三维非均匀各向异性介质中的纵波走时反演研究

Many observations show that seismic anisotropy is very common in the crust and upper mantle of the Earth. Seismic anisotropy can provide some clue about the changing and transporting process inside the earth. in recent years, abundant earthquake travel time data are accumulated, computers become more powerful, and these make the inversion of earthquake travel time data practical. In this thesis we studied the theory of elastic wave in anisotropic media, some formule for travel time inversion were derived. We present an iterative procedure to determine 21 elastic parameters from qP wave travel times. No a priori assumptions about heterogeneity and anisotropy of the model are made. The procedure is suitable for the case when we know nothing about the symmetry of anisotropy of the media, as well as for the case of earthquake travel time inversion which may contain various symmetry of anisotropy. The procedure is tested with a synthetic multiple-source offset VSP experiment. The results proved that the formulae are correct, and the procedure is practical. The results and the related theory indicate that the anisotropic inversion needs more rays than isotropic case. For a 2-D weak anisotropic (WA) medium, we need at least 5 rays in different directions to retrieve the elastic parameters on one grid point, and for a 3-D WA medium we need at least 15 rays in different directions to retrieve the elastic parameters on one grid point. The results also indicate that the starting background velocity has no influence on the final results, at least for the model we specified. Our results also show that insufficient illumination coverage will slow down the convergence rate, and make the results more sensitive to noise. We apply the procedure to a set of field travel time data. The data is from an artificial seismic observation. This observation is for locating micro-seismic events around a tunnel, its purpose is to find out if the digging process and the stress condition around the tunnel can generate micro-cracks. The size of this area is around 100m. The anisotropy derived from qP travel times is the same as the anisotropy showed by apparent velocities, and is also consistent with the anisotropy derived from S-wave splitting phenomena.

云南岩石圈流变学及多震层孕震环境

The Study on rheology of the lithosphere and the environments of the seismogenic layer is currently the basic project of the international earthquake research. Yunnan is the ideal place for studying this project. Through the multi-disciplinary comprehensive study of petrology, geophysics, seismo-geology, rock mechanics, etc., the depth-strength profiles of the lithosphere have been firstly constructed, and the seismogenic layer and its geophysical and tectonic environments in Yunnan have been systematically expounded in this paper. The related results achieved are of the important significances for further understanding the mechanism of strong earthquake generation, dividing the potential foci and exposing recent geodynamical processes in Yunnan. Through the comprehensive contrast of the metamorphic rocks in early and middle Proterozoic outcropping on the surface, DSS data and experimental data of rock seismic velocity under high temperature and high pressure, the petrological structure of the crust and upper mantle has been studied on Yunnan: the upper, middle and lower crust is composed of the metamorphic rocks of greenschist, amphibolite and granulite facies, respectively or granitoids, diorites and gabbros, respectively, and the upper mantle composed of the peridotites. Through the contrast studies of the heat flow and epicenters of the strong earthquakes, the distribution of the geotemperature and the data of focal depth, the relationship of between seismicity and geothermal structure of the lithosphere in Yunnan has been studied: the strong earthquakes with magnitude M ≥ 6.0 mainly take place at the geothermal gradient zone, and the seismic foci densely distribute between 200～500 ℃ isogeotherms. On the basis of studies of the rock properties and constituents of the crust and upper mantle and geothermal structure of the lithosphere, the structure of the rheological stratification of the lithosphere has been studied, and the corresponding depth-strength profiles have been constructed in Yunnan. The lithosphere in majority region of Yunnan has the structure of the rheological stratification, i.e. the brittle regime in the upper crust or upper part of the upper crust, ductile regime in the middle crust or lower part of the upper crust to middle crust, ductile regime in the lower crust and ductile regime in the subcrustal lithosphere. The rheological stratification has the quite marked lateral variations in the various tectonic units. The distributions of the seismogenic layer have been determined by using the high accurate data of focal depth. Through the contrast of the petrological structure, the structure of seismic velocity, electric structure, geotemperature structure, and rheological structure and the study of the focal mechanism in the seismogenic layer, the geophysical environments of the seismogenic layer in Yunnan have been studied. The seismogenic layer in Yunnan is located at the depths of 3 ～ 20 km; the rocks in the seismogenic layer are composed of the metamorphic rocks of greenschist to amphibolite facies (or granites to diorites); the seismogenic layer and its internal focal regions of strong earthquakes have the structure of medium properties with the relatively high seismic velocity, high density and high resistivity; there exists the intracrustal low seismic velocity and high conductivity layer bellow the seismogenic layer, the geotemperature is generally 100～500 ℃ in the depth range in which the seismogenic layer is located. The horizontal stress field predominates in the seismogenic layer, the seismogenic layer corresponds to the brittle regime of the upper crust or brittle regime of the upper crust to semibrittle regime of the middle crust. The formation of the seismogenic layer, preparedness and occurrence of the strong earthquakes is the result of the comprehensive actions of the source fault, rock constituent, structure of the medium properties, distribution of the geotemperature, rheological structure of the seismogenic layer and its external environments. Through the study of the structure, active nature, slip rate, segmentation of the active faults, and seismogenic faults, the tectonic environments of the seismogenic layer in Yunnan have been studied. The source faults of the seismogenic layer in Yunnan are mainly A-type ones and embody mainly the strike slip faults with high dip angle. the source faults are the right-lateral strike slip ones with NW-NNW trend and left-lateral strike slip ones with NE-NEE trend in Southwestern Yunnan, the right-lateral strike slip ones with NNW trend and left-lateral strike slip ones with NNE trend (partially normal ones) in Northwestern Yunnan, the right-lateral strike slip ones with NWW trend in Central Yunnan and left-lateral strike slip ones with NW-NNW trend in Eastern Yunnan. Taking Lijiang earthquake with Ms = 7.0 for example. The generating environments of the strong earthquake and seismogenic mechanical mechanism have been studied: the source region of the strong earthquake has the media structure with the relatively high seismic velocity and high resistivity, there exists the intracrustal low velocity and high conductivity layer bellow it and the strong earthquakes occur near the transitional zone of the crustal brittle to ductile deformation. These characteristics are the generality of the generating environments of strong earthquakes. However, the specific seismogenic tectonic environments and action of the stress field of the seismic source in the various regions, correspondingly constrains the dislocation and rupture mechanical mechanism of source fault of strong earthquake.

