Systematically analyzing the impact mechanisms of policy on Land Use Conflict(LUC)is crucial for constructing effective conflict mitigation strategies.However,previous research on how policy influences LUC remains rel...Systematically analyzing the impact mechanisms of policy on Land Use Conflict(LUC)is crucial for constructing effective conflict mitigation strategies.However,previous research on how policy influences LUC remains relatively limited.Focusing on the indirect driving role of policy on LUC,this study proposed County Development Level(CDL)under Major Function Oriented Zone Planning(MFOZP)guidance as an intermediary variable,bridging the implicit influence of MFOZP and the explicit changes in LUC.Using the Beijing-Tianjin-Hebei(BTH)region in China as a case study,we analyzed the spatio-temporal evolution characteristics of LUC and CDL for the periods 2000-2010 and 2010-2020,before and after MFOZP implementation.Panel models and Geographically Weighted Regression(GWR)were employed to explore the mechanism by which CDL influences LUC under MFOZP guidance.The results show that:1)MFOZP implementation effectively alleviates land use pressure from regional development,with LUC continuously declining at a rate of 2.41%,while CDL exhibits slight growth(3.84%),during 2010-2020.2)Under MFOZP guidance,CDL reduces pressure on Land Use Structure Conflict(LUSC)and Land Use Process Conflict(LUPC),enhances its inhibitory effect on Land Use Function Conflict(LUFC),and significantly contributes to LUC coordination,with notable spatial heterogeneity.3)The coupling relationship between CDL and LUC has improved post-implementation.Based on this,tailored LUC coordination strategies are proposed for different functional zones.This study confirms the effectiveness of MFOZP in coordinating LUC and provides a scientific reference for LUC research under policy frameworks and the governance of LUC in the BTH region.展开更多
Drilling and blasting tunneling is a cyclic process in which tunnel rock undergoes repeated blast loading,affecting its dynamic characteristics,energy evolution,and damage progression.To explore the dynamic mechanical...Drilling and blasting tunneling is a cyclic process in which tunnel rock undergoes repeated blast loading,affecting its dynamic characteristics,energy evolution,and damage progression.To explore the dynamic mechanical properties and damage mechanisms of carbonaceous slate under cyclic impact loads of varying intensities,cyclic dynamic tests are conducted using a triaxial split Hopkinson pressure bar.This study analyzes the stress-strain relationship,energy damage evolution,and macro-to-micro failure characteristics.The results show that peak stress and strain are significantly influenced by impact intensity and the number of impacts.The initial dynamic stress is positively correlated with the impact intensity,but with more impact,the dynamic stress decreases while the peak strain increases.Energy evolution follows a pattern of"slow growthfluctuating growthrapid growth,"with the crack initiation stress and its proportion decreasing.CT and SEM analyses reveal that as the impact intensity increases,failure becomes more chaotic,the fracture volume increases,and the fracture mode shifts from interlayer and intergranular to through-layer and trans-granular fractures.These findings provide an experimental basis for soft rock tunnel stability analysis.展开更多
Many hydropower projects have been constructed in Southwest China with the strategic goal of achieving carbon neutrality.Most of these hydropower projects utilize concrete face rockfilldams(CFRDs)built on a deep overb...Many hydropower projects have been constructed in Southwest China with the strategic goal of achieving carbon neutrality.Most of these hydropower projects utilize concrete face rockfilldams(CFRDs)built on a deep overburden layer.The deep overburden layer causes uneven settlement between the overburden layer and the dam,which poses a serious threat to the safety of both the construction and operation of the dam.In this study,microseismic(MS)monitoring technology was employed for the firsttime in the fieldof dam fillingengineering,allowing for the real-time monitoring of microfracture in the bedrock during dam construction.The time-frequency analysis method was used to summarize the MS waveform characteristics induced by dam filling.The fracture mechanism of bedrock was revealed,and the relationships among slope deformation,dam settlement,and MS activity were analyzed.The following research results have been obtained.The MS signal induced by dam fillinghas low energy and amplitude,short duration,and high frequency.The fracture of the bedrock was mainly shear failure.MS monitoring can predict deformation during blasting excavation and capture the large settlement that may occur during dam fillingin advance.Research findingshave demonstrated the significantapplication value of MS monitoring technology in predicting the risk of dam settlement and provide a reference for similar projects.展开更多
The effective early warning of surrounding rock mass deformation is crucial in geotechnical engineering for ensuring the safety and stability of underground constructions.This study introduces a novel risk early warni...The effective early warning of surrounding rock mass deformation is crucial in geotechnical engineering for ensuring the safety and stability of underground constructions.This study introduces a novel risk early warning model based on multi-parameter fuzzy comprehensive evaluation,which quantitatively assesses the risk state of the surrounding rock mass.The microseismic(MS)monitoring system is set up for the underground powerhouse.The spatial and temporal distribution of MS events and the frequency characteristics of MS signals are analyzed during the top arch excavation.The early warning indices for characterizing MS spatial aggregation and frequency-energy dispersion are proposed based on the octree theory to assess the deformation of the surrounding rock mass.The risk warning model for the surrounding rock mass in underground engineering is developed through the integration of the formulated index and the frequency characteristics of MS signals.The results indicate that the multiparameter fuzzy comprehensive assessment model can achieve three-dimensional visualization of risk warnings for the surrounding rock mass.The quantitative results regarding warning time and potential deformation areas are highly consistent with the characteristics of MS precursors.These research results can provide an important reference for early warning of surrounding rock mass risk in similar underground projects.展开更多
Surrounding rock deterioration and large deformation have always been a significant difficulty in designing and constructing tunnels in soft rock.The key lies in real-time perception and quantitative assessment of the...Surrounding rock deterioration and large deformation have always been a significant difficulty in designing and constructing tunnels in soft rock.The key lies in real-time perception and quantitative assessment of the damaged area around the tunnel.An in situ microseismic(MS)monitoring system is established in the plateau soft tock tunnel.This technique facilitates spatiotemporal monitoring of the rock mass's fracturing expansion and squeezing deformation,which agree well with field convergence deformation results.The formation mechanisms of progressive failure evolution of soft rock tunnels were discussed and analyzed with MS data and numerical results.The results demonstrate that:(1)Localized stress concentration and layered rock result in significant asymmetry in micro-fractures propagation in the tunnel radial section.As excavation continues,the fracture extension area extends into the deep surrounding rockmass on the east side affected by the weak bedding;(2)Tunnel excavation and long-term deformation can induce tensile shear action on the rock mass,vertical tension fractures(account for 45%)exist in deep rockmass,which play a crucial role in controlling the macroscopic failure of surrounding rock;and(3)Based on the radiated MS energy,a three-dimensional model was created to visualize the damage zone of the tunnel surrounding rock.The model depicted varying degrees of damage,and three high damage zones were identified.Generally,the depth of high damage zone ranged from 4 m to 12 m.This study may be a valuable reference for the warning and controlling of large deformations in similar projects.展开更多
