slope stability assessments,thereby enhancing the safety and efficiency of mining operations.展开更多
The spatial distribution of overburden layer thickness(OLT)is crucial for landslide susceptibility prediction and slope stability analysis.Due to OLT spatial heterogeneity in hillslope regions,combined with the diffic...The spatial distribution of overburden layer thickness(OLT)is crucial for landslide susceptibility prediction and slope stability analysis.Due to OLT spatial heterogeneity in hillslope regions,combined with the difficulty and time consumption of OLT sample collection,accurately predicting OLT distribution remains a challenging.To address this,a novel framework has been developed.First,OLT samples are collected through field surveys,remote sensing,and geological drilling.Next,the heterogeneity of OLT’s spatial distribution is analyzed using the probability distribution of OLT samples and their horizontal and vertical distributions.The OLT samples are categorized and the small sample categories are expanded using the synthetic minority over-sampling technique(SMOTE).The slope position is selected as a key conditioning factor.Subsequently,16 conditioning factors are applied to construct OLT prediction model using the random forest regression algorithm.Weights are assigned to each OLT sample category to balance the uneven distribution of sample sizes.Finally,the Pearson correlation coefficient,mean absolute error(MAE),root mean square error(RMSE),and Lin’s concordance correlation coefficient(Lin’s CCC)are employed to validate the OLT prediction results.The Huangtan town serves as the case study.Results show:(1)heterogeneity analysis,SMOTE-based OLT sample expansion strategy and slope position selection can significantly mitigate the effect of spatial heterogeneity on OLT prediction.(2)The Pearson correlation coefficient,RMSE,MAE and Lin’s CCC values are 0.84,1.173,1.378 and 0.804,respectively,indicating excellent prediction performance.This research provides an effective solution for predicting OLT distribution in hillslope regions.展开更多
Minor errors in the spoil deposition process,such as placing stronger materials with higher shear strength over weaker ones,can lead to potential dump failure.Irregular deposition and inadequate compaction complicate ...Minor errors in the spoil deposition process,such as placing stronger materials with higher shear strength over weaker ones,can lead to potential dump failure.Irregular deposition and inadequate compaction complicate coal spoil behaviour,neces-sitating a robust methodology for temporal monitoring.This study explores using unmanned aerial vehicles(UAV)equipped with red-green-blue(RGB)sensors for efficient data acquisition.Despite their prevalence,raw UAV data exhibit temporal inconsistency,hindering accurate assessments of changes over time which could be attributed to radiometric errors.To this end,the study introduces an empirical line calibration with invariant targets(ELC-IT),for precise calibration across diverse scenes,particularly in the context of UAV imagery used to monitor the evolving nature of spoil dumps.To evaluate the effec-tiveness of this calibration approach,accuracy assessment of an object-based classification is conducted on both calibrated and uncalibrated data.This classification involves several steps:performing segmentation,carrying out feature extraction,and integrating the extracted features and ground truth labels collected over the time period of UAV image capture into machine learning pipelines.Calibrated RGB data exhibit a substantial performance advantage,achieving a 90.7%overall accuracy for spoil pile classification using ensemble(subspace discriminant),representing a noteworthy 7%improvement compared to classifying uncalibrated data.The study highlights the critical role of data calibration in optimising UAV effectiveness for spatio-temporal mine dump monitoring.These findings play a crucial role in informing and refining sustainable management practices within the domain of mine waste management.展开更多
Shrubland expansion is a globally occurring phenomenon under global change and has caused a wide range of ecological consequences.However,due to the visual similarity between shrubland and grassland,the accuracy of sh...Shrubland expansion is a globally occurring phenomenon under global change and has caused a wide range of ecological consequences.However,due to the visual similarity between shrubland and grassland,the accuracy of shrubland interpretation and its spatial distribution varies across different products,making shrub encroachment on the Tibetan Plateau(TP)uncertain.To address these challenges,we developed a phenology-based and pixel-wise method utilizing the Landsat,Sentinel-1,and Sentinel-2 image archives to map shrubland distribution from 1990 to 2022 across the TP.We also investigated the factors affecting shrubland distribution.Using the Random Forest(RF)model,we achieved moderate to high accuracies(Kappa=0.70–0.81)in predicting shrubland d istributions,and we found that shrubland primarily occupies transitional zones between forest and grassland.In the southeast TP,solar radiation intensity is the dominant factor explaining the spatial distribution of shrubland,whereas in arid regions,water availability is the most important.From 1990 to 2022,the shrubland area slightly increased from 3.40%to 4.71%,with expansion showing a clustered pattern,mainly in the shaded aspects of arid regions.The shrubland identification method proposed here shows potential applicability in other areas with similar environmental conditions,such as arid landscapes or high-altitude ecosystems with pronounced seasonal vegetation dynamics.It also plays a crucial role in evaluating vegetation responses to climatic changes.展开更多
Iron oxide-copper–gold(IOCG)deposits encompass a diverse set of mineralization styles,leading to outstanding questions about how different alteration facies are related across a single ore-producing system and the ov...Iron oxide-copper–gold(IOCG)deposits encompass a diverse set of mineralization styles,leading to outstanding questions about how different alteration facies are related across a single ore-producing system and the overarching mechanisms of ore genesis.This study investigates the age and characteristics of mineralization at the La Farola deposit,a hematite-dominated IOCG deposit located at the southern margin of the Candelaria-Punta del Cobre IOCG district of northern Chile.Two lithologically-controlled ore bodies occur along the WSW-ENE striking,∼18°NNW-dipping contact between the Lower Cretaceous Chañarcillo Group and Punta del Cobre Formation.Syn-mineralization N-S to NNW-SSE striking sinistral strike-slip faults likely acted as fluid pathways.Distinct mineral assemblages include an early Na-Ca assemblage(albite-scapolite)overprinted by skarnoid garnet with minor pyroxene,Ca-Fe(magnetite-actinolite),and K-Fe(magnetite-k-feldspar-biotite and minor sulfides)assemblages.The main sulfide mineralization(chalcopyrite-pyrite with minor bornite)is associated with specular hematite-white mica-K-feldspar-calcite and overprints all previous assemblages.The presence of hematite as the dominant Fe-oxide phase associated with Cu mineralization is characteristic of lower-temperature IOCG deposits,and may be a result of La Farola’s stratigraphic position<700 m higher than other deposits in the district.New U-Pb ages of 115.7±1.2 Ma for garnet and Re-Os ages of∼113–114 Ma for sulfides indicate mineralization occurred within a 3-million-year timeframe.These findings confirm hematite-dominant mineralization at La Farola was coeval with IOCG mineralization across the district.This research contributes to understanding IOCG systems and their formation mechanisms,highlighting the control local geological structures and alteration processes has on the diversity of mineralization types associated with a single IOCG system.展开更多
