90 resultados para Puzzle difficulty
Resumo:
The oil and gas potential of Northeast Asia is enormous, but the degree of exploration is very low in Northeast Asia (the degree is below 3%-10%).The reasons are as follows: First, it is relatively difficult to study the oil and gas bearing basins(OGB), which are of multiple types, in different tectonic settings, with complex geologic frameworks and with long-term geologic evolution. Secondly, because of the non-equilibrium in development of economy and regional market, application of theories and techniques and the research levels in different countries, the conclusions are not conformable, and even contradictory. Thirdly, most of the former researches were limited to one territory or one basin, and lack of systematical and in-depth study on geotectonic evolution, classification of basins, and the evaluation of hydrocarbon resources. In this thesis, integrated study of the regional tectonic feature and basin features of Northeast Asia was done, to understand the basin evolution history and the controlling action on oil and gas. Then, new conclusions are and exploration proposals are as following: 1. Geotectonic evolution in Northeast Asia: The main structural motion system in Paleozoic Era was longitudinal, and in Meso-cenozoic was latitudinal with the Pacific Ocean. The whole evolution history was just the one of pulling-apart, cutting-out, underthrusting and collision of the Central Asia- Mongolia Ocean and the Pacific Ocean. 2. The evolution characteristics of basins in Northeast Asia: mainly developed from longitudinal paste-up, collision and relaxation rifting motion in Paleozoic-Early Mesozoic Era and from underthrust, accretion, and receding of subducted zone of the Pacific Ocean in Late Mesozoic Era-Cenozoic Era. 3. The research in basin classification of Northeast Asia: According to geotectonic system, the basins can be classified into three types: intracratonic, pericratonic and active zone basin. And they can be further classified into 18 different types according to genetic mechanism and dynamic features. 4. The master control factors of oil and gas accumulation in Northeast Asia: high quality cap-rock for craton and pericrationic basin, the effective source rock and high quality cap-rock for Mesozoic rifted basins, intra-arc, fore-arc and back-arc basins. Graded exploration potential of oil and gas for basin in Northeast Asia according to 7 factor, hereby, divided the oil and gas potential of basins into 5 levels. 5. Evaluation of hydrocarbon resources: The difference of resource potential among these basins is huge in Northeast Asia. The evaluation of Mesozoic rifted basin and Pacific Ocean basin showed that the large scale rifted basin and retroarc basin(including backarc marginal sea basin) have great resource potential. 6. The writer believes that the next step should pay more attention to the evaluation of petroleum resource in Far East part of Russia and trace them. On the other hand, according to integrated analysis of oil/gas resource potential and the operation difficulty in this area, suggests that East-Siberia basin, East-Gobi-Tamchag basin, Sakhalin basin, North-Okhotck basin, West-Kamchatka basin could be as cooperation priority basins in future.
Resumo:
Today, because of high petroleum consumption of our country, society steady development and difficulty increase in new resources exploration, deep exploitation of the existing oilfield is needed. More delicate reservoir imaging and description, such as thin layer identification, interlayer exploitation monitoring, subtle structure imaging, reservoir anisotropy recognition, can provide more detail evidence for new development adjustment scheme and enhanced oil recovery. Now, the people have already realized the 3D VSP technique more effective than the general methods in solving these aspects. But VSP technique especially 3D VSP develop slowly due to some reasons. Carrying out the research of VSP technique, it will be very useful to the EOR service. 3D VSP techniques include acquisition、data processing and interpretation. In this paper, the author carried out some researches around acquisition and processing. The key point of acquisition is the survey design, it is critical to the quality of the data and it will influence the reservoir recognition as follows. The author did detailed researches on the layout pattern of shot point and geophone. Some attributes relate to survey design such as reflectivity, incidence angle, observation area, reflection points distribution, fold, minimum well source distance, azimuth angle and so on are studied seriously. In this geometry design of 3D-VSP exploration in deviated wells, the main problems to be solved are: determining the center position of shots distribution, the effect of shots missing on coverage areas and coverage times,locating the shots and receivers of multi-wells. Through simulating and analyzing, the above problems are discussed and some beneficial conclusions are drawn. These will provide valuable references to actual survey design. In data processing, researches emphasize on those relatively key techniques such as wavefield separation, VSP-CDP imaging, the author carried out deep researches around these two aspects. As a result, variant apparent slowness wavefield separation method developed in this article suit the underground variant velocity field and make wavefield separation well, it can overcome reflection bending shortage aroused by conventional imaging method. The attenuateion range of underground seismic wave is very important for amplitude compensation and oil/gas identification.In this paper, seismic wave attenuateion mechanism is studied by 3D-VSP simulateion and Q-inversion technique. By testing with seismic data, the method of VSP data attenuateion and relationship of attenuateion attribute variant with depth is researched. Also the software of survey design and data processing is developed, it fill the gap of VSP area in our country. The technique developed applied successfully in SZXX-A Oilfield、QKYY-B Oilfield、A area and B area. The good results show that this research is valuable, and it is meaningful to the VSP technique development and application of offshore oil industry and other areas in our country.
