During the Cambrian, gypsum-bearing evaporites formed in the Sichuan Basin, SW China. These rocks are important for oil and gas sealing, but details of their distribution and origin are not well established. This stud...During the Cambrian, gypsum-bearing evaporites formed in the Sichuan Basin, SW China. These rocks are important for oil and gas sealing, but details of their distribution and origin are not well established. This study examines the regional distribution and origin of the gypsum-bearing evaporites using a comprehensive analysis of drilling data from 34 wells, 5 measured cross-sections in the basin and surrounding area, and 96 maps of area-survey data. Results show that in the stratigraphic succession, the gypsum-bearing evaporites occur mainly in the Lower Cambrian Longwangmiao Formation, the Middle Cambrian Douposi Formation, and the Middle-Upper Cambrian Xixiangchi Group. Geographically, the rocks are found mainly in the southeastern part of the basin, and the distribution of deposits shows an overall SW-NE trend. The sedimentary environments for evaporite formation were evaporative lagoon and inter-platform basin in a platform setting. Gypsum was generated by the underwater concentration of sea water in a strongly evaporative environment. Both an evaporative restricted platform and a mixeddeposition restricted platform model appear to be applicable to the development of gypsum in the Sichuan Basin. The gypsum-bearing evaporites with the best sealing capacity are located mostly in the southeastern part of the basin. These constraints can be applied directly to regional exploration, and have implications for the regional paleogeography and paleoclimate.展开更多
The newly-discovered supergiant Huayangchuan uranium(U)-polymetallic(Sr,Se,REEs,Ba,Nb and Pb)deposit is located in the Qinling Orogen,central China.The deposit underwent multistage mineralization,with the main carbona...The newly-discovered supergiant Huayangchuan uranium(U)-polymetallic(Sr,Se,REEs,Ba,Nb and Pb)deposit is located in the Qinling Orogen,central China.The deposit underwent multistage mineralization,with the main carbonatite ore stage being the most important for the U,Nb,REE,Sr and Ba endowments.According to the mineral assemblages,the main carbonatite ore stage can be divided into three substages,i.e.,sulfate(Ba-Sr),alkali-rich U and REE-U mineralization.Main-stage titanite from the Huayangchuan igneous carbonatite are rich in high field strength elements(HFSEs,e.g.,Zr,Nb and REEs),and show clear elemental substitutions(e.g.,Ti vs.Nb+Fe+Al and Ca+Ti vs.Fe+Al+REE).High-precision LA-ICP-MS titanite dating yielded a U-Pb age of 209.0±2.9 Ma,which represents the mainstage mineralization age at Huayangchuan,and is coeval with the local carbonatite dyke intrusion.This mineralization age is further constrained by the Re-Os dating of molybdenite from the Huayangchuan carbonatite,which yielded a weighted mean age of 196.8±2.4 Ma.Molybdenite Re contents(337.55-392.75 ppm)and C-OSr-Nd-Pb isotopic evidence of the Huayangchuan carbonatite both suggest a mantle origin for the carbonatite.Our study supports that the Late Triassic carbonatite magmatism was responsible for the world-class U-Mo-REE mineralization in the Qinling Orogen,and that the regional magmatism and ore formation was likely caused by the closure of the Mianlue ocean and the subsequent North China-South China continent-continent collision.展开更多
A recent study suggests that the deep dolomites in well Xike-1 located more than 1000 m deep have a very low porosity,and no permeability for most of the samples.Given that the largest oil and gas fields in the South ...A recent study suggests that the deep dolomites in well Xike-1 located more than 1000 m deep have a very low porosity,and no permeability for most of the samples.Given that the largest oil and gas fields in the South China Sea are all composed of biohermal dolomites while the deep dolomites of Xike-1 serve as the caprock formations rather than the reservoirs,this represents the first discovery and is of great theoretical importance.In this paper,core photos of the tight dolomites are presented.Hand specimens description and systematic porosity-permeability reveal a very low porosity,and no permeability for most of the samples.PLM,SEM and XRPD analysis discovered that the dolostones in the deep tight dolomites are quite large in size and euhedral or subhedral in shape.Alizarin red-stained sections are mostly pink in color and have a full coverage,which are considered as evidence for multiple calcite intrusions after the formation of ankerite dolomites.Biological relict textures are developed.The order degree is medium to low.The dolomites could be the product of penecontemporaneous dolomitization.展开更多
