西秦岭晚古生代弧前盆地沉积与成矿作用

The Western Qinling Orogenie belt in the Taibai-Fengxian and Xihe-Lixian areas can be subdivided into three units structurally from north to south, which are the island-arc, forearc basin and accretionary wedge, respectively. The forearc basin developed in the Late Paleozoic mainly controls sedimentation and some larger lead-zinc and gold deposits in the western Qinling. Stratigraphically, the island arc is dissected into the Liziyuan Group, the Danfeng Group and the Luohansi Group. The metavolcanic rocks include basic, intermediate and acidic rocks, and their geochemistry demonstrates that these igneous rocks generated in an island arc. Where, the basalts are subalkaline series charactered by low-medium potassium, with enriched LREE, negative Eu anomaly, and positive Nd anomaly. Cr-content of volcanic rocks is 2-3 times higher than that of island arc tholeiite all over the world. In addition, the lightly metamorphosed accretionary wedge in the areas of Huixian, Chengxian, Liuba and Shiqun is dominated by terrigenous sediments with carbonatite, chert, mafic and volcanic rocks. The age of the wedge is the Late Palaeozoic to the Trassic, while previous work suggested that it is the Silurian. The Upper Paleozoic between the island arc belt and accretionary wedge are mainly the sediments filled in the fore arc basin. The fillings in the forearc basin were subdivided into the Dacaiotan Group, the Tieshan Group, the Shujiaba Group and the Xihanshui Group, previously. They outcropped along the southern margins of the Liziyuan Group. The Dacaotan Group, the Upper Devonian, is close to the island arc complex, and composed of a suite of red and gray-green thick and coarse terrestrial elastics. The Shujiaba Group, the Mid-Upper Devonian, is located in the middle of the basin, is mainly fine-grained elastics with a few intercalations of limestone. The Xihanshui Group, which distributes in the southern of the basin, is mainly slates, phyllites and sandstones with carbonatite and reef blocks. The Tieshan Group, the Upper Devonian, just outcrops in the southwest of the basin, is carbonatite and clastic rocks, and deposited in the shallow -sea environment. The faults in the basin are mainly NW trend. The sedimentary characteristics, slump folds, biological assemblages in both sides of and within those faults demonstrate that they were syn-sedimentary faults with multi-period activities. They separated the forearc basin into several sub-basins, which imbricate in the background of a forearc basin with sedimentary characteristics of the piggyback basin. The deep hydrothermal fluid erupted along the syn-sedimentary faults, supported nutrition and energy for the reef, and resulted in hydrothermal-sedimentary rocks, reef and lead-zinc deposits along these faults. The sedimentary facies in the basin varies from the continental slope alluvial fan, to shallow-sea reef facies, and then to deep-water from north to south, which implies that there was a continental slope in the Devonian in the west Qinling. The strata overlap to north and to east respectively. Additionally, the coeval sedimentary facies in north and south are significantly different. The elastics become more and more coarser to north in the basin as well as upward coarsing. These features indicate prograding fillings followed by overlaps of the different fans underwater. The paleocurrent analyses show that the forearc basin is composed of thrust-ramp-basins and deep-water basins. The provenance of the fillings in the basin is the island arc in the north. The lead-zinc deposits were synchronous with the Xihanshui Group in the early stage of development of the forearc basin. They were strongly constrained by syn-sedimentary faults and then modified by the hydrothermal fluids. The gold deposits distributed in the north of the basin resulted from the tectonic activities and magmatism in the later stage of the basin evolution, and occurred at the top of the lead-zinc deposits spatially. The scales of lead-zinc deposits in the south of the basin are larger than that of the gold-deposits. The Pb-Zn deposits in the west of the basin are larger than those in the east, while the Gold deposits in the west of the basin are smaller than those in the east. Mineralizing ages of these deposits become younger and younger to west.