Resumo:
Compared with the conventional P wave, multi-component seismic data can markedly provide more information, thus improve the quality of reservoir evaluation like formation evaluation etc. With PS wave, better imaging result can be obtained especially in areas involved with gas chimney and high velocity formation. However, the signal-to-noise of multi-component seismic data is normally lower than that of the conventional P wave seismic data, while the frequency range of converted wave is always close to that of the surface wave which adds to the difficulty of removing surface wave. To realize common reflection point data stacking from extracted common conversion point data is a hard nut to crack. The s wave static correction of common receiver point PS wave data is not easy neither. In a word, the processing of multi-component seismic data is more complicated than P wave data. This paper shows some work that has been done, addressing those problems mentioned above. (1) Based on the AVO feature of converted wave, this paper has realized the velocity spectrum of converted waves by using Sarkar’s generalized semblance method taking into account of AVO factor in velocity analysis. (2)We achieve a method of smoothly offset division normal method.Firstly we scan the stacking velocities in different offset divisions for a t0, secondly obtain some hyperbolas using these stacking velocities, then get the travel time for every trace using these hyperbolas; in the end we interpolate the normal move out between two t0 for every trace. (3) Here realize a method of stepwise offset division normal moveout.It is similar to the method of smoothly offset division normal moveout.The main difference is using quadratic curve, sixth order curve or fraction curve to fit these hyperbolas. (4)In this paper, 4 types of travel time versus distance functions in inhomogeneous media whose velocity or slowness varies with depth and vertical travel time have been discussed and used to approximate reflection travel time. The errors of ray path and travel time based on those functions in four layered models were analyzed, and it has shown that effective results of NMO in synthetic or real data can be obtained. (5) The velocity model of converted PS-wave can be considered as that of P -wave based on the ghost source theory, thus the converted wave travel time can be approximated by calculation from 4 equivalent velocity functions: velocity or slowness vary linearly with depth or vertical travel time. Then combining with P wave velocity analysis, the converted wave data can be corrected directly to the P-wave vertical travel time. The improvements were shown in Normal Move out of converted waves with numerical examples and real data. (6) This paper introduces the methods to compute conversion point location in vertical inhomogeneous media based on linear functions of velocity or slowness versus depth or vertical travel time, and introduce three ways to choose appropriate equivalent velocity methods, which are velocity fitting, travel time approximation and semblance coefficient methods.
Resumo:
Sandstone-type uranium deposits are frequently found close to oil fields or uraniferous sandstones contain bitumen or petroleum. However, few evidence has been presented to indicate the association of uranium mineralization with petroleum oxidation. Thus, Dongsheng uranium deposit in Ordos Basin and Qianjiadian deposit in Kailu Basin are taken for examples to solve the puzzle. Integration data from sedimentary petrology, mineralogy, race elements geochemistry, isotope geochemistry and organic geochemistry, the uranium and petroleum sources, and diagenetic paragenesis of the host sandstone are analyzed, and then the genetic relationship between microbes, petroleum and uranium deposits are discussed. The observation under microscope shows that the host sandstone samples from Middle Jurassic Zhiluo Formation in the Dongsheng deposit contained different kinds of metamorphic rock fragments, which should have been derived form outcrops north to this basin. The LREE/HREE ratios of gneiss and amphibolite sampled from outcrops were close to the highest and the lowest LREE/HREE ratios of the sandstones with well-compared chondrite-normalized REE patterns, respectively. So these results consistently indicated that parent rocks of sandstones were mainly contributed from these two kinds of metamorphic rocks. There was very high Th/U ratio for granite gneiss, which was a mainly potential U resource. Hydrocarbon inclusions and adsorbed hydrocarbons are observed under fluorescence microscope in the host sandstone of Dongsheng uranium deposit, suggesting that the sandstones may have been utilized as oil migration pathways. Based on biomarker parameters, it is indicated that the inclusion oils and adsorbed hydrocarbons were marginally mature to mature, and were derived from humic-sapropel type organic matter under poor reducing freshwater to semi-saline environment. The features are similar to those of organic matter extracted from Triassic sandstone and source rock, but are different from that of cretaceous sandstone. Thus, it can be concluded that the inclusion oils and adsorbed hydrocarbons were mainly derived from Triassic lacustrine facies source rock. Observation results under Scanning Electron Microscopy and Electron Microprobe with Energy Spectrum Analysis show that, in Dongsheng area, the main uranium ore mineral is coffinite. The coffinite is intimately intergrown or coexists with pyrite and calcite, thus, the solution during mineralization stage is inferred to be alkaline. The alkaline environment is not favored for uranium to be pre-concentrated by absorption, and then be reduced abiogenetically. δ34S of pyrite and δ13C of calcite indicate that pyrite was formed by bacterial sulfate reduction (BSR) and part of the carbon of calcite has been dirived from oxidation of petroleum, respectively. Additionally, petroleum is found biodegraded. All the lines of evidence consistently indicate that petroleum was involved in uranium mineralization. Coffinite with microbe-like structures is found in the high U sandstone samples and is composed of nanoparticles, indicating