Accurate prediction of the internal corrosion rates of oil and gas pipelines could be an effective way to prevent pipeline leaks.In this study,a proposed framework for predicting corrosion rates under a small sample o...Accurate prediction of the internal corrosion rates of oil and gas pipelines could be an effective way to prevent pipeline leaks.In this study,a proposed framework for predicting corrosion rates under a small sample of metal corrosion data in the laboratory was developed to provide a new perspective on how to solve the problem of pipeline corrosion under the condition of insufficient real samples.This approach employed the bagging algorithm to construct a strong learner by integrating several KNN learners.A total of 99 data were collected and split into training and test set with a 9:1 ratio.The training set was used to obtain the best hyperparameters by 10-fold cross-validation and grid search,and the test set was used to determine the performance of the model.The results showed that theMean Absolute Error(MAE)of this framework is 28.06%of the traditional model and outperforms other ensemblemethods.Therefore,the proposed framework is suitable formetal corrosion prediction under small sample conditions.展开更多
Oil and gas seismic exploration have to adopt irregular seismic acquisition due to the increasingly complex exploration conditions to adapt to complex geological conditions and environments.However,the irregular seism...Oil and gas seismic exploration have to adopt irregular seismic acquisition due to the increasingly complex exploration conditions to adapt to complex geological conditions and environments.However,the irregular seismic acquisition is accompanied by the lack of acquisition data,which requires high-precision regularization.The sparse signal feature in the transform domain in compressed sensing theory is used in this paper to recover the missing signal,involving sparse transform base optimization and threshold modeling.First,this paper analyzes and compares the effects of six sparse transformation bases on the reconstruction accuracy and efficiency of irregular seismic data and establishes the quantitative relationship between sparse transformation and reconstruction accuracy and efficiency.Second,an adaptive threshold modeling method based on sparse coefficient is provided to improve the reconstruction accuracy.Test results show that the method has good adaptability to different seismic data and sparse transform bases.The f-x domain reconstruction method of effective frequency samples is studied to address the problem of low computational efficiency.The parallel computing strategy of curvelet transform combined with OpenMP is further proposed,which substantially improves the computational efficiency under the premise of ensuring the reconstruction accuracy.Finally,the actual acquisition data are used to verify the proposed method.The results indicate that the proposed method strategy can solve the regularization problem of irregular seismic data in production and improve the imaging quality of the target layer economically and efficiently.展开更多
Forward modeling is the basis of inversion imaging and quantitative interpretation for DC resistivity exploration.Currently,a numerical model of the DC resistivity method must be finely divided to obtain a highly accu...Forward modeling is the basis of inversion imaging and quantitative interpretation for DC resistivity exploration.Currently,a numerical model of the DC resistivity method must be finely divided to obtain a highly accurate solution under complex conditions,resulting in a long calculation time and large storage.Therefore,we propose a 3D numerical simulation method in a mixed space-wavenumber domain to overcome this challenge.The partial differential equation about abnormal potential is transformed into many independent ordinary differential equations with different wavenumbers using a 2D Fourier transform along the x axis and y axis direction.In this way,a large-scale 3D numerical simulation problem is decomposed into several 1D numerical simulation problems,which significantly reduces the computational and storage requirements.In addition,these ordinary 1D differential equations with different wavenumbers are independent of each other and high parallelelism of the algorithm.They are solved using a finite-element algorithm combined with a chasing method,and the obtained solution is modified using a contraction operator.In this method,the vertical direction is reserved as the spatial domain,then grid size can be determined flexibly based on the underground current density distribution,which considers the solution accuracy and calculation efficiency.In addition,for the first time,we use the contraction operator in the integral equation method to iterate the algorithm.The algorithm takes advantage of the high efficiency of the standard Fourier transform and chasing method,as well as the fast convergence of the contraction operator.We verified the accuracy of the algorithm and the convergence of the contraction operator.Compared with a volume integral method and goal-oriented adaptive finite-element method,the proposed algorithm has lower memory requirements and high computational efficiency,making it suitable for calculating a model with large-scale nodes.Moreover,different examples are used to verify the high adaptability and parallelism of the proposed algorithm.The findings show that the 3D numerical simulation method of DC resistivity method in a mixed space-wavenumber domain is highly efficient,precise,and parallel.展开更多