塔里木盆地轮南地区三叠系油气地质模型及油气预测研究

As an important measure to understand oil and gas accumulation during petroleum exploration and development, Petroleum geological model is an integrated system of theories and methods, which includes sedimentology, reservoir geology, structural geology, petroleum geology and other geological theories, and is used to describe or predict the distribution of oil and gas. Progressive exploration and development for oil and gas is commonly used in terrestrial sedimentary basin in China for the oil and gas generation, accumulation and exploitation are very intricate. It is necessary to establish petroleum geological model, adaptive to different periods of progressive exploration and development practice. Meanwhile there is lack of an integrated system of theories and methods of petroleum geological model suitable for different exploration and development stages for oil and gas, because the current different models are intercrossed, which emphasize their different aspects. According to the characteristics of exploration and development for the Triassic oil and gas pool in Lunnan area, Tarim Basin, the Lunnan horst belt was selected as the major study object of this paper. On the basis of the study of petroleum geological model system, the petroleum geological models for different exploration and development stages are established, which could be applied to predict the distribution of oil and gas distribution. The main results are as follows. (1) The generation-accumulation and exploration-development of hydrocarbon are taken as an integrated system during the course of time, so petroleum exploration and development are closely combined. Under the guidance of some philosophical views that the whole world could be understood, the present writer realizes that any one kind of petroleum geological models can be used to predict and guide petroleum exploration and development practice. The writer do not recognize that any one kind of petroleum geological models can be viewed as sole model for guiding the petroleum exploration and development in the world. Based on the differences of extents and details of research work during various stage of exploration and development for oil and gas, the system of classification for petroleum geological models is established, which can be regarded as theoretical basis for progressive petroleum exploration and development. (2) A petroleum geological model was established based on detailed researches on the Triassic stratigraphy, structure, sedimentology and reservoir rocks in the Lunnan area, northern Tarim Basin. Some sub-belt of hydrocarbon accumulation in the Lunnan area are divided and the predominate controlling factors for oil and gas distribution in the Lunnan area are given out. (3) Geological models for Lunnan and Jiefangqudong oil fields were rebuilt by the combinations of seismology and geology, exploration and development, dynamic and static behavior, thus finding out the distribution of potential zones for oil and gas accumulations. Meanwhile Oil and gas accumulations were considered as the important unit in progressive exploration and development, and the classification was made for Lunnan Triassic pools. Petroleum geological model was created through 3D seismic fine interpretation and detailed description of characteristics of reservoir rocks and the distribution of oil and gas, especially for LN3 and LN26 well zones. The possible distribution of Triassic oil traps and their efficiency in the Lunnan area has been forecasted, and quantitative analysis for original oil(water) saturation in oil pools was performed. (4) The concept of oil cell is proposed by the writer for the first time. It represents the relatively oil-rich zones in oil pool, which were formed by the differences of fluid flows during the middle stage of reservoir development. The classification of oil cells is also given out in this paper. After the studies of physical and numerical modeling, the dominant controlling factors for the formation of various oil cells are analyzed. Oil cells are considered as the most important hydrocarbon potential zones after first recovery, which are main object of progressive development adjustment and improvement oil recovery. An example as main target of analysis was made for various oil cells of Triassic reservoir in the LN2 well area. (5) It is important and necessary that the classification of flow unit and the establishment of geological model of flow unit based on analysis of forecast for inter-well reservoir parameters connected with the statistical analysis of reservoir character of horizontal wells. With the help of self-adaptive interpolation and stochastic simulation, the geological model of flow units was built on the basis of division and correlation of flow units, with which the residual oil distribution in TIII reservoir in the LN2 well area after water flooding can be established.

