Accurate acquisition of the lithological composition of a tunnel face is crucial for efficient tunneling and hazard prevention in large-diameter slurry shield tunnels.While widely applied,current data-driven methods o...Accurate acquisition of the lithological composition of a tunnel face is crucial for efficient tunneling and hazard prevention in large-diameter slurry shield tunnels.While widely applied,current data-driven methods often face challenges such as indirect prediction,data sparsity,and data drift,which limit their accuracy and generalizability.This study develops an integrated method that combines a knowledge-driven method to directly compute distribution patterns of lithological components,which are used as a priori knowledge to guide the development of a data-driven method.Coupled Markov chain(CMC)and deep neural networks(DNNs)serve as the knowledge-driven and data-driven components,respectively.Additionally,a dynamic prediction strategy is proposed,where the model is continuously optimized as construction progresses and training samples accumulate,rather than being statically trained on post-construction data,as is common in data-driven methods.Finally,the proposed method is evaluated using a real-world project.The evaluation results show that the integrated method outperforms both individual data-and knowledge-driven methods,demonstrating higher predictive performance,greater stability,and greater robustness to data scarcity and data drift.Furthermore,the dynamic prediction strategy better captures the effects of gradual data accumulation and lithological spatial variability on prediction performance during construction,providing new insights for real-time prediction in practical tunneling applications.展开更多
In petroleum engineering,real-time lithology identification is very important for reservoir evaluation,drilling decisions and petroleum geological exploration.A lithology identification method while drilling based on ...In petroleum engineering,real-time lithology identification is very important for reservoir evaluation,drilling decisions and petroleum geological exploration.A lithology identification method while drilling based on machine learning and mud logging data is studied in this paper.This method can effectively utilize downhole parameters collected in real-time during drilling,to identify lithology in real-time and provide a reference for optimization of drilling parameters.Given the imbalance of lithology samples,the synthetic minority over-sampling technique(SMOTE)and Tomek link were used to balance the sample number of five lithologies.Meanwhile,this paper introduces Tent map,random opposition-based learning and dynamic perceived probability to the original crow search algorithm(CSA),and establishes an improved crow search algorithm(ICSA).In this paper,ICSA is used to optimize the hyperparameter combination of random forest(RF),extremely random trees(ET),extreme gradient boosting(XGB),and light gradient boosting machine(LGBM)models.In addition,this study combines the recognition advantages of the four models.The accuracy of lithology identification by the weighted average probability model reaches 0.877.The study of this paper realizes high-precision real-time lithology identification method,which can provide lithology reference for the drilling process.展开更多
Objective The aim was to reveal relationship between lithological character soil and productivity of Cunninghamia lanceolata and lay a foundation for systemic management of C. lanceolata fast-growing and high yield pl...Objective The aim was to reveal relationship between lithological character soil and productivity of Cunninghamia lanceolata and lay a foundation for systemic management of C. lanceolata fast-growing and high yield plantation. Method By using experimental ecology method and variance analysis, the biomass and growth of planting eleven years＇ C. lanceolata on the soils with six different lithologicel characters were studied. Result The effects of soils with six different lithological characters on the height, diameter growth and biomass of C. lanceolata were different, in which the growth order of C. lanceolata was： Feldspathic quartzy sandstone （ average height 523. 270 cm, average diameter 4.720 cm, average individual biomass 5.059kg） 〉 Basalt （ average height 511. 570 cm, average diameter 4.650 cm, average individual biomass 4.848 kg） 〉 Quartzy sandstone 〉 Blastopsammite 〉 The Quarternary Period red clay 〉 Coal-series siliceous sand-shale, and the difference was smaller between the last two lithological characters. Conclusion Feldspathic quartzy sandstone and Basalt are beneficial to C. lanceolata.展开更多
With the popularization and application of fast drilling technology in Sichuan-Chongqing gas provinces,the returned cuttings are fine and even powdered,so the traditional cutting lithology identification methods are n...With the popularization and application of fast drilling technology in Sichuan-Chongqing gas provinces,the returned cuttings are fine and even powdered,so the traditional cutting lithology identification methods are not applicable any longer.In this paper,qualitative lithology identification and quantitative interpretation based on element logging were conducted on the key oil and gas bearing layers in this area according to the principle of elemental geochemistry.The study results show that:(1)different lithologies can be identified easily because of their different element logging characteristics.For example,basalts have the element characteristics of 0.35<Fe/Si<0.55 and Ca/(Na+K)<4.00,while sedimentary rocks have Fe/Si<0.35 or>0.55.(2)Clastic rocks,carbonate rocks,sulphate and transition rocks in the category of sedimentary rocks can be identified based on the element combination of(Al+Si+Fe)and(Ca+Mg+S).Among them,clastic rocks have(Al+Si+Fe)>31%,carbonate rocks have(Al+Si+Fe)<8%and(Ca+Mg+S)<36%,and sulphate rocks have(Al+Si+Fe)<5%and(Ca+Mg+S)>36%.(3)Then,based on the element combination of(Si+K+Ca)tSi/Al and(Al+Si+Fe+K)t(Ca+S)/Mg,sandstone,mudstone(shale),gypsum,dolomite,limestone and transition rocks can be identified.Finally,a qualitative identification chart and a set of quantitative interpretation software of element logging on key horizons in Sichuan-Chongqing gas provinces were developed to make this method convenient for field application.This method was applied on site in ten wells(such as Well MX207)in Sichuan-Chongqing gas provinces.It is indicated that the coincidence rate of lithology identification is in the range of 88.75-95.22%(averaging 92.42%).Obviously,it can satisfy the requirements of fast lithology identification while drilling of key oil and gas horizons in Sichuan-Chongqing gas provinces.展开更多
The Ordos basin is a stable craton whose late Paleozoic undergoes two sedimentary stages: from the middle- late Carboniferous offshore plain to the Permian continental river and lake delta. Sandstones in delta plain c...The Ordos basin is a stable craton whose late Paleozoic undergoes two sedimentary stages: from the middle- late Carboniferous offshore plain to the Permian continental river and lake delta. Sandstones in delta plain channels, delta-front river mouth bars and tidal channels are well developed. The sandstones are distributed on or between the genetic source rocks, forming good gas source conditions with widespread subtle lithologic gas pools of low porosity, low permeability, low pressure and low abundance. In recent years, a series of experiments has been done, aimed at overcoming difficulties in the exploration of lithologic gas pools. A set of exploration techniques, focusing on geological appraisal, seismic exploration, accurate logging evaluation and interpretation, well testing fracturing, has been developed to guide the exploration into the upper Paleozoic in the basin, leading to the discoveries of four large gas fields: Sulige, Yulin, Wushenqi and Mizhi.展开更多
