In this paper we discuss the edge-preserving regularization method in the reconstruction of physical parameters from geophysical data such as seismic and ground-penetrating radar data. In the regularization method a p...In this paper we discuss the edge-preserving regularization method in the reconstruction of physical parameters from geophysical data such as seismic and ground-penetrating radar data. In the regularization method a potential function of model parameters and its corresponding functions are introduced. This method is stable and able to preserve boundaries, and protect resolution. The effect of regularization depends to a great extent on the suitable choice of regularization parameters. The influence of the edge-preserving parameters on the reconstruction results is investigated and the relationship between the regularization parameters and the error of data is described.展开更多
After graduating from university in 1983,Zhan Shifan was recruited by the former Geophysical Prospecting Bureau as an interpreter of No.237 Seismic Team of No.1 Division of Geological Survey.Step by step,he was promot...After graduating from university in 1983,Zhan Shifan was recruited by the former Geophysical Prospecting Bureau as an interpreter of No.237 Seismic Team of No.1 Division of Geological Survey.Step by step,he was promoted to the interpretation team leader and then the chief engineer of the Institute of Methodology,before he became the chief engineer of Front Headquarters in Eastern Xinjiang,and then the chief engineer of No.1 Division of Geological Survey,after 15 years of frontline experiences in oil and gas exploration.展开更多
Aspan of twenty-five years,for a company,constitutes a engthy and eventful journey.Twenty-five years ago,a group of oil professionals from the Bureau of Geophysical Prospecting INC (hereinafter referred to as BGP),set...Aspan of twenty-five years,for a company,constitutes a engthy and eventful journey.Twenty-five years ago,a group of oil professionals from the Bureau of Geophysical Prospecting INC (hereinafter referred to as BGP),set foot on the land of Nigeria and embarked on a legendary journey.This is a narrative of resilience,commitment,and heartfelt passion,an inspiring saga that touches the soul.展开更多
A shift sampling theory established by author （1997a） is a generalization of Fourier transform computation theory. Based on this theory, I develop an Algorithm-Error （A-E） equation of potential field transformatio...A shift sampling theory established by author （1997a） is a generalization of Fourier transform computation theory. Based on this theory, I develop an Algorithm-Error （A-E） equation of potential field transformations in the wavenumber domain, which not only gives a more flexible algorithm of potential field transformations, but also reveals the law of error of potential field transformations in the wavenumber domain. The DFT0η η（0.5, 0.5） reduction-to-pole （RTP） technique derived from the A-E equation significantly improves the resolution and accuracy of RTP anomalies at low magnetic latitudes, including the magnetic equator. The law （origin, form mechanism, and essential properties） of the edge oscillation revealed by the A-E equation points out theoretically a way of improving the effect of existing padding methods in high-pass transformations in the wavenumber domain.展开更多
In the past few years, three-dimensional（3-D） seismogram has become an essential tool for the interpretation of subsurface stratigraphy and depositional systems. Seismic stratigraphy in conjunction with seismic geom...In the past few years, three-dimensional（3-D） seismogram has become an essential tool for the interpretation of subsurface stratigraphy and depositional systems. Seismic stratigraphy in conjunction with seismic geomorphology has elevated the degree to which seismic data can facilitate geological interpretation, especially in a deepwater environment. Technologies such as time slicing and interval attribute analysis can enhance geomorphological interpretations, and, when integrated with stratigraphic analyses, can yield insights regarding distribution of seal and reservoir facies. Multiple attributes corendering can further bring out features of geological interest that other technologies may overlook. This method involves corender spectral decomposition components（SDC） with semblance attributes to describe the distribution of deepwater channel elements and the boundaries of deepwater sinuous channel. Applying this technology to four elements is observed：（1） point-bars,（2） migration of channel meander loops,（3） channel erosion/cut, and（4） avulsion. The planview expression of the deepwater channel ranges from low sinuosity to high sinuosity. Furthermore, this technology has enabled interpreters to visualize details of complex depositional elements and can be used to predict net-to-gross ratio in channel systems, which can be incorporated into borehole planning for exploration as well as development needs to improve risk management significantly. The technology is applied to the study area in an effort to illustrate the variety of interpretation technologies available to the geoscientist.展开更多
The Middle Jurassic Shaximiao Formation encompasses tens of meters of thick lowstand meandering valley （LMV） strata in the western Sichuan foreland basin. Ancient LMVs newly discovered in this area were further stud...The Middle Jurassic Shaximiao Formation encompasses tens of meters of thick lowstand meandering valley （LMV） strata in the western Sichuan foreland basin. Ancient LMVs newly discovered in this area were further studied based on sequence stratigraphy and seismic sedimentology. The aim of the present study was to investigate the sedimentary characteristics, sequence architecture, and the controls on LMV deposition in this tectonically active basin using field survey data, seismic sections, seismic amplitude imaging, core description, and comprehensive application of drilling data. The results show the following： （1） Three regional sequence boundaries and two flooding surfaces were recognized, and the Shaximiao For- mation was divided into two-third-order sequences and four systems tracts. （2） Three sedimentary facies associations were identified： incised valley-fill, tributary channel, and overbank facies. Incised valleys are 5-17 km wide, 20-60 m deep and traceable for 120 km along their axes. （3） In the downstream segment, the role of tectonism gradually diminishes, and periodic base-level changes control the form and evolution of the incised valleys. Three types of LMVs--AI, A2, and A3--developed with changes in base level （lake level）; of these types, the base level of the A3 LMV was likely the lowest.展开更多