The strike-slip fault system in the central Tarim Craton controls a complex petroleum system with estimated reserves exceeding 1×10^(9)t,the fault-related fractures are important for hydrocarbon accumulation.In t...The strike-slip fault system in the central Tarim Craton controls a complex petroleum system with estimated reserves exceeding 1×10^(9)t,the fault-related fractures are important for hydrocarbon accumulation.In this paper,the basic parameters such as density and width of fractures are counted and classified,and the effects of fractures on reservoirs are analyzed.The results show that:(1)Structural fractures and stylolite were widely developed in Halahatang area and experienced at least three stages of activity based on the infilling materials and crosscutting relationship.(2)Fracture density,width,aperture,and dip angle vary in different wells,but the relationship between the above parameters and the distance to the fault core indicates the fracture differences in the fault damage zone and further provides a method to divide the inner units in the fault damage zone.In addition,oil and gas wells with high production mainly concentrate in the inner unit.(3)The infilling materials and degree of fractures vary.Fractures formed in the early stage are more filled and less open,while the fractures formed in the late stage are relatively less filled and more open.(4)Fractures improve porosity to a certain extent but greatly increase permeability,especially in the inner zone of fault damage zone with large quantity,multiple inclinations,less filling and large width.These features contribute to the formation of a higher-quality reservoir,further improving oil and gas production.This paper provides a quantitative characterization method for the study of strike-slip fault-related fracture-caved reservoirs,and points out that fault damage zone,especially the inner zone of the fault damage zone,is the potential goal for oil and gas exploration.展开更多
The Wufeng-Longmaxi marine shale in the Eastern Sichuan Basin is the key target for shale gas exploration in China.Based on logging response and lithofacies type,three paleo-geomorphological units are identified in th...The Wufeng-Longmaxi marine shale in the Eastern Sichuan Basin is the key target for shale gas exploration in China.Based on logging response and lithofacies type,three paleo-geomorphological units are identified in the deep-water shelf during the Wufeng-Longmaxi deposition:subaqueous slope(SS),subaqueous plain(SP),and subaqueous sub-sag(SSS).Using methods such as mercury intrusion porosimetry(MIP),field emission scanning electron microscopy(FE-SEM),nuclear magnetic resonance(NMR),and X-ray diffraction(XRD),the differences of environmental conditions,mineral composition,organic matter(OM)content,and pore structure in different units are determined,and the factors controlling the differences in shale reservoirs are discussed.The results show that redox conditions of bottom water and productivity of surface water affect OM enrichment,resulting in SSS being the most organic-rich unit.Terrigenous detrital input affects mineral composition in different units,and SSS is the most quartz-rich unit.From SS to SSS shale,the proportion of OM pores gradually increased,while the proportion of inorganic pores and microfractures gradually decreased.The pore size distribution dominated by mesopores in SP and SSS shale is generally consistent,much higher than in SS.The differences in sedimentary environments result in differences in reservoir quality.The OM and brittle mineral content in SSS are relatively high,which is beneficial for reservoir development.SSS has the best environmental conditions;therefore,the quality of the marine shale reservoirs formed is the best.展开更多
The Jurassic Lianggaoshan Formation in eastern Sichuan Basin is a key target for shale oil exploration.It faces challenges in three-pressure prediction due to complex structural and sedimentary interactions,as well as...The Jurassic Lianggaoshan Formation in eastern Sichuan Basin is a key target for shale oil exploration.It faces challenges in three-pressure prediction due to complex structural and sedimentary interactions,as well as strong reservoir anisotropy.These issues often lead to wellbore instability and gas logging anomalies during drilling.This study presents an integrated workflow that combines residual moveout correction using correlation-based dynamic time warping(CDTW),high-resolution seismic waveform indication inversion,and three-pressure prediction of jointing well-seismic data.Applied to the LT1 well block,the workflow effectively corrects anisotropic residual moveout in image gathers,leading to a signal strength increase of over 10%in frequency bands above 30 Hz and enhancing event continuity.High-resolution rock mechanical parameters are obtained through seismic waveform inversion and regional calibration,enabling the prediction of three-dimensional pore pressure,collapse pressure and fracture pressure.The results are consistent with actual drilling gas shows and core data,confirming the method's accuracy and supporting mud weight planning and wellbore stability efforts.This cost-effective and technically robust approach proves highly reliable in complex environments with significant heterogeneity and anisotropy,assisting drilling decisions and risk management in eastern Sichuan and similar challenging geological settings.展开更多
Research on the distribution and development of black shales in the Lianggaoshan Formation has been deficient,which has hindered exploration for lacustrine shale oil in the Sichuan Basin.Our study characterized the we...Research on the distribution and development of black shales in the Lianggaoshan Formation has been deficient,which has hindered exploration for lacustrine shale oil in the Sichuan Basin.Our study characterized the well logging data,core samples,outcrops,and geochemistry of black shales in the Lianggaoshan Formation in the Sichuan Basin.Our analysis focused on the lake basin evolution and the migration characteristics,paleoenvironmental features,formation mechanisms,and developmental model of the black shales.The results indicated that black shales in the Lianggaoshan Formation exhibited significant lateral migration,with an overall thickening trend from east to west.Within the 1st Member of the formation,black shale occurred as a single thick layer in the eastern region that gradually thinned toward the central region.Multiple sets of shale developed within the 2nd and 3rd members,and these had lower thicknesses than the 1st Member and migrated toward central Sichuan.Paleoproductivity and terrigenous input were the main factors controlling the deposition of black shales.A semi-humid climate influenced the deposition of black shales,bringing abundant freshwater,terrigenous debris,and nutrients into the basin.Decomposition of organic matter consumed oxygen in sediment and bottom water,causing localized oxygen deficiency in the strata.展开更多