松辽盆地河流-三角洲体系高分辩率层序地层学、储层构形及非均质模型研究

This dissertation tries to combine the new theories of high-resolution sequence stratigraphy and reservoir architecture with fine sedimentology to form a integral theory system -"high-resolution sequence sedimentology", which can be applied widely ranging from the early petroleum exploration to the tertiary recovery stage in marine and terrestrial basin. So the west slope area in south of Songliao basin, in which, early-fine exploration have been developed, and Xingnan area of Daqing placantictine in high water-bearing and tertiary recovery stage, are selected as target areas to research and analyze. By applying high-resolution sequence stratigraphy theory as well as analysis of source area-facies, the west slope area has been divided into two source areas and three drainage systems and the following conclusions have been drawn: three high values sandstone areas, two sandstone pinchout zones and one stratigraphic pinchout overlap; the facies between Baicheng-Tongyu drainage system is frist ascertained as large-scale argillaceous filled plain facies; fine-grained braided channel-delta depositional system has been found; plane sedimentary facies and microfacies maps of different-scale sequence have been completed, and then twenty-eight lithologic traps have been detected in the east of Taobao-Zhenlai reverse fault zone; In no exploration area of the west, large-scale stratigraiphic overlap heavy oil reservoirs has first been found, which has become an important prograss. In Xingnan area, in the view of high-resolution sequence stratigraphy, the surface of unconformity (the bottom of SSC13) in P I group has been identified, and the following method and technique have been advanced: the division and correlation methods of short-scale base-level cycle sequence (SSC); the comprehensive research methods of SSC plane microfacies; the division technique of hierarchy and type of flow unit, the origin of large-scale composite sandbody and flow unit; And ,on the basis of these, 103 monosandstone bodies and 87 flow units of the third levels have been identified, and four levels of flow units model of five sandstone-bodies types have been established. Because it is a very difficult task all over the world to research architecture in subsurface monosandstone body, brings forward a series of techniques as follows: technique of researching architecture of thin interbed in subsurface monosandstone body; classification, type and liquid-resisting mechanism of thin interbed; multiple-remember vertical subsequence model of remaining oil in monosadstone body. Models of heterogeneity and architecture of thin interbed in five types of monosandstone body have been established. Applying these techniques, type and distribution of remaining oil in different types of monosandstone bodies have been predicated.

黄东海及朝鲜海峡冰后期陆架沉积物的环境磁学研究

There are four chapters in this dissertation. The first chapter briefly synthesizes the basic theories, methods and present-day applying situation of environmental magnetism. The second chapter probes into the magnetic mineral diagenesis in the post-glacial muddy sediments from the southeastern South Yellow Sea and its response to marine environmental changes, using the muddy sediment of Core YSDP103 formed in the shelf since about 13 ka BP. The third chapter illustrates the high-resolution early diagenetic processes by investigating the rapidly deposited muddy sediments during the last 6 ka in Cores SSDP-102 and SSDP-103 from the near-shore shelf of Korea Strait. The fourth chapter presents the results of detailed rock magnetic investigation of the surface sediments from the fine-grained depositional area on the outer shelf of the East China Sea in an attempt to provide environmental magnetic evidence for the provenance of the fine-grained deposit. Core YSDP103 was retrieved in the muddy deposit under the cold eddy of the southeastern South Yellow Sea, and the uppermost 29.79 m core represents the muddy sediments formed in the shelf since about 13 ka BP. The lower part from 29.79 to 13.35 m, called Unit A2, was deposited during the period from the post-glacial transgression to the middle Holocene (at about 6 ~(14)C ka BP) when the rising sea level reached its maximum, while the upper part above 13.35 m (called Unit Al) was deposited in a cold eddy associated with the formation of the Yellow Sea Warm Current just after the peak of post-glacial sea level rise. For the the uppermost 29.79 m core, detailed investigation of rock-magnetic properties and analyses of grain sizes and geochemistry were made. The experimental results indicate that the magnetic mineralogy of the core is dominated by magnetite, maghemite and hematite and that, except for the uppermost 2.35 m, the magnetic