the coffinite is biogenic. The conclusion are also supportted by laboratory experiment studies, which have shown that SRB are capable of utilizing U(VI) as the preferred electron acceptor for respiration and reduce U(VI) to U(IV) directly, coupled the oxidaton of organic matter and sulfate reduction. Based on the research results mentioned above, in the Dongsheng area, coffinite is likely to have formed by mixing of brine containing petroleum derived from Triassic with uranium-bearing meteoric water from outcrops north to Ordos Basin. SRB utilize hydrocarbon as carbon source, and directly reduce U(VI) resulting in precipitation of coffinite. The product of metabolism, H2S and CO2, was precipitated as pyrite and calcite during mineralization stage. Petroleum in fluid inclusions and adsorbed type in host sandstone from Lower Cretaceous Yaojia Formation in Qianjiadian uranium deposit, Kailu Basin, are derived from Jurassic Jiufotang Formation in this basin and the uranium mineral consists mainly of pitchblende. The δ34S and δ13C values of pyrite and calcite during mineralization stage indicate SRB have likely degraded petroleum, which is similar to that of Dongsheng deposit. The alkaline environment as indicated by the diagenetic mineral assemblage calcite, Fe dolomite, pyrite and pitchblende deposit suggests that U ore in the Qiangjiajiadian has a similar origin, i.e., direct reduction by SRB. However, less part of pitchblende is intergrown with kaolinite, suggesting the solution during mineralization stage is acidic. The environment is favorable for U(VI) to be adsorded on quartz or other mineral, and then reduced by H2S produced by SRB. Thus, it can be concluded that U(VI) reduction with petroleum oxidation by SRB and other microbes is an important ore-forming mechanism in petroleum-related sandstone-type uranium deposits. The finding is significant in that it provides a theoretical basis for exploration of both uranium and petroleumr.
Resumo:
Aiming at solving the seismic imaging difficulty in complex area, the static correction methods and the migration imaging techniques taking the anisotropy into account are studied in this dissertation. To solve the static correction problems, a new tomography inversion approach is presented which takes use of the apparent slowness and apparent velocity and inverts both head and diving waves over the complete offset ranges. This approach is also taken practice to the practical seismic data processing of south areas of China and gets ideal effects. There are obvious differences between the actual statics and the statics based on the surface consistency hypothesis. In this dissertation, the exact differences formula is derived. The wave-eqation datuming method based on a single shot gather and the hybrid zero-offset wave-equation datuming algorithm based on f-x domain and f-k domain are presented at the same time. Further more, some forward modelings are made and tested. These methods are also put into practical seismic data processing and good results are made. In this dissertation, the true amplitude Kirchhoff pre-stack time migration fomula in VTI media is presented. The high-dense bispectral scanning technique based on the anelliptical time-shifted hyperbola and the geostatistical filtering are adopted to extract the anellipticity parameter. Simultaneously, combined with the practical seismic data imaging, the anisotropic pre-stack time migration flow is proposed and good processing results are made.
Resumo:
In research field of oil geophysical prospecting, reservoir prediction is refers to forecasting physical properties of petroleum reservoir by using data of seismic and well logging, it is a research which can guide oil field development. Singularities of seismic and logging data are caused by the heterogeneity of reservoir physical property. It's one of important methods that using singularity characteristics of seismic and logging data to study the reservoir physical property in recently. Among them, realization of reservoir quantitative prediction by analyzing singularity of the data and enhancing transition description of data is difficulty in method research. Based on wavelet transform and the fractal theory, the paper studied the singularity judgment criterion for seismic and logging data, not only analyzed quantitative relation between singularity data and reservoir physical property, but also applied it in practical reservoir prediction. The main achievements are: 1. A new method which provides singular points and their strength information estimation at only one single scale is proposed by Herrmann (1999). Based on that, the dissertation proposed modified algorithm which realized singularity polarity detection. 2. The dissertation introduced onset function to generalize the traditional geologic boundaries variations model which used singularity characteristics to represent the abruptness of the lithologic velocity transition. We show that singularity analysis reveals generic singularity information conducted from velocity or acoustic impedance to seismogram based on the convolution seismic-model theory. Theory and applications indicated that singularity information calculated from seismic data was a natural attribute for delineating stratigraphy boundaries due to its excellent ability in detecting detailed geologic features. We demonstrated that singularity analysis was a powerful tool to delineate stratigraphy boundaries and inverse acoustic impedance and velocity. 3. The geologic significances of logging data singularity information were also presented. According to our analysis, the positions of singularities indicate the sequence stratigraphic boundary, and there is subtle relationship between the singularity strength and sedimentary environment, meanwhile the singularity polarity used to recognize stratigraphic base-level cycle. Based on all those above, a new method which provided sedimentary cycle analysis based on the singularity information of logging data in multiple scales was proposed in this dissertation. This method provided a quantitative tool for judging interface of stratum sequence and achieved good results in the actual application.