For an improved understanding of gas enrichment mechanism in the eastern Sichuan Basin,South China,twelve natural gas samples were obtained from carbonate reservoirs of the Upper Permian strata to analyze the hydrocar...For an improved understanding of gas enrichment mechanism in the eastern Sichuan Basin,South China,twelve natural gas samples were obtained from carbonate reservoirs of the Upper Permian strata to analyze the hydrocarbon and non-hydrocarbon gas compositions,stable carbon and hydrogen isotopes ratios of hydrocarbons,and noble gas isotope ratios.The gas samples in the Upper Permian reservoirs principally consist of alkane gas with a dryness ratio ranging from 127.9 to 1564.4.The carbon isotope ratio of methane(δ^(13)C_(1))was almost constant at-34.1 to-31.3‰,but the carbon isotope ratio of ethane(δ^(13)C2)varied from-36.6‰to-25.8‰.The hydrogen isotope ratio of methane(δ^2HC_(1))also displayed a wide range from-137‰to-127‰.The large variations in the dryness ratio,δ^(13)C_(2),andδ^2HC_(1)with almost constantδ^(13)C_(1)suggest the mixing of sapropelic and humic origins for hydrocarbon gases in these reservoirs.A high concentration of hydrogen sulfide(H_(2)S)originated from the thermochemical sulfate reduction(TSR),which was positively correlated withδ^(13)C_(1)(orδ^(13)C_(2))in individual gas fields.TSR alteredδ^(13)C_(1)(orδ^(13)C_(2))and resulted in the abnormal character of isotopic reversal in the individual samples.Theδ^(13)C_(1)(orδ^(13)C_(2))in most gas samples,independent of H_(2)S concentration,further displayed reversed carbon isotopes because of the mixture of thermogenic gases with various thermal maturity levels.The measured argon isotope ratio(^(40)Ar/^(36)Ar)varied from 310 to 1225,which suggests that the oldest 320 Ma source rock age corresponds to Permian shales.The analysis of the gas origin and the identification of primary source rock have made a significant contribution to further understanding the resource potential and distribution of natural gas in the Upper Permian,and have great implications for gas exploration in the eastern Sichuan Basin.展开更多
The glacial lake in the Boqu Basin in Tibetan Plateau has changed significantly in recent years due to global warming,seriously affecting the natural and social environments in downstream areas.We obtained the change ...The glacial lake in the Boqu Basin in Tibetan Plateau has changed significantly in recent years due to global warming,seriously affecting the natural and social environments in downstream areas.We obtained the change characteristics of glacial lakes by analyzing remote sensing images and evaluated the outburst floods susceptibility of glacial lakes in the Boqu Basin by combining fuzzy mathematics and random forest methods.An empirical formula for glacial lake hazard evaluation was established based on a fuzzy comprehensive evaluation.The confusion matrix were used to assess the evaluation effect of each method.The conclusions were as follows:(1)Under the influence of climate warming,glaciers are retreating further from the glacial lakes,and the size of glaciers that can impact these lakes is shrinking.Geological conditions,such as steep slopes around the lakes,have replaced glacier tongues as the primary factors threatening the susceptibility of the glacial lakes;(2)Among the three evaluation methods,the empirical formula offers high calculation accuracy and is the most convenient to use,which provides an accuracy rate of 85.71%in susceptibility evaluation of the Boqu Basin glacial lake and can be applied to other areas in the rapid evaluation of the susceptibility of glacial lakes;(3)The impact analysis of the collapse shows that the collapse of the Galongco fault would cause large economic losses.展开更多
The Jianglang Dome has integral tectonostratigraphic units and contains a suite of high-grade stratiform Cu deposits.However,the formation mechanism of this dome and genetic model of Cu mineralization remain a matter ...The Jianglang Dome has integral tectonostratigraphic units and contains a suite of high-grade stratiform Cu deposits.However,the formation mechanism of this dome and genetic model of Cu mineralization remain a matter of debate.The resolution of these problems hinges on the presence of magmatic intrusions in the core.Here,we report bulk geochemical and zircon U-Pb data of a newly discovered syenite intrusion as well as chalcopyrite Re-Os dating results.We aim to explore genesis of the Jianglang Dome,genetic model of the stratiform Cu deposits,and rare metal mineralization potential of the syenite intrusion.The dated syenite sample yields an emplacement age of 207.1±2.0 Ma,which matches post-collisional extension in the Songpan-Ganze Orogen.The syenite rocks have average high(Zr+Nb+Ce+Y)concentrations of 512 ppm,10000.Ga/Al ratios of 3.97,and crystallization temperatures of 827°C,together with low Mg#values of 1.73;they fi t the A-type granitoid defi nition and a crustal origin.Chalcopyrite separates yield a Re-Os isochron age of 207.1±5.3 Ma,which markedly postdates the formation age of their orehosting rocks(the Liwu Group,ca.553 Ma).Our new age determination,together with previous chalcopyrite Re–Os isochron age of ca.151.1 Ma and sulfi de sulfur isotope(δ^(34)S_(V-CDT)=8.7‰–5.6‰)and tourmaline boron isotope(δ^(11)B=−15.47‰to−5.91‰)data,confi rms multistage epigenetic Cu mineralization related to magmatic-hydrothermal fl uids.Compared with regional ca.209–207 Ma fertile granitoids,the studied syenite intrusion shows unevolved and barren affi nities and negligible rare metal mineralization potential.Combined with residual gravity low anomalies in the core of the Jianglang Dome,which suggest a large deepseated granitic batholith,we prefer thermal doming resulting from magma-induced uplift for the nature of this dome.展开更多
Accurate prediction of reservoir parameters is essential for reservoir evaluation.Recent machine learning methods have spurred significant advancements in reservoir prediction;however,limited well logging data and str...Accurate prediction of reservoir parameters is essential for reservoir evaluation.Recent machine learning methods have spurred significant advancements in reservoir prediction;however,limited well logging data and strong reservoir heterogeneity still hinder the accuracy and reliability of such predictions.Addressing these challenges requires methods capable of effectively predicting reservoir parameters under data scarcity and complex reservoir structures.In this study,we propose CAF2,a feature-fusion cross-modal alignment framework guided by large language models(LLMs).CAF2 integrates data augmentation,knowledge distillation,cross-modal alignment,and feature fusion.The data augmentation module employs the RealTabFormer model to generate synthetic datasets that mirror the distribution of real logging data,addressing the challenge of data scarcity.Knowledge distillation extracts essential domain knowledge from LLMs,guiding cross-modal alignment between well logging data and textual knowledge.This alignment mitigates modality gaps via token and sequence alignment,enhancing depth-domain feature representation.Finally,a cross-variable and cross-depth feature fusion strategy exploits both variable information and depth correlations,overcoming the difficulties in accurate reservoir parameter prediction posed by reservoir heterogeneity.Experimental results demonstrate that CAF2 significantly outperforms existing models in predicting tight sandstone reservoir parameters,serving as an effective tool for oil and gas exploration and development.展开更多
There are abundant hydrothermal events within the Dengying Formation dolomite of the Precambrian system in southwest China.Methods including petrography identification,fluid-inclusion observation,in-situ U-Pb dating,a...There are abundant hydrothermal events within the Dengying Formation dolomite of the Precambrian system in southwest China.Methods including petrography identification,fluid-inclusion observation,in-situ U-Pb dating,and in-situ measurement of rare earth element(REE),etc.are integrated to characterize hydrothermal activity process within the Dengying Formation dolomite.The hydrothermal activity therein can be divided into four stages on the basis of in-situ U-Pb dating results of saddle dolomite cements.The 1st-stage(415.0-400.0 Ma)and 2nd-stage(259.4-248.0 Ma)hydrothermal events are characterized by saddle dolomite filling along the margin of fractures,or filling within dilational breccia and zebra textures.Compared with matrix dolomite and seawater-derived fibrous dolomite,saddle dolomite exhibits obvious negative anomalies of Ce elements.The 3rd-stage(225.6-199.0 Ma)hydrothermal event is represented by galena,sphalerite and other Mississipppi Valley-type(MVT)mineral cements in residual space.The formation of lead-zinc ore is due to the precipitation of metal sulfide caused by the thermo-chemical sulfate reduction(TSR)reaction between hydrothermal fluids and hydrocarbons during the large-scale hydrocarbon charging period.The 4th-stage(130.0-41.0 Ma)hydrothermal event is characterized by quartz and a small amount of fluorite filling the residual pores with dolomites.Quartz and fluorite record the migration of deep high-temperature hydrothermal fluid along early fractures and residual pores.During this period,the hydrothermal fluids result in the heterogeneous structure of bitumen,which is a clear response to high-temperature hydrothermal activity.展开更多