minerals were subject to reductive diagenesis leading to significant decline of magnetic mineral content and the proportion of low-coercivity component. More importantly, ferrimagnetic iron sulphide (greigite) is found in Unit A2 but absent in Unit Al, suggesting the control of marine environmental conditions on the magnetic mineral diagenesis. Magnetic parameters show abrupt changes across the boundary between the Unit Al and A2, which reflects a co-effect of environmental conditions and primary magnetic components of the sediments on the diagenesis. Alternating zones of high and low magnetic parameters are observed in Unit A2 of Core YSDP103, which is presumably due to periodic changes of the concentration and/or grain size of magnetic minerals carried into the study area. Cores SSDP-102 and SSDP-103, two studied sediment cores from the Korea Strait contain mud sequences (14 m and 32.62 m in thickness) that were deposited during the last 6,000 years. Analyses of grain sizes and geochemistry of the cores have demonstrated that the sediments have uniform lithology and geochemical properties, however, marked down-core changes in magnetic properties suggest that diagenesis has significantly impacted the magnetic properties. An expanded view of early diagenetic reactions that affect magnetic mineral assemblages is evident in these rapidly deposited continental shelf sediments compared to deep-sea sediments. The studied sediments can be divided into four descending intervals, based on magnetic property variations. Interval 1 is least affected by diagenesis and has the highest concentrations of detrital magnetite and hematite, and the lowest solid-phase sulfur contents. Interval 2 is characterized by the presence of paramagnetic pyrite and sharply decreasing magnetite and hematite concentrations, which suggest active reductive dissolution of detrital magnetic minerals, the absolute minimum abundance of magnetite is reached at the end of this interval. Interval 3 is marked by a progressive loss of hematite with depth, and at the base of this interval, 82% to 88% of the hematite component was depleted and the bulk magnetic mineral concentration was reduced to the lowest value in the entire studied mud section. Interval 4 has an increasing down-core enhancement of authigenic greigite, which is interpreted to have formed due to arrested pyritization resulting from consumption of pore water sulfate with depth. This is the first clear demonstration from an active depositional environment for a delay of thousands of years for acquisition of a magnetization carried by greigite. This detailed view of diagenetic processes in continental shelf sediments suggests that studies of geomagnetic field behavior from such sediments should be conducted with care. Paleoceanographic and paleoclimatic studies based on the magnetic properties of shelf sediments with high sedimentation rates like those in the Korea Strait are also unlikely to provide a meaningful signature associated with syn-depositional environmental processes. The rock magnetic properties of the surface sediments from the fine-grained depositional area on the outer shelf of the East China Sea, an area surrounded by sands, are investigated with a view to providing information on the sediment provenance. Multiple magnetic parameters such as magnetic susceptibility (%), anhysteretic remanent magnetization (ARM), saturation rernanent magnetization (SIRM), coercivities of SIRM (Her), and S ratios (relative abundance of low-coercivity magnetic minerals) are measured for all 179 surface samples, and partial representative samples are examined for their magnetic hysteresis parameters, temperature-dependence of magnetic susceptibility and x-ray diffraction spectra. Our research indicates that the magnetic mineralogy is dominated by magnetite with a small amount of hematite and is primarily of pseudo-single domain (PSD) to multidomain (MD) nature with a detrital origin. In the surface sediments, the granulometry of magnetic fractions is basically independent of grain sizes of the sediment containing the magnetic grains, and the composition of magnetic minerals remains almost homogeneous, that is, with a relatively constant ratio of low to high coercivity fraction throughout the area. The magnetic concentration in the study area generally decreases to the east or southeast accompanied by magnetic-particle fining to the east or to the northeast. The geographic pattern of magnetic properties is most reasonably explained by a major source of sediment jointly from the erosion of the old Huanghe River deposit and the discharge of the Changjiang River. The rock magnetic data facilitate understanding of the transport mechanism of fine-grained sediments in the outer shelf of the East China Sea.