Assessing the benefits and costs of digitalization in the energy industry is a complex issue.Traditional cost-benefit analysis(CBA)might encounter problems in addressing uncertainties,dynamic stakeholder interactions,...Assessing the benefits and costs of digitalization in the energy industry is a complex issue.Traditional cost-benefit analysis(CBA)might encounter problems in addressing uncertainties,dynamic stakeholder interactions,and feedback loops arising out of the evolving nature of digitalization.This paper introduces a methodological framework to help address the intricate inter connections between digital applications and business models in the energy industry.The proposed framework leverages system dynamics to achieve two primary objectives.It investigates how digitalization generally influences the value proposi-tion,value capture,and value creation dimensions of business models.It also quantifies the financial and social impacts of digitalization from a dynamic perspective.The proposed dynamic CBA allows for a more precise quantification of the benefits and costs,associated with evidence-based decision-making.Findings from an illustrative case study challenge the static assumptions of conventional methods.These methods often presume continuous operation,neglecting reinvestment and operational feedback loops,and resulting in negative net present values.Conversely,the outcomes of the proposed method indicate positive net present values when accounting for factors such as reinvestment rates and the will-ingness to invest in digitalization projects.The principles outlined in this paper can enable a more accu-rate assessment of digitalization projects,thus catalyzing the development of new CBA applications and guidelines for digitalization.展开更多
Surge-type glaciers are widely developed in mountainous areas around the world.Understanding the trigger mechanism of glacier surge is a prerequisite for addressing their impacts on hydrological assessments,disentangl...Surge-type glaciers are widely developed in mountainous areas around the world.Understanding the trigger mechanism of glacier surge is a prerequisite for addressing their impacts on hydrological assessments,disentangling climate-glacier linkages,and mitigating downstream hazards.Most glacier surges occur in the compound glaciers;however,attention paid to the trigger mechanisms of such surges is minimal.This study confirmed two surges in the northern and southern branches of the Aru-4 glacier,respectively,in the Western Tibetan Plateau,using multisource remote sensing data.The northern branch of the Aru-4 glacier entered the active phase in 1999 and the active phase lasted for 6 years.The southern branch of the Aru-4 glacier entered the active phase in 2007 and the active phase lasted for 9 years.The southern branch of the Aru-4 glacier experienced a long period of retreat before the northern branch surged and their tongues were in a detached state.The northern branch surge carried a large amount of ice to the frontal area,blocking the downward transport of ice from the southern branch and initiated surge.Through the analysis of two surge processes of Aru-4 glacier,we found a new surge mechanism for compound glaciers.It was revealed that surges in such glaciers are not only triggered by the reduction in basal sliding resistance caused by the internal factors.These surges initiated in the upper part of the glacier then propagated to down glacier by intense compression force.Furthermore,surges can also be triggered by external intervention of blocking by other branches.This external trigger initiates the surge in the lower part of the glacier then propagated to the upper part by longitudinal traction force.In addition,comparing with the surge triggered by the internal factors,the surge triggered by the external intervention may have a more dramatic process.展开更多
The Late Paleozoic marked Earth’s most recent icehouse–greenhouse transition,providing valuable insights into future climate and environmental changes.Although the aridification of the North China Craton(NCC)during ...The Late Paleozoic marked Earth’s most recent icehouse–greenhouse transition,providing valuable insights into future climate and environmental changes.Although the aridification of the North China Craton(NCC)during the Late Paleozoic is well established,its pattern and causes remain unclear.Here,we identify four aridification intervals from the late Gzhelian to Lopingian by analyzing continuous records of elemental climate proxies(MgO/CaO,Sr/Cu),a volcanism proxy(Hg/TOC),and spore–pollen assemblages.Interval I(∼303–295 Ma),during which the NCC was located at low paleolatitudes,was characterized by humid conditions and a predominance of ferns,associated with weak volcanism.Interval II(∼295–286 Ma)was subhumid,with increasing gymnosperm presence,and significant climate fluctuations linked to volcanism.CO_(2) emissions from the Tarim LIP and Panjal Traps drove aridification from the late Asselian to late Artinskian,contributing to the decline of the Late Paleozoic Ice Age.As a result,aridification in the NCC lagged behind that of Pangea.Interval III(∼286–280.98 Ma)marked the transition to subarid conditions and the onset of dominance by gymnosperms,associated with a rapid northward drift of the NCC and an increase in atmosphericρCO_(2).Interval IV(∼259.51–251.902 Ma),separated from the underlying Interval III by a major regional unconformity(∼280.98–259.51),coincided with global aridification and intensified volcanism.These findings highlight the significant influences of both tectonic plate motion and volcanism on the climate evolution of the NCC,with shifts in the dominant controlling factors through time.This study provides new insights into the distinct trajectories of global and regional climate dynamics.展开更多
The environmental magnetic proxies of stalagmites hold significant potential for reconstructing regional hydroclimate changes by revealing the content and grain size of magnetic particles within stalagmites.In this st...The environmental magnetic proxies of stalagmites hold significant potential for reconstructing regional hydroclimate changes by revealing the content and grain size of magnetic particles within stalagmites.In this study,we present the contents and grain sizes of magnetic particles within a stalagmite SZ-1,from Shizhu Cave in southwestern China from 70.4 to 22.3 thousand years ago(ka)during the last glacial period.Specifically,the parameters IRM_(soft),soil-derived magnetic minerals,and ARM/SIRM(anhysteretic remanent magnetization/saturation isothermal remanent magnetization),the ratio of fine magnetic particles to total ferrimagnetic particles preserved in stalagmite SZ-1,indicate the fluctuation of regional precipitation.Obvious half-precessional cycles are evident in these two proxies,indicating that hydroclimatic variations in southwestern China may predominantly arise from the heat and moisture transported from tropical oceans.These variations are likely influenced by shifts in the Intertropical Convergence Zone and fluctuations in the Asian Summer Monsoon.展开更多
In common practice in the oil fields,the injection of water and gas into reservoirs is a crucial technique to increase production.The control of the waterflooding front in oil/gas exploitation is a matter of great con...In common practice in the oil fields,the injection of water and gas into reservoirs is a crucial technique to increase production.The control of the waterflooding front in oil/gas exploitation is a matter of great concern to reservoir engineers.Monitoring the waterflooding front in oil/gas wells plays a very important role in adjusting the well network and later in production,taking advantage of the remaining oil po-tential and ultimately achieving great success in improving the recovery rate.For a long time,micro-seismic monitoring,numerical simulation,four-dimensional seismic and other methods have been widely used in waterflooding front monitoring.However,reconciling their reliability and cost poses a significant challenge.In order to achieve real-time,reliable and cost-effective monitoring,we propose an innovative method for waterflooding front monitoring through the similarity analysis of passive source time-lapse seismic images.Typically,passive source seismic data collected from oil fields have extremely low signal-to-noise ratio(SNR),which poses a serious problem for obtaining structural images.The proposed method aims to visualize and analyze underground changes by highlighting time-lapse images and provide a strategy for underground monitoring using long-term passive source data under low SNR conditions.First,we verify the feasibility of the proposed method by designing a theoretical model.Then,we conduct an analysis of the correlation coefficient(similarity)on the passive source time-lapse seismic imaging results to enhance the image differences and identify the simulated waterflooding fronts.Finally,the proposed method is applied to the actual waterflooding front monitoring tasks in Shengli Oilfield,China.The research findings indicate that the monitoring results are consistent with the actual devel-opment conditions,which in turn demonstrates that the proposed method has great potential for practical application and is very suitable for monitoring common development tasks in oil fields.展开更多