Resumo:
Seismic technique is in the leading position for discovering oil and gas trap and searching for reserves throughout the course of oil and gas exploration. It needs high quality of seismic processed data, not only required exact spatial position, but also the true information of amplitude and AVO attribute and velocity. Acquisition footprint has an impact on highly precision and best quality of imaging and analysis of AVO attribute and velocity. Acquisition footprint is a new conception of describing seismic noise in 3-D exploration. It is not easy to understand the acquisition footprint. This paper begins with forward modeling seismic data from the simple sound wave model, then processes it and discusses the cause for producing the acquisition footprint. It agreed that the recording geometry is the main cause which leads to the distribution asymmetry of coverage and offset and azimuth in different grid cells. It summarizes the characters and description methods and analysis acquisition footprint’s influence on data geology interpretation and the analysis of seismic attribute and velocity. The data reconstruct based on Fourier transform is the main method at present for non uniform data interpolation and extrapolate, but this method always is an inverse problem with bad condition. Tikhonov regularization strategy which includes a priori information on class of solution in search can reduce the computation difficulty duo to discrete kernel condition disadvantage and scarcity of the number of observations. The method is quiet statistical, which does not require the selection of regularization parameter; and hence it has appropriate inversion coefficient. The result of programming and tentat-ive calculation verifies the acquisition footprint can be removed through prestack data reconstruct. This paper applies migration to the processing method of removing the acquisition footprint. The fundamental principle and algorithms are surveyed, seismic traces are weighted according to the area which occupied by seismic trace in different source-receiver distances. Adopting grid method in stead of accounting the area of Voroni map can reduce difficulty of calculation the weight. The result of processing the model data and actual seismic demonstrate, incorporating a weighting scheme based on the relative area that is associated with each input trace with respect to its neighbors acts to minimize the artifacts caused by irregular acquisition geometry.
Resumo:
The unsaturated expansive soil is a hotspot and difficulty in soil mechanics inland and outland. The expansive soil in our China is one of the widest in distributing and greatest in area, and the disaster of expansive soil happens continually as a result. The soil mechanics test, monitor, numerical simulation and engineering practice are used to research swell and shrinkage characteristic, edge strength characteristic and unsaturated strength characteristic of Mengzi expansive soil. The seep and stability of the slope for expansive soil associated with fissure are analyzed and two kinds of new technique are put forward to be used in expansive soil area, based on disaster mechnics proposed of the slope.The technique of reinforcement in road embankment is optimized also. Associated with engineering geology research of Mengzi expansive soil, mineral composition, chemical composition, specific area and cation content, dissolubility salt and agglutinate, microcosmic fabric characteristic, cause of formation and atmosphere effect depth are analyzed to explain the intrinsic cause and essence of swell and shrinkage for expansive soil. The rule between swell-shrinkage and initial state, namely initial water content, initial dry density and initial pressure, can be used to construction control. Does Response model is fit to simulate the rule, based on ternary regression analysis. It has great meaning to expansive soil engineering in area with salt or alkali. The mechanics under CD, CU and GCU of expansive soil is researched by edge surface theory to explain the remarkable effect of consolidation pressure, initial dry density, initial water content, cut velocity, drainage and reinforcement to the edge strength characteristic. The infirm hardening stress strain curves can be fitted with hyperbola model and the infirm softening curves can be fitted with exponential model. The normalization theory can be used to reveal the intrinsic unity of the otherness which is brought by different methods to the shear strength of the same kinds of samples. The unsaturated strain softening characteristic and strength envelope of remolding samples are researched by triaxial shear test based on suction controlled, the result of which is simulated by exponential function. The strength parameters of the unsaturated samples are obtained to be used in the unsaturated seep associated with rainfall. The elasticity and plasticity characters of expansive soil are researched to attain the model parameters by using modified G-A model. The humidification destroy characteristic of expansive soil is discussed to research the disaster mechanism of the slope with the back pressure increasing and suction decreasing under bias pressure consolidation. The indoor and outdoor SWCCs are measured to research the effect factors and the rule between different stress and filling environment. The moisture absorption curves can express the relationship between suction and water content in locale. The SWCCs of Mengzi expansive soil are measured by GDS stress path trixial system. The unsaturated infiltration function is gained to research seep and stability of the slope of expansive soil. The rainfall infiltration and ability of slope considering multifarious factors are studied by analyzing fissure cause of Mengzi expansive soil. The mechanism of the slope disaster is brought forward by the double controlling effect between suction and fissure. Two new kinds of technique are put forward to resolve disaster of expansive soil and the technique of reinforcement on embankment is optimized, which gives a useful help to solving engineering trouble.