By examining structures,sediments,reservoirs and accumulation assemblages in the Deyang-Anyue rift and its surrounding area,four new understandings are obtained.First,during the initiation period of Deyang-Anyue rift,...By examining structures,sediments,reservoirs and accumulation assemblages in the Deyang-Anyue rift and its surrounding area,four new understandings are obtained.First,during the initiation period of Deyang-Anyue rift,multiple groups of faults developed in the rift due to the effect of tensile force,bringing about multiple mound and shoal belts controlled by horsts in the second member of the Sinian Dengying Formation;in the development stage of the rift,the boundary faults of the rift controlled the development of mound and shoal belts at the platform margin in the fourth member of Dengying Formation;during the shrinkage period of the rift,platform margin grain shoals of the Cambrian Canglangpu Formation developed in the rift margin.Second,four sets of large-scale mound and shoal reservoirs in the second member of Dengying Formation,the fourth member of Dengying Formation,Canglangpu Formation and Longwangmiao Formation overlap with several sets of source rocks such as Qiongzhusi Formation source rocks and Dengying Formation argillaceous limestone or dolomite developed inside and outside the rift,forming good source-reservoir-cap rock combinations;the sealing of tight rock layers in the lateral and updip direction results in the formation model of large lithologic gas reservoirs of oil pool before gas,continuous charging and independent preservation of each gas reservoir.Third,six favorable exploration zones of large-scale lithologic gas reservoirs have been sorted out through comprehensive evaluation,namely,mound and shoal complex controlled by horsts in the northern part of the rift in the second member of Dengying Formation,isolated karst mound and shoal complex of the fourth member of Dengying Formation in the south of the rift,the superimposed area of multi-stage platform margin mounds and shoals of the second and fourth members of Dengying Formation and Canglangpu Formation in the north slope area,the platform margin mounds and shoals of the second and fourth members of Dengying Formation in the west side of the rift,the platform margin mound and shoal bodies of the fourth member of Dengying Formation in the south slope area,etc.Fourth,Well Pengtan-1 drilled on the mound and shoal complex controlled by horsts of the second member of Dengying Formation in the rift and Well Jiaotan-1 drilled on the platform margin mound and shoal complex of the North Slope have obtained high-yield gas flows in multiple target layers,marking the discovery of a new gas province with reserves of(2-3)×10^(12) m^(3).This has proved the huge exploration potential of large lithologic gas reservoir group related to intracratonic rift.展开更多
The dry-hot valley of the Jinsha River is one of the typical eco-fragile areas in Southwest China, as well as a focus of revegetation study in the upper and middle reaches of the Changjiang River. Due to its extremely...The dry-hot valley of the Jinsha River is one of the typical eco-fragile areas in Southwest China, as well as a focus of revegetation study in the upper and middle reaches of the Changjiang River. Due to its extremely dry and hot climate, severely degraded vegetation and the intense soil and water loss, there are extreme difficulties in vegetation restoration in this area and no great breakthrough has ever been achieved on studies of revegetation over the last several decades. Through over ten years’ research conducted in the typical areas-the Yuanmou dry-hot valley, the authors found that the lithologic property is one of the crucial factors determining soil moisture conditions and vegetation types in the dry-hot valley, and the rainfall infiltration capability is also one of the key factors affecting the tree growth. Then the revegetation zoning based on different slopes was conducted and revegetation patterns for different zones were proposed.展开更多
Taking the Jiyang depression as an example,this paper discusses the control of the formation of lithological reservoir by surrounding rocks by integrated application of geological analysis,physical simulation,and the ...Taking the Jiyang depression as an example,this paper discusses the control of the formation of lithological reservoir by surrounding rocks by integrated application of geological analysis,physical simulation,and the analysis of oil&gas accumulation mechanism.Geological statistical shows that the major burial depth and interval of lithological reservoirs in the Jiyang depression are related to the hydrocarbon generation in and expulsion from the Lower Tertiary source rocks and the time of the formation of most lithological reservoirs coincides with the peak of hydrocarbon generation and expulsion.The lithological traps located in the center of effective source rocks are propitious to high oil saturation than those located on the margin of effective source rocks.The hydrocarbon charge degree of the lithological reservoir has a positive correlation with the intensity of hydrocarbon expulsion from surrounding source rocks.Geological analyses and NMR experiments also show that the oil saturation of surrounding source rocks control the hydrocarbon potential of lithological traps,and a critical value for oil saturation of surrounding mudstone is required,that is,when the oil saturation of surrounding mudstone is lower than this critical value,no oil and gas accumulate in the lithological trap.The control of surrounding mudstone on the oil-bearing properties of lithological reservoirs is also analyzed by the mechanisms of hydrocarbon generation and expulsion as well as accumulation.展开更多
As a case study of the Panji No.1 Coal Mine in Anhui Province, based on thesite measured and statistical data, summarized the lithologic associations, characteristicsand distribution laws of interlayer-gliding structu...As a case study of the Panji No.1 Coal Mine in Anhui Province, based on thesite measured and statistical data, summarized the lithologic associations, characteristicsand distribution laws of interlayer-gliding structures and tectonic coal in the No.11-2 coalseams.The results show that 9 modes of lithologic association can form interlayer-glidingstructures.It is more easy for rock slip to occur when the lithologic associations are mainroof + coal seam + immediate floor type, compound roof+immediate roof + coal seam +immediate floor type and immediate roof + coal seam + immediate floor type.Lithologicassociations of roof and floor are the precondition to the formation of interlayer-glidingstructures.展开更多
Controllable D-D neutron sources have a long service life,low cost,and non-radioactivity.There are favorable prospects for its application in geophysical well logging,since traditional chemical radioactive sources use...Controllable D-D neutron sources have a long service life,low cost,and non-radioactivity.There are favorable prospects for its application in geophysical well logging,since traditional chemical radioactive sources used for well logging pose potential threats to the safety of the human body and environment.This paper presents an improved method to measure formation density that employs a D-D neutron source.In addition,the lithological effect on the measured density was removed to better estimate the formation porosity.First,we investigated the spatial distribution of capture gamma rays through Monte Carlo simulations as well as the relationship between the ratio of capture gamma ray counts and formation density to establish theoretical support for the design of density logging tools and their corresponding data processing methods.Second,we obtained the far to near detector counts of captured gamma rays for an optimized tool structure and then established its correlation with the density and porosity of three typical formations with pure quartz,calcite,and dolomite minerals.Third,we determined the values for correcting the densities of sandstone and dolomite with the same porosity using limestone data as the reference and established the equations for calculating the correction values,which lays a solid foundation for accurately calculating formation porosity.We observed that the capture gamma ray counts first increased then decreased and varied in different formations;this was especially observed in high-porosity formations.Under the same lithologic conditions(rock matrix),as the porosity increases,the peak value of gamma ray counts moves toward the neutron source.At different detector-source distances,the ratio of the capture gamma ray counts was well correlated with the formation density.An equation of the formation density conversion was established based on the ratio of capture gamma ray counts at the detector-source distances of 30 cm and 65 cm,and the calculated values were consistent with the true values.After correction,the formation density was highly consistent with the true value of the limestone density,and the mean absolute error was 0.013 g/cm3.The calculated porosity values were very close to the true values,and the mean relative error was 2.33%,highlighting the accuracy of the proposed method.These findings provide a new method for developing D-D neutron source logging tools and their well-log data processing methods.展开更多