0 INTRODUCTION.The global availability of digital elevation model(DEM)data,such as 90-m Shuttle Radar Topography Mission(SRTM)DEM and 30-m Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital ...0 INTRODUCTION.The global availability of digital elevation model(DEM)data,such as 90-m Shuttle Radar Topography Mission(SRTM)DEM and 30-m Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model(ASTER GDEM),has been extensively utilized in morphotectonic analyses(e.g.,Wang et al.,2024;Cheng et al.,2018;Pérez-Pe?a et al.,2010;El Hamdouni et al.,2008).展开更多
Ensuring the stability of the surrounding rock mass is of great importance during the construction of a large underground powerhouse.The presence of unfavorable structural planes within the rock mass,such as faults,ca...Ensuring the stability of the surrounding rock mass is of great importance during the construction of a large underground powerhouse.The presence of unfavorable structural planes within the rock mass,such as faults,can lead to substantial deformation and subsequent collapse.A series of in situ experiments and discrete element numerical simulations have been conducted to gain insight into the progressive failure behavior and deformation response of rocks in relation to controlled collapse scenarios involving gently inclined faults.First,the unloading damage evolution process of the surrounding rock mass is characterized by microscopic analysis using microseismic(MS)data.Second,the moment tensor inversion method is used to elucidate the temporal distribution of MS event fracture types in the surrounding rock mass.During the development stage of the collapse,numerous tensile fracture events occur,while a few shear fractures corresponding to structural plane dislocation precede their occurrence.The use of the digital panoramic borehole camera,acoustic wave test,and numerical simulation revealed that gently inclined faults and deep cracks at a certain depth from the cavern periphery are the primary factors contributing to rock collapse.These results provide a valuable case study that can help anticipate and mitigate fault-slip collapse incidents while providing practical insights for underground cave excavation.展开更多
The black shales of Wufeng and Longmaxi Formation(Late Ordovician-Early Silurian period)in Sichuan Basin are the main strata for marine shale gas exploration,which have a yearly shale gas production of 228×10^(8)...The black shales of Wufeng and Longmaxi Formation(Late Ordovician-Early Silurian period)in Sichuan Basin are the main strata for marine shale gas exploration,which have a yearly shale gas production of 228×10^(8)m^(3)and cumulative shale gas production of 919×10^(8)m^(3).According to the lithological and biological features,filling sequences,sedimentary structures and lab analysis,the authors divided the Wufeng/Guanyinqiao and Longmaxi Formations into shore,tidal flat,shoal,shallow water shelf and deep water shelf facies,and confirmed that a shallow water deposition between the two sets of shales.Although both Formations contain similar shales,their formation mechanisms differ.During the deposition of Wufeng shale,influenced by the Caledonian Movement,the Central Sichuan and Guizhou Uplifts led to the transformation of the Sichuan Basin into a back-bulge basin.Coinstantaneous volcanic activity provided significant nutrients,contributing to the deposition of Wufeng Formation black shales.In contrast,during the deposition of Longmaxi shale,collisions caused basement subsidence,melting glaciers raised sea levels,and renewed volcanic activity provided additional nutrients,leading to Longmaxi Formation black shale accumulation.Considering the basic sedimentary geology and shale gas characteristics,areas such as Suijiang-Leibo-Daguan,Luzhou-Zigong,Weirong-Yongchuan,and Nanchuan-Dingshan are identified as key prospects for future shale gas exploration in the Wufeng-Longmaxi Formations.展开更多
Deep carbonate reservoirs affected by prominent strike-slip faults represent crucial targets in oil and gas exploration owing to their immense resource potential.However,the complex geological environments and poorly ...Deep carbonate reservoirs affected by prominent strike-slip faults represent crucial targets in oil and gas exploration owing to their immense resource potential.However,the complex geological environments and poorly understood histories of the associated paleo-fluid activity have hindered the development of robust theories regarding pore formation and preservation mechanisms,resulting in suboptimal exploration strategies.Leveraging the extensive well deployment by the China Sinopec Group in the Shunbei area of the Tarim Basin,this study addresses these challenges by establishing a comprehensive framework for the evolution of diagenetic fluids within the Middle-Lower Ordovician carbonate formations.Using core samples,thin-section analysis,and cathodoluminescence observations,this study employs high-resolution geochemical methodologies,including isotopic analyses,rare earth element profiling,fluid inclusion studies,and uranium-lead dating,as primary tools for identifying and interpreting paleo-fluid characteristics across various rock types and calcite cement varieties within this stratigraphic interval.The findings reveal several key insights:(i)both RFC and C1 cements are derived from seawater,with C1 forming under burial conditions;(ii)C2,C3,and VC cements result from distinct tectonic events,specifically during the first and third episodes of the Middle Caledonian movement,with meteoric water infiltrating fault systems independently of orogenic belts or paleo-karst systems;and(iii)previous conclusions are challenged,as the influence of hydrothermal activity in this area is found to be minimal.Furthermore,the model presented here serves as a valuable reference for understanding fluid activity events at distal locations within orogenic belts under compressive stress,while accurately capturing fluid variations over different temporal scales within fault zones plays a decisive role.展开更多
Fractures significantly impact oil and gas production by altering the mechanical properties of subsurface rocks.This study investigates the forward and inverse problems associated with monoclinic anisotropic media,whi...Fractures significantly impact oil and gas production by altering the mechanical properties of subsurface rocks.This study investigates the forward and inverse problems associated with monoclinic anisotropic media,which arise from the presence of two sets of inclined fractures within an isotropic matrix.We first derive the stiffness matrix for this monoclinic medium by applying Schoenberg's linear slip theory.Subsequently,we employ the point spread function and the steady phase method to derive and simplify the reflection coefficient equation for seismic waves interacting with this complex medium.Finally,we verify the rationality of the method by using synthetic seismic records and actual seismic records.The proposed equations and inversion techniques offer a more accurate framework for characterizing monoclinic anisotropic media affected by inclined fractures,thereby enhancing the interpretation of subsurface structures in hydrocarbon exploration.展开更多