Resumo:
The real earth is far away from an ideal elastic ball. The movement of structures or fluid and scattering of thin-layer would inevitably affect seismic wave propagation, which is demonstrated mainly as energy nongeometrical attenuation. Today, most of theoretical researches and applications take the assumption that all media studied are fully elastic. Ignoring the viscoelastic property would, in some circumstances, lead to amplitude and phase distortion, which will indirectly affect extraction of traveltime and waveform we use in imaging and inversion. In order to investigate the response of seismic wave propagation and improve the imaging and inversion quality in complex media, we need not only consider into attenuation of the real media but also implement it by means of efficient numerical methods and imaging techniques. As for numerical modeling, most widely used methods, such as finite difference, finite element and pseudospectral algorithms, have difficulty in dealing with problem of simultaneously improving accuracy and efficiency in computation. To partially overcome this difficulty, this paper devises a matrix differentiator method and an optimal convolutional differentiator method based on staggered-grid Fourier pseudospectral differentiation, and a staggered-grid optimal Shannon singular kernel convolutional differentiator by function distribution theory, which then are used to study seismic wave propagation in viscoelastic media. Results through comparisons and accuracy analysis demonstrate that optimal convolutional differentiator methods can solve well the incompatibility between accuracy and efficiency, and are almost twice more accurate than the same-length finite difference. They can efficiently reduce dispersion and provide high-precision waveform data. On the basis of frequency-domain wavefield modeling, we discuss how to directly solve linear equations and point out that when compared to the time-domain methods, frequency-domain methods would be more convenient to handle the multi-source problem and be much easier to incorporate medium attenuation. We also prove the equivalence of the time- and frequency-domain methods by using numerical tests when assumptions with non-relaxation modulus and quality factor are made, and analyze the reason that causes waveform difference. In frequency-domain waveform inversion, experiments have been conducted with transmission, crosshole and reflection data. By using the relation between media scales and characteristic frequencies, we analyze the capacity of the frequency-domain sequential inversion method in anti-noising and dealing with non-uniqueness of nonlinear optimization. In crosshole experiments, we find the main sources of inversion error and figure out how incorrect quality factor would affect inverted results. When dealing with surface reflection data, several frequencies have been chosen with optimal frequency selection strategy, with which we use to carry out sequential and simultaneous inversions to verify how important low frequency data are to the inverted results and the functionality of simultaneous inversion in anti-noising. Finally, I come with some conclusions about the whole work I have done in this dissertation and discuss detailly the existing and would-be problems in it. I also point out the possible directions and theories we should go and deepen, which, to some extent, would provide a helpful reference to researchers who are interested in seismic wave propagation and imaging in complex media.
Resumo:
Rock mass is widely recognized as a kind of geologic body which consists of rock blocks and discontinuities. The deformation and failure of rock mass is not only determined by rock block,but also by discontinuity which is virtually more important. Mutual cutting and combination of discontinuities controlled mechanical property of rock mass. The complex cutting of discontinuities determine the intense anisotropy on mechanical property of rock mass,especially under the effect of ground stress. Engineering practice has show that the brittle failure of hard rock always occurs when its working stress is far lower than the yield strength and compressive strength,the failure always directly related to the fracture propagation of discontinuities. Fracture propagation of discontinuities is the virtue of hard rock’s failure. We can research the rock mass discontinuous mechanical properties precisely by the methods of statistical analysis of discontinuities and Fracture Mechanics. According to Superposition Principle in Fracture Mechanics,A Problem or C Problem could be chosen to research. Problem A mainly calculates the crack-tip stress field and displacement field on internal discontinuities by numerical method. Problem C calculate the crack-tip stress field and displacement field under the assumption of that the mainly rock mass stress field has been known. So the Problem C avoid the complex mutual interference of stress fields of discontinuities,which is called crack system problem in Fracture Mechanics. To solve Problem C, field test on stress field in the rock mass is needed. The linear Superposition of discontinuities strain energies are Scientific and Rational. The difference of Fracture Mechanics between rock mass and other materials can mostly expression as:other materials Fracture Mechanics mostly face the problem A,and can’t avoid multi-crack puzzle, while the Rock mass Fracture Mechanics answer to the Problem C. Problem C can avoid multi-discontinuities mutual interference puzzle via the ground stress test. On the basis of Problem C, Fracture Mechanics could be used conveniently in rock mass. The rock mass statistics fracture constitutive relations, which introduced in this article, are based on the Problem C and the Discontinuity Strain Energy linear superposition. This constitutive relation has several merits: first, it is physical constitutive relation rather than