1 Introduction From geological point of view, the development of shale pore is dually controlled by external and internal factors. The external factors include tectonic position, tectonic stress, sedimentary diagenesi...1 Introduction From geological point of view, the development of shale pore is dually controlled by external and internal factors. The external factors include tectonic position, tectonic stress, sedimentary diagenesis and high abnormal pressure caused by hydrocarbon generation; internal factors include organic carbon content, maturity and mineral composition etc. Therefore, to study influencing factors in the development of shale porosity is of great significance for the shale gas commercial exploitation.展开更多
On the basis of making clear diversity characteristics of soil functions and multiple characteristics of income, this paper points out that the monetization of soil functions based functional maintenance and change de...On the basis of making clear diversity characteristics of soil functions and multiple characteristics of income, this paper points out that the monetization of soil functions based functional maintenance and change decision process can be regarded as a game process of different utilization methods at the background of different functions. The balance of this game process will determine monetary value of soil functions. After understanding money and monetization concepts, it introduces that measurability and exchangeability of soil functions provide objective conditions for monetization of soil functions. Finally, it discusses that usefulness value of soil functions provide basis for monetization of soil functions.展开更多
The organic heterogeneity evaluation technology has been very important in the unconventional oil and gas exploration. In the different basin , the accurate description of the shale's organic carbon content in the ve...The organic heterogeneity evaluation technology has been very important in the unconventional oil and gas exploration. In the different basin , the accurate description of the shale's organic carbon content in the vertical and horizontal distribution characteristics, having a very important influence on the evaluation of the hydrocarbon source rock, the calculation of the hydrocarbon generation and expulsion efficiency, even the prediction of hydrocarbon distribution and so on.展开更多
Karst in interbedded carbonates and evaporites has been reported to have important and complex impacts on reservoir. It is significant for exploration and karst geology. Here, we report such a new case from Middle Tri...Karst in interbedded carbonates and evaporites has been reported to have important and complex impacts on reservoir. It is significant for exploration and karst geology. Here, we report such a new case from Middle Triassic Leikoupo Formation of Sichuan Basin, Southwest China. Stratigraphic incompleteness and the occurrence of unconformity provide evidence for the presence of eogenetic karst. Under the impact of this eogenetic karst, residual weathered and solution-collapse breccia, solution pores and silicification and dedolomitization have been observed. Classic stratigraphic zonation of karst is not readily distinguishable, which is ascribed to the stratigraphic collapse of carbonate rocks resulting from the dissolution of evaporites by lateral subsurface fluid flow. In terms of impact on reservoir quality, karst can generally improve the initial physical property of the porous layers in theory. However, subsurface fluid flow dissolved the evarporitic beds and facilitated the collapse of overlying strata. As a consequence, the lateral continuity of the reservoirs would be destroyed, and relatively high-quality reservoirs can only be developed with little collapse of overlying strata, reflecting reservoir heterogeneities. This may be a general feature of reservoir formation under the impact of karst in interbedded carbonates and evaporites.展开更多
Lacustrine shale oil resources in China are abundant,with remarkable exploration breakthroughs being achieved.Compared to marine shale oil in North America,efficient exploration of lacustrine shale oil is more difficu...Lacustrine shale oil resources in China are abundant,with remarkable exploration breakthroughs being achieved.Compared to marine shale oil in North America,efficient exploration of lacustrine shale oil is more difficult;thus,selecting favorable layer and optimization zone for horizontal wells is more important.In this study,based on systematic coring of approximately 500 m fine-grained deposits of the Kong 2 Member,combining laboratory tests and log data,source rock geochemistry and reservoir physical properties,the favorable rock fabric facies for oil accumulation was analyzed and classified.First,the dominant lithologic facies,organic facies,and bed combination facies were determined based on mineral composition from logging,total organic content(TOC),and sedimentary structure.Secondly,10 fabric facies were classified by combining these three facies,with 4 fabric facies were found to have high TOC content,high total hydrocarbon,and strong fluorescence features,indicating good shale oil enrichment.Thirdly,the distribution of the upon good fabric facies was identified to be located at the top of the Kong 2 Member,with evidences of seismic resistivity inversion,thermal maturity,structure depth,and strata thickness.And the favorable facies were found to be stably distributed lateral at the area of about 100 km2.High oil flow has been detected at this layer within this area by several wells,including horizontal wells.The exploratory study of fabric facies classification and evaluation provides a new research idea for lacustrine shale oil exploration and effectively promotes breakthroughs in lacustrine shale oil exploration in Bohai Bay Basin.展开更多