The newly discovered early Paleozoic Delenuoer ophiolite,in the western margin of the Central Qilian Shan,is composed of serpentinized peridotite,cumulate gabbro,diabase,massive basalt,and pillow basalt.This study pre...The newly discovered early Paleozoic Delenuoer ophiolite,in the western margin of the Central Qilian Shan,is composed of serpentinized peridotite,cumulate gabbro,diabase,massive basalt,and pillow basalt.This study presents geochronological and geochemical data for the cumulate gabbro and basalt.LA-ICP-MS U-Pb dating of zircons from the cumulate gabbro yielded a magmatic crystallization age of 472±4 Ma.The basalts have normal mid-ocean ridge basalt(N-MORB)compositions and a narrow range ofεNd(t)values(+4.5 to+5.3),which indicates they were derived from a depleted mantle source.On the basis of regional geological constraints,it is proposed that the Delenuoer ophiolite is a westward extension of the South Ophiolite Belt(Yushigou-Youhulugou-Donggou-Dongcaohe Ophiolite Belt)in the North Qilian Shan.The Delenuoer ophiolite,along with the Gulangxia-Delenuoer fault,defines the westernmost part of the tectonic boundary between the North and Central Qilian Shan.This ophiolite may have formed during southward subduction of the Qilian Ocean slab during the early Paleozoic.展开更多
The features of the unconformity,fault and tectonic inversion in the eastern Doseo Basin,Chad,were analyzed,and the genetic mechanisms and basin evolution were discussed using seismic and drilling data.The following r...The features of the unconformity,fault and tectonic inversion in the eastern Doseo Basin,Chad,were analyzed,and the genetic mechanisms and basin evolution were discussed using seismic and drilling data.The following results are obtained.First,four stratigraphic unconformities,i.e.basement(Tg),Mangara Group(T10),lower Upper Cretaceous(T5)and Cretaceous(T4),four faulting stages,i.e.Barremian extensional faults,Aptian–Coniacian strike-slip faults,Campanian strike-slip faults,and Eocene strike-slip faults,and two tectonic inversions,i.e.Santonian and end of Cretaceous,were developed in the Doseo Basin.Second,the Doseo Basin was an early failed intracontinental passive rift basin transformed by the strike-slip movement and tectonic inversion.The initial rifting between the African and South American plates induced the nearly N-S stretching of the Doseo Basin,giving rise to the formation of the embryonic Doseo rift basin.The nearly E-W strike-slip movement of Borogop(F1)in the western section of the Central African Shear Zone resulted in the gradual cease of the near north-south rifting and long-term strike-slip transformation,forming a dextral transtension fault system with inherited activity but gradually weakened in intensity(interrupted by two tectonic inversions).This fault system was composed of the main shear(F1),R-type shear(F2-F3)and P-type shear(F4-F5)faults,with the strike-slip associated faults as branches.The strike-slip movements of F1 in Cretaceous and Eocene were controlled by the dextral shear opening of the equatorial south Atlantic and rapid expanding of the Indian Ocean,respectively.The combined function of the strike-slip movement of F1 and the convergence between Africa and Eurasia made the Doseo Basin underwent the Santonian dextral transpressional inversion characterized by intensive folding deformation leading to the echelon NE-SW and NNE-SSW nose-shaped uplifts and unconformity(T5)on high parts of the uplifts.The convergence between Africa and Eurasia caused the intensive tectonic inversion of Doseo Basin at the end of Cretaceous manifesting as intensive uplift,denudation and folding deformation,forming the regional unconformity(T4)and superposing a nearly E-W structural configuration on the Santonian structures.Third,the Doseo Basin experienced four evolutional stages with the features of short rifting and long depression,i.e.Barremian rifting,Aptian rifting–depression transition,Albian–Late Cretaceous depression,and Cenozoic extinction,under the control of the tectonic movements between Africa and its peripheral plates.展开更多
Samples in the two oil fields with reported gas-washing and water-washing were collected for fluid inclusion analysis.Micro-fluorescence and Fourier infrared spectra of single oil inclusions were measured to study the...Samples in the two oil fields with reported gas-washing and water-washing were collected for fluid inclusion analysis.Micro-fluorescence and Fourier infrared spectra of single oil inclusions were measured to study the different effects of gas-washing and water-washing on oil compositions.The results show that spectral parameter QF_(535)values of the oils altered by gas-washing were expanded toward decreasing and increasing,respectively.The CH_(2)/CH_(3)distribution range ratio does not expand significantly,but the peak values are averaged.And the distribution of H_(2)O/Alkanes has no change.The QF_(535)values of the oils affected by water-washing increased towards the increase direction,and the distribution ranges of both CH_(2)/CH_(3)and H_(2)O/Alkanes increase significantly.The changes of QF_(535)in light oil reservoirs altered by gas-washing and CH_(2)/CH_(3)in heavy oil reservoirs by water-washing are not obvious.Therefore,two spectral parameter distribution trend charts of light and heavy oil reservoirs are summarized to discriminate the gas-washing and water-washing processes.This study is of great practical significance to utilize fluid inclusion analysis to restructure stages and processes of petroleum accumulation.展开更多
This paper addresses the Phanerozoic tectonic evolution of the western Tarim Basin based on an integrated stratigraphic,structural and tectonic analysis.P-wave velocity data show that the basin has a stable and rigid ...This paper addresses the Phanerozoic tectonic evolution of the western Tarim Basin based on an integrated stratigraphic,structural and tectonic analysis.P-wave velocity data show that the basin has a stable and rigid basement.The western Tarim Basin experienced a complex tectonic evolutionary history,and this evolution can be divided into six stages:Neoproterozoic to Early Ordovician,Middle Ordovician to Middle Devonian,Late Devonian to Permian,Triassic,Jurassic to Cretaceous and Paleogene to Quaternary.The western Tarim Basin was a rift basin in the Neoproterozoic to Early Ordovician.From the Middle Ordovician to Middle Devonian,the basin consisted of a flexural depression in the south and a depression that changed from a rift depression to a flexural depression in the north during each period,i.e.,the Middle-Late Ordovician and the Silurian to Middle Devonian.During the Late Devonian to Permian,the basin was a depression basin early and then changed into a flexural basin late in each period,i.e.,the Late Devonian to Carboniferous and the Permian.In the Triassic,the basin was a foreland basin,and from the Jurassic to Cretaceous,it was a downwarped basin.After the Paleogene,the basin became a rejuvenated foreland basin.Based on two cross sections,we conclude that the extension and shortening in the profile reflect the tectonic evolution of the Tarim Basin.The Tarim Basin has become a composite and superimposed sedimentary basin because of its long-term and complicated tectonic evolutionary history,highly rigid and stable basement and large size.展开更多