The rift lake basins in the eastern China have abundant hydrocarbon resources of lithologic deposits, which resulted from excellent source rocks and multi-type sandbodies developed during strong rifting. Vertically, t...The rift lake basins in the eastern China have abundant hydrocarbon resources of lithologic deposits, which resulted from excellent source rocks and multi-type sandbodies developed during strong rifting. Vertically, the lithologic deposits are mainly distributed in the lowstand, lacustrine invasion and early highstand systems of third-order sequence corresponding to a secondary tectonic episode of strong rifting, and laterally they are closely related to various fans and turbidite sandbodies controlled by syn-sedimentary faults. A variety of lithologic traps have been developed in the rift lake basins, and they generally have favorable conditions of source-reservoir-seal assemblage and hydrocarbon accumulation dynamics, indicating that there is a great exploration potential of lithologic deposits in the rift lake basins. In order to obtain satisfactory effects of lithologic deposit exploration, it is required to combine new theories with advanced technical methods.展开更多
Based on the practice of oil and gas exploration and the analysis of shallow lithologic reservoirs,combined with the allocation relationship and enrichment law of oil and gas accumulation factors,main controlling fact...Based on the practice of oil and gas exploration and the analysis of shallow lithologic reservoirs,combined with the allocation relationship and enrichment law of oil and gas accumulation factors,main controlling factors and models of hydrocarbon accumulation of large lithologic reservoirs in shallow strata around the Bozhong sag are summarized,and favorable exploration areas are proposed.The coupling of the four factors of“ridge-fault-sand-zone”is crucial for the hydrocarbon enrichment in the shallow lithologic reservoirs.The convergence intensity of deep convergence ridges is the basis for shallow oil and gas enrichment,the activity intensity of large fault cutting ridges and the thickness of cap rocks control the vertical migration ability of oil and gas,the coupling degree of large sand bodies and fault cutting ridges control large-scale oil and gas filling,the fault sealing ability of structural stress concentration zones affects the enrichment degree of lithologic oil and gas reservoirs.Three enrichment models including uplift convergence type,steep slope sand convergence type and depression uplift convergence type are established through the case study of lithologic reservoirs in shallow strata around the Bozhong sag.展开更多
Six representative parent rocks of sand, including limestone, quartzite, gneisses, granite, Basalt and Marble were selected to conduct a systematical research on the effects of various lithologies of manufactured sand...Six representative parent rocks of sand, including limestone, quartzite, gneisses, granite, Basalt and Marble were selected to conduct a systematical research on the effects of various lithologies of manufactured sand on the workability, mechanism properties, volume stability and durability of manufacturedsand concrete. The experimental results show that the strength of manufactured-sand concrete is slightly higher than that of natural-sand concrete. Furthermore, substituting 15% cement of the concrete mixture with equal quantity of the six different lithology stone powder respectively, the data indicated that they can improve the concrete’s workability, postpone the plastic cracking time, enhance the anti-cracking grade, and have no obvious effect on the properties of antifreeze and sulfate attack resistance but reduce the capability to resist chloride ion penetration. Moreover, the differences in concrete’s workability, mechanism properties, volume stability and durability caused by various lithologies of manufactured sand and stone powder were not significant and the influence of lithology variety on the macro properties of concrete could be neglected eventually.展开更多
In recent years, a series of large low and medium abundance oil and gas fields are discovered through exploration activities onshore China, which are commonly characterized by low porosity-permeability reservoirs, low...In recent years, a series of large low and medium abundance oil and gas fields are discovered through exploration activities onshore China, which are commonly characterized by low porosity-permeability reservoirs, low oil/gas column height, multiple thin hydrocarbon layers, and distribution in overlapping and connection, and so on. The advantageous conditions for large-area accumulation of low-medium abundance hydrocarbon reservoirs include： （1） large （fan） delta sandbodies are developed in the hinterland of large flow-uncontrolled lake basins and they are alternated with source rocks extensively in a structure like ＂sandwiches＂; （2） effective hydrocarbon source kitchens are extensively distributed, offering maximum contact chances with various sandbodies and hydrocarbon source rocks; （3） oil and gas columns are low in height, hydrocarbon layers are mainly of normal-low pressure, and requirements for seal rock are low; （4） reservoirs have strong inheterogeneity and gas reservoirs are badly connected; （5） the hydrocarbon desorption and expulsion under uplifting and unloading environments cause widely distributed hydrocarbon source rocks of coal measures to form large-area reservoirs; （6） deep basin areas and synclinal areas possess reservoir-forming dynamics. The areas with great exploration potential include the Paleozoic and Mesozoic in the Ordos Basin, the Xujiahe Formation in Dachuanzhong in the Sichuan basin, deep basin areas in the Songliao basin etc. The core techniques of improving exploration efficiency consist of the sweetspot prediction technique that focuses on fine characterization of reservoirs, the hydrocarbon layer protecting and high-speed drilling technique, and the rework technique for enhancing productivity.展开更多
Besides the cross sections of roadways and the tendency and obliquity of roadway axes, the major controlling factors affecting the height of a collapsing roof include the weak lithological structure of surrounding roc...Besides the cross sections of roadways and the tendency and obliquity of roadway axes, the major controlling factors affecting the height of a collapsing roof include the weak lithological structure of surrounding rocks. This thesis analyzes the effect of two single and weak lithological structures of both sides and the roof on the height of a collapsing roof in a deep soft rock road- way. Using the two-dimensional UDEC3.1 software, a numerical structures of both sides of a roadway and of two weak lithological simulation was carried out on the models of weak lithological structures of roof of different depths. We reconstruct the overall processes from a break-away layer, bending, subsidence and the cracking of a collapsing roof. We also illustrate the distribution characteristics of displacement fields in the surrounding rock after the roof collapse in a deep soft rock roadway. The results of our numerical simulations indicate that the form of a roof collapse is side-expanding when the roadway is a weak structure at both sides The height of the roof collapse is related to the lithological combination of the roof when the roadway is a weak structure of the roof.展开更多