基金funded by the Major State Basic Research Development Program of China ("973" project, Grant No. 2012CB214803)National Science and Technology Major Project of China (Grant No. 2016ZX05004)
文摘During the Cambrian, gypsum-bearing evaporites formed in the Sichuan Basin, SW China. These rocks are important for oil and gas sealing, but details of their distribution and origin are not well established. This study examines the regional distribution and origin of the gypsum-bearing evaporites using a comprehensive analysis of drilling data from 34 wells, 5 measured cross-sections in the basin and surrounding area, and 96 maps of area-survey data. Results show that in the stratigraphic succession, the gypsum-bearing evaporites occur mainly in the Lower Cambrian Longwangmiao Formation, the Middle Cambrian Douposi Formation, and the Middle-Upper Cambrian Xixiangchi Group. Geographically, the rocks are found mainly in the southeastern part of the basin, and the distribution of deposits shows an overall SW-NE trend. The sedimentary environments for evaporite formation were evaporative lagoon and inter-platform basin in a platform setting. Gypsum was generated by the underwater concentration of sea water in a strongly evaporative environment. Both an evaporative restricted platform and a mixeddeposition restricted platform model appear to be applicable to the development of gypsum in the Sichuan Basin. The gypsum-bearing evaporites with the best sealing capacity are located mostly in the southeastern part of the basin. These constraints can be applied directly to regional exploration, and have implications for the regional paleogeography and paleoclimate.
基金supported by the Type-B Strategic Pilot Science and Special Technology Program,Chinese Academy of Sciences(XDB18030206)Academician Workstation of Sino Shaanxi Nuclear Industry Group(ZSH-YS180101 and YS190101)。
文摘The newly-discovered supergiant Huayangchuan uranium(U)-polymetallic(Sr,Se,REEs,Ba,Nb and Pb)deposit is located in the Qinling Orogen,central China.The deposit underwent multistage mineralization,with the main carbonatite ore stage being the most important for the U,Nb,REE,Sr and Ba endowments.According to the mineral assemblages,the main carbonatite ore stage can be divided into three substages,i.e.,sulfate(Ba-Sr),alkali-rich U and REE-U mineralization.Main-stage titanite from the Huayangchuan igneous carbonatite are rich in high field strength elements(HFSEs,e.g.,Zr,Nb and REEs),and show clear elemental substitutions(e.g.,Ti vs.Nb+Fe+Al and Ca+Ti vs.Fe+Al+REE).High-precision LA-ICP-MS titanite dating yielded a U-Pb age of 209.0±2.9 Ma,which represents the mainstage mineralization age at Huayangchuan,and is coeval with the local carbonatite dyke intrusion.This mineralization age is further constrained by the Re-Os dating of molybdenite from the Huayangchuan carbonatite,which yielded a weighted mean age of 196.8±2.4 Ma.Molybdenite Re contents(337.55-392.75 ppm)and C-OSr-Nd-Pb isotopic evidence of the Huayangchuan carbonatite both suggest a mantle origin for the carbonatite.Our study supports that the Late Triassic carbonatite magmatism was responsible for the world-class U-Mo-REE mineralization in the Qinling Orogen,and that the regional magmatism and ore formation was likely caused by the closure of the Mianlue ocean and the subsequent North China-South China continent-continent collision.
基金This work was supported by the National Natural Science Foundation of China(41106064)the Science and Technology Basic Resources Investigation Program of China(2017FY201407).
文摘A recent study suggests that the deep dolomites in well Xike-1 located more than 1000 m deep have a very low porosity,and no permeability for most of the samples.Given that the largest oil and gas fields in the South China Sea are all composed of biohermal dolomites while the deep dolomites of Xike-1 serve as the caprock formations rather than the reservoirs,this represents the first discovery and is of great theoretical importance.In this paper,core photos of the tight dolomites are presented.Hand specimens description and systematic porosity-permeability reveal a very low porosity,and no permeability for most of the samples.PLM,SEM and XRPD analysis discovered that the dolostones in the deep tight dolomites are quite large in size and euhedral or subhedral in shape.Alizarin red-stained sections are mostly pink in color and have a full coverage,which are considered as evidence for multiple calcite intrusions after the formation of ankerite dolomites.Biological relict textures are developed.The order degree is medium to low.The dolomites could be the product of penecontemporaneous dolomitization.