Ground Penetrating Radar method was used in detecting the flaws of underground pipeline. The GPR layer disturbing image was summarized by using a rational method in fieldwork and the in-door interpretation of data. Th...Ground Penetrating Radar method was used in detecting the flaws of underground pipeline. The GPR layer disturbing image was summarized by using a rational method in fieldwork and the in-door interpretation of data. The mark radar images of disturbance of slight, middle, and strong were obtained. The result shows that the radar method can not only determine the position of the concrete pipeline underground, but it can detect the laying quality of pipeline as well.展开更多
Red beds are not entirely red sometimes, in which grey-green spheroids or irregular spots can be found. However, the formation mechanism of grey-green spheroids or irregular spots in red beds is not clear so far. Samp...Red beds are not entirely red sometimes, in which grey-green spheroids or irregular spots can be found. However, the formation mechanism of grey-green spheroids or irregular spots in red beds is not clear so far. Samples taken from well JK1 in Jiaozhou area of Jiaolai Basin displayed that the reduction spheroids have more Vanadium (V) element, less TFe3O4 and Lead (Pb) element, almost the same content of other elements such as FeO and so on, comparing the red parts of the samples. The existence of organisms can explain the existence of green reductive spheres in the red beds formed under the oxidation environment.展开更多
Objective: To evaluate fetal ventricular systolic function in preeclampsia and its correlation with placental hypoxia degree. Methods: A total of 45 pregnant women diagnosed with preeclampsia in our hospital between M...Objective: To evaluate fetal ventricular systolic function in preeclampsia and its correlation with placental hypoxia degree. Methods: A total of 45 pregnant women diagnosed with preeclampsia in our hospital between March 2016 and June 2017 were selected as PE group, 60 cases of health pregnant women receiving prenatal examination and giving birth during the same period were selected as control group. Fetal left and right ventricular fractional shortening (FS) were measured by color Doppler ultrasound. Placenta was collected after delivery, and hypoxia-induced oxidative stress and apoptosis indexes were determined. Results: There was no significant difference in fetal left ventricular FS between PE group and control group, and right ventricular FS was significantly lower than that of control group;MDA, AOPP, 8-OHdG, Bax, Caspase-9 and Caspase-3 contents in placenta of PE group were significantly higher than those of control group whereas Bcl-2 content was significantly lower than that of control group;fetal right ventricular FS was negatively correlated with MDA, AOPP, 8-OHdG, Bax, Caspase-9 and Caspase-3 contents in placenta, and positively correlated with Bcl-2 content in placenta. Conclusions: Fetal right ventricular systolic function is weakened in pregnant women with preeclampsia, and FS can be used to evaluate the systolic function of the right ventricle, and is related to the oxidative stress response and apoptosis caused by placental hypoxia.展开更多
At the end of July,2021,good news came from Chad Project Company and Niger Project Company of China National Oil and Gas Exploration and Development Company Ltd.(CNODC);both companies had made major oil and gas discov...At the end of July,2021,good news came from Chad Project Company and Niger Project Company of China National Oil and Gas Exploration and Development Company Ltd.(CNODC);both companies had made major oil and gas discoveries of 100 million tons in their key blocks!The Chad Project Company has passed the overall evaluation of basins in Basin D and Basin B,and the proven reserves reached 100 million tons,respectively.Niger Project has also discovered the main oil and gas control fault recently.At present,there are abundant oil and gas discoveries in the completed drilling wells,which will also form a scale reserve reaching hundreds of millions of tons.These major discoveries in oil and gas are a big achievement of the long-term technical cooperation between the Bureau of Geophysical Prospecting INC(BGP INC)and CNODC,which embodies the wisdom and hard work of collectors and technicians at the BGP INC.展开更多
The Belt and Road Initiative has brought economic development and prosperity to the countries along its route. Latin America is an important area of economic investment for China, with special focus on oil and gas,How...The Belt and Road Initiative has brought economic development and prosperity to the countries along its route. Latin America is an important area of economic investment for China, with special focus on oil and gas,However, investment is bound to be accompanied by opportunities and risks. Before investing in oil and gas in the corresponding countries, it is necessary to analyze the risk factors from a risk management perspective so as to establish a risk identification system and early warning mechanism. In this way, enterprises can gain competitive advantages and develop in a sustainable way.展开更多
Objective: To study the correlation between the umbilical artery flow ultrasound parameters of intrauterine fetal distress and fetal ischemic hypoxic damage. Methods: A total of 158 puerperae who gave birth in our hos...Objective: To study the correlation between the umbilical artery flow ultrasound parameters of intrauterine fetal distress and fetal ischemic hypoxic damage. Methods: A total of 158 puerperae who gave birth in our hospital between July 2016 and June 2017 were selected and divided into the intrauterine distress group (Apgar<7 points) and normal pregnancy group (Apgar≥7 points) according to the neonatal Apgar score, the umbilical artery flow ultrasound parameters at 24-30 weeks, 31-36 weeks and 37-41 weeks of gestation were determined, and the umbilical arterial blood gas parameters and oxidative stress molecule levels were determined. Results: At 24-30 weeks, 31-36 weeks and 37-41 weeks of gestation, umbilical arterial RI, PI and S/D of intrauterine distress group were significantly higher than those of normal pregnancy group;umbilical arterial pH and PaO2 of intrauterine distress group were significantly lower than those of normal pregnancy group and negatively correlated with RI, PI and S/D while PaCO2 and lactic acid levels were significantly higher than those of normal pregnancy group and positively correlated with RI, PI and S/D;SOD, GSH-px and CAT levels in umbilical artery of intrauterine distress group were significantly lower than those of normal pregnancy group and negatively correlated with RI, PI and S/D while MDA and 8-OHdG levels were significantly higher than those of normal pregnancy group and positively correlated with RI, PI and S/D. Conclusion: Umbilical artery flow ultrasound characteristics of intrauterine fetal distress are characterized by the increased resistance and decreased blood flow and are correlated with the degree of fetal hypoxia and oxidative stress.展开更多