基金Under the auspices of the National Key Research and Development Program of China(No.2018YFD1100803)the Fundamental Research Fund for the Central Universities(Ph.D.Top Innovative Talents Fund of CUMTB)(No.BBJ2024029)。
文摘Systematically analyzing the impact mechanisms of policy on Land Use Conflict(LUC)is crucial for constructing effective conflict mitigation strategies.However,previous research on how policy influences LUC remains relatively limited.Focusing on the indirect driving role of policy on LUC,this study proposed County Development Level(CDL)under Major Function Oriented Zone Planning(MFOZP)guidance as an intermediary variable,bridging the implicit influence of MFOZP and the explicit changes in LUC.Using the Beijing-Tianjin-Hebei(BTH)region in China as a case study,we analyzed the spatio-temporal evolution characteristics of LUC and CDL for the periods 2000-2010 and 2010-2020,before and after MFOZP implementation.Panel models and Geographically Weighted Regression(GWR)were employed to explore the mechanism by which CDL influences LUC under MFOZP guidance.The results show that:1)MFOZP implementation effectively alleviates land use pressure from regional development,with LUC continuously declining at a rate of 2.41%,while CDL exhibits slight growth(3.84%),during 2010-2020.2)Under MFOZP guidance,CDL reduces pressure on Land Use Structure Conflict(LUSC)and Land Use Process Conflict(LUPC),enhances its inhibitory effect on Land Use Function Conflict(LUFC),and significantly contributes to LUC coordination,with notable spatial heterogeneity.3)The coupling relationship between CDL and LUC has improved post-implementation.Based on this,tailored LUC coordination strategies are proposed for different functional zones.This study confirms the effectiveness of MFOZP in coordinating LUC and provides a scientific reference for LUC research under policy frameworks and the governance of LUC in the BTH region.
基金support from the Joint Funds of the National Natural Science Foundation of China(Grant No.U23A2060)the National Natural Science Foundation of China(Grant Nos.42177143 and 52474150).
文摘Drilling and blasting tunneling is a cyclic process in which tunnel rock undergoes repeated blast loading,affecting its dynamic characteristics,energy evolution,and damage progression.To explore the dynamic mechanical properties and damage mechanisms of carbonaceous slate under cyclic impact loads of varying intensities,cyclic dynamic tests are conducted using a triaxial split Hopkinson pressure bar.This study analyzes the stress-strain relationship,energy damage evolution,and macro-to-micro failure characteristics.The results show that peak stress and strain are significantly influenced by impact intensity and the number of impacts.The initial dynamic stress is positively correlated with the impact intensity,but with more impact,the dynamic stress decreases while the peak strain increases.Energy evolution follows a pattern of"slow growthfluctuating growthrapid growth,"with the crack initiation stress and its proportion decreasing.CT and SEM analyses reveal that as the impact intensity increases,failure becomes more chaotic,the fracture volume increases,and the fracture mode shifts from interlayer and intergranular to through-layer and trans-granular fractures.These findings provide an experimental basis for soft rock tunnel stability analysis.
基金support from the Joint Funds of the National Natural Science Foundation of China(Grant No.42177143)the National Natural Science Foundation of China(Grant No.U23A2060).
文摘Many hydropower projects have been constructed in Southwest China with the strategic goal of achieving carbon neutrality.Most of these hydropower projects utilize concrete face rockfilldams(CFRDs)built on a deep overburden layer.The deep overburden layer causes uneven settlement between the overburden layer and the dam,which poses a serious threat to the safety of both the construction and operation of the dam.In this study,microseismic(MS)monitoring technology was employed for the firsttime in the fieldof dam fillingengineering,allowing for the real-time monitoring of microfracture in the bedrock during dam construction.The time-frequency analysis method was used to summarize the MS waveform characteristics induced by dam filling.The fracture mechanism of bedrock was revealed,and the relationships among slope deformation,dam settlement,and MS activity were analyzed.The following research results have been obtained.The MS signal induced by dam fillinghas low energy and amplitude,short duration,and high frequency.The fracture of the bedrock was mainly shear failure.MS monitoring can predict deformation during blasting excavation and capture the large settlement that may occur during dam fillingin advance.Research findingshave demonstrated the significantapplication value of MS monitoring technology in predicting the risk of dam settlement and provide a reference for similar projects.
基金support from the Sichuan Science and Technology Program(Grant No.2023NSFSC0812).
文摘The effective early warning of surrounding rock mass deformation is crucial in geotechnical engineering for ensuring the safety and stability of underground constructions.This study introduces a novel risk early warning model based on multi-parameter fuzzy comprehensive evaluation,which quantitatively assesses the risk state of the surrounding rock mass.The microseismic(MS)monitoring system is set up for the underground powerhouse.The spatial and temporal distribution of MS events and the frequency characteristics of MS signals are analyzed during the top arch excavation.The early warning indices for characterizing MS spatial aggregation and frequency-energy dispersion are proposed based on the octree theory to assess the deformation of the surrounding rock mass.The risk warning model for the surrounding rock mass in underground engineering is developed through the integration of the formulated index and the frequency characteristics of MS signals.The results indicate that the multiparameter fuzzy comprehensive assessment model can achieve three-dimensional visualization of risk warnings for the surrounding rock mass.The quantitative results regarding warning time and potential deformation areas are highly consistent with the characteristics of MS precursors.These research results can provide an important reference for early warning of surrounding rock mass risk in similar underground projects.
基金the funding support from the National Natural Science Foundation of China(Grant Nos.U23A2060,42177143 and 42277461).
文摘Surrounding rock deterioration and large deformation have always been a significant difficulty in designing and constructing tunnels in soft rock.The key lies in real-time perception and quantitative assessment of the damaged area around the tunnel.An in situ microseismic(MS)monitoring system is established in the plateau soft tock tunnel.This technique facilitates spatiotemporal monitoring of the rock mass's fracturing expansion and squeezing deformation,which agree well with field convergence deformation results.The formation mechanisms of progressive failure evolution of soft rock tunnels were discussed and analyzed with MS data and numerical results.The results demonstrate that:(1)Localized stress concentration and layered rock result in significant asymmetry in micro-fractures propagation in the tunnel radial section.As excavation continues,the fracture extension area extends into the deep surrounding rockmass on the east side affected by the weak bedding;(2)Tunnel excavation and long-term deformation can induce tensile shear action on the rock mass,vertical tension fractures(account for 45%)exist in deep rockmass,which play a crucial role in controlling the macroscopic failure of surrounding rock;and(3)Based on the radiated MS energy,a three-dimensional model was created to visualize the damage zone of the tunnel surrounding rock.The model depicted varying degrees of damage,and three high damage zones were identified.Generally,the depth of high damage zone ranged from 4 m to 12 m.This study may be a valuable reference for the warning and controlling of large deformations in similar projects.