empirical; second, it is very fit to describe the rock mass anisotropy properties; third, it elaborates the exogenous factors such as ground stress. The rock mass statistics fracture constitutive relation is the available approach to answer to the physical, anisotropic and ground stress impacted rock mass problems. This article stand on the foundation of predecessor’s statistics fractures constitutive relation, and improved the discontinuity distributive function. This article had derived the limitation of negative exponential distribution in the course of regression analysis, and advocated to using the two parameter negative exponential distribution for instead. In order to solve the problems of two-dimension stability on engineering key cross-sectional view in rock mass, this article derived the rock mass planar flexibility tensor, and established rock mass two-dimension penetrate statistics fracture constitutive relation on the basis of penetrate fracture mechanics. Based on the crack tip plasticity research production of penetrate fracture, for example the Irwin plasticity equifinality crack, this article established the way to deal with the discontinuity stress singularity and plastic yielding problem at discontinuity tip. The research on deformation parameters is always the high light region of rock mass mechanics field. After the dam foundation excavation of XiaoWan hydroelectric power station, dam foundation rock mass upgrowthed a great deal of unload cracks, rock mass mechanical property gotten intricacy and strong anisotropy. The dam foundation rock mass mostly upgrowthed three group discontinuities: the decantation discontinuity, the steep pitch discontinuity, and the schistosity plane. Most of the discontinuities have got partial unload looseness. In accordance with ground stress field data, the dam foundation stress field greatly non-uniform, which felled under the great impaction of tectonic stress field, self-weight stress field, excavation geometric boundary condition, and excavation, unload. The discontinuity complexity and stress field heterogeneity, created the rock mass mechanical property of dam foundation intricacy and levity. The research on the rock mass mechanics, if not take every respected influencing factor into consideration as best as we can, major errors likely to be created. This article calculated the rock mass elastic modulus that after Xiao Wan hydroelectric power station dam foundation gutter excavation finished. The calculation region covered possession monolith of Xiao Wan concrete double-curvature arch dam. Different monolith were adopted the penetrate fracture statistics constitutive relation or bury fracture statistics constitutive relation selectively. Statistics fracture constitutive relation is fit for the intensity anisotropy and heterogeneity rock mass of Xiao Wan hydroelectric power station dam foundation. This article had contrastive analysis the statistics fracture constitutive relation result with the inclined plane load test actual measurement elastic modulus and RMR method estimated elastic modulus, and find that the three methods elastic modulus have got greatly comparability. So, the statistics fracture constitutive relations are qualified for trust. Generally speaking,this article had finished following works based on predecessors job: “Argumentation the C Problems of superposition principle in Fracture Mechanics, establish two-dimension penetrate statistics fracture constitutive relation of rock mass, argue the negative exponential distribution limitation and improve it, improve of the three-dimension berry statistics fracture constitutive relation of rock mass, discontinuity-tip plastic zone isoeffect calculation, calculate the rock mass elastic modulus on two-dimension cross-sectional view”. The whole research clue of this article inherited from the “statistics rock mass mechanics” of Wu Faquan(1992).
Resumo:
Butovskaya, a scholar of Former Soviet Union, first determined the depth of basalt layer in Tashkent Zone by using converted waves on seismogram in 1952. From then on, more and more scholars developed the comprehensive research that imaged the earth interior structures by applying converted waves information. With the digitalization of earthquake observation, The inversion imaging of complete or partial waveform record can efficiently improve inversion quality and widen its usage scope, therefore great progress is made in converted wave imaging. This paper makes a certain study in converted wave imaging on that basis. Transmitted PP waves and converted PS waves are generated when a P-wave propagates through an interface separating two media with large impedance contracts. A PS converted wave is a seismic body wave, which result from the conversion of an incident parent P wave at a boundary within the crust to a refracted S wave. The thickness of a single crustal layer can theoretically be determined by observing, with three-componented seismometer at a single station, the difference in time of the arrival of the parent P wave and the arrival of the PS converted wave. For a multilayered media, PS converted wave arrivals corresponding to each of the layers can theoretically be observed, provided the station is sufficiently from the source of the parent P wave to allow initial penetration of the P wave beneath the deepest layer considered. To avoid the difficulty of picking up transmitted P-wave and converted wave phases, this paper proposed a converted wave migration method by estimating the travel time difference between PS converted wave and PP transmitted wave. To verify its validity, we apply the converted wave PS migration algorithm to synthetic data generated by three forward modeling. The migration results indicate that PS converted wave may be migrated to reconstruct the transmitting interface. This technique is helpful to investigate the deep earth structures by using earthquake data.