矾山杂岩体成因及其与磷（铁）矿的成矿关系

The Fanshan complex consists of layered potassic ultramafic-syenite intrusions. The Fanshan apatite (-magnetite) deposit occurs in the Fanshan complex, and is an important style of phosphorus deposit in China. The Fanshan complex consists of three (First- to Third-) Phases of intrusion, and then the dikes. The First-Phase Intrusive contains ten typical layered rocks: clinopyroxenite, biotite clinopyroxenite, coarse-grained biotite clinopyroxenite, pegmatitic orthoclase-biotite clinopyroxenite, variegated orthoclase clinopyroxenite, interstitial orthoclase clinopyroxenite, biotite rock, biotite-apatite rock, biotite rock and magnetite-apatite rock. This layered intrusive consists of nine rhythmic units. Each rhythmic unit essentially comprises a pair of layers: clinopyroxenite at the bottom and biotite clinopyroxenite at the top. The apatite (-magnetite) deposit is situated near the top of rhythmic Unit no. 6 of the First-Phase Intrusive. The Second-Phase Intrusive contains three typical rocks: coarse-grained orthoclase clinopyroxenite, . coarse-grained salite syenite and schorlomite-salite syenite. The Third-Phase Intrusive includes pseudo-trachytic salite syenite, porphyritic augite syenite, fine-grained orthoclase clinopyroxenite and fine-grained salite syenite. The origin of the Fanshan complex is always paid attention to it in China. Because most layered igneous intrusion in the world not only have important deposit in it, but also carry many useful information for studying the formation of the intrusion and the evolvement of magma. Two sketch maps were drawn through orebodies along no. 25 cross-cut on 425 mL and no. 1 cross-cut on 491 mL in the Fanshan mine. Through this mapping, a small-scaled rhythmic layering (called sub-rhythmic layering in the present study) was newly found at the top of the rhythmic Unit no. 6. The concept of sub-rhythmic layering is defined in this article. The sub-rhythmic layering is recognized throughout this apatite-rich part, except for magnetite-apatite rock. Presence of the layered magnetite-apatite rock is one of the characteristics of the Fanshan apatite (-magnetite) deposit. Thus, from this layer downwards six units of sub-rhythmic layering are recognized in the present study. Each unit consists of biotite clinopyroxenite (or biotite rock and biotite-apatite rock) layer at the bottom and apatite rock layer at the top. To study this feature in detail is an important work for understanding the origin of the Fanshan complex and apatite (-magnetite) deposit. The origin of the Fanshan complex and the relation of the formation of the apatite(-magnetite)deposit will be interpreted by the study of sub-rhythmic layering on the basis of previous research works. The magma formed the Fanshan complex was rich in K2O, early crystallized pyroxene, and after this phase more biotite crystallized, but no amphibole appeared. This indicated that the activity of H2O in the magma was low. Major element compositions of biotite and clinopyroxene (on thin sections) in the sub-rhythmic layering were analyzed using electron microprobe analyzer. The analytical results indicate Mg/(Mg+Fe*+Mn) atomic ratios (Fe*, total iron) of these two minerals rhythmically changed in sub-rhythmic layering. The trends of Mg/(Mg+Fe*+Mn) atomic ratio (Fe*, total iron) of biotite and clinopyroxene indicate that the magma evolved markedly from relatively magnesian bottom layer to less magnesian top layer in each sub-rhythmic unit. A general trend through the sub-rhythmic layering sequence is both minerals becoming relatively magnesian upwards. The formation temperatures for sub-rhythmic layering yield values between 600 and 800 ℃, were calculated using the ratio of Mg/(Mg+Fe+Mn) in the salite and biotite assemblage. The equilibrium pressures in the rhythmic layers calculated using the contents of Al in the salite were plotted in the section map, shown a concave curve. This indicates that the magma formed the First-Phase Intrusive crystallized by two vis-a-vis ways, from its bottom and top to its centre, and the magnetite-apatite rock was crytallized in the latest stage. The values of equilibrium pressures in the sub-rhythmic layering were 3.6-6.8(xlO8) Pa with calculated using the contents of Al in the salite. The characteristics of geochemistry in various intrusive rocks and the rocks or apatite of sub-rhythmic layers indicated that the Fanshan complex formed by the comagmatic crystallization. The contents of immiscible elements and REEs of apatite rock at the top of one sub-rhythmic unit are more than biotite clinopyroxenite at the bottom. The contents of immiscible elements and REEs of apatite of biotite clinopyroxenite at the bottom of one sub-rhythmic unit are higher than apatite rock at the top. The curves of rocks (or apatite) in the upper sub-rhythmic units are between two curves of the below sub-rhythmic unit in the primitive mantle-normalized trace element abundance spider diagram and the primitive mantle-normalized REE pattern. The trend for the contents of immiscible elements and REEs inclines to the same contents from the bottom to the top in sub-rhythmic layering. These characteristics of geochemistry of rocks or apatites from sub-rhythmic layering indicate that the latter sub-rhythmic unit was produced by the residual magma after crystallization of the previous sub-rhythmic unit. The characteristics of petrology, petrochemistry, geochemistry in the Fanshan complex and sub-rhythmic layers and the trends of Mg/(Mg+Fe+Mn) atomic ratio of biotite and clinopyroxene in sub-rhytmic layering rejected the hypotheses, such as magma immiscibility, ravitational settling and multiple and pulse supplement of magma. The hypothesis of differentiation by crystallization lacks of evidences of field and excludes by this study. On the base of the trends of formation temperatures and pressures, the characteristics of petrology, petrochemistry, geochemistry for the Fanshan complex and the characteristics of geochemistry for the rocks (or apatites), the trends of Mg/(Mg+Fe+Mn) atomic ratio of biotite and clinopyroxene in sub-rhytmic layering, and the data of oxygen, hydrogen, strontium and neodymium isotopes, this study suggests that the magma formed the Fanshan complex was formed by low degree partial melting of mantle at a low activity of H2O, and went through the differentiation at the depth of mantle, then multiply intruded and crystallized. The rhythmic layers of the First-Phase Intrusive formed by the magma fractional crystallized in two vis-a-vis ways, from the bottom and top to the centre in-situ fractional crystallization. The apatite (-magnetite) deposit of the Fanshan complex occurs in sub-rhythmic layering sequence. The the origin of the sub-rhythmic layering is substantially the origin of the Fanshan apatite (-magnetite) deposit. The magma formed the rhythmic layers of First-Phase Intrusive was rich in H2O, F and P at the later stage of its in-situ fractional crystallization. The Fanshan apatite (-magnetite) deposit was formed by this residual magma in-situ fractional crystallization. The magnetite-apatite rock was crystallized by two vis-a-vis ways at the latest stage in-situ fractional crystallization in the rhythmic layers. The result was light apatite layer below heavy the magnetite-apatite layer, formed an "inversion" phenomenon.