Natural fractures controlled by faults in ultradeep carbonate strata play substantial roles as both fluid migration channels and storage spaces.However,characterizing the heterogeneous distribution of underground frac...Natural fractures controlled by faults in ultradeep carbonate strata play substantial roles as both fluid migration channels and storage spaces.However,characterizing the heterogeneous distribution of underground fractures within the complex three-dimensional geometry of strike-slip fault zones remains challenging.This study investigates the characteristics of natural fractures controlled by strike-slip faults in the fractured Middle and Lower Ordovician reservoirs of the central and northern Tarim Basin,China.Seismics,cores,and image logs were integrated to quantitatively analyze the intensity and dip angle of natural fractures and findings were verified using published sandbox simulations.The carbonate reservoir contains three main types of natural fractures:tectonic fractures,abnormal high-pressure-related fractures,and stylolites.Strike-slip faults control the distribution and characteristics of tectonic fractures across various scales.Generally,both fracture intensity and porosity exhibit a decreasing trend as the distance from the main fault surface increases.Compared with those in non-stepover zones along a strike-slip fault,natural fractures and faults in stepover zones are more developed along the fault strike,with significantly greater development intensity in central stepover regions than that at its two ends.Furthermore,strike-slip faults influence the dip angles of both natural fractures and secondary faults.The proportion of medium-to-low-dip angle fractures and faults in the stepover zone is greater than that in the non-stepover zone.Additionally,the proportion of medium-to low-dip angle fractures and faults in the middle of the stepover is greater than that at both ends.Therefore,strike-slip fault structures control the dip angle of natural fracture and the heterogeneity of secondary fault and fracture intensity.The linking damage zone in the stepover contains a larger volume of fractured rocks,making it a promising petroleum exploration target.The development of stepovers and the orientation of present-day in-situ stress substantially influence the productivity of fractured reservoirs controlled by strike-slip faults.The analysis in this study reveals that reservoir productivity increases as the angle between the strike-slip fault segment and the maximum horizontal principal stress decreases.This study provides valuable insights for quantitatively evaluating fracture heterogeneity in fractured reservoirs and establishing optimized selection criteria for favorable targets in fault-related fractured reservoirs.展开更多
The Pressure-Volume-Temperature(PVT)properties of crude oil are typically determined through laboratory analysis during the early phases of exploration and fielddevelopment.However,due to extensive data required,time-...The Pressure-Volume-Temperature(PVT)properties of crude oil are typically determined through laboratory analysis during the early phases of exploration and fielddevelopment.However,due to extensive data required,time-consuming nature,and high costs,laboratory methods are often not preferred.Machine learning,with its efficiencyand rapid convergence,has emerged as a promising alternative for PVT properties estimation.This study employs the modified particle swarm optimization-based group method of data handling(PSO-GMDH)to develop predictive models for estimating both the oil formation volume factor(OFVF)and bubble point pressure(P_(b)).Data from the Mpyo oil fieldin Uganda were used to create the models.The input parameters included solution gas-oil ratio(R_(s)),oil American Petroleum Institute gravity(API),specificgravity(SG),and reservoir temperature(T).The results demonstrated that PSO-GMDH outperformed backpropagation neural networks(BPNN)and radial basis function neural networks(RBFNN),achieving higher correlation coefficientsand lower prediction errors during training and testing.For OFVF prediction,PSO-GMDH yielded a correlation coefficient(R)of 0.9979(training)and 0.9876(testing),with corresponding root mean square error(RMSE)values of 0.0021 and 0.0099,and mean absolute error(MAE)values of 0.00055 and 0.00256,respectively.For P_(b)prediction,R was 0.9994(training)and 0.9876(testing),with RMSE values of 6.08 and 8.26,and MAE values of 1.35 and 2.63.The study also revealed that R_(s)significantlyimpacts OFVF and P_(b)predictions compared to other input parameters.The models followed physical laws and remained stable,demonstrating that PSO-GMDH is a robust and efficientmethod for predicting OFVF and P_(b),offering a time and cost-effective alternative.展开更多
The West Kunlun orogenic belt(WKOB) along the northern margin of the Tibetan Plateau is important for understanding the evolution of the Proto-and Paleo-Tethys oceans. Previous investigations have focused on the igneo...The West Kunlun orogenic belt(WKOB) along the northern margin of the Tibetan Plateau is important for understanding the evolution of the Proto-and Paleo-Tethys oceans. Previous investigations have focused on the igneous rocks and ophiolites distributed mostly along the Xinjiang-Tibet road and the China-Pakistan road, and have constructed a preliminary tectonic model for this orogenic belt. However, few studies have focused on the so-called Precambrian basement in this area. As a result, the tectonic affinity of the individual terranes of the WKOB and their detailed evolution process are uncertain. Here we report new field observations, zircon and monazite U-Pb ages of the "Precambrian basement" of the South Kunlun terrane(SKT) and the Tianshuihai terrane(TSHT), two major terranes in the WKOB. Based on new zircon U-Pb age data, the amphibolite-facies metamorphosed volcanosedimentary sequence within SKT was deposited during the late Neoproterozoic to Cambrian(600-500 Ma), and the flysch-affinity Tianshuihai Group, as the basement of the TSHT, was deposited during the late Neoproterozoic rather than Mesoproterozoic. The rock association of the volcano-sedimentary sequence within SKT suggests a large early Paleozoic accretionary wedge formed by the long-term lowangle southward subduction of the Proto-Tethys Ocean between Tarim and TSHT. The amphibolitefacies metamorphism in SKT occurred at ca. 440 Ma. This ca. 440 Ma metamorphism is genetically related to the closure of the Proto-Tethys Ocean between Tarim and the Tianshuihai terrane, which led to the assembly of Tarim to Eastern Gondwana and the final formation of the Gondwana. Since the late Paleozoic to early Mesozoic, the northward subduction of the Paleo-Tethys Ocean along the HongshihuQiaoertianshan belt produced the voluminous early Mesozoic arc-signature granites along the southern part of NKT-TSHT. The Paleo-Tethys ocean between TSHT and Karakorum closed at ca. 200 Ma, as demonstrated by the monazite age of the paragneiss in the Kangxiwa Group. Our study does not favor the existence of a Precambrian basement in SKT.展开更多
基金funded by the Natural Science Foundation of China(Grant Nos.42377164 and 41972280)the Badong National Observation and Research Station of Geohazards(Grant No.BNORSG-202305).