基金supported by the Natural Science Foundation of China-Youth Foundation(42402163)Natural Science Foundation of Sichuan Province of China(2024NSFSC0814)Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(2020CX010101).
文摘The strike-slip fault system in the central Tarim Craton controls a complex petroleum system with estimated reserves exceeding 1×10^(9)t,the fault-related fractures are important for hydrocarbon accumulation.In this paper,the basic parameters such as density and width of fractures are counted and classified,and the effects of fractures on reservoirs are analyzed.The results show that:(1)Structural fractures and stylolite were widely developed in Halahatang area and experienced at least three stages of activity based on the infilling materials and crosscutting relationship.(2)Fracture density,width,aperture,and dip angle vary in different wells,but the relationship between the above parameters and the distance to the fault core indicates the fracture differences in the fault damage zone and further provides a method to divide the inner units in the fault damage zone.In addition,oil and gas wells with high production mainly concentrate in the inner unit.(3)The infilling materials and degree of fractures vary.Fractures formed in the early stage are more filled and less open,while the fractures formed in the late stage are relatively less filled and more open.(4)Fractures improve porosity to a certain extent but greatly increase permeability,especially in the inner zone of fault damage zone with large quantity,multiple inclinations,less filling and large width.These features contribute to the formation of a higher-quality reservoir,further improving oil and gas production.This paper provides a quantitative characterization method for the study of strike-slip fault-related fracture-caved reservoirs,and points out that fault damage zone,especially the inner zone of the fault damage zone,is the potential goal for oil and gas exploration.
基金the National Natural Science Foundation of China,China(No.42272171)National Natural Science Foundation of China,China(No.42302166)Science and Technology Cooperation Project of the CNPCSWPU Innovation Alliance Q3(Grant No.2020CX030101)。
文摘The Wufeng-Longmaxi marine shale in the Eastern Sichuan Basin is the key target for shale gas exploration in China.Based on logging response and lithofacies type,three paleo-geomorphological units are identified in the deep-water shelf during the Wufeng-Longmaxi deposition:subaqueous slope(SS),subaqueous plain(SP),and subaqueous sub-sag(SSS).Using methods such as mercury intrusion porosimetry(MIP),field emission scanning electron microscopy(FE-SEM),nuclear magnetic resonance(NMR),and X-ray diffraction(XRD),the differences of environmental conditions,mineral composition,organic matter(OM)content,and pore structure in different units are determined,and the factors controlling the differences in shale reservoirs are discussed.The results show that redox conditions of bottom water and productivity of surface water affect OM enrichment,resulting in SSS being the most organic-rich unit.Terrigenous detrital input affects mineral composition in different units,and SSS is the most quartz-rich unit.From SS to SSS shale,the proportion of OM pores gradually increased,while the proportion of inorganic pores and microfractures gradually decreased.The pore size distribution dominated by mesopores in SP and SSS shale is generally consistent,much higher than in SS.The differences in sedimentary environments result in differences in reservoir quality.The OM and brittle mineral content in SSS are relatively high,which is beneficial for reservoir development.SSS has the best environmental conditions;therefore,the quality of the marine shale reservoirs formed is the best.
基金supported by Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(No.2020CX010202).
文摘The Jurassic Lianggaoshan Formation in eastern Sichuan Basin is a key target for shale oil exploration.It faces challenges in three-pressure prediction due to complex structural and sedimentary interactions,as well as strong reservoir anisotropy.These issues often lead to wellbore instability and gas logging anomalies during drilling.This study presents an integrated workflow that combines residual moveout correction using correlation-based dynamic time warping(CDTW),high-resolution seismic waveform indication inversion,and three-pressure prediction of jointing well-seismic data.Applied to the LT1 well block,the workflow effectively corrects anisotropic residual moveout in image gathers,leading to a signal strength increase of over 10%in frequency bands above 30 Hz and enhancing event continuity.High-resolution rock mechanical parameters are obtained through seismic waveform inversion and regional calibration,enabling the prediction of three-dimensional pore pressure,collapse pressure and fracture pressure.The results are consistent with actual drilling gas shows and core data,confirming the method's accuracy and supporting mud weight planning and wellbore stability efforts.This cost-effective and technically robust approach proves highly reliable in complex environments with significant heterogeneity and anisotropy,assisting drilling decisions and risk management in eastern Sichuan and similar challenging geological settings.
基金funded by Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(2020CX050103).
文摘Research on the distribution and development of black shales in the Lianggaoshan Formation has been deficient,which has hindered exploration for lacustrine shale oil in the Sichuan Basin.Our study characterized the well logging data,core samples,outcrops,and geochemistry of black shales in the Lianggaoshan Formation in the Sichuan Basin.Our analysis focused on the lake basin evolution and the migration characteristics,paleoenvironmental features,formation mechanisms,and developmental model of the black shales.The results indicated that black shales in the Lianggaoshan Formation exhibited significant lateral migration,with an overall thickening trend from east to west.Within the 1st Member of the formation,black shale occurred as a single thick layer in the eastern region that gradually thinned toward the central region.Multiple sets of shale developed within the 2nd and 3rd members,and these had lower thicknesses than the 1st Member and migrated toward central Sichuan.Paleoproductivity and terrigenous input were the main factors controlling the deposition of black shales.A semi-humid climate influenced the deposition of black shales,bringing abundant freshwater,terrigenous debris,and nutrients into the basin.Decomposition of organic matter consumed oxygen in sediment and bottom water,causing localized oxygen deficiency in the strata.