By using drilling,high-precision 3 D seismic data,data of geochemistry,logging and testing,the reservoir characteristics and accumulation conditions of the KL6-1 lithologic oilfield in the Laibei Low Uplift in the Boh...By using drilling,high-precision 3 D seismic data,data of geochemistry,logging and testing,the reservoir characteristics and accumulation conditions of the KL6-1 lithologic oilfield in the Laibei Low Uplift in the Bohai Sea are examined comprehensively.The study shows that:KL6-1 oilfield is a monolithic,high-quality,large-scale Neogene lithologic oilfield featuring shallow reservoir depth,high productivity,concentrated oil-bearing intervals,large oil-bearing area,and high reserve abundance;hydrocarbon source supply from two directions provides a sufficient material basis for the formation of large oil field;two types of"inherited structural ridge"developed under the effect of block rotation,late active faults formed by Neotectonic movement,and widely distributed contiguous sand bodies provide an efficient oil and gas transportation system for the large-scale accumulation of oil and gas;contiguous channel and lacustrine lowstand system sand bodies developed in low accommodation condition provide the basic condition for the formation of large-scale lithologic traps;deep formations structural ridge,faults(dominant migration pathways)and large-scale superimposed contiguous sand bodies constitute a"vine type"oil and gas migration and accumulation system in the Laibei Low Uplift,which is conducive to the formation of large-scale and high-abundance lithologic reservoir in this area.The successful discovery of KL6-1,100 million ton reserve order lithologic oil field,has revealed the exploration potential of Neogene large lithologic reservoirs in Bohai Sea,expanded the exploration field,and also has certain reference significance for the exploration of large lithologic reservoirs in similar areas.展开更多
Based on analyses of characteristics,hydrocarbon charging history and geological conditions for the formation of Sinian-Cambrian reservoirs in the north slope area of central Sichuan paleo-uplift,the natural gas origi...Based on analyses of characteristics,hydrocarbon charging history and geological conditions for the formation of Sinian-Cambrian reservoirs in the north slope area of central Sichuan paleo-uplift,the natural gas origin,accumulation evolution,accumulation pattern and formation conditions of large lithologic gas reservoirs have been investigated.Through comprehensive analyses of natural gas composition,carbon and hydrogen isotopic compositions,fluid inclusions,reservoir bitumen,and geological conditions such as lithofacies paleogeography and beach body characterization,it is concluded that:(1)The natural gas in the Sinian-Cambrian of the north slope area is mainly oil cracking gas,and different contribution ratios of multiple sets of source rocks lead to different geochemical characteristics of natural gas in different reservoirs.(2)Although the both Sinian and Cambrian gas reservoirs in this area are lithologic gas reservoirs under monocline background,the former has normal-pressure and the latter has high-pressure.There are three types of source-reservoir-caprock combinations:single source with lower generation and upper reservoir,double sources with lower generation and upper reservoir or with side source and lateral reservoir,double sources with lower generation and upper reservoir or with upper generation and lower reservoir.The Permian-Triassic is the main generation period of oil,Early-Middle Jurassic is the main generation period of oil cracking gas and wet gas,and Late Jurassic-Cretaceous is the main generation period of dry gas.(3)The Sinian-Cambrian system of the north slope area has two favorable conditions for formation of large lithologic gas reservoirs,one is that the large scale beach facies reservoirs are located in the range of ancient oil reservoirs or near the source rocks,which is conducive to the"in-situ"large-scale accumulation of cracked gas in the paleo-oil reservoirs,the other is that the large scale mound-beach complex reservoirs and sealing layers of inter beach tight zones match effectively to form large lithologic traps under the slope background.The research results confirm that the north slope area has large multi-layer lithologic gas reservoirs with more than one trillion cubic meters of natural gas resources and great exploration potential.展开更多
Thousands of landslide data being taken as the nation wide statistics of sampling and the two state variables of landslide being processed with two methods described in the references, the main types of lithologica...Thousands of landslide data being taken as the nation wide statistics of sampling and the two state variables of landslide being processed with two methods described in the references, the main types of lithological groups of landslides in China have been sieved and selected.On the other hand, through the displacement table of Pascal Yanghui triangle used in the information encoding theory, the mark weight of sampling can be calculated and the main lithological groups which have close relationship with landslide occurrence can be gained.In comparison with the both results, the characteristics of main sliding lithological groups are determinated, and the main distribution regions of landslides can be prognosticated.展开更多
In the frame of landslide susceptibility assessment, a spectral library was created to support the identification of materials confined to a particular region using remote sensing images. This library, called Pakistan...In the frame of landslide susceptibility assessment, a spectral library was created to support the identification of materials confined to a particular region using remote sensing images. This library, called Pakistan spectral library(pklib) version 0.1, contains the analysis data of sixty rock samples taken in the Balakot region in Northern Pakistan.The spectral library is implemented as SQLite database. Structure and naming are inspired by the convention system of the ASTER Spectral Library. Usability, application and benefit of the pklib were evaluated and depicted taking two approaches, the multivariate and the spectral based. The spectral information were used to create indices. The indices were applied to Landsat and ASTER data tosupportthespatial delineation of outcropping rock sequences instratigraphic formations. The application of the indices introduced in this paper helps to identify spots where specific lithological characteristics occur. Especially in areas with sparse or missing detailed geological mapping, the spectral discrimination via remote sensing data can speed up the survey. The library can be used not only to support the improvement of factor maps for landslide susceptibility analysis, but also to provide a geoscientific basisto further analyze the lithological spotin numerous regions in the Hindu Kush.展开更多
Sedimentary heterogeneity conditions of Catania Plain quaternary aquifer (CPQA), the wider alluvial multi-aquifer system of Sicily, were rebuilt to simulate and quantify groundwater flow. Transition probabilities base...Sedimentary heterogeneity conditions of Catania Plain quaternary aquifer (CPQA), the wider alluvial multi-aquifer system of Sicily, were rebuilt to simulate and quantify groundwater flow. Transition probabilities based on a Markov Chain (MC) and Sequential Indicator Simulation (SIS) are the structure-imitating simulators utilized for generating stochastic distributions of hydraulic conductivity fields of CPQA, basing on borehole data: plausible equiprobable solutions of the complex geological structure of the CPQA were simulated. This study highlights that the choice of geostatistical simulation method plays a fundamental role in predictive scenarios for groundwater resources managing of CPQA. Indeed, simulated characteristics of the sedimentary heterogeneity constituted the basis of finite difference models for simulating the groundwater flow of CPQA. In heterogeneous systems such as CPQA, SIS may be inadequate for reproducing the macrostructures. Instead, MC adequately reproduced spatial connection of lithofacies, representing a more realistic solution dealing to the proposed geological model of CPQA. MC and SIS models were utilized to both assess the uncertainty of the generated hydraulic conductivity fields of CPQA and predictions about its behavior under normal stress conditions induced by urbanization. The calibration of CPQA groundwater flow models based on MC and SIS simulations allowed to achieve a realistic feedback about the quality of the geostatistical reconstructions of the geological heterogeneity field.展开更多
基金supported by the Beijing Natural Science Foundation(Grant No.8252012)the National Natural Science Foundation of China(Grant No.52378475).