基金supported by the National Natural Science Foundation of China(Grant No.52174062).
文摘Accurate prediction of the internal corrosion rates of oil and gas pipelines could be an effective way to prevent pipeline leaks.In this study,a proposed framework for predicting corrosion rates under a small sample of metal corrosion data in the laboratory was developed to provide a new perspective on how to solve the problem of pipeline corrosion under the condition of insufficient real samples.This approach employed the bagging algorithm to construct a strong learner by integrating several KNN learners.A total of 99 data were collected and split into training and test set with a 9:1 ratio.The training set was used to obtain the best hyperparameters by 10-fold cross-validation and grid search,and the test set was used to determine the performance of the model.The results showed that theMean Absolute Error(MAE)of this framework is 28.06%of the traditional model and outperforms other ensemblemethods.Therefore,the proposed framework is suitable formetal corrosion prediction under small sample conditions.
基金supported by the National Science and Technology Major project(No.2016ZX05024001003)the Innovation Consortium Project of China Petroleum,and the Southwest Petroleum University(No.2020CX010201).
文摘Oil and gas seismic exploration have to adopt irregular seismic acquisition due to the increasingly complex exploration conditions to adapt to complex geological conditions and environments.However,the irregular seismic acquisition is accompanied by the lack of acquisition data,which requires high-precision regularization.The sparse signal feature in the transform domain in compressed sensing theory is used in this paper to recover the missing signal,involving sparse transform base optimization and threshold modeling.First,this paper analyzes and compares the effects of six sparse transformation bases on the reconstruction accuracy and efficiency of irregular seismic data and establishes the quantitative relationship between sparse transformation and reconstruction accuracy and efficiency.Second,an adaptive threshold modeling method based on sparse coefficient is provided to improve the reconstruction accuracy.Test results show that the method has good adaptability to different seismic data and sparse transform bases.The f-x domain reconstruction method of effective frequency samples is studied to address the problem of low computational efficiency.The parallel computing strategy of curvelet transform combined with OpenMP is further proposed,which substantially improves the computational efficiency under the premise of ensuring the reconstruction accuracy.Finally,the actual acquisition data are used to verify the proposed method.The results indicate that the proposed method strategy can solve the regularization problem of irregular seismic data in production and improve the imaging quality of the target layer economically and efficiently.
文摘Forward modeling is the basis of inversion imaging and quantitative interpretation for DC resistivity exploration.Currently,a numerical model of the DC resistivity method must be finely divided to obtain a highly accurate solution under complex conditions,resulting in a long calculation time and large storage.Therefore,we propose a 3D numerical simulation method in a mixed space-wavenumber domain to overcome this challenge.The partial differential equation about abnormal potential is transformed into many independent ordinary differential equations with different wavenumbers using a 2D Fourier transform along the x axis and y axis direction.In this way,a large-scale 3D numerical simulation problem is decomposed into several 1D numerical simulation problems,which significantly reduces the computational and storage requirements.In addition,these ordinary 1D differential equations with different wavenumbers are independent of each other and high parallelelism of the algorithm.They are solved using a finite-element algorithm combined with a chasing method,and the obtained solution is modified using a contraction operator.In this method,the vertical direction is reserved as the spatial domain,then grid size can be determined flexibly based on the underground current density distribution,which considers the solution accuracy and calculation efficiency.In addition,for the first time,we use the contraction operator in the integral equation method to iterate the algorithm.The algorithm takes advantage of the high efficiency of the standard Fourier transform and chasing method,as well as the fast convergence of the contraction operator.We verified the accuracy of the algorithm and the convergence of the contraction operator.Compared with a volume integral method and goal-oriented adaptive finite-element method,the proposed algorithm has lower memory requirements and high computational efficiency,making it suitable for calculating a model with large-scale nodes.Moreover,different examples are used to verify the high adaptability and parallelism of the proposed algorithm.The findings show that the 3D numerical simulation method of DC resistivity method in a mixed space-wavenumber domain is highly efficient,precise,and parallel.