文摘Landslide susceptibility prediction(LSP)is significantly affected by the uncertainty issue of landslide related conditioning factor selection.However,most of literature only performs comparative studies on a certain conditioning factor selection method rather than systematically study this uncertainty issue.Targeted,this study aims to systematically explore the influence rules of various commonly used conditioning factor selection methods on LSP,and on this basis to innovatively propose a principle with universal application for optimal selection of conditioning factors.An'yuan County in southern China is taken as example considering 431 landslides and 29 types of conditioning factors.Five commonly used factor selection methods,namely,the correlation analysis(CA),linear regression(LR),principal component analysis(PCA),rough set(RS)and artificial neural network(ANN),are applied to select the optimal factor combinations from the original 29 conditioning factors.The factor selection results are then used as inputs of four types of common machine learning models to construct 20 types of combined models,such as CA-multilayer perceptron,CA-random forest.Additionally,multifactor-based multilayer perceptron random forest models that selecting conditioning factors based on the proposed principle of“accurate data,rich types,clear significance,feasible operation and avoiding duplication”are constructed for comparisons.Finally,the LSP uncertainties are evaluated by the accuracy,susceptibility index distribution,etc.Results show that:(1)multifactor-based models have generally higher LSP performance and lower uncertainties than those of factors selection-based models;(2)Influence degree of different machine learning on LSP accuracy is greater than that of different factor selection methods.Conclusively,the above commonly used conditioning factor selection methods are not ideal for improving LSP performance and may complicate the LSP processes.In contrast,a satisfied combination of conditioning factors can be constructed according to the proposed principle.
基金financially supported by the National Natural Science Foundation of China(Grant No.42102202)U.S.Department of Energy Geosciences program(DE-SC0016271)。
文摘Hydrocarbons are one of the important fluids within the Earth's crust,and different biotic and abitoic processes can generate hydrocarbon during geological periods.Tracing the sources and sinks of hydrocarbons can help us better understand the carbon cycle of the earth.In this study,an improved approach of adsorbed hydrocarbons extraction from sediments was established.The improved thermal desorption approach,compound-specific isotope analysis and position-specific isotope analysis were integrated to investigate the molecular and intramolecular isotope fractionation between trace hydrocarbon gases within sediments and geological hydrocarbon deposits.The isotopic compositions of the terminal position carbon of propane(δ^(13)C_(terminal))serves as a correlation indicator between trace hydrocarbon gases within sediments and geological hydrocarbon deposits.The tight sandstone gas from the Turpan-Hami Basin is a first case study for the application of this novel method to trace hydrocarbon origins.The results showed that the hydrocarbons in the tight sandstone gases in the study area most likely originated from humic organic matter(typeⅢkerogen)at an early mature stage.δ^(13)C_(terminal)values of the thermally desorbed propane gases from different source rocks were distinguishable and the values of the tight sandstone gases significantly overlap with those of the Lower Jurassic Sangonghe source rocks,suggesting their genetic relationship.Overall,the results provided novel position-specific carbon isotopic constraints on origins of hydrocarbons.
文摘Overpressure prediction for exploratory drilling has become robust in most basins with increasing well control,high-quality seismic datasets,and proactive real-time overpressure monitoring while drilling.However,accurate overpressure prediction remains challenging in offshore Northwest Borneo despite several decades of drilling experience.This paper focuses on two exploration wells drilled by Brunei Shell Petroleum 40 years apart that faced similar challenges with overpressure prediction and well control.An integrated lookback study is attempted using seismic and well-log data to explore the causes of the unsatisfactory Pore Pressure Prediction(PPP)outcome in pre-drill and real-time operation settings for thesewells.Our study indicates that the misprediction of overpressures is due to real differences in shale pressure(basis of pre-drill work and monitoring)and sand pressure(source of drill kick and well control chal-lenges)due to large-scale vertical leak or expulsion of deep-seated fluids into pre-compacted normally pressured overlying sediments in several regions through a mix of shear and tensile failure mechanisms.Such migrated fluids inflate the sand pressure in the normally compacted shallower sequences with the shale pressure remaining low.A predictive framework for upward fluid expulsion was attempted but found impracticable due to complex spatial and temporal variations in the horizontal stress field responsible for such leakage.As such,it is proposed that these migratory overpressures are essentially'unpredictable'from conventional PPP workflows viewed in the broad bucket of compaction disequi-librium(undercompaction)and fluid expansion(unloading)mechanisms.Further study is recommended to understand if such migrated overpressures in the sand can produce a discernible and predictable geophysical or petrophysical signature in the abutting normally compacted shales.The study highlights the possibility of large lateral variability in the sand overpressure within the same stratigraphic unit in regions with complex tectonostratigraphic evolution like Northwest Borneo.
文摘An integrated study on source rock characterization and hydrocarbon generation potential modeling was conducted for the selected Dingo Claystone,Barrow Sub-basin,Australia.In this study,data were collected solely from two wells represented by the Bambra-1 and Bambra-2 wells.The collected data include those from bulk geochemical analyses of cuttings and sidewall cores sampled from the Late Jurassic Dingo Claystone.Geochemical data obtained from Rock-Eval pyrolysis and gas chromatography(GC)of extracted organic matter were integrated for source rock characterization and the construction of burial history and hydrocarbon generation in the Dingo Claystone.To improve the accuracy of thermal maturity estimations,only samples with S2 greater than 1 were considered due to potential issues with peak integration and uncertainties of Tmax determination in samples with lower S2 values.Furthermore,Rock-Eval data from the Bambra wells may be unreliable due to the contamination of cuttings and sidewall core(SWC)samples by drilling mud additives and natural hydrocarbons,which could impact the reliability of the data for determining thermal maturity.This study reveals that the Dingo Claystone Formation has total organic carbon(TOC)contents ranging from 0.66%to 8.31%.A poor to good hydrocarbon generation potential is indicated,with a production yield(PY=S_(1)+S_(2))ranging from 1.37 to 10.44 mg HC/g rock.Hydrogen index values vary between 42 and 226 mg HC/g TOC,confirming that the Dingo Claystone is dominantly kerogen TypeⅢ,with minor contributions from typesⅡ/ⅢandⅣ.Thermal maturity ranges from immature to late mature and is mostly in the oil window.This is indicated by T_(max)values of 398-462℃and vitrinite reflectance(Ro,%)of 0.47-1.99.Some samples show suppressed T_(max)and a higher production index,which is typical for samples affected by drilling fluids during drilling operations.Additionally,gas chromatography(GC)analyses are used to interpret the paleodepositional environment showing mixed input between marine and terrestrial origins of the source rocks.One-dimensional basin modeling for the Bambra-1 and Bambra-2 wells was carried out to evaluate the burial and thermal history of the formation.The transformation ratio suggests that hydrocarbon generation has not reached its peak and is still in an ongoing phase.An indication of hydrocarbon migration can be observed in this formation based on the transformation ratio.The effects of contamination warrant further investigation,as it could significantly impact maturity estimates and data reliability.