文摘Accurate acquisition of the lithological composition of a tunnel face is crucial for efficient tunneling and hazard prevention in large-diameter slurry shield tunnels.While widely applied,current data-driven methods often face challenges such as indirect prediction,data sparsity,and data drift,which limit their accuracy and generalizability.This study develops an integrated method that combines a knowledge-driven method to directly compute distribution patterns of lithological components,which are used as a priori knowledge to guide the development of a data-driven method.Coupled Markov chain(CMC)and deep neural networks(DNNs)serve as the knowledge-driven and data-driven components,respectively.Additionally,a dynamic prediction strategy is proposed,where the model is continuously optimized as construction progresses and training samples accumulate,rather than being statically trained on post-construction data,as is common in data-driven methods.Finally,the proposed method is evaluated using a real-world project.The evaluation results show that the integrated method outperforms both individual data-and knowledge-driven methods,demonstrating higher predictive performance,greater stability,and greater robustness to data scarcity and data drift.Furthermore,the dynamic prediction strategy better captures the effects of gradual data accumulation and lithological spatial variability on prediction performance during construction,providing new insights for real-time prediction in practical tunneling applications.
基金supported by CNPC-CZU Innovation Alliancesupported by the Program of Polar Drilling Environmental Protection and Waste Treatment Technology (2022YFC2806403)。
文摘In petroleum engineering,real-time lithology identification is very important for reservoir evaluation,drilling decisions and petroleum geological exploration.A lithology identification method while drilling based on machine learning and mud logging data is studied in this paper.This method can effectively utilize downhole parameters collected in real-time during drilling,to identify lithology in real-time and provide a reference for optimization of drilling parameters.Given the imbalance of lithology samples,the synthetic minority over-sampling technique(SMOTE)and Tomek link were used to balance the sample number of five lithologies.Meanwhile,this paper introduces Tent map,random opposition-based learning and dynamic perceived probability to the original crow search algorithm(CSA),and establishes an improved crow search algorithm(ICSA).In this paper,ICSA is used to optimize the hyperparameter combination of random forest(RF),extremely random trees(ET),extreme gradient boosting(XGB),and light gradient boosting machine(LGBM)models.In addition,this study combines the recognition advantages of the four models.The accuracy of lithology identification by the weighted average probability model reaches 0.877.The study of this paper realizes high-precision real-time lithology identification method,which can provide lithology reference for the drilling process.
基金Supported by the National Key Technology R&D Program during the11~(th)Five-years Plan(2006BAD24B0301)~~
文摘Objective The aim was to reveal relationship between lithological character soil and productivity of Cunninghamia lanceolata and lay a foundation for systemic management of C. lanceolata fast-growing and high yield plantation. Method By using experimental ecology method and variance analysis, the biomass and growth of planting eleven years＇ C. lanceolata on the soils with six different lithologicel characters were studied. Result The effects of soils with six different lithological characters on the height, diameter growth and biomass of C. lanceolata were different, in which the growth order of C. lanceolata was： Feldspathic quartzy sandstone （ average height 523. 270 cm, average diameter 4.720 cm, average individual biomass 5.059kg） 〉 Basalt （ average height 511. 570 cm, average diameter 4.650 cm, average individual biomass 4.848 kg） 〉 Quartzy sandstone 〉 Blastopsammite 〉 The Quarternary Period red clay 〉 Coal-series siliceous sand-shale, and the difference was smaller between the last two lithological characters. Conclusion Feldspathic quartzy sandstone and Basalt are beneficial to C. lanceolata.
基金Project supported by the Science and Technology Project of CNPC Chuanqing Drilling Engineering Co.,Ltd“Element logging features of key horizons and application in SichuaneChongqing gas provinces”(No.:CQ2014B-14-1-1).
文摘With the popularization and application of fast drilling technology in Sichuan-Chongqing gas provinces,the returned cuttings are fine and even powdered,so the traditional cutting lithology identification methods are not applicable any longer.In this paper,qualitative lithology identification and quantitative interpretation based on element logging were conducted on the key oil and gas bearing layers in this area according to the principle of elemental geochemistry.The study results show that:(1)different lithologies can be identified easily because of their different element logging characteristics.For example,basalts have the element characteristics of 0.35<Fe/Si<0.55 and Ca/(Na+K)<4.00,while sedimentary rocks have Fe/Si<0.35 or>0.55.(2)Clastic rocks,carbonate rocks,sulphate and transition rocks in the category of sedimentary rocks can be identified based on the element combination of(Al+Si+Fe)and(Ca+Mg+S).Among them,clastic rocks have(Al+Si+Fe)>31%,carbonate rocks have(Al+Si+Fe)<8%and(Ca+Mg+S)<36%,and sulphate rocks have(Al+Si+Fe)<5%and(Ca+Mg+S)>36%.(3)Then,based on the element combination of(Si+K+Ca)tSi/Al and(Al+Si+Fe+K)t(Ca+S)/Mg,sandstone,mudstone(shale),gypsum,dolomite,limestone and transition rocks can be identified.Finally,a qualitative identification chart and a set of quantitative interpretation software of element logging on key horizons in Sichuan-Chongqing gas provinces were developed to make this method convenient for field application.This method was applied on site in ten wells(such as Well MX207)in Sichuan-Chongqing gas provinces.It is indicated that the coincidence rate of lithology identification is in the range of 88.75-95.22%(averaging 92.42%).Obviously,it can satisfy the requirements of fast lithology identification while drilling of key oil and gas horizons in Sichuan-Chongqing gas provinces.