Seismic migration and inversion are closely related techniques to portray subsurface images and identify hydrocarbon reservoirs.Seismic migration aims at obtaining structural images of subsurface geologic discontinuit...Seismic migration and inversion are closely related techniques to portray subsurface images and identify hydrocarbon reservoirs.Seismic migration aims at obtaining structural images of subsurface geologic discontinuities.More specifically,seismic migration estimates the reflectivity function(stacked average reflectivity or pre-stack angle-dependent reflectivity)from seismic reflection data.On the other hand,seismic inversion quantitatively estimates the intrinsic rock properties of subsurface formulations.Such seismic inversion methods are applicable to detect hydrocarbon reservoirs that may exhibit lateral variations in the inverted parameters.Although there exist many differences,pre-stack seismic migration is similar with the first iteration of the general linearized seismic inversion.Usually,seismic migration and inversion techniques assume an acoustic or isotropic elastic medium.Unconventional reservoirs such as shale and tight sand formation have notable anisotropic property.We present a linearized waveform inversion(LWI)scheme for weakly anisotropic elastic media with vertical transversely isotropic(VTI)symmetry.It is based on two-way anisotropic elastic wave equation and simultaneously inverts for the localized perturbations(ΔVp_(0)/Vp_(0)/Vs_(0)/Vs_(0)/,Δ∈,Δδ)from the long-wavelength reference model.Our proposed VTI-elastic LWI is an iterative method that requires a forward and an adjoint operator acting on vectors in each iteration.We derive the forward Born approximation operator by perturbation theory and adjoint operator via adjoint-state method.The inversion has improved the quality of the images and reduces the multi-parameter crosstalk comparing with the adjoint-based images.We have observed that the multi-parameter crosstalk problem is more prominent in the inversion images for Thomsen anisotropy parameters.Especially,the Thomsen parameter is the most difficult to resolve.We also analyze the multi-parameter crosstalk using scattering radiation patterns.The linearized waveform inversion for VTI-elastic media presented in this article provides quantitative information of the rock properties that has the potential to help identify hydrocarbon reservoirs.展开更多
This study investigates the mechanical properties of Q235B steel through quasi-static tests at both room temperature and elevated temperature.The initial values of the Johnson-Cook model parameters are determined usin...This study investigates the mechanical properties of Q235B steel through quasi-static tests at both room temperature and elevated temperature.The initial values of the Johnson-Cook model parameters are determined using a fitting method.The global response surface algorithm is employed to optimize and calibrate the Johnson-Cook model parameters for Q235B steel under both room temperature and elevated temperature conditions.A simulation model is established at room temperature,and the simulated mechanical performance curves for displacement and stress are monitored.Multiple optimization algorithms are applied to optimize and calibrate the model parameters at room temperature.The global response surface algorithm is identified as the most suitable algorithm for this optimization problem.Sensitivity analysis is conducted to explore the impact of model parameters on the objective function.The analysis indicates that the optimized material model better fits the experimental values,aligning more closely with the actual test results of material strain mechanisms over a wide temperature range.展开更多
China＇s continental deposition basins are characterized by complex geological structures and various reservoir lithologies. Therefore, high precision exploration methods are needed. High density spatial sampling is a...China＇s continental deposition basins are characterized by complex geological structures and various reservoir lithologies. Therefore, high precision exploration methods are needed. High density spatial sampling is a new technology to increase the accuracy of seismic exploration. We briefly discuss point source and receiver technology, analyze the high density spatial sampling in situ method, introduce the symmetric sampling principles presented by Gijs J. O. Vermeer, and discuss high density spatial sampling technology from the point of view of wave field continuity. We emphasize the analysis of the high density spatial sampling characteristics, including the high density first break advantages for investigation of near surface structure, improving static correction precision, the use of dense receiver spacing at short offsets to increase the effective coverage at shallow depth, and the accuracy of reflection imaging. Coherent noise is not aliased and the noise analysis precision and suppression increases as a result. High density spatial sampling enhances wave field continuity and the accuracy of various mathematical transforms, which benefits wave field separation. Finally, we point out that the difficult part of high density spatial sampling technology is the data processing. More research needs to be done on the methods of analyzing and processing huge amounts of seismic data.展开更多