内蒙古东部喀喇沁地区早中生代底侵作用

Mafic granulite xenoliths have been extensively concerned over the recent years because they are critical not only to studies of composition and evolution of the deep parts of continental crust but to understanding of the crust-mantle interaction. Detailed petrology, geochemistry and isotope geochronology of the Early Mesozoic mafic-ultramafic cumulate xenoliths and mafic granulite xenoliths and their host diorites from Harqin area, eastern Inner-Mongolia have been studied here. Systematic Rb-Sr isochron, ~(40)Ar-~(39)Ar and K-Ar datings for mafic-ultramafic cumulate xenoliths give ages ranging from 237Ma to 221Ma. Geochemical research and forming temperature and pressure estimates suggest that cumulates are products of the Early Mesozoic mantle-derived magmatic underplating and they formed in the magmatic ponds at the lowermost of the continental crust and are later enclaved by the dioritic magma. Detailed study on the first-discovered mafic granulite xenoliths reveals that their modal composition, mineral chemistry and metamorphic P-T conditions are all different from those of the Precambrian granulite exposed on the earth surface of the North China craton. High-resolution zircon U-Pb dating suggests that the granulite facies metamorphism may take place in 253 ～ 236Ma. Hypersthene single mineral K-Ar dating gives an age of 229Ma, which is believed to represent a cooling age of the granulite. As the host rock of the cumulate and granulite xenoliths, diorites intruded into Archean metamorphic rocks and Permian granite. They are mainly composed of grandodiorite, tonalite and monzogranite and show metaluminous and calc-alkaline features. Whole rock and single mineral K-Ar dating yields age of 221 ～ 223Ma, suggesting a rapid uplift in the forming process of the diorites. Detailed field investigation and geochemical characteristics indicate that these diorites with different rock types are comagmatic rocks, and they have no genetic correlation with cumulate and granulite xenoliths. Geochemical model simulating demonstrates that these diorites in different lithologies are products of highly partial melting of Archean amphibolite. It is considered that the Early Mesozoic underplating induced the intrusion of diorites, and it reflects an extensional geotectonic setting. Compression wave velocity V_P have been measured on 10 representative rock samples from the Early Mesozoic granulite and mafic-ultramafic cumulate xenoliths population as an aid to interpret in-situ seismic velocity data and investigating velocity variation with depth in a mafic lower crust. The experiments have been carried out at constant confining pressures up to 1000MPa and temperatures ranging from 20 ℃ to around 1300 ℃, using the ultrasonic transmission technique. After corrections for estimated in situ crustal pressures and temperatures, elastic wave velocities range from 6.5 ～ 7.4 km s~(-1). On the basis of these experimental data, the Early-Mesozoic continental compression velocity profile has also been reestablished and compared with those of the present and of the different tectonic environments in the world. The result shows that it is similar to the velocity structure of the extensional tectonic area, providing new constraints on the Early Mesozoic continental structure and tectonic evolution of the North-China craton. Combining with some newly advancements about the regional geology, the thesis further proposes some constraints on the Mesozoic geotectonic evolution history, especially the features of deep geology of the North China craton.