文摘The Ordos basin is a stable craton whose late Paleozoic undergoes two sedimentary stages: from the middle- late Carboniferous offshore plain to the Permian continental river and lake delta. Sandstones in delta plain channels, delta-front river mouth bars and tidal channels are well developed. The sandstones are distributed on or between the genetic source rocks, forming good gas source conditions with widespread subtle lithologic gas pools of low porosity, low permeability, low pressure and low abundance. In recent years, a series of experiments has been done, aimed at overcoming difficulties in the exploration of lithologic gas pools. A set of exploration techniques, focusing on geological appraisal, seismic exploration, accurate logging evaluation and interpretation, well testing fracturing, has been developed to guide the exploration into the upper Paleozoic in the basin, leading to the discoveries of four large gas fields: Sulige, Yulin, Wushenqi and Mizhi.
基金Supported by the National Science and Technology Major Project(2016ZX05007-002)。
文摘By examining structures,sediments,reservoirs and accumulation assemblages in the Deyang-Anyue rift and its surrounding area,four new understandings are obtained.First,during the initiation period of Deyang-Anyue rift,multiple groups of faults developed in the rift due to the effect of tensile force,bringing about multiple mound and shoal belts controlled by horsts in the second member of the Sinian Dengying Formation;in the development stage of the rift,the boundary faults of the rift controlled the development of mound and shoal belts at the platform margin in the fourth member of Dengying Formation;during the shrinkage period of the rift,platform margin grain shoals of the Cambrian Canglangpu Formation developed in the rift margin.Second,four sets of large-scale mound and shoal reservoirs in the second member of Dengying Formation,the fourth member of Dengying Formation,Canglangpu Formation and Longwangmiao Formation overlap with several sets of source rocks such as Qiongzhusi Formation source rocks and Dengying Formation argillaceous limestone or dolomite developed inside and outside the rift,forming good source-reservoir-cap rock combinations;the sealing of tight rock layers in the lateral and updip direction results in the formation model of large lithologic gas reservoirs of oil pool before gas,continuous charging and independent preservation of each gas reservoir.Third,six favorable exploration zones of large-scale lithologic gas reservoirs have been sorted out through comprehensive evaluation,namely,mound and shoal complex controlled by horsts in the northern part of the rift in the second member of Dengying Formation,isolated karst mound and shoal complex of the fourth member of Dengying Formation in the south of the rift,the superimposed area of multi-stage platform margin mounds and shoals of the second and fourth members of Dengying Formation and Canglangpu Formation in the north slope area,the platform margin mounds and shoals of the second and fourth members of Dengying Formation in the west side of the rift,the platform margin mound and shoal bodies of the fourth member of Dengying Formation in the south slope area,etc.Fourth,Well Pengtan-1 drilled on the mound and shoal complex controlled by horsts of the second member of Dengying Formation in the rift and Well Jiaotan-1 drilled on the platform margin mound and shoal complex of the North Slope have obtained high-yield gas flows in multiple target layers,marking the discovery of a new gas province with reserves of(2-3)×10^(12) m^(3).This has proved the huge exploration potential of large lithologic gas reservoir group related to intracratonic rift.
基金Under the auspices of the National Natural Science Foundation of China (No .30470297)and theNationalBasicRe-searchProgram ofChina (973 Program)(No .2003CB415201 )
文摘The dry-hot valley of the Jinsha River is one of the typical eco-fragile areas in Southwest China, as well as a focus of revegetation study in the upper and middle reaches of the Changjiang River. Due to its extremely dry and hot climate, severely degraded vegetation and the intense soil and water loss, there are extreme difficulties in vegetation restoration in this area and no great breakthrough has ever been achieved on studies of revegetation over the last several decades. Through over ten years’ research conducted in the typical areas-the Yuanmou dry-hot valley, the authors found that the lithologic property is one of the crucial factors determining soil moisture conditions and vegetation types in the dry-hot valley, and the rainfall infiltration capability is also one of the key factors affecting the tree growth. Then the revegetation zoning based on different slopes was conducted and revegetation patterns for different zones were proposed.
基金Supported by National Natural Science Fund 40472078 and the Project of"973 plan"G1999043310
文摘Taking the Jiyang depression as an example,this paper discusses the control of the formation of lithological reservoir by surrounding rocks by integrated application of geological analysis,physical simulation,and the analysis of oil&gas accumulation mechanism.Geological statistical shows that the major burial depth and interval of lithological reservoirs in the Jiyang depression are related to the hydrocarbon generation in and expulsion from the Lower Tertiary source rocks and the time of the formation of most lithological reservoirs coincides with the peak of hydrocarbon generation and expulsion.The lithological traps located in the center of effective source rocks are propitious to high oil saturation than those located on the margin of effective source rocks.The hydrocarbon charge degree of the lithological reservoir has a positive correlation with the intensity of hydrocarbon expulsion from surrounding source rocks.Geological analyses and NMR experiments also show that the oil saturation of surrounding source rocks control the hydrocarbon potential of lithological traps,and a critical value for oil saturation of surrounding mudstone is required,that is,when the oil saturation of surrounding mudstone is lower than this critical value,no oil and gas accumulate in the lithological trap.The control of surrounding mudstone on the oil-bearing properties of lithological reservoirs is also analyzed by the mechanisms of hydrocarbon generation and expulsion as well as accumulation.
基金Supported by the National Natural Science Foundation of China(40772092)
文摘As a case study of the Panji No.1 Coal Mine in Anhui Province, based on thesite measured and statistical data, summarized the lithologic associations, characteristicsand distribution laws of interlayer-gliding structures and tectonic coal in the No.11-2 coalseams.The results show that 9 modes of lithologic association can form interlayer-glidingstructures.It is more easy for rock slip to occur when the lithologic associations are mainroof + coal seam + immediate floor type, compound roof+immediate roof + coal seam +immediate floor type and immediate roof + coal seam + immediate floor type.Lithologicassociations of roof and floor are the precondition to the formation of interlayer-glidingstructures.