Sequences of wave-enhanced sediment-gravity flows(WESGFs) have been widely recognized in the marine shelf environment. In this study, we show observations of WESGF deposits in lacustrine settings using well core and t...Sequences of wave-enhanced sediment-gravity flows(WESGFs) have been widely recognized in the marine shelf environment. In this study, we show observations of WESGF deposits in lacustrine settings using well core and thin section data from the Paleogene in the Jiyang sub-basin, Bohai Bay basin, eastern China. The findings of this study include the following: 1) the sequence of WESGFs in the lacustrine basin is similar to that of marine; it consists of three units, MF1 unit: siltstone with basal erosion surface, MF2 unit: silt-streaked claystone, and MF3 unit: silty-mudstone; and 2) prodelta sand sheets are found in the lacustrine WESGF sequence and are classified as the MFd unit: clay-streaked siltstone. However, because the system size and variability in hydrodynamic conditions are different between the lacustrine and marine basins, lacustrine WESGFs do appear to have three distinguishable features: 1) the sediment grain size and sand content are slightly higher than those of the marine WESGFs; 2) lacustrine WESGFs may contain prodelta sediments or sedimentary sequences of other types of gravity flows, such as hyperpycnal flows; and 3) the scale of the sedimentary structures for lacustrine WESGFs is smaller. The WESGFs found in the continental lacustrine basin provide a new model for sediment dispersal processes in lake environments and may be helpful to explain and predict the distribution of sandy reservoirs for oil and gas exploration.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant-in-Aid 40574053the Program for New Century Excellent Talents in University of China (NCET-06-0602)the National 973 Key Basic Research Development Program (No.2007CB209601)
文摘In this paper we discuss the edge-preserving regularization method in the reconstruction of physical parameters from geophysical data such as seismic and ground-penetrating radar data. In the regularization method a potential function of model parameters and its corresponding functions are introduced. This method is stable and able to preserve boundaries, and protect resolution. The effect of regularization depends to a great extent on the suitable choice of regularization parameters. The influence of the edge-preserving parameters on the reconstruction results is investigated and the relationship between the regularization parameters and the error of data is described.
文摘After graduating from university in 1983,Zhan Shifan was recruited by the former Geophysical Prospecting Bureau as an interpreter of No.237 Seismic Team of No.1 Division of Geological Survey.Step by step,he was promoted to the interpretation team leader and then the chief engineer of the Institute of Methodology,before he became the chief engineer of Front Headquarters in Eastern Xinjiang,and then the chief engineer of No.1 Division of Geological Survey,after 15 years of frontline experiences in oil and gas exploration.
文摘Aspan of twenty-five years,for a company,constitutes a engthy and eventful journey.Twenty-five years ago,a group of oil professionals from the Bureau of Geophysical Prospecting INC (hereinafter referred to as BGP),set foot on the land of Nigeria and embarked on a legendary journey.This is a narrative of resilience,commitment,and heartfelt passion,an inspiring saga that touches the soul.
文摘A shift sampling theory established by author （1997a） is a generalization of Fourier transform computation theory. Based on this theory, I develop an Algorithm-Error （A-E） equation of potential field transformations in the wavenumber domain, which not only gives a more flexible algorithm of potential field transformations, but also reveals the law of error of potential field transformations in the wavenumber domain. The DFT0η η（0.5, 0.5） reduction-to-pole （RTP） technique derived from the A-E equation significantly improves the resolution and accuracy of RTP anomalies at low magnetic latitudes, including the magnetic equator. The law （origin, form mechanism, and essential properties） of the edge oscillation revealed by the A-E equation points out theoretically a way of improving the effect of existing padding methods in high-pass transformations in the wavenumber domain.
基金The National Natural Science Foundation of China under contract Nos 41102059 and 91328201the National Science and Technology Major Project of China under contract No.2017ZX05032-001
文摘In the past few years, three-dimensional（3-D） seismogram has become an essential tool for the interpretation of subsurface stratigraphy and depositional systems. Seismic stratigraphy in conjunction with seismic geomorphology has elevated the degree to which seismic data can facilitate geological interpretation, especially in a deepwater environment. Technologies such as time slicing and interval attribute analysis can enhance geomorphological interpretations, and, when integrated with stratigraphic analyses, can yield insights regarding distribution of seal and reservoir facies. Multiple attributes corendering can further bring out features of geological interest that other technologies may overlook. This method involves corender spectral decomposition components（SDC） with semblance attributes to describe the distribution of deepwater channel elements and the boundaries of deepwater sinuous channel. Applying this technology to four elements is observed：（1） point-bars,（2） migration of channel meander loops,（3） channel erosion/cut, and（4） avulsion. The planview expression of the deepwater channel ranges from low sinuosity to high sinuosity. Furthermore, this technology has enabled interpreters to visualize details of complex depositional elements and can be used to predict net-to-gross ratio in channel systems, which can be incorporated into borehole planning for exploration as well as development needs to improve risk management significantly. The technology is applied to the study area in an effort to illustrate the variety of interpretation technologies available to the geoscientist.
基金supported by the Natural Science Foundation of China(Grant No.41672098)the National Science and Technology Major Project(Grant No.2016ZX05002006)
文摘The Middle Jurassic Shaximiao Formation encompasses tens of meters of thick lowstand meandering valley （LMV） strata in the western Sichuan foreland basin. Ancient LMVs newly discovered in this area were further studied based on sequence stratigraphy and seismic sedimentology. The aim of the present study was to investigate the sedimentary characteristics, sequence architecture, and the controls on LMV deposition in this tectonically active basin using field survey data, seismic sections, seismic amplitude imaging, core description, and comprehensive application of drilling data. The results show the following： （1） Three regional sequence boundaries and two flooding surfaces were recognized, and the Shaximiao For- mation was divided into two-third-order sequences and four systems tracts. （2） Three sedimentary facies associations were identified： incised valley-fill, tributary channel, and overbank facies. Incised valleys are 5-17 km wide, 20-60 m deep and traceable for 120 km along their axes. （3） In the downstream segment, the role of tectonism gradually diminishes, and periodic base-level changes control the form and evolution of the incised valleys. Three types of LMVs--AI, A2, and A3--developed with changes in base level （lake level）; of these types, the base level of the A3 LMV was likely the lowest.