泥河湾盆地磁性地层学研究——以东谷索和岑家湾剖面为例

The Nihewan Basin is a key area for research into human occupation at high northern latitudes in northeast Asia after the initial expansion of early humans out of Africa. Well-developed late Cenozoic lacustrine deposit sequence in this basin offers a unique opportunity to address this issue. In this thesis, detailed magnetostratigraphic investigation coupled with mineral magnetism was conducted on the Donggutuo and Cenjiawan sections in the eastern basin, where lacustrine deposits sequences containing the Donggutuo, Maliang and Cenjiawan Paleolithic sites are well developed. The sequences are mainly composed of grayish-white clays, grayish-green clayey silts, grayish-yellow silts and fine-grained brown sands, which have recorded reliable polarity variations of geomagnetic field.Characteristics of the anisotropy of magnetic susceptibility show that the sediments have preserved typical original magnetic fabric for sediments, indicating that the strata were developed in a low-energy lake environment and were never perturbed by tectonic stress since deposition. High-temperature magnetic susceptibility measurements (x-T) of representative specimens and demagnetization experiments indicate that the dominant magnetic mineral and remanent carrier at the two sections is magnetite. In addition, hematite and possibly minor maghemite exists in some portions of the sequences. The majority of the samples have relatively simple demagnetization behaviors. After removal of soft magnetic components, the stable characteristic remanent magnetizations (ChRMs) are isolated, which can represent the original remanences.The Donggutuo section mainly records the Brunhes chron, the Matuyama chron and the Jaramillo subchron. The Maliang stone artifact layer occurs just below the Brunhes/Matuyama boundary; and the Donggutuo artifact layer, just below the Jaramillo onset. Accordingly, the Maliang and Donggutuo sites can be dated at about 0.78 Ma and 1.1 Ma, respectively. The Cenjiawan section has recorded a portion of the Matuyama chron. After correlations with the magnetic polarity sequence of the Majuangou section adjacent to this section, the Cenjiawan stone artifact layer is determined below the Jaramillo onset, with an estimated age of 1.1 Ma.To establish the magnetic stratigraphy framework for the lacustrine sediments in the eastern Nihewan Basin, this thesis draws on the magnetic polarity sequences of the Donggutuo and Cenjiawan sections as well as previously obtained results from the Majuangou, Haojiatai, Xiaochangliang and Donggou sections for magnetostratigraphic correlations. The accumulation of the lacustrine sequences at the east margin of the basin commenced from about 2.0 Ma. These sequences record not only the coarse magnetostratigraphy of the Brunhes normal chron and the middle to late Matuyama reverse chron (that is, the Jaramillo and Olduvai subchrons) but also some of the fine structure (that is, the Kamikatsura, Santa Rosa, Punaruu and Cobb Mountain geomagnetic events). The development of the Nihewan paleolake experienced at least twice large expansion periods, split by a large-scale shrinking event in the middle period of the paleolake development. The accumulation of the lacustrine strata was controlled by fault activities.After temporal control for the Donggutuo, Maliang and Cenjiawan Paleolithic sites were established, the three sites along with other well-dated Paleolithic/hominin sites of the Early Pleistocene in North China were combined to construct a chronological sequence of early human occupation in northeastern Asia. Furthermore, after incorporation of paleoclimate changes retrieved from Chinese loess/paleosol sequences and marine sediments, it could be possibly proposed that human groups of the Early Pleistocene in North China might have survived repeated warm/humid interglacials and cold/dry glacials, which were paced by earth orbital variations of the Eastern paleomonsoon.