基金supported by the National Key Research and Development Project(No.2019YFA0708601)the National Natural Science Foundation of China(No.4231101056)the Chinese Academy of Geological Sciences Basic Research Fund(No.JKYZD202402)。
文摘0 INTRODUTION The Kuqa Depression,situated along the northern margin of the Tarim Basin,holds substantial geological significance due to its intricate sedimentary burial history,tectonic history,and the evolution of hydrocarbon source rocks(Jiang et al.,2024;Zhang et al.,2023;Huang et al.,2019;Yang et al.,2017;Jia et al.,2003;Hendrix,2000).
文摘The offshore Tanzanian Basin contains numerous igneous intrusions emplaced at various stratigraphic levels.Previous studies indicate these intrusions have impacted petroleum systems,affecting key elements such as source rocks,reservoirs,seals,migration pathways,and trapping mechanisms.However,due to the limited number of wells drilled in the region,there have been few studies reporting the associated thermal effects on source rock maturation and their role in hydrocarbon generation.To gain a comprehensive understanding of the intricate relationship between intrusions and the petroleum system,particularly source rock,an integrated geochemical and resistivity log analysis was carried out.The geochemical results show that the Cretaceous-Cenozoic sediments of the study area have low total organic carbon contents(TOC<1 wt%),kerogen yield(<1 Mg HC/g),and Hydrogen Index(<100 Mg HC/g),primarily composed of TypeⅢ(gas-prone)to TypeⅣ(inert)kerogens.These sediments have undergone varying levels of thermal maturity,ranging from post-mature(within Cretaceous),matured(in Paleocene)to immature(in Eocene)thermal states.The Cretaceous strata located proximal to the intrusions exhibit significant thermal alteration,resulting in a reduction of both organic matter(OM)content and source potential compared to the Eocene and Paleocene samples.This observation is consistent with the estimated paleotemperature(T)and resistivity log(ILD)along the depth profile,which have mapped local thermal alteration increasing from base Paleocene to Cretaceous.These findings have implications for source rock potential and thermal evolution history in the offshore Tanzanian Basin.This study highlights the necessity for thorough subsurface mapping in the area to identify both younger and older intrusive rocks.These intrusions pose a potential risk in petroleum exploration,especially when they intrude into matured source rock intervals.
文摘Conventional borehole image log interpretation of linear fractures on volcanic rocks,represented as sinusoids on unwrapped cylinder projections,is relatively straight-forward,however,interpreting non-linear rock structures and complex facies geometries can be more challenging.To characterize diverse volcanic paleoenvironments related to the formation of the South American continent,this study presents a new methodology based on image logs,petrography,seismic data,and outcrop analogues.The presented methodology used pseudo-boreholes images generated from outcrop photographs with typical igneous rock features worldwide simulating 2D unwrapped cylinder projections of a 31 cm(12.25 in)diameter well.These synthetic images and standard outcrop photographs were used to define morphological patterns of igneous structures and facies for comparison with wireline borehole image logs from subsurface volcanic and subvolcanic units,providing a“visual scale”for geological evaluation of volcanic facies,significantly enhancing the identification efficiency and reliability of complex geological structures.Our analysis focused on various scales of columnar jointing and pillow lava lobes with additional examples including pahoehoe lava,ignimbrite,hyaloclastite,and various intrusive features in Campos,Santos,and Parnaíba basins in Brazil.This approach increases confidence in the interpretation of subvolcanic,subaerial,and subaqueous deposits.The image log interpretation combined with regional geological knowledge has enabled paleoenvironmental insights into the rift magmatism system related to the breakup of Gondwana with associated implications for hydrocarbon exploration.
基金supported by the Australian coal industry's research(Grant No.C29048).
文摘Open pit mining operations generate significant spoil dumps that need to be characterised for stability to identify potentially unstable slopes.However,the current subjective practice for spoil characterisation often involves tedious and risky field work.To this end,this study demonstrated the use of periodically acquired unmanned aerial vehicle(UAV)-based images over a coal mine spoil dump in New South Wales,Australia.A granular approach that captures the variability of each truck offload pile on a dump was adopted through morphology-based segmentation and ensemble algorithm-based classification which consolidates predictions from multiple classifiers.Overall accuracy of over 90% in the material characterisation based on the classification framework was achieved.The two-dimensional classification outcome was then transformed into three-dimensional(3D)block models using a point-based interpolation approach for stability analysis.The factor of safety derived from the granular approach offered improved assessment of failure risk compared to the conventional approaches,which treat the entire dump as a uniform category.This rapid classification and assessment method proposed in this study will help reduce the uncertainty associated with the variability of spoil dumps in slope stability assessments,thereby enhancing the safety and efficiency of mining operations.
基金funded by the Natural Science Foundation of China(No.42407241,42272326 and 52222905)Jiangxi Provincial Natural Science Foundation(Nos.20242BAB20241,20242BAB23052 and 20242BAB24001).
文摘The spatial distribution of overburden layer thickness(OLT)is crucial for landslide susceptibility prediction and slope stability analysis.Due to OLT spatial heterogeneity in hillslope regions,combined with the difficulty and time consumption of OLT sample collection,accurately predicting OLT distribution remains a challenging.To address this,a novel framework has been developed.First,OLT samples are collected through field surveys,remote sensing,and geological drilling.Next,the heterogeneity of OLT’s spatial distribution is analyzed using the probability distribution of OLT samples and their horizontal and vertical distributions.The OLT samples are categorized and the small sample categories are expanded using the synthetic minority over-sampling technique(SMOTE).The slope position is selected as a key conditioning factor.Subsequently,16 conditioning factors are applied to construct OLT prediction model using the random forest regression algorithm.Weights are assigned to each OLT sample category to balance the uneven distribution of sample sizes.Finally,the Pearson correlation coefficient,mean absolute error(MAE),root mean square error(RMSE),and Lin’s concordance correlation coefficient(Lin’s CCC)are employed to validate the OLT prediction results.The Huangtan town serves as the case study.Results show:(1)heterogeneity analysis,SMOTE-based OLT sample expansion strategy and slope position selection can significantly mitigate the effect of spatial heterogeneity on OLT prediction.(2)The Pearson correlation coefficient,RMSE,MAE and Lin’s CCC values are 0.84,1.173,1.378 and 0.804,respectively,indicating excellent prediction performance.This research provides an effective solution for predicting OLT distribution in hillslope regions.