基金supported by the National Natural Science Foundation of China(Nos.42072184 and 41702157)the Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance。
文摘For an improved understanding of gas enrichment mechanism in the eastern Sichuan Basin,South China,twelve natural gas samples were obtained from carbonate reservoirs of the Upper Permian strata to analyze the hydrocarbon and non-hydrocarbon gas compositions,stable carbon and hydrogen isotopes ratios of hydrocarbons,and noble gas isotope ratios.The gas samples in the Upper Permian reservoirs principally consist of alkane gas with a dryness ratio ranging from 127.9 to 1564.4.The carbon isotope ratio of methane(δ^(13)C_(1))was almost constant at-34.1 to-31.3‰,but the carbon isotope ratio of ethane(δ^(13)C2)varied from-36.6‰to-25.8‰.The hydrogen isotope ratio of methane(δ^2HC_(1))also displayed a wide range from-137‰to-127‰.The large variations in the dryness ratio,δ^(13)C_(2),andδ^2HC_(1)with almost constantδ^(13)C_(1)suggest the mixing of sapropelic and humic origins for hydrocarbon gases in these reservoirs.A high concentration of hydrogen sulfide(H_(2)S)originated from the thermochemical sulfate reduction(TSR),which was positively correlated withδ^(13)C_(1)(orδ^(13)C_(2))in individual gas fields.TSR alteredδ^(13)C_(1)(orδ^(13)C_(2))and resulted in the abnormal character of isotopic reversal in the individual samples.Theδ^(13)C_(1)(orδ^(13)C_(2))in most gas samples,independent of H_(2)S concentration,further displayed reversed carbon isotopes because of the mixture of thermogenic gases with various thermal maturity levels.The measured argon isotope ratio(^(40)Ar/^(36)Ar)varied from 310 to 1225,which suggests that the oldest 320 Ma source rock age corresponds to Permian shales.The analysis of the gas origin and the identification of primary source rock have made a significant contribution to further understanding the resource potential and distribution of natural gas in the Upper Permian,and have great implications for gas exploration in the eastern Sichuan Basin.
基金supported by the Scientific Research Project of POWERCHINA Chengdu Engineering Corporation Limited(Grant No.P50922)。
文摘The glacial lake in the Boqu Basin in Tibetan Plateau has changed significantly in recent years due to global warming,seriously affecting the natural and social environments in downstream areas.We obtained the change characteristics of glacial lakes by analyzing remote sensing images and evaluated the outburst floods susceptibility of glacial lakes in the Boqu Basin by combining fuzzy mathematics and random forest methods.An empirical formula for glacial lake hazard evaluation was established based on a fuzzy comprehensive evaluation.The confusion matrix were used to assess the evaluation effect of each method.The conclusions were as follows:(1)Under the influence of climate warming,glaciers are retreating further from the glacial lakes,and the size of glaciers that can impact these lakes is shrinking.Geological conditions,such as steep slopes around the lakes,have replaced glacier tongues as the primary factors threatening the susceptibility of the glacial lakes;(2)Among the three evaluation methods,the empirical formula offers high calculation accuracy and is the most convenient to use,which provides an accuracy rate of 85.71%in susceptibility evaluation of the Boqu Basin glacial lake and can be applied to other areas in the rapid evaluation of the susceptibility of glacial lakes;(3)The impact analysis of the collapse shows that the collapse of the Galongco fault would cause large economic losses.
基金supported by the National Natural Science Foundation of China(Nos.41902068,42272106)Young Scholars Development Fund of Southwest Petroleum University(No.201499010083)China Geological Survey Project(Nos.DD20230338,DD20242494)。
文摘The Jianglang Dome has integral tectonostratigraphic units and contains a suite of high-grade stratiform Cu deposits.However,the formation mechanism of this dome and genetic model of Cu mineralization remain a matter of debate.The resolution of these problems hinges on the presence of magmatic intrusions in the core.Here,we report bulk geochemical and zircon U-Pb data of a newly discovered syenite intrusion as well as chalcopyrite Re-Os dating results.We aim to explore genesis of the Jianglang Dome,genetic model of the stratiform Cu deposits,and rare metal mineralization potential of the syenite intrusion.The dated syenite sample yields an emplacement age of 207.1±2.0 Ma,which matches post-collisional extension in the Songpan-Ganze Orogen.The syenite rocks have average high(Zr+Nb+Ce+Y)concentrations of 512 ppm,10000.Ga/Al ratios of 3.97,and crystallization temperatures of 827°C,together with low Mg#values of 1.73;they fi t the A-type granitoid defi nition and a crustal origin.Chalcopyrite separates yield a Re-Os isochron age of 207.1±5.3 Ma,which markedly postdates the formation age of their orehosting rocks(the Liwu Group,ca.553 Ma).Our new age determination,together with previous chalcopyrite Re–Os isochron age of ca.151.1 Ma and sulfi de sulfur isotope(δ^(34)S_(V-CDT)=8.7‰–5.6‰)and tourmaline boron isotope(δ^(11)B=−15.47‰to−5.91‰)data,confi rms multistage epigenetic Cu mineralization related to magmatic-hydrothermal fl uids.Compared with regional ca.209–207 Ma fertile granitoids,the studied syenite intrusion shows unevolved and barren affi nities and negligible rare metal mineralization potential.Combined with residual gravity low anomalies in the core of the Jianglang Dome,which suggest a large deepseated granitic batholith,we prefer thermal doming resulting from magma-induced uplift for the nature of this dome.
基金supported by the Special Funds for Science and Technology Planning Projects of Sichuan Province(No.2024YFHZ0158)。
文摘Accurate prediction of reservoir parameters is essential for reservoir evaluation.Recent machine learning methods have spurred significant advancements in reservoir prediction;however,limited well logging data and strong reservoir heterogeneity still hinder the accuracy and reliability of such predictions.Addressing these challenges requires methods capable of effectively predicting reservoir parameters under data scarcity and complex reservoir structures.In this study,we propose CAF2,a feature-fusion cross-modal alignment framework guided by large language models(LLMs).CAF2 integrates data augmentation,knowledge distillation,cross-modal alignment,and feature fusion.The data augmentation module employs the RealTabFormer model to generate synthetic datasets that mirror the distribution of real logging data,addressing the challenge of data scarcity.Knowledge distillation extracts essential domain knowledge from LLMs,guiding cross-modal alignment between well logging data and textual knowledge.This alignment mitigates modality gaps via token and sequence alignment,enhancing depth-domain feature representation.Finally,a cross-variable and cross-depth feature fusion strategy exploits both variable information and depth correlations,overcoming the difficulties in accurate reservoir parameter prediction posed by reservoir heterogeneity.Experimental results demonstrate that CAF2 significantly outperforms existing models in predicting tight sandstone reservoir parameters,serving as an effective tool for oil and gas exploration and development.