黄骅坳陷高尘头地区储层非均质性及成藏研究

Gaochentou region is located in the southwest direction of Gaochentou village in Huanghua city of Hebei province. In regionally structural position, It lies in Qikou sag In the middle part of Huanghua depression, which belongs to the east part of the south Dagang structure zone in the middle part of Huanghua depression. Its' very beneficial at regional structure in Gaochentou , and It becomes the advantage area for oil and gas gathered and preserved, Sandstone reservoir of Dongying Formation is main bearing bed .Dongying Formation in Gaochentou region of Huanghua depression is consisted of set of mudstone and sandstone interbeds by deposited delta fades . Dongying Formation can be divided into 3 members from above to below: the first member of Dongying Formation (FMDF), the second member of Dongying Formation (SMDF), and third member of Dongying Formation (TMDF). The lithology of the upper part of FMDF was consisted of mostly middle-grained and fine-grained sandstone, and it is small for the oil-bearing area of the sand bodies .The lithology of the lower part is coarse-grained sandstone bodies which are well connected between sandstone bodies of wells, and the lower part was main bed of oil production in Dongying Formation; SMDF and TMDF are consisted of larger scale set of mudstone, in which the sandbodies are lenticular and pinch out quickly, and the lithology was mostly fine sandstone and silt stone, in which there are little oil and gas .Because the reservoirs in this area are largely influenced by the factors such as lithology, fault and others, and the reservoirs have the strong,heterogeneity , there exists the problem of oil-down and water-up for vertical distribution of oil and gas bearing. It is not very clearly for the three dimension distribution of sandstone , and the geology researchs is not enough. So, it can't satisfy the need of further development and production for Gaochentou oilfield.Having the key problem of oil-down and water-up and the mechanism of the reservoir for Gaochentou area, There are as follow study works, the first, is study of the high-resolution correlation of sequence stratigraphy and sedimentary microfacies. Dongying Formation was divided into three parasequence sets and each parasequence set was divided into different amount of parasequences. FMDF, as the main oil and gas producing bed, can be divided into seven parasequences. Oil and gas are discovered in six parasequences except the seventh. On the basis of study of sedimentary microfacies, the sediments of Dongying Formation are considered deposited mainly in delta front subfacies. The microfacies types of Dongying Formation are sub-water distirbutary channel, sub-water natural bank, inter distributary channel bay, distributary channel mouth dam, and delta front mat sand.Seismic facies analysis and logging-constrained inversion technique were applied by Author for transverse prediction of sandstone reservoir. Having 4 modes of interwell single sandbodies correlation technique, Author have described distribution characteristics of sandbodies, and established geological reservoir model of Gaochentou reservoir.Author presented that the reservoirs characteristic have very strong heterogeneity ,and In the section of sandstone interlayed with mudstone,the folium sandstone interlayed with each other, and the wedge shaped sandbodies pinched out in the mudstone. So the pinch-out up sandstone trap and lenticular sandstone trap are easily formed. They are most small scale overlying pinches out in the place of slope. This article applies the concept of deep basin oil to resolve reasonably the problem of which the oil is below the water in Gaochentou area. Combined with the study of sedimentary facies, reservoir and other aspects, the mechanism and patterns of deep basin oil are studied on the basis of characteristics in Gaochentou area.On the basis of the above study, the mechanism of the oil and gas' migration and accumulation in isotropic sandstone and heterogeneous sandstone are thoroughly analyzed through experiments on physical modeling. Experiments on physical modeling show that the discrepancy between sand layers with different permeability and thickness has important influence on the direction, path, and injection layer of oil's migration. At the beginning of the injection of oil and gas in high permeability sand layer, the pressure is low, the migration resistance is small, and the oil and gas are more easily displacing the water in sand. So it can act as good transformation layer or reservoir. But at the beginning of the injection of oil and gas in sand layer with low permeability, the pressure is high, the migration resistance is big, and the oil and gas are more difficultly displacing the water in sand. So it can only act as bad or worse transformation layer or reservoir. Even if it cannot act as transformation layer or reservoir, it can act as water layer or dry layer. The discrepancy between sand layers on permeability and thickness can make discrepancy in injection of oil and gas between different layers. Consequently it leads to small amount of oil and gas injection in sand layers with low permeability. Ultimately it affects the oil's accumulation and distribution in different sand layers.At Last, combining analysis of the structure and pool forming condition, The thesis has established models of reservoir formation to predict the advantage distribution of oil and gas bearing , and put forward the prospective target It is not only of theoretical signification for explosion and importance, but also has realistic value in guiding the progressive petroleum exploration and exploitation.

克拉2异常高压气藏地质特征及开发技术研究

Kela-2 gas field in Tarim Basin is the main supply source for West-to-East Pipeline project, also the largest abnormally-pressured gas field discovered in China currently. The geological characterization, fine geological modeling and field development plan are all the world-class difficult problems. This work includes an integrated geological and gas reservoir engineering study using advanced technology and approaches, the scientific development plan of Kela-2 gas field as well as the optimizations of the drilling, production and surface schemes. Then, it's expected that the Kela-2 gas field can be developed high-efficiently.Kuche depression is one part of the thrust belt of the South Tianshan Mountains, Kela-2 field is located at the Kelasu structural zone in the north of Kuche depression. The field territory is heavily rugged with deeply cut gullies, complex geological underground structure, variable rock types, thrust structure development. Therefore, considerable efforts have been made to develop an integrated technique to acquire, process and interpret the seismic data in complicated mountain region. Consequently a set of seismic-related techniques in the complicated mountain region has been developed and successfully utilized to interpret the structure of Kela-2 gas field.The main reservoir depositional system of Kela 2 gas field is a platform - fan delta - braided river system. The reservoir rocks are medium-fine and extremely fine grained sandstones with high structure maturity and low composition maturity. The pore system structure is featured by medium-small pore, medium-fine throat and medium-low assortment. The reservoir of Kela-2 gas field is characteristic of medium porosity and medium permeability. The pay zone is very thick and its lateral distribution is stable with a good connection of sand body. The overpressure is caused mainly by the strongly tectonic squash activities, and other factors including the later rapid raise and compartment of the high-pressure fluid, the injection of high-pressure fluid into the reservoir.Based on the deliverability tests available, the average binomial deliverability equation is provided applicable for the overall field. The experimental results of rock stress-sensitive tests are employed to analyze the change trend of petrophysical properties against net confining stress, and establish the stress-based average deliverability equation. The results demonstrate the effect of rock deformation on the deliverability is limited to less than 5% in the early period of Kela-2 gas field, indicating the insignificant effect on deliverability of rock deformation.In terms of the well pattern comparisons and development planning optimizations, it is recommended that the producers should be located almost linearly along the structural axis. A total of 9 producers have a stable gas supply volume of 10.76 BCMPY for 17 years. For Kela-2 gas field the total construction investment is estimated at ￥7,697,690,000 RMB with the internal earning rate of 25.02% after taxation, the net present value of ￥7,420,160,000 RMB and the payback period of 5.66 years. The high profits of this field development project are much satisfactory.