基金supported by the Australian Coal Industry's Research Program(ACARP)(C29048).
文摘Minor errors in the spoil deposition process,such as placing stronger materials with higher shear strength over weaker ones,can lead to potential dump failure.Irregular deposition and inadequate compaction complicate coal spoil behaviour,neces-sitating a robust methodology for temporal monitoring.This study explores using unmanned aerial vehicles(UAV)equipped with red-green-blue(RGB)sensors for efficient data acquisition.Despite their prevalence,raw UAV data exhibit temporal inconsistency,hindering accurate assessments of changes over time which could be attributed to radiometric errors.To this end,the study introduces an empirical line calibration with invariant targets(ELC-IT),for precise calibration across diverse scenes,particularly in the context of UAV imagery used to monitor the evolving nature of spoil dumps.To evaluate the effec-tiveness of this calibration approach,accuracy assessment of an object-based classification is conducted on both calibrated and uncalibrated data.This classification involves several steps:performing segmentation,carrying out feature extraction,and integrating the extracted features and ground truth labels collected over the time period of UAV image capture into machine learning pipelines.Calibrated RGB data exhibit a substantial performance advantage,achieving a 90.7%overall accuracy for spoil pile classification using ensemble(subspace discriminant),representing a noteworthy 7%improvement compared to classifying uncalibrated data.The study highlights the critical role of data calibration in optimising UAV effectiveness for spatio-temporal mine dump monitoring.These findings play a crucial role in informing and refining sustainable management practices within the domain of mine waste management.
基金supported by the Science and Technology Project of Tibet Autonomous Region(grant number XZ202202YD0010C)Major Science and Technology Project of Tibet Autonomous Region(grant number XZ202201ZD0005G01)Science and Technology Project of Southwest Joint Graduate School of Yunnan Province(grant number 202302AO370016).
文摘Shrubland expansion is a globally occurring phenomenon under global change and has caused a wide range of ecological consequences.However,due to the visual similarity between shrubland and grassland,the accuracy of shrubland interpretation and its spatial distribution varies across different products,making shrub encroachment on the Tibetan Plateau(TP)uncertain.To address these challenges,we developed a phenology-based and pixel-wise method utilizing the Landsat,Sentinel-1,and Sentinel-2 image archives to map shrubland distribution from 1990 to 2022 across the TP.We also investigated the factors affecting shrubland distribution.Using the Random Forest(RF)model,we achieved moderate to high accuracies(Kappa=0.70–0.81)in predicting shrubland d istributions,and we found that shrubland primarily occupies transitional zones between forest and grassland.In the southeast TP,solar radiation intensity is the dominant factor explaining the spatial distribution of shrubland,whereas in arid regions,water availability is the most important.From 1990 to 2022,the shrubland area slightly increased from 3.40%to 4.71%,with expansion showing a clustered pattern,mainly in the shaded aspects of arid regions.The shrubland identification method proposed here shows potential applicability in other areas with similar environmental conditions,such as arid landscapes or high-altitude ecosystems with pronounced seasonal vegetation dynamics.It also plays a crucial role in evaluating vegetation responses to climatic changes.
基金National Science Foundation Grant#1822064 to J.Singleton,Fondecyt grant#1230161 to I.del Real,and a Society of Economic Geologists Student Research Grant to N.Seymour supported this work.
文摘Iron oxide-copper–gold(IOCG)deposits encompass a diverse set of mineralization styles,leading to outstanding questions about how different alteration facies are related across a single ore-producing system and the overarching mechanisms of ore genesis.This study investigates the age and characteristics of mineralization at the La Farola deposit,a hematite-dominated IOCG deposit located at the southern margin of the Candelaria-Punta del Cobre IOCG district of northern Chile.Two lithologically-controlled ore bodies occur along the WSW-ENE striking,∼18°NNW-dipping contact between the Lower Cretaceous Chañarcillo Group and Punta del Cobre Formation.Syn-mineralization N-S to NNW-SSE striking sinistral strike-slip faults likely acted as fluid pathways.Distinct mineral assemblages include an early Na-Ca assemblage(albite-scapolite)overprinted by skarnoid garnet with minor pyroxene,Ca-Fe(magnetite-actinolite),and K-Fe(magnetite-k-feldspar-biotite and minor sulfides)assemblages.The main sulfide mineralization(chalcopyrite-pyrite with minor bornite)is associated with specular hematite-white mica-K-feldspar-calcite and overprints all previous assemblages.The presence of hematite as the dominant Fe-oxide phase associated with Cu mineralization is characteristic of lower-temperature IOCG deposits,and may be a result of La Farola’s stratigraphic position<700 m higher than other deposits in the district.New U-Pb ages of 115.7±1.2 Ma for garnet and Re-Os ages of∼113–114 Ma for sulfides indicate mineralization occurred within a 3-million-year timeframe.These findings confirm hematite-dominant mineralization at La Farola was coeval with IOCG mineralization across the district.This research contributes to understanding IOCG systems and their formation mechanisms,highlighting the control local geological structures and alteration processes has on the diversity of mineralization types associated with a single IOCG system.
基金conducted as part of the project Innovative Tools for Cyber-Physical Energy Systems(InnoCyPES)received funding from the European Union’s Horizon 2020 research and innovation pro-gram under the Marie Skłodowska-Curie(956433).
文摘Assessing the benefits and costs of digitalization in the energy industry is a complex issue.Traditional cost-benefit analysis(CBA)might encounter problems in addressing uncertainties,dynamic stakeholder interactions,and feedback loops arising out of the evolving nature of digitalization.This paper introduces a methodological framework to help address the intricate inter connections between digital applications and business models in the energy industry.The proposed framework leverages system dynamics to achieve two primary objectives.It investigates how digitalization generally influences the value proposi-tion,value capture,and value creation dimensions of business models.It also quantifies the financial and social impacts of digitalization from a dynamic perspective.The proposed dynamic CBA allows for a more precise quantification of the benefits and costs,associated with evidence-based decision-making.Findings from an illustrative case study challenge the static assumptions of conventional methods.These methods often presume continuous operation,neglecting reinvestment and operational feedback loops,and resulting in negative net present values.Conversely,the outcomes of the proposed method indicate positive net present values when accounting for factors such as reinvestment rates and the will-ingness to invest in digitalization projects.The principles outlined in this paper can enable a more accu-rate assessment of digitalization projects,thus catalyzing the development of new CBA applications and guidelines for digitalization.