文摘There are abundant hydrothermal events within the Dengying Formation dolomite of the Precambrian system in southwest China.Methods including petrography identification,fluid-inclusion observation,in-situ U-Pb dating,and in-situ measurement of rare earth element(REE),etc.are integrated to characterize hydrothermal activity process within the Dengying Formation dolomite.The hydrothermal activity therein can be divided into four stages on the basis of in-situ U-Pb dating results of saddle dolomite cements.The 1st-stage(415.0-400.0 Ma)and 2nd-stage(259.4-248.0 Ma)hydrothermal events are characterized by saddle dolomite filling along the margin of fractures,or filling within dilational breccia and zebra textures.Compared with matrix dolomite and seawater-derived fibrous dolomite,saddle dolomite exhibits obvious negative anomalies of Ce elements.The 3rd-stage(225.6-199.0 Ma)hydrothermal event is represented by galena,sphalerite and other Mississipppi Valley-type(MVT)mineral cements in residual space.The formation of lead-zinc ore is due to the precipitation of metal sulfide caused by the thermo-chemical sulfate reduction(TSR)reaction between hydrothermal fluids and hydrocarbons during the large-scale hydrocarbon charging period.The 4th-stage(130.0-41.0 Ma)hydrothermal event is characterized by quartz and a small amount of fluorite filling the residual pores with dolomites.Quartz and fluorite record the migration of deep high-temperature hydrothermal fluid along early fractures and residual pores.During this period,the hydrothermal fluids result in the heterogeneous structure of bitumen,which is a clear response to high-temperature hydrothermal activity.
基金supported by the National Key Research and Development Project of China(No.2023YFC3007303)the Open Research Project of the Hubei Key Laboratory of Intelligent Geo-Information Processing(No.KLIGIP-2019B08)。
文摘0 INTRODUCTION.The global availability of digital elevation model(DEM)data,such as 90-m Shuttle Radar Topography Mission(SRTM)DEM and 30-m Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model(ASTER GDEM),has been extensively utilized in morphotectonic analyses(e.g.,Wang et al.,2024;Cheng et al.,2018;Pérez-Pe?a et al.,2010;El Hamdouni et al.,2008).
基金funding support from the National Natural Science Foundation of China(Grant Nos.U23A2060,42177143,and 42277461).
文摘Ensuring the stability of the surrounding rock mass is of great importance during the construction of a large underground powerhouse.The presence of unfavorable structural planes within the rock mass,such as faults,can lead to substantial deformation and subsequent collapse.A series of in situ experiments and discrete element numerical simulations have been conducted to gain insight into the progressive failure behavior and deformation response of rocks in relation to controlled collapse scenarios involving gently inclined faults.First,the unloading damage evolution process of the surrounding rock mass is characterized by microscopic analysis using microseismic(MS)data.Second,the moment tensor inversion method is used to elucidate the temporal distribution of MS event fracture types in the surrounding rock mass.During the development stage of the collapse,numerous tensile fracture events occur,while a few shear fractures corresponding to structural plane dislocation precede their occurrence.The use of the digital panoramic borehole camera,acoustic wave test,and numerical simulation revealed that gently inclined faults and deep cracks at a certain depth from the cavern periphery are the primary factors contributing to rock collapse.These results provide a valuable case study that can help anticipate and mitigate fault-slip collapse incidents while providing practical insights for underground cave excavation.
基金supported by the project of the China Geological Survey(DD20221661).
文摘The black shales of Wufeng and Longmaxi Formation(Late Ordovician-Early Silurian period)in Sichuan Basin are the main strata for marine shale gas exploration,which have a yearly shale gas production of 228×10^(8)m^(3)and cumulative shale gas production of 919×10^(8)m^(3).According to the lithological and biological features,filling sequences,sedimentary structures and lab analysis,the authors divided the Wufeng/Guanyinqiao and Longmaxi Formations into shore,tidal flat,shoal,shallow water shelf and deep water shelf facies,and confirmed that a shallow water deposition between the two sets of shales.Although both Formations contain similar shales,their formation mechanisms differ.During the deposition of Wufeng shale,influenced by the Caledonian Movement,the Central Sichuan and Guizhou Uplifts led to the transformation of the Sichuan Basin into a back-bulge basin.Coinstantaneous volcanic activity provided significant nutrients,contributing to the deposition of Wufeng Formation black shales.In contrast,during the deposition of Longmaxi shale,collisions caused basement subsidence,melting glaciers raised sea levels,and renewed volcanic activity provided additional nutrients,leading to Longmaxi Formation black shale accumulation.Considering the basic sedimentary geology and shale gas characteristics,areas such as Suijiang-Leibo-Daguan,Luzhou-Zigong,Weirong-Yongchuan,and Nanchuan-Dingshan are identified as key prospects for future shale gas exploration in the Wufeng-Longmaxi Formations.
基金supported by the National Natural ScienceFoundation of China(42102191)。
文摘Deep carbonate reservoirs affected by prominent strike-slip faults represent crucial targets in oil and gas exploration owing to their immense resource potential.However,the complex geological environments and poorly understood histories of the associated paleo-fluid activity have hindered the development of robust theories regarding pore formation and preservation mechanisms,resulting in suboptimal exploration strategies.Leveraging the extensive well deployment by the China Sinopec Group in the Shunbei area of the Tarim Basin,this study addresses these challenges by establishing a comprehensive framework for the evolution of diagenetic fluids within the Middle-Lower Ordovician carbonate formations.Using core samples,thin-section analysis,and cathodoluminescence observations,this study employs high-resolution geochemical methodologies,including isotopic analyses,rare earth element profiling,fluid inclusion studies,and uranium-lead dating,as primary tools for identifying and interpreting paleo-fluid characteristics across various rock types and calcite cement varieties within this stratigraphic interval.The findings reveal several key insights:(i)both RFC and C1 cements are derived from seawater,with C1 forming under burial conditions;(ii)C2,C3,and VC cements result from distinct tectonic events,specifically during the first and third episodes of the Middle Caledonian movement,with meteoric water infiltrating fault systems independently of orogenic belts or paleo-karst systems;and(iii)previous conclusions are challenged,as the influence of hydrothermal activity in this area is found to be minimal.Furthermore,the model presented here serves as a valuable reference for understanding fluid activity events at distal locations within orogenic belts under compressive stress,while accurately capturing fluid variations over different temporal scales within fault zones plays a decisive role.
基金National Natural Science Foundation of China under the Special Fund for Basic Research Operations of the Central Universities(U23B6010)the CNOOC“14th Five Year Plan”Major Science and Technology Project(KJGG2022-0304).
文摘Fractures significantly impact oil and gas production by altering the mechanical properties of subsurface rocks.This study investigates the forward and inverse problems associated with monoclinic anisotropic media,which arise from the presence of two sets of inclined fractures within an isotropic matrix.We first derive the stiffness matrix for this monoclinic medium by applying Schoenberg's linear slip theory.Subsequently,we employ the point spread function and the steady phase method to derive and simplify the reflection coefficient equation for seismic waves interacting with this complex medium.Finally,we verify the rationality of the method by using synthetic seismic records and actual seismic records.The proposed equations and inversion techniques offer a more accurate framework for characterizing monoclinic anisotropic media affected by inclined fractures,thereby enhancing the interpretation of subsurface structures in hydrocarbon exploration.