基金funded by the Science and Technology Major Project of Gansu Province(No.1002FKDA04)the Fundamental Research Funds for the Central Universities,China(Lzujbky2016-197,Lzujbky2018it20)the National Nature Science Foundation of China(No.41702044)。
文摘The newly discovered early Paleozoic Delenuoer ophiolite,in the western margin of the Central Qilian Shan,is composed of serpentinized peridotite,cumulate gabbro,diabase,massive basalt,and pillow basalt.This study presents geochronological and geochemical data for the cumulate gabbro and basalt.LA-ICP-MS U-Pb dating of zircons from the cumulate gabbro yielded a magmatic crystallization age of 472±4 Ma.The basalts have normal mid-ocean ridge basalt(N-MORB)compositions and a narrow range ofεNd(t)values(+4.5 to+5.3),which indicates they were derived from a depleted mantle source.On the basis of regional geological constraints,it is proposed that the Delenuoer ophiolite is a westward extension of the South Ophiolite Belt(Yushigou-Youhulugou-Donggou-Dongcaohe Ophiolite Belt)in the North Qilian Shan.The Delenuoer ophiolite,along with the Gulangxia-Delenuoer fault,defines the westernmost part of the tectonic boundary between the North and Central Qilian Shan.This ophiolite may have formed during southward subduction of the Qilian Ocean slab during the early Paleozoic.
基金Supported by the PetroChina Science and Technology Project(2021DJ3103)。
文摘The features of the unconformity,fault and tectonic inversion in the eastern Doseo Basin,Chad,were analyzed,and the genetic mechanisms and basin evolution were discussed using seismic and drilling data.The following results are obtained.First,four stratigraphic unconformities,i.e.basement(Tg),Mangara Group(T10),lower Upper Cretaceous(T5)and Cretaceous(T4),four faulting stages,i.e.Barremian extensional faults,Aptian–Coniacian strike-slip faults,Campanian strike-slip faults,and Eocene strike-slip faults,and two tectonic inversions,i.e.Santonian and end of Cretaceous,were developed in the Doseo Basin.Second,the Doseo Basin was an early failed intracontinental passive rift basin transformed by the strike-slip movement and tectonic inversion.The initial rifting between the African and South American plates induced the nearly N-S stretching of the Doseo Basin,giving rise to the formation of the embryonic Doseo rift basin.The nearly E-W strike-slip movement of Borogop(F1)in the western section of the Central African Shear Zone resulted in the gradual cease of the near north-south rifting and long-term strike-slip transformation,forming a dextral transtension fault system with inherited activity but gradually weakened in intensity(interrupted by two tectonic inversions).This fault system was composed of the main shear(F1),R-type shear(F2-F3)and P-type shear(F4-F5)faults,with the strike-slip associated faults as branches.The strike-slip movements of F1 in Cretaceous and Eocene were controlled by the dextral shear opening of the equatorial south Atlantic and rapid expanding of the Indian Ocean,respectively.The combined function of the strike-slip movement of F1 and the convergence between Africa and Eurasia made the Doseo Basin underwent the Santonian dextral transpressional inversion characterized by intensive folding deformation leading to the echelon NE-SW and NNE-SSW nose-shaped uplifts and unconformity(T5)on high parts of the uplifts.The convergence between Africa and Eurasia caused the intensive tectonic inversion of Doseo Basin at the end of Cretaceous manifesting as intensive uplift,denudation and folding deformation,forming the regional unconformity(T4)and superposing a nearly E-W structural configuration on the Santonian structures.Third,the Doseo Basin experienced four evolutional stages with the features of short rifting and long depression,i.e.Barremian rifting,Aptian rifting–depression transition,Albian–Late Cretaceous depression,and Cenozoic extinction,under the control of the tectonic movements between Africa and its peripheral plates.
基金National Science and Technology Projects(2011ZX05023-004-010)National Science Foundation of Hubei Province(2020CFB372)。
文摘Samples in the two oil fields with reported gas-washing and water-washing were collected for fluid inclusion analysis.Micro-fluorescence and Fourier infrared spectra of single oil inclusions were measured to study the different effects of gas-washing and water-washing on oil compositions.The results show that spectral parameter QF_(535)values of the oils altered by gas-washing were expanded toward decreasing and increasing,respectively.The CH_(2)/CH_(3)distribution range ratio does not expand significantly,but the peak values are averaged.And the distribution of H_(2)O/Alkanes has no change.The QF_(535)values of the oils affected by water-washing increased towards the increase direction,and the distribution ranges of both CH_(2)/CH_(3)and H_(2)O/Alkanes increase significantly.The changes of QF_(535)in light oil reservoirs altered by gas-washing and CH_(2)/CH_(3)in heavy oil reservoirs by water-washing are not obvious.Therefore,two spectral parameter distribution trend charts of light and heavy oil reservoirs are summarized to discriminate the gas-washing and water-washing processes.This study is of great practical significance to utilize fluid inclusion analysis to restructure stages and processes of petroleum accumulation.
基金supported by the China Postdoctoral Science Foundation(No.2019M650960)the Petro-China Tarim Oilfield Company(No.041011080018).