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The discovery of the highly productive Renqiu buried hill reservoir in Bohai Bay Basin in 1975 started the high tide of finding buried hill reservoirs in China and their research. As the advance of E&P technologies, the study of buried hill reservoir in China had a qualitative leap. The reservoir description and some other aspects of development have reached or approached to the international leading level. However, some core techniques for reservoir study such as structure & faulting system study, formation prediction and connection study and heterogeneous model's construction could not completely carry out the quantitative or accurate reservoir description, e. g. the areal distribution of porosity, permeability and oil saturation. Especially, the modeling for reservoir simulation is still wandering in the stage of simplicity. The inaccurate understanding of geology could not derive 3D heterogeneous geological model that can reveal the actual underground situation thus could not design practical and feasible oilfield development plan. Therefore, the problems of low oil recovery rate, low recovery factor and poor development effectiveness have not been solved. The poor connection of the reservoir determined that waterflooding could not get good development effect and the production had to depend on the reservoir elastic energy, and this will bring big difficulty for development modification and improvement of oil recovery. This study formed a series of techniques for heterogeneous model research that can be used to construct heterogeneous model consistent with the reservoir geology. Thus the development effectiveness, success ratio of drilling and percent of producing reserves can be enhanced. This study can make the development of buried hill reservoir be of high recovery rate and high effect. The achievements of this study are as follows: 1. Evaluated the resources, summarized the geological characteristics and carried out the reservoir classification of the buried hill reservoirs in Shengli petroliferous area; 2. Established the markers for stratigraphical correlation and formed the correlation method for complex buried hill reservoirs; 3. Analyzed the structural features of the buried hill reservoirs, finished the structure interpretation and study of faulting system using synthetic seismograms, horizontal slices and coherent analysis, and clarified structural development history of the buried hill reservoirs in Shengli petroliferous area; 4. Determined the 3 classes and 7 types of pore space and the main pore space type, the logging response characteristics and the FMI logging identified difference between artificial and natural fractures by the comprehensive usage of core analysis, other lab analyses, conventional logging, FMI logging and CMR logging; 5. Determined the factors controlled the growth of the fractures, vugs and cavities, proposed the main formation prediction method for buried hill reservoir and analyzed their technical principium and applicability, and formed the seismic method and process for buried hill reservoir description; 6. Established the reserve calculation method for buried hill reservoirs, i. e. the reserves of fractures and matrix are calculated separately; the recoverable reserves are calculated by decline method and are classified by the SPE criteria; 7. Studied restraining barriers and the sealing of the faults thus clarified the oil-bearing formations of the buried hill reservoirs, and verified the multiple reservoir forming theory; 8. Formed reasonable procedure of buried hill reservoir study; 9. Formed the 3 D modeling technology for buried hill reservoirs; 10. Studied a number of buried hill blocks on the aspects of reservoir description, reservoir engineering and development plan optimization based on the above research and the profit and social effect are remarkable.
Resumo:
The foundation of reservoir model and residual oil prediction have been the core of reservoir detailed description for improved oil production and enhanced oil recovery. The traditional way of sandstone correlation based on the geometrical similarity of well-logs which emphasizes "based on the cycle and correlating from larger to smaller" has shown its theoretical limits when explaining the correlating and the scale, geometry, continuity, connectivity of sandstones and the law of the reservoir property. It has been an urgent and difficult subject to find new theory and methods to solve the reservoir correlation and property prediction. It's a new way to correlate strata and found framework of reservoir through the process-response analysis in the base-level cycles. And it is also possible to analyze the reservoir property in reservoir framework. Taking the reservoir of zonation 6-10 in S3~2 of Pucheng Oil Field in Henan Province as an example, we founded the detailed reservoir stratigraphic framework through base-level correlation. In the strata frame, sediment distribution and its development are discussed based on sediment volume partitioning and facies differentiation analysis. Reservoir heterogeneities and its relation to base-level are also discussed. The analysis of primary oil distribution shows the base-level controlled oil distribution in reservoir. In this paper, subjects as following are discussed in detail. Based on the analysis of sedimentary structure and sedimentary energy, the facies model was founded. Founding stratigraphy framework through base level analysis In the studying zone, one long term cycle, 6 middle term cycles and 27 short term cycles was identified and correlated. 3 Predicting the property of reservoir for improving oil development The base level controlled the property of sandbody. The short and very short term cycle controlled the pattern of heterogeneities in sandbody, and the middle and long term cycle controlled the area and inter-layer heterogeneities. On the lower location of the middle and long term base level, the sandbody is well developed, with a wide area and large thickness, while on the high location of base level, there is an opposite reservoir character. 4 The studying of reservoir development response and oil distribution making a solid base for development adjustment Primary oil distribution is controlled by base level location. It tells that the sandbody on the high base level location was poor developed for its difficulty to develop. While on the low location of the base level, the sandbody is well developed for its relative easy to develop and dominant role in the development, but high residual oil for its high original oil content.