基金funded by the Open Research Fund of TPESER(Grant No.TPESER202502)the National Key Research and Development Program of China(Grant No.2024YFF0810700)+3 种基金the Science and Technology Program Project of Gansu Province,China(Grant No.25JRRA138)the Hydraulic Science Experimental Research and Technology Extension Project of Gansu Province,China(Grant No.25GSLK094)the Open Foundation of MOE Key Laboratory of Western China's Environmental System,Lanzhou Universitythe Fundamental Research Funds for the Central Universities(Grant No.1zujbky-2025-jdzx02)。
文摘Surge-type glaciers are widely developed in mountainous areas around the world.Understanding the trigger mechanism of glacier surge is a prerequisite for addressing their impacts on hydrological assessments,disentangling climate-glacier linkages,and mitigating downstream hazards.Most glacier surges occur in the compound glaciers;however,attention paid to the trigger mechanisms of such surges is minimal.This study confirmed two surges in the northern and southern branches of the Aru-4 glacier,respectively,in the Western Tibetan Plateau,using multisource remote sensing data.The northern branch of the Aru-4 glacier entered the active phase in 1999 and the active phase lasted for 6 years.The southern branch of the Aru-4 glacier entered the active phase in 2007 and the active phase lasted for 9 years.The southern branch of the Aru-4 glacier experienced a long period of retreat before the northern branch surged and their tongues were in a detached state.The northern branch surge carried a large amount of ice to the frontal area,blocking the downward transport of ice from the southern branch and initiated surge.Through the analysis of two surge processes of Aru-4 glacier,we found a new surge mechanism for compound glaciers.It was revealed that surges in such glaciers are not only triggered by the reduction in basal sliding resistance caused by the internal factors.These surges initiated in the upper part of the glacier then propagated to down glacier by intense compression force.Furthermore,surges can also be triggered by external intervention of blocking by other branches.This external trigger initiates the surge in the lower part of the glacier then propagated to the upper part by longitudinal traction force.In addition,comparing with the surge triggered by the internal factors,the surge triggered by the external intervention may have a more dramatic process.
基金financially supported by CNPC Innovation Found(2021DQ02-1003)the Fundamental Research Funds for the Central Universities(Ph.D.Top Innovative Talents Fund of CUMTB)(BBJ2025043).
文摘The Late Paleozoic marked Earth’s most recent icehouse–greenhouse transition,providing valuable insights into future climate and environmental changes.Although the aridification of the North China Craton(NCC)during the Late Paleozoic is well established,its pattern and causes remain unclear.Here,we identify four aridification intervals from the late Gzhelian to Lopingian by analyzing continuous records of elemental climate proxies(MgO/CaO,Sr/Cu),a volcanism proxy(Hg/TOC),and spore–pollen assemblages.Interval I(∼303–295 Ma),during which the NCC was located at low paleolatitudes,was characterized by humid conditions and a predominance of ferns,associated with weak volcanism.Interval II(∼295–286 Ma)was subhumid,with increasing gymnosperm presence,and significant climate fluctuations linked to volcanism.CO_(2) emissions from the Tarim LIP and Panjal Traps drove aridification from the late Asselian to late Artinskian,contributing to the decline of the Late Paleozoic Ice Age.As a result,aridification in the NCC lagged behind that of Pangea.Interval III(∼286–280.98 Ma)marked the transition to subarid conditions and the onset of dominance by gymnosperms,associated with a rapid northward drift of the NCC and an increase in atmosphericρCO_(2).Interval IV(∼259.51–251.902 Ma),separated from the underlying Interval III by a major regional unconformity(∼280.98–259.51),coincided with global aridification and intensified volcanism.These findings highlight the significant influences of both tectonic plate motion and volcanism on the climate evolution of the NCC,with shifts in the dominant controlling factors through time.This study provides new insights into the distinct trajectories of global and regional climate dynamics.
基金supported by the National Natural Science Foundation of China(Nos.42074071,42274094,42261144739)the Shenzhen Science and Technology Program(No.KQTD20170810111725321)+2 种基金supported by the Taiwan University Core Consortiums Project(No.112L894202)the Higher Education Sprout Project of the Ministry of Education(No.112L901001)the National Science and Technology Council(No.111-2116-M-002-022-MY3)。
文摘The environmental magnetic proxies of stalagmites hold significant potential for reconstructing regional hydroclimate changes by revealing the content and grain size of magnetic particles within stalagmites.In this study,we present the contents and grain sizes of magnetic particles within a stalagmite SZ-1,from Shizhu Cave in southwestern China from 70.4 to 22.3 thousand years ago(ka)during the last glacial period.Specifically,the parameters IRM_(soft),soil-derived magnetic minerals,and ARM/SIRM(anhysteretic remanent magnetization/saturation isothermal remanent magnetization),the ratio of fine magnetic particles to total ferrimagnetic particles preserved in stalagmite SZ-1,indicate the fluctuation of regional precipitation.Obvious half-precessional cycles are evident in these two proxies,indicating that hydroclimatic variations in southwestern China may predominantly arise from the heat and moisture transported from tropical oceans.These variations are likely influenced by shifts in the Intertropical Convergence Zone and fluctuations in the Asian Summer Monsoon.
基金supported by the CNPC-SWPU Innovation Alliance Technology Cooperation Project(2020CX020000)the National Natural Science Foundation of China(42022028)+1 种基金the Natural Science Foundation of Sichuan Province(24NSFSC0808)the China Scholarship Council(202306440144)。
文摘In common practice in the oil fields,the injection of water and gas into reservoirs is a crucial technique to increase production.The control of the waterflooding front in oil/gas exploitation is a matter of great concern to reservoir engineers.Monitoring the waterflooding front in oil/gas wells plays a very important role in adjusting the well network and later in production,taking advantage of the remaining oil po-tential and ultimately achieving great success in improving the recovery rate.For a long time,micro-seismic monitoring,numerical simulation,four-dimensional seismic and other methods have been widely used in waterflooding front monitoring.However,reconciling their reliability and cost poses a significant challenge.In order to achieve real-time,reliable and cost-effective monitoring,we propose an innovative method for waterflooding front monitoring through the similarity analysis of passive source time-lapse seismic images.Typically,passive source seismic data collected from oil fields have extremely low signal-to-noise ratio(SNR),which poses a serious problem for obtaining structural images.The proposed method aims to visualize and analyze underground changes by highlighting time-lapse images and provide a strategy for underground monitoring using long-term passive source data under low SNR conditions.First,we verify the feasibility of the proposed method by designing a theoretical model.Then,we conduct an analysis of the correlation coefficient(similarity)on the passive source time-lapse seismic imaging results to enhance the image differences and identify the simulated waterflooding fronts.Finally,the proposed method is applied to the actual waterflooding front monitoring tasks in Shengli Oilfield,China.The research findings indicate that the monitoring results are consistent with the actual devel-opment conditions,which in turn demonstrates that the proposed method has great potential for practical application and is very suitable for monitoring common development tasks in oil fields.