文摘1 Introduction From geological point of view, the development of shale pore is dually controlled by external and internal factors. The external factors include tectonic position, tectonic stress, sedimentary diagenesis and high abnormal pressure caused by hydrocarbon generation; internal factors include organic carbon content, maturity and mineral composition etc. Therefore, to study influencing factors in the development of shale porosity is of great significance for the shale gas commercial exploitation.
基金Supported by Hebei Provincial Social Science Foundation Project in 2012(HB12YJ055)
文摘On the basis of making clear diversity characteristics of soil functions and multiple characteristics of income, this paper points out that the monetization of soil functions based functional maintenance and change decision process can be regarded as a game process of different utilization methods at the background of different functions. The balance of this game process will determine monetary value of soil functions. After understanding money and monetization concepts, it introduces that measurability and exchangeability of soil functions provide objective conditions for monetization of soil functions. Finally, it discusses that usefulness value of soil functions provide basis for monetization of soil functions.
文摘The organic heterogeneity evaluation technology has been very important in the unconventional oil and gas exploration. In the different basin , the accurate description of the shale's organic carbon content in the vertical and horizontal distribution characteristics, having a very important influence on the evaluation of the hydrocarbon source rock, the calculation of the hydrocarbon generation and expulsion efficiency, even the prediction of hydrocarbon distribution and so on.
基金funded by the “13th Five-Year Plan” National Science and Technology Major Project of China(No.2016ZX05004002)
文摘Karst in interbedded carbonates and evaporites has been reported to have important and complex impacts on reservoir. It is significant for exploration and karst geology. Here, we report such a new case from Middle Triassic Leikoupo Formation of Sichuan Basin, Southwest China. Stratigraphic incompleteness and the occurrence of unconformity provide evidence for the presence of eogenetic karst. Under the impact of this eogenetic karst, residual weathered and solution-collapse breccia, solution pores and silicification and dedolomitization have been observed. Classic stratigraphic zonation of karst is not readily distinguishable, which is ascribed to the stratigraphic collapse of carbonate rocks resulting from the dissolution of evaporites by lateral subsurface fluid flow. In terms of impact on reservoir quality, karst can generally improve the initial physical property of the porous layers in theory. However, subsurface fluid flow dissolved the evarporitic beds and facilitated the collapse of overlying strata. As a consequence, the lateral continuity of the reservoirs would be destroyed, and relatively high-quality reservoirs can only be developed with little collapse of overlying strata, reflecting reservoir heterogeneities. This may be a general feature of reservoir formation under the impact of karst in interbedded carbonates and evaporites.
基金supported by PetroChina Major Science and Technology Project“Research and Application of Key Technology for Efficient Reservoir Increase and Stable Production in Dagang Oil and Gas Field”(2018E-11)。
文摘Lacustrine shale oil resources in China are abundant,with remarkable exploration breakthroughs being achieved.Compared to marine shale oil in North America,efficient exploration of lacustrine shale oil is more difficult;thus,selecting favorable layer and optimization zone for horizontal wells is more important.In this study,based on systematic coring of approximately 500 m fine-grained deposits of the Kong 2 Member,combining laboratory tests and log data,source rock geochemistry and reservoir physical properties,the favorable rock fabric facies for oil accumulation was analyzed and classified.First,the dominant lithologic facies,organic facies,and bed combination facies were determined based on mineral composition from logging,total organic content(TOC),and sedimentary structure.Secondly,10 fabric facies were classified by combining these three facies,with 4 fabric facies were found to have high TOC content,high total hydrocarbon,and strong fluorescence features,indicating good shale oil enrichment.Thirdly,the distribution of the upon good fabric facies was identified to be located at the top of the Kong 2 Member,with evidences of seismic resistivity inversion,thermal maturity,structure depth,and strata thickness.And the favorable facies were found to be stably distributed lateral at the area of about 100 km2.High oil flow has been detected at this layer within this area by several wells,including horizontal wells.The exploratory study of fabric facies classification and evaluation provides a new research idea for lacustrine shale oil exploration and effectively promotes breakthroughs in lacustrine shale oil exploration in Bohai Bay Basin.