基金supported by the National Natural Science Foundation of China(Nos.41704113,41674129)Key R&D Projects in Shandong Province(No.2019GSF109047)+1 种基金China Postdoctoral Science Foundation Grant(No.2019M661912)Science and Technology Plan Project of Shandong Education of China(Nos.J18KA190 and J18KA128)。
文摘Controllable D-D neutron sources have a long service life,low cost,and non-radioactivity.There are favorable prospects for its application in geophysical well logging,since traditional chemical radioactive sources used for well logging pose potential threats to the safety of the human body and environment.This paper presents an improved method to measure formation density that employs a D-D neutron source.In addition,the lithological effect on the measured density was removed to better estimate the formation porosity.First,we investigated the spatial distribution of capture gamma rays through Monte Carlo simulations as well as the relationship between the ratio of capture gamma ray counts and formation density to establish theoretical support for the design of density logging tools and their corresponding data processing methods.Second,we obtained the far to near detector counts of captured gamma rays for an optimized tool structure and then established its correlation with the density and porosity of three typical formations with pure quartz,calcite,and dolomite minerals.Third,we determined the values for correcting the densities of sandstone and dolomite with the same porosity using limestone data as the reference and established the equations for calculating the correction values,which lays a solid foundation for accurately calculating formation porosity.We observed that the capture gamma ray counts first increased then decreased and varied in different formations;this was especially observed in high-porosity formations.Under the same lithologic conditions(rock matrix),as the porosity increases,the peak value of gamma ray counts moves toward the neutron source.At different detector-source distances,the ratio of the capture gamma ray counts was well correlated with the formation density.An equation of the formation density conversion was established based on the ratio of capture gamma ray counts at the detector-source distances of 30 cm and 65 cm,and the calculated values were consistent with the true values.After correction,the formation density was highly consistent with the true value of the limestone density,and the mean absolute error was 0.013 g/cm3.The calculated porosity values were very close to the true values,and the mean relative error was 2.33%,highlighting the accuracy of the proposed method.These findings provide a new method for developing D-D neutron source logging tools and their well-log data processing methods.
文摘The rift lake basins in the eastern China have abundant hydrocarbon resources of lithologic deposits, which resulted from excellent source rocks and multi-type sandbodies developed during strong rifting. Vertically, the lithologic deposits are mainly distributed in the lowstand, lacustrine invasion and early highstand systems of third-order sequence corresponding to a secondary tectonic episode of strong rifting, and laterally they are closely related to various fans and turbidite sandbodies controlled by syn-sedimentary faults. A variety of lithologic traps have been developed in the rift lake basins, and they generally have favorable conditions of source-reservoir-seal assemblage and hydrocarbon accumulation dynamics, indicating that there is a great exploration potential of lithologic deposits in the rift lake basins. In order to obtain satisfactory effects of lithologic deposit exploration, it is required to combine new theories with advanced technical methods.
基金Supported by the China National Science and Technology Major Project(2011ZX05023-006-002,2016ZX05024-003).
文摘Based on the practice of oil and gas exploration and the analysis of shallow lithologic reservoirs,combined with the allocation relationship and enrichment law of oil and gas accumulation factors,main controlling factors and models of hydrocarbon accumulation of large lithologic reservoirs in shallow strata around the Bozhong sag are summarized,and favorable exploration areas are proposed.The coupling of the four factors of“ridge-fault-sand-zone”is crucial for the hydrocarbon enrichment in the shallow lithologic reservoirs.The convergence intensity of deep convergence ridges is the basis for shallow oil and gas enrichment,the activity intensity of large fault cutting ridges and the thickness of cap rocks control the vertical migration ability of oil and gas,the coupling degree of large sand bodies and fault cutting ridges control large-scale oil and gas filling,the fault sealing ability of structural stress concentration zones affects the enrichment degree of lithologic oil and gas reservoirs.Three enrichment models including uplift convergence type,steep slope sand convergence type and depression uplift convergence type are established through the case study of lithologic reservoirs in shallow strata around the Bozhong sag.
基金Funded by the National West Communication Construction Technology Project(No.2013 318 354 190)
文摘Six representative parent rocks of sand, including limestone, quartzite, gneisses, granite, Basalt and Marble were selected to conduct a systematical research on the effects of various lithologies of manufactured sand on the workability, mechanism properties, volume stability and durability of manufacturedsand concrete. The experimental results show that the strength of manufactured-sand concrete is slightly higher than that of natural-sand concrete. Furthermore, substituting 15% cement of the concrete mixture with equal quantity of the six different lithology stone powder respectively, the data indicated that they can improve the concrete’s workability, postpone the plastic cracking time, enhance the anti-cracking grade, and have no obvious effect on the properties of antifreeze and sulfate attack resistance but reduce the capability to resist chloride ion penetration. Moreover, the differences in concrete’s workability, mechanism properties, volume stability and durability caused by various lithologies of manufactured sand and stone powder were not significant and the influence of lithology variety on the macro properties of concrete could be neglected eventually.
文摘In recent years, a series of large low and medium abundance oil and gas fields are discovered through exploration activities onshore China, which are commonly characterized by low porosity-permeability reservoirs, low oil/gas column height, multiple thin hydrocarbon layers, and distribution in overlapping and connection, and so on. The advantageous conditions for large-area accumulation of low-medium abundance hydrocarbon reservoirs include： （1） large （fan） delta sandbodies are developed in the hinterland of large flow-uncontrolled lake basins and they are alternated with source rocks extensively in a structure like ＂sandwiches＂; （2） effective hydrocarbon source kitchens are extensively distributed, offering maximum contact chances with various sandbodies and hydrocarbon source rocks; （3） oil and gas columns are low in height, hydrocarbon layers are mainly of normal-low pressure, and requirements for seal rock are low; （4） reservoirs have strong inheterogeneity and gas reservoirs are badly connected; （5） the hydrocarbon desorption and expulsion under uplifting and unloading environments cause widely distributed hydrocarbon source rocks of coal measures to form large-area reservoirs; （6） deep basin areas and synclinal areas possess reservoir-forming dynamics. The areas with great exploration potential include the Paleozoic and Mesozoic in the Ordos Basin, the Xujiahe Formation in Dachuanzhong in the Sichuan basin, deep basin areas in the Songliao basin etc. The core techniques of improving exploration efficiency consist of the sweetspot prediction technique that focuses on fine characterization of reservoirs, the hydrocarbon layer protecting and high-speed drilling technique, and the rework technique for enhancing productivity.
基金supported by the National Basic Research Program of China (No2006 CB202200)
文摘Besides the cross sections of roadways and the tendency and obliquity of roadway axes, the major controlling factors affecting the height of a collapsing roof include the weak lithological structure of surrounding rocks. This thesis analyzes the effect of two single and weak lithological structures of both sides and the roof on the height of a collapsing roof in a deep soft rock road- way. Using the two-dimensional UDEC3.1 software, a numerical structures of both sides of a roadway and of two weak lithological simulation was carried out on the models of weak lithological structures of roof of different depths. We reconstruct the overall processes from a break-away layer, bending, subsidence and the cracking of a collapsing roof. We also illustrate the distribution characteristics of displacement fields in the surrounding rock after the roof collapse in a deep soft rock roadway. The results of our numerical simulations indicate that the form of a roof collapse is side-expanding when the roadway is a weak structure at both sides The height of the roof collapse is related to the lithological combination of the roof when the roadway is a weak structure of the roof.