文摘This paper addresses the Phanerozoic tectonic evolution of the western Tarim Basin based on an integrated stratigraphic,structural and tectonic analysis.P-wave velocity data show that the basin has a stable and rigid basement.The western Tarim Basin experienced a complex tectonic evolutionary history,and this evolution can be divided into six stages:Neoproterozoic to Early Ordovician,Middle Ordovician to Middle Devonian,Late Devonian to Permian,Triassic,Jurassic to Cretaceous and Paleogene to Quaternary.The western Tarim Basin was a rift basin in the Neoproterozoic to Early Ordovician.From the Middle Ordovician to Middle Devonian,the basin consisted of a flexural depression in the south and a depression that changed from a rift depression to a flexural depression in the north during each period,i.e.,the Middle-Late Ordovician and the Silurian to Middle Devonian.During the Late Devonian to Permian,the basin was a depression basin early and then changed into a flexural basin late in each period,i.e.,the Late Devonian to Carboniferous and the Permian.In the Triassic,the basin was a foreland basin,and from the Jurassic to Cretaceous,it was a downwarped basin.After the Paleogene,the basin became a rejuvenated foreland basin.Based on two cross sections,we conclude that the extension and shortening in the profile reflect the tectonic evolution of the Tarim Basin.The Tarim Basin has become a composite and superimposed sedimentary basin because of its long-term and complicated tectonic evolutionary history,highly rigid and stable basement and large size.
文摘Ground Penetrating Radar method was used in detecting the flaws of underground pipeline. The GPR layer disturbing image was summarized by using a rational method in fieldwork and the in-door interpretation of data. The mark radar images of disturbance of slight, middle, and strong were obtained. The result shows that the radar method can not only determine the position of the concrete pipeline underground, but it can detect the laying quality of pipeline as well.
文摘Red beds are not entirely red sometimes, in which grey-green spheroids or irregular spots can be found. However, the formation mechanism of grey-green spheroids or irregular spots in red beds is not clear so far. Samples taken from well JK1 in Jiaozhou area of Jiaolai Basin displayed that the reduction spheroids have more Vanadium (V) element, less TFe3O4 and Lead (Pb) element, almost the same content of other elements such as FeO and so on, comparing the red parts of the samples. The existence of organisms can explain the existence of green reductive spheres in the red beds formed under the oxidation environment.
文摘Objective: To evaluate fetal ventricular systolic function in preeclampsia and its correlation with placental hypoxia degree. Methods: A total of 45 pregnant women diagnosed with preeclampsia in our hospital between March 2016 and June 2017 were selected as PE group, 60 cases of health pregnant women receiving prenatal examination and giving birth during the same period were selected as control group. Fetal left and right ventricular fractional shortening (FS) were measured by color Doppler ultrasound. Placenta was collected after delivery, and hypoxia-induced oxidative stress and apoptosis indexes were determined. Results: There was no significant difference in fetal left ventricular FS between PE group and control group, and right ventricular FS was significantly lower than that of control group;MDA, AOPP, 8-OHdG, Bax, Caspase-9 and Caspase-3 contents in placenta of PE group were significantly higher than those of control group whereas Bcl-2 content was significantly lower than that of control group;fetal right ventricular FS was negatively correlated with MDA, AOPP, 8-OHdG, Bax, Caspase-9 and Caspase-3 contents in placenta, and positively correlated with Bcl-2 content in placenta. Conclusions: Fetal right ventricular systolic function is weakened in pregnant women with preeclampsia, and FS can be used to evaluate the systolic function of the right ventricle, and is related to the oxidative stress response and apoptosis caused by placental hypoxia.
文摘At the end of July,2021,good news came from Chad Project Company and Niger Project Company of China National Oil and Gas Exploration and Development Company Ltd.(CNODC);both companies had made major oil and gas discoveries of 100 million tons in their key blocks!The Chad Project Company has passed the overall evaluation of basins in Basin D and Basin B,and the proven reserves reached 100 million tons,respectively.Niger Project has also discovered the main oil and gas control fault recently.At present,there are abundant oil and gas discoveries in the completed drilling wells,which will also form a scale reserve reaching hundreds of millions of tons.These major discoveries in oil and gas are a big achievement of the long-term technical cooperation between the Bureau of Geophysical Prospecting INC(BGP INC)and CNODC,which embodies the wisdom and hard work of collectors and technicians at the BGP INC.
文摘The Belt and Road Initiative has brought economic development and prosperity to the countries along its route. Latin America is an important area of economic investment for China, with special focus on oil and gas,However, investment is bound to be accompanied by opportunities and risks. Before investing in oil and gas in the corresponding countries, it is necessary to analyze the risk factors from a risk management perspective so as to establish a risk identification system and early warning mechanism. In this way, enterprises can gain competitive advantages and develop in a sustainable way.
文摘Objective: To study the correlation between the umbilical artery flow ultrasound parameters of intrauterine fetal distress and fetal ischemic hypoxic damage. Methods: A total of 158 puerperae who gave birth in our hospital between July 2016 and June 2017 were selected and divided into the intrauterine distress group (Apgar<7 points) and normal pregnancy group (Apgar≥7 points) according to the neonatal Apgar score, the umbilical artery flow ultrasound parameters at 24-30 weeks, 31-36 weeks and 37-41 weeks of gestation were determined, and the umbilical arterial blood gas parameters and oxidative stress molecule levels were determined. Results: At 24-30 weeks, 31-36 weeks and 37-41 weeks of gestation, umbilical arterial RI, PI and S/D of intrauterine distress group were significantly higher than those of normal pregnancy group;umbilical arterial pH and PaO2 of intrauterine distress group were significantly lower than those of normal pregnancy group and negatively correlated with RI, PI and S/D while PaCO2 and lactic acid levels were significantly higher than those of normal pregnancy group and positively correlated with RI, PI and S/D;SOD, GSH-px and CAT levels in umbilical artery of intrauterine distress group were significantly lower than those of normal pregnancy group and negatively correlated with RI, PI and S/D while MDA and 8-OHdG levels were significantly higher than those of normal pregnancy group and positively correlated with RI, PI and S/D. Conclusion: Umbilical artery flow ultrasound characteristics of intrauterine fetal distress are characterized by the increased resistance and decreased blood flow and are correlated with the degree of fetal hypoxia and oxidative stress.