基金supported by the National Natural Science Foundation of China(No.U21B2062)funding from the Chinese Scholarship Council(CSC)and the American Association of Petroleum Geologists Foundation Grantsin-Aid Program.
文摘Natural fractures controlled by faults in ultradeep carbonate strata play substantial roles as both fluid migration channels and storage spaces.However,characterizing the heterogeneous distribution of underground fractures within the complex three-dimensional geometry of strike-slip fault zones remains challenging.This study investigates the characteristics of natural fractures controlled by strike-slip faults in the fractured Middle and Lower Ordovician reservoirs of the central and northern Tarim Basin,China.Seismics,cores,and image logs were integrated to quantitatively analyze the intensity and dip angle of natural fractures and findings were verified using published sandbox simulations.The carbonate reservoir contains three main types of natural fractures:tectonic fractures,abnormal high-pressure-related fractures,and stylolites.Strike-slip faults control the distribution and characteristics of tectonic fractures across various scales.Generally,both fracture intensity and porosity exhibit a decreasing trend as the distance from the main fault surface increases.Compared with those in non-stepover zones along a strike-slip fault,natural fractures and faults in stepover zones are more developed along the fault strike,with significantly greater development intensity in central stepover regions than that at its two ends.Furthermore,strike-slip faults influence the dip angles of both natural fractures and secondary faults.The proportion of medium-to-low-dip angle fractures and faults in the stepover zone is greater than that in the non-stepover zone.Additionally,the proportion of medium-to low-dip angle fractures and faults in the middle of the stepover is greater than that at both ends.Therefore,strike-slip fault structures control the dip angle of natural fracture and the heterogeneity of secondary fault and fracture intensity.The linking damage zone in the stepover contains a larger volume of fractured rocks,making it a promising petroleum exploration target.The development of stepovers and the orientation of present-day in-situ stress substantially influence the productivity of fractured reservoirs controlled by strike-slip faults.The analysis in this study reveals that reservoir productivity increases as the angle between the strike-slip fault segment and the maximum horizontal principal stress decreases.This study provides valuable insights for quantitatively evaluating fracture heterogeneity in fractured reservoirs and establishing optimized selection criteria for favorable targets in fault-related fractured reservoirs.
基金support from the Chinese Scholarship Council(Grant No.2022GXZ005733)。
文摘The Pressure-Volume-Temperature(PVT)properties of crude oil are typically determined through laboratory analysis during the early phases of exploration and fielddevelopment.However,due to extensive data required,time-consuming nature,and high costs,laboratory methods are often not preferred.Machine learning,with its efficiencyand rapid convergence,has emerged as a promising alternative for PVT properties estimation.This study employs the modified particle swarm optimization-based group method of data handling(PSO-GMDH)to develop predictive models for estimating both the oil formation volume factor(OFVF)and bubble point pressure(P_(b)).Data from the Mpyo oil fieldin Uganda were used to create the models.The input parameters included solution gas-oil ratio(R_(s)),oil American Petroleum Institute gravity(API),specificgravity(SG),and reservoir temperature(T).The results demonstrated that PSO-GMDH outperformed backpropagation neural networks(BPNN)and radial basis function neural networks(RBFNN),achieving higher correlation coefficientsand lower prediction errors during training and testing.For OFVF prediction,PSO-GMDH yielded a correlation coefficient(R)of 0.9979(training)and 0.9876(testing),with corresponding root mean square error(RMSE)values of 0.0021 and 0.0099,and mean absolute error(MAE)values of 0.00055 and 0.00256,respectively.For P_(b)prediction,R was 0.9994(training)and 0.9876(testing),with RMSE values of 6.08 and 8.26,and MAE values of 1.35 and 2.63.The study also revealed that R_(s)significantlyimpacts OFVF and P_(b)predictions compared to other input parameters.The models followed physical laws and remained stable,demonstrating that PSO-GMDH is a robust and efficientmethod for predicting OFVF and P_(b),offering a time and cost-effective alternative.
基金funded by the National 305 Project of China (2018A03004-1, 2015BAB05B01-02)the Fundamental Research Fund for Central Universities(B16020127)
文摘The West Kunlun orogenic belt(WKOB) along the northern margin of the Tibetan Plateau is important for understanding the evolution of the Proto-and Paleo-Tethys oceans. Previous investigations have focused on the igneous rocks and ophiolites distributed mostly along the Xinjiang-Tibet road and the China-Pakistan road, and have constructed a preliminary tectonic model for this orogenic belt. However, few studies have focused on the so-called Precambrian basement in this area. As a result, the tectonic affinity of the individual terranes of the WKOB and their detailed evolution process are uncertain. Here we report new field observations, zircon and monazite U-Pb ages of the "Precambrian basement" of the South Kunlun terrane(SKT) and the Tianshuihai terrane(TSHT), two major terranes in the WKOB. Based on new zircon U-Pb age data, the amphibolite-facies metamorphosed volcanosedimentary sequence within SKT was deposited during the late Neoproterozoic to Cambrian(600-500 Ma), and the flysch-affinity Tianshuihai Group, as the basement of the TSHT, was deposited during the late Neoproterozoic rather than Mesoproterozoic. The rock association of the volcano-sedimentary sequence within SKT suggests a large early Paleozoic accretionary wedge formed by the long-term lowangle southward subduction of the Proto-Tethys Ocean between Tarim and TSHT. The amphibolitefacies metamorphism in SKT occurred at ca. 440 Ma. This ca. 440 Ma metamorphism is genetically related to the closure of the Proto-Tethys Ocean between Tarim and the Tianshuihai terrane, which led to the assembly of Tarim to Eastern Gondwana and the final formation of the Gondwana. Since the late Paleozoic to early Mesozoic, the northward subduction of the Paleo-Tethys Ocean along the HongshihuQiaoertianshan belt produced the voluminous early Mesozoic arc-signature granites along the southern part of NKT-TSHT. The Paleo-Tethys ocean between TSHT and Karakorum closed at ca. 200 Ma, as demonstrated by the monazite age of the paragneiss in the Kangxiwa Group. Our study does not favor the existence of a Precambrian basement in SKT.