黄土高原全新世风成沉积的岩石磁学性质

Chinese eolian deposits are especially suitable for the studies of paleoclimatic changes, environmental magnetism and remanence acquisition mechanisms. In the past two decades, many studies have documented their magnetic properties. However, some important problems, such as the origin of magnetic minerals, the mechanisms for enhancing magnetic susceptibility and the lock-in effect, remain debatable. Therefore, it is essential to detail the rock-magnetic properties of the eolian deposits. This study shows thermomagnetic analyses, petrographic measurements and soil chemistry methods can be combined to obtain a better understanding of the sequence of magnetic mineral alterations during thermal treatment and of the pedogenic mechanism responsible for the susceptibility enhancement. This helps to further develop the interpretation of paleoclimate records in the Holocene eolian deposits along a NW-SE transect of the loess plateau. A partial heating/cooling method and X-ray diffraction (XRD) analysis were performed on representative samples of the present-day loess, in order to investigate mineralogical changes during thermal treatment. The temperature-dependent susceptibility (TDS) and XRD results show complex alteration of magnetic phases during heating and cooling. The 300 ℃ susceptibility hump in heating curves might be due to the production of maghemite from less magnetic lepidocrocite during heating. Goethite is transformed into hematite when heating to above 300 ℃. The susceptibility decrease from 300 ℃ to 450 ℃ can be interpreted as the conversion of maghemite to hematite. This thermal instability makes it possible to quantatively estimate the maghemite contribution to the pedogenically-enhanced susceptibility in loess or paleosols. Minor occurrence of thermally-stable maghemite in the present-day loess is possible; nevertheless, the TDS measurements show that the degree of the thermally-induced alteration is closely related to pedogenesis. The TDS measurement and XRD analysis results demonstrate that although magnetite and hematite both exist in the Holocene loess eolian deposits and their modern source area, magnetite is the predominant contributor to magnetic susceptibility. Both magnetite and hematite are the primary carriers of the remanent magnetization. Fine-grained maghemite, mainly produced by pedogenesis, is significantly responsible for enhancement of the magnetic susceptibility in the Chinese loess and paleosols. Since the degree of oxidation of magnetite grains depends on climate, the presence of maghemite has paleoclimatic significance, and variations in climate could be reflected as variations in the amount of low-temperature oxidation. If that is the case, the TDS curves can be used to compare the effects of climate at different sampling sites. The TDS results along the studied NW-SE transect suggest that stronger pedogenesis results in higher content of maghemite and greater susceptibility decrease during thermal treatment. This behavior seems to indicate that the final product of pedogenic magnetite in Chinese loess and paleosols is maghemite, which makes significant contributions to the enhanced magnetic susceptibility of Chinese eolian deposits. It is interesting to note that the 510 ℃ Hopkinson/alteration peak is larger in the present-day loess than in the black loam for each section. Obiviously, the Hopkinson/alteration peak of the Holocene eolian deposits is closely related to the degree of pedogenesis, which is a function of climate, and thus the peak itself could be a useful climate indicator. There are three effects that may be important in producing this trend. First, low-temperature oxidation preferentially affects the finer single-domain magnetites responsible for the Hopkinson peak, which is therefore suppressed in the more oxidized loams. Second, the possible production of uniaxial magnetite with shape anisotropy can also lead to a relatively muted Hopkinson peak. There is, additionally, a third alternative, and the one preferred here, that the natural alteration processes involved in pedogenic susceptibility enhancement have probably depleted the supply of iron-bearing precursor phases, so that less new magnetite is formed on heating. In summary, the TDS method is very reliable and highly sensitive in detecting magnetic phase changes in eolian deposits during thermal treatment, which are closely related to pedogenic processes. Thus, the studied NW-SE transect clearly exhibits paleoclimatically-induced mineral- and rock-magnetic variations. It is suggested that TDS can be used as a new method for the analysis of pedogenesis and climatic change.

Microstructure and Evolution of Mechanically-Induced Ultrafine Grain in Surface Layer of Al-Alloy Subjected to USSP

Experiments were conducted to investigate the ultrafine-grained (UFG) microstructures in the surface layer of an aluminum alloy 7075 heavily worked by ultrasonic shot peening. Conventional and high-resolution electron microscopy was performed at various depths of the deformed layer. Results showed that UFG structures were introdued into the surface layer of 62 μm thick. With increasing strain, the various microstructural features, e.g., the dislocation emission source, elongated microbands, dislocation cells, dislocation cell blocks, equiaxed submicro-, and nano-crystal grains etc., were successively produced. The grain subdivision into the subgrains was found to be the main mechanism responsible for grain refinement. The simultaneous evolution of high boundary misorientations was ascribed to the subgrain boundary rotation for accommodating further strains. Formed microstructures were highly nonequilibratory.  2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.