基金Supported by the China National Science and Technology Major Project(2016ZX05024-003)。
文摘By using drilling,high-precision 3 D seismic data,data of geochemistry,logging and testing,the reservoir characteristics and accumulation conditions of the KL6-1 lithologic oilfield in the Laibei Low Uplift in the Bohai Sea are examined comprehensively.The study shows that:KL6-1 oilfield is a monolithic,high-quality,large-scale Neogene lithologic oilfield featuring shallow reservoir depth,high productivity,concentrated oil-bearing intervals,large oil-bearing area,and high reserve abundance;hydrocarbon source supply from two directions provides a sufficient material basis for the formation of large oil field;two types of"inherited structural ridge"developed under the effect of block rotation,late active faults formed by Neotectonic movement,and widely distributed contiguous sand bodies provide an efficient oil and gas transportation system for the large-scale accumulation of oil and gas;contiguous channel and lacustrine lowstand system sand bodies developed in low accommodation condition provide the basic condition for the formation of large-scale lithologic traps;deep formations structural ridge,faults(dominant migration pathways)and large-scale superimposed contiguous sand bodies constitute a"vine type"oil and gas migration and accumulation system in the Laibei Low Uplift,which is conducive to the formation of large-scale and high-abundance lithologic reservoir in this area.The successful discovery of KL6-1,100 million ton reserve order lithologic oil field,has revealed the exploration potential of Neogene large lithologic reservoirs in Bohai Sea,expanded the exploration field,and also has certain reference significance for the exploration of large lithologic reservoirs in similar areas.
基金Chinese Academy of Sciences Strategic Pilot Science and Technology Project(Class A)(XDA14010403)National Science and Technology Major Project(2016ZX05007)PetroChina Science and Technology Project(2021DJ0604,kt2020-01-03)。
文摘Based on analyses of characteristics,hydrocarbon charging history and geological conditions for the formation of Sinian-Cambrian reservoirs in the north slope area of central Sichuan paleo-uplift,the natural gas origin,accumulation evolution,accumulation pattern and formation conditions of large lithologic gas reservoirs have been investigated.Through comprehensive analyses of natural gas composition,carbon and hydrogen isotopic compositions,fluid inclusions,reservoir bitumen,and geological conditions such as lithofacies paleogeography and beach body characterization,it is concluded that:(1)The natural gas in the Sinian-Cambrian of the north slope area is mainly oil cracking gas,and different contribution ratios of multiple sets of source rocks lead to different geochemical characteristics of natural gas in different reservoirs.(2)Although the both Sinian and Cambrian gas reservoirs in this area are lithologic gas reservoirs under monocline background,the former has normal-pressure and the latter has high-pressure.There are three types of source-reservoir-caprock combinations:single source with lower generation and upper reservoir,double sources with lower generation and upper reservoir or with side source and lateral reservoir,double sources with lower generation and upper reservoir or with upper generation and lower reservoir.The Permian-Triassic is the main generation period of oil,Early-Middle Jurassic is the main generation period of oil cracking gas and wet gas,and Late Jurassic-Cretaceous is the main generation period of dry gas.(3)The Sinian-Cambrian system of the north slope area has two favorable conditions for formation of large lithologic gas reservoirs,one is that the large scale beach facies reservoirs are located in the range of ancient oil reservoirs or near the source rocks,which is conducive to the"in-situ"large-scale accumulation of cracked gas in the paleo-oil reservoirs,the other is that the large scale mound-beach complex reservoirs and sealing layers of inter beach tight zones match effectively to form large lithologic traps under the slope background.The research results confirm that the north slope area has large multi-layer lithologic gas reservoirs with more than one trillion cubic meters of natural gas resources and great exploration potential.
文摘Thousands of landslide data being taken as the nation wide statistics of sampling and the two state variables of landslide being processed with two methods described in the references, the main types of lithological groups of landslides in China have been sieved and selected.On the other hand, through the displacement table of Pascal Yanghui triangle used in the information encoding theory, the mark weight of sampling can be calculated and the main lithological groups which have close relationship with landslide occurrence can be gained.In comparison with the both results, the characteristics of main sliding lithological groups are determinated, and the main distribution regions of landslides can be prognosticated.
文摘In the frame of landslide susceptibility assessment, a spectral library was created to support the identification of materials confined to a particular region using remote sensing images. This library, called Pakistan spectral library(pklib) version 0.1, contains the analysis data of sixty rock samples taken in the Balakot region in Northern Pakistan.The spectral library is implemented as SQLite database. Structure and naming are inspired by the convention system of the ASTER Spectral Library. Usability, application and benefit of the pklib were evaluated and depicted taking two approaches, the multivariate and the spectral based. The spectral information were used to create indices. The indices were applied to Landsat and ASTER data tosupportthespatial delineation of outcropping rock sequences instratigraphic formations. The application of the indices introduced in this paper helps to identify spots where specific lithological characteristics occur. Especially in areas with sparse or missing detailed geological mapping, the spectral discrimination via remote sensing data can speed up the survey. The library can be used not only to support the improvement of factor maps for landslide susceptibility analysis, but also to provide a geoscientific basisto further analyze the lithological spotin numerous regions in the Hindu Kush.
文摘Sedimentary heterogeneity conditions of Catania Plain quaternary aquifer (CPQA), the wider alluvial multi-aquifer system of Sicily, were rebuilt to simulate and quantify groundwater flow. Transition probabilities based on a Markov Chain (MC) and Sequential Indicator Simulation (SIS) are the structure-imitating simulators utilized for generating stochastic distributions of hydraulic conductivity fields of CPQA, basing on borehole data: plausible equiprobable solutions of the complex geological structure of the CPQA were simulated. This study highlights that the choice of geostatistical simulation method plays a fundamental role in predictive scenarios for groundwater resources managing of CPQA. Indeed, simulated characteristics of the sedimentary heterogeneity constituted the basis of finite difference models for simulating the groundwater flow of CPQA. In heterogeneous systems such as CPQA, SIS may be inadequate for reproducing the macrostructures. Instead, MC adequately reproduced spatial connection of lithofacies, representing a more realistic solution dealing to the proposed geological model of CPQA. MC and SIS models were utilized to both assess the uncertainty of the generated hydraulic conductivity fields of CPQA and predictions about its behavior under normal stress conditions induced by urbanization. The calibration of CPQA groundwater flow models based on MC and SIS simulations allowed to achieve a realistic feedback about the quality of the geostatistical reconstructions of the geological heterogeneity field.