文摘Seismic migration and inversion are closely related techniques to portray subsurface images and identify hydrocarbon reservoirs.Seismic migration aims at obtaining structural images of subsurface geologic discontinuities.More specifically,seismic migration estimates the reflectivity function(stacked average reflectivity or pre-stack angle-dependent reflectivity)from seismic reflection data.On the other hand,seismic inversion quantitatively estimates the intrinsic rock properties of subsurface formulations.Such seismic inversion methods are applicable to detect hydrocarbon reservoirs that may exhibit lateral variations in the inverted parameters.Although there exist many differences,pre-stack seismic migration is similar with the first iteration of the general linearized seismic inversion.Usually,seismic migration and inversion techniques assume an acoustic or isotropic elastic medium.Unconventional reservoirs such as shale and tight sand formation have notable anisotropic property.We present a linearized waveform inversion(LWI)scheme for weakly anisotropic elastic media with vertical transversely isotropic(VTI)symmetry.It is based on two-way anisotropic elastic wave equation and simultaneously inverts for the localized perturbations(ΔVp_(0)/Vp_(0)/Vs_(0)/Vs_(0)/,Δ∈,Δδ)from the long-wavelength reference model.Our proposed VTI-elastic LWI is an iterative method that requires a forward and an adjoint operator acting on vectors in each iteration.We derive the forward Born approximation operator by perturbation theory and adjoint operator via adjoint-state method.The inversion has improved the quality of the images and reduces the multi-parameter crosstalk comparing with the adjoint-based images.We have observed that the multi-parameter crosstalk problem is more prominent in the inversion images for Thomsen anisotropy parameters.Especially,the Thomsen parameter is the most difficult to resolve.We also analyze the multi-parameter crosstalk using scattering radiation patterns.The linearized waveform inversion for VTI-elastic media presented in this article provides quantitative information of the rock properties that has the potential to help identify hydrocarbon reservoirs.
文摘This study investigates the mechanical properties of Q235B steel through quasi-static tests at both room temperature and elevated temperature.The initial values of the Johnson-Cook model parameters are determined using a fitting method.The global response surface algorithm is employed to optimize and calibrate the Johnson-Cook model parameters for Q235B steel under both room temperature and elevated temperature conditions.A simulation model is established at room temperature,and the simulated mechanical performance curves for displacement and stress are monitored.Multiple optimization algorithms are applied to optimize and calibrate the model parameters at room temperature.The global response surface algorithm is identified as the most suitable algorithm for this optimization problem.Sensitivity analysis is conducted to explore the impact of model parameters on the objective function.The analysis indicates that the optimized material model better fits the experimental values,aligning more closely with the actual test results of material strain mechanisms over a wide temperature range.
文摘China＇s continental deposition basins are characterized by complex geological structures and various reservoir lithologies. Therefore, high precision exploration methods are needed. High density spatial sampling is a new technology to increase the accuracy of seismic exploration. We briefly discuss point source and receiver technology, analyze the high density spatial sampling in situ method, introduce the symmetric sampling principles presented by Gijs J. O. Vermeer, and discuss high density spatial sampling technology from the point of view of wave field continuity. We emphasize the analysis of the high density spatial sampling characteristics, including the high density first break advantages for investigation of near surface structure, improving static correction precision, the use of dense receiver spacing at short offsets to increase the effective coverage at shallow depth, and the accuracy of reflection imaging. Coherent noise is not aliased and the noise analysis precision and suppression increases as a result. High density spatial sampling enhances wave field continuity and the accuracy of various mathematical transforms, which benefits wave field separation. Finally, we point out that the difficult part of high density spatial sampling technology is the data processing. More research needs to be done on the methods of analyzing and processing huge amounts of seismic data.
基金support by the National Nature Science Foundation of China (General Program) Grant No. 41572134National Program on Key Basic Research Project of China (973 Program) Grant No. 2014CB239102
文摘Sequences of wave-enhanced sediment-gravity flows(WESGFs) have been widely recognized in the marine shelf environment. In this study, we show observations of WESGF deposits in lacustrine settings using well core and thin section data from the Paleogene in the Jiyang sub-basin, Bohai Bay basin, eastern China. The findings of this study include the following: 1) the sequence of WESGFs in the lacustrine basin is similar to that of marine; it consists of three units, MF1 unit: siltstone with basal erosion surface, MF2 unit: silt-streaked claystone, and MF3 unit: silty-mudstone; and 2) prodelta sand sheets are found in the lacustrine WESGF sequence and are classified as the MFd unit: clay-streaked siltstone. However, because the system size and variability in hydrodynamic conditions are different between the lacustrine and marine basins, lacustrine WESGFs do appear to have three distinguishable features: 1) the sediment grain size and sand content are slightly higher than those of the marine WESGFs; 2) lacustrine WESGFs may contain prodelta sediments or sedimentary sequences of other types of gravity flows, such as hyperpycnal flows; and 3) the scale of the sedimentary structures for lacustrine WESGFs is smaller. The WESGFs found in the continental lacustrine basin provide a new model for sediment dispersal processes in lake environments and may be helpful to explain and predict the distribution of sandy reservoirs for oil and gas exploration.