Microstructure Study Of Laser Welding Cast Nickel-Based Superalloy K418

Experiments of laser welding cast nickel-based superalloy K418 were conducted. Microstructure of the welded seam was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectrometer (EDS). Mechanical properties of the welded seam were evaluated by microhardness. The corresponding mechanisms were discussed in detail. Results show that the laser welded seam have non-equilibrium solidified microstructures consisting of Cr-Ni-Fe-C austenite solid solution dendrites as the dominant and some fine and dispersed Ni-3(Al,Ti) gamma' phase as well as little amount of MC needle carbides and particles enriched in Nb, Ti and Mo distributed in the interdendritic regions, cracks originated from the liquation of the low melting points eutectics in the HAZ grain boundary are observed, the average microhardness of the welded seam and HAZ is higher than that of the base metal due to alloy elements' redistribution of the strengthening phase gamma'. (C) 2008 Elsevier B.V. All rights reserved.

Microstructure of shear localization in low-carbon ferrite pearlite steel

A study has been made of the microstructure of the thermally assisted band in a low carbon ferrite-pearlite steel, resulting from high speed torsional testing with an average strain rate of about 1500 s−1. Metallographic examination showed that there are several fine shear bands distributed over a deformed region (the gauge length of the specimen). The width of these bands is estimated to be of the order of magnitude of 50 μm, and the spacing between them is roughly about 100 μm. Detailed scanning electron microscopy studies indicate that damage of the microstructure within the band is very apparent, as evidenced by microcrack initiation and coalescence along the shear deformation band. However, there is no evidence that the material in the band had become microcrystalline or non-crystalline.

Investigation on microstructure and optical properties of titanium dioxide coatings annealed at various temperature

TiO2 coatings were prepared on fused silica with conventional electron beam evaporation deposition. After TiO2 thin films were annealed at different temperatures for 4 h, several properties were investigated by X-ray diffraction (XRD), spectrometer.. photoelectron spectroscopy (XPS) and AFM. It was found that with the annealing temperature increasing, the transmittance of TiO2 coatings decreased, and the cutoff wavelength shifted to long wavelength in near ultraviolet band. Especially, when coatings were annealed at high temperature, the optical loss is very serious, which can be attributed to the scattering and the absorption of TiO2 coatings. XRD patterns revealed that only anatase phase was observed in TiO2 coatings regardless of the different annealing temperatures. XPS results indicated that the fine chemical shift of TiO2 2p(1/2) should be attributed to existence of oxygen vacancies around Ti+4 ion. The investigation on surface morphology by AFM showed that the RMS of titania thin films gradually increases from less than 0.40 nm to 5.03 nm and it should be ascribed to the growth of titanium dioxide grain size with the increase of annealing temperature. (C) 2005 Elsevier B.V. All rights reserved.

Influence of processing temperature on microstructure and microhardness of copper subjected to high-pressure torsion

Cu samples were subjected to high-pressure torsion (HPT) with up to 6 turns at room temperature (RT) and liquid nitrogen temperature (LNT), respectively. The effects of temperature on grain refinement and microhardness variation were investigated. For the samples after HPT processing at RT, the grain size reduced from 43 mu m to 265 nm, and the Vickers microhardness increased from HV52 to HV140. However, for the samples after HPT processing at LNT, the value of microhardness reached its maximum of HV150 near the center of the sample and it decreased to HV80 at the periphery region. Microstructure observations revealed that HPT straining at LNT induced lamellar structures with thickness less than 100 nm appearing near the central region of the sample, but further deformation induced an inhomogeneous distribution of grain sizes, with submicrometer-sized grains embedded inside micrometer-sized grains. The submicrometer-sized grains with high dislocation density indicated their nonequilibrium nature. On the contrary, the micrometer-sized grains were nearly free of dislocation, without obvious deformation trace remaining in them. These images demonstrated that the appearance of micrometer-sized grains is the result of abnormal grain growth of the deformed fine grains.

Microstructure and mechanical properties of Mg–12.3Zn–5.8Y–1.4Al alloy

Microstructure and mechanical properties of as-cast and heat-treated Mg–12.3Zn–5.8Y–1.4Al (ZYA1261) alloy were investigated. The phase compositions of the as-cast alloy are -Mg, Mg3YZn6 (I-phase), Mg3Y2Zn3 (W-phase), Mg12YZn (Z-phase), Mg24Y5, MgZn and a small quantity of Al-containing phase. The phase compositions change with various heat treatment conditions. The highest Vickers hardness is obtained in the alloy aged at 200 ◦C for 5 h, the transmission electron microscopy indicated that fine scale Z-phase precipitates in the matrix. The tensile properties of the as-cast and heat-treated alloys were reported.