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Because of the complexity and particularity, especially the result is more depend on the expert' s experience, the calculate method which is based on the simplicity mathematical model can hardly have any effective role in the oilfield .The coalescent method of artificial intelligence and signal manage in the correlation of reservoir use log curve has been put forward.in this paper. Following the principle of "controlled by classification and correlation by deposit gyration ". The system of correlation has been setup, which can identify "standard layer" first by the improved method of gray connection system, and then on the basis of identified "standard layer", interpret the fault, and last identify the layer in the reservoir. A effective method of "the consistent character of a reservoir "has been adopt to solved the puzzle of interpret the fault. On the basis of sedimentary theory and the quantity analysis of log curve shape of different type microfacies, a serial of different type micofacies' s models has been build that use eight optimized parameters, five of eight rationed parameters being used to describe microfacies with log curve, the distribution area of every parameters for the microfacies has been give. Because the classical math can only be used in the areas that principles are very clearly, not be fit for the description of geology character, so The fuzzy math integrate judgment has been adopt in the using log curve to determine microfacies; the accordance ration is 85 percent. A set of software has been programmed which is on the system of Windows. the software has the integration function of data process, auto-contrast reservoir layer, determination of microfacies using log curve, character the connectivity of sandstones and plotting of geology map. Through the application, this system has high precision and has become a useful tool in the study of geology.
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Oil and gas exploration of marine strata in China's Pre-Cenozoic residual basins is regarded as a worldwide puzzle because of existent problems and cruxes. Objectively speaking, the subsurface geologic structure is complicated, and the surface conditions of some areas are tough. On the other hand, there are still many problems to be solved in oil and gas exploration technologies of Pre-Cenozoic marine fades, and theoretic cognition about petroleum geology is not profound yet. Therefore, it is principal to explore integrated geophysical research ways of Pre-Cenozoic residual basins. Seismic prospecting and geophysical integrated interpretation technologies aimed at middle Paleozoic marine facies with deeper burial and complicated geologic conditions have not formed due to bad quality of deep strata data. Pre-Cenozoic strata, and especially extension, thickness and internal structure of Paleozoic strata can not be recognized from seismic profiles, so it is hard to systematically cognize structural features and oil-gas resources prospect of Pre-Cenozoic basins. To further investigation of fabric and structural features, basin prototype, formation and evolution pattern of Pre-Cenozoic basins, and also their control over formation, migration and aggregation of oil and gas, will play a guiding and promotive role in developing new surveying areas, selecting advantageous zones and predicting oil-gas resources.This paper follows the modem macrocontrol theory of "Region constrains local, deep strata controls shallow ones", and uses the integrated geophysical method of "One guide, two hinges, three combinations and multi feedbacks'*. Based on several years of geological and geophysical results of the Shengli Oilfield, and 14 newly-joint regional seismic profiles, deep structure and oil-gas bearing capacity of the Jiyang area are discussed and new cognitions are drawn as below.Seismic identification marks Tr, Tg, Tgl and Tg2 are established for importantPre-Cenozoic geological interfaces, and promoted to the whole Jiyang area.Through area-wide tracking and clogging of important seismic reflection marker,the isochronic framework of pre-Tertiary basin is set up in the Jiyang area for the firsttime, which is vital for basin research.Integrated with geological and geophysical research results, the Jiyang area isdivided into four first-order tectonic sequences- basement, lower tectonic layer,upper tectonic layer, and top tectonic layer. The basement and lower tectonic sequence which are related to Pre-Cenozoic are studied with emphasis.Through the research of regional seismic profiles, the point of view is given thatthe Kongdian Formation of Jiyang is structural transition period. The top-bottomunconformable interface of the Kongdian Formation is found out for the first time,and the basin model is determined primarily, which lay a basis for prototype basinresearch of the Jiyang Kongdian Formation.The distribution status of Middle-Paleozoic is delineated in the Jiyang area.The maximum thickness of Paleozoic lies in the top of the south declivity of half-graben. The thickness gets thinner towards the center of Mesozoic and Cenozoic half-graben basin, and even disappears. Structural action in the west-north affects the distribution of Paleozoic residual strata.6. The features of second-order tectonic sequence of the Jiyang depression isstudied and its evolution history of is rebuilt.Combined with the 5-stage evolution history of the China continent and structure evolution features of the Jiyang area, the structure sedimentary process since Paleozoic is divided into 5 periods - basement forming , Indosinian orogenic, Yanshan negative reversal, Himalayan extension and Neogene subsidence period.Combined with the research results of gravity, magnetic surveying and regionalprofiles, this paper brings forward the idea for the first time that the western boundaryof the Jiyang depression is the Ningjin-Yangpan fracture zone, and forms aside-column assemblage with the Wudi fracture zone.The opinion that under Middle-Cenozoic basins in the middle Jiyang area theremight superimpose an old residual basin is given for the first time. And if it is provedto be true, a new exploration space will be pioneered for Jiyang and even north China.There exists many types of tectonic-stratigraphic traps formed under piezotropy,extension and compound action in Pre-Cenozoic Jiyang. Therein all kinds of burialhills are the most important oil-gas trap type of Pre-Cenozoic, which should besurveyed layeredly according to the layout of oil sources.As such a new challenging project and field, the paper systematically analyses different geophysical responses of the Jiyang area, frames the deep structure of the area, and preliminarily recognizes the Pre-Cenozoic residual basins. It breaks through to a certain extent in both theory and practice, and is expected to provide new geophysical and geotectonic clues for deep exploration in Shengli.