大别山岩石圈有效弹性厚度初步研究

As powerful tools to study the lithosphere dynamics, the effective elastic thickness (Te) as well as the envelope of yielding stress of lithosphere have been attracted great attention of geoscientists in the past thirty years. The oceanic lithosphere, contrary to the continental lithosphere, has more fruits for its simple structures and evolution process. In continent, the lithosphere commonly is complex and variable in the rheological, thermal structures, and has a complicated history. Therefore, the application of the effective elastic thickness in continent is still a subject to learn in a long time. Te, with the definition of the thickness of an elastic plate in theory flexured by the equal benging of the real stress in the lithosphere plate (Turcotte, 1982), marks the depth of transition between elastic and fluid behaviors of rocks subjected to stress exceeding 100 MPa over the geological timescales (McNutt, 1990). There are three methods often adapted: admittance or isostatic response function, coherence and forwarding. In principle, the models of Te consist of thermal-rheological, non-linear Maxwell, non-linear work hardening and rheological layered models. There is a tentative knowledge of Te that it is affected by the following factors: crustal thickness, crust-mantle decoupling, plate bending, boundary conditions of plate (end forces and bending moments), stress state, sedimentary layer, faulting effect, variation in the mountain belts' strike, foreland basin, inheritance of tectonic evolution, convection of mantle, seismic depth and lithosphere strength. In this thesis, the author introduces the geological sketch of the Dabie collisional orogenic belt and the Hefei Basin. The Dabie Mts. is famous for the ultra-high pressure metamorphism. The crustal materials subducted down to the depth of at least 100 km and exhumed. So that the front subjects arise such as the deeply subduction of continent, and the post-collisional crust-mantle interaction. In a geological journey at June of 1999, the author found the rarely variolitic basaltic andesite in the Dabie Mts. It occurs in Susong Group, near Zhifenghe Countryside, Susong County, Anhui Province. It is just to the south of the boundary between the high-grade Susong melange and the ultra-high grade South Dabie melange. It has a noticeable knobby or pitted appearance in the surface. The size of the varioles is about 1-4 mm. In hand-specimen and under microscope, there are distinct contacts between the varioles and the matrice. The mineralogy of the varioles is primarily radiate plagioclase, with little pyroxene, hornblende and quartz. The pyroxene, hornblende and quartz are in the interstices between plagioclase. The matrix is consisted of glass, and micro-crystals of chlorite, epidote and zoisite. It is clearly subjected and extensive alteration. The andesite has an uncommon chemical composition. The SiO_2 content is about 56.8%, TiO_2 = 0.9%, MgO = 6.4%, (Fe_2O_3)_(Total) = 6.7% ～ 7.6%, 100 Mg/(Mg+Fe) = 64.1 ～ 66.2. Mg# is significantly high. The andesite has higher abundances of large-lithophile trace elements (e.g. K, Ba, Sr, LREE), e.g. La/Nd = 5.56-6.07, low abundances of high-strength-field elements (HFSE, e.g. Ta, Nb, P, Ti), particularly Ta and Nb strongly depleted. These are consistent with the characteristics of subducted-related magmas (Pearcce, 1982; Sun and McDonaugh, 1989). In the spider diagram of trace elements, from Ce to right hand, the abundances of elements decrease quickly, showing a characteristic of the continental margins (Pearce, 1982). There has a strongly enrichment of light-rare-earth elements, with a significant diffraction of REEs (the mean value of (La/Yb)_N is 32.84). No Eu anomaly, but there are anomaly high (La/Yb)_N = 28.63-36.74, (La/Y)_N = 70.33 - 82.84. The elements Y and Yb depleted greatly, Y < 20 ppm, Y_N = 2.74-2.84, Yb_N = 2.18 - 2.35. From the La-(La/Sm) diagram, the andesite is derived from partial melting. But the epsilone value of Nd is -18.7 ～ -19.2, so that the material source may be the mantle materials affected by the crustal materials. The Nd model age is 1.9 Ga indicating that the basaltic andesite was resulted from the post-collisional crust-mantle interaction between the subducted Yangze carton and the mantle of Sino-Korea carton. To obtain the Te of the lithosphere beneath the Dabie Mts. and the Hefei Basin, the author applies the coherence method in this thesis. The author makes two topography-gravity profiles (profiles 7~(th) and 9~(th)) across the Dabie Mts. and the Hefei Basin, and calculates the auto-coherence, across coherence, power spectrum, across power spectrum of the topography and gravity of the two profiles. From the relationships between the coherence and the wave-number of profiles. From the relationships between the coherence and the wave-number of profiles 7~(th) and 9~(th), it is obtained that the characteristic wavelengths respectively are 157 km and 126 km. Consequently the values of effective elastic thickness are 6.5 km and 4.8 km, respectively. However, the Te values merely are the minimum value of the lithosphere because the coherencemethod in a relative small region will generate a systemic underestimation. Why there is a so low Te value? In order to check the strength of the lithosphere beneath the Dabie Mts., the authore tries to outline the yielding-stress envelope of the lithosphere. It is suggested that the elastic layers in the crust and upper mantle are 18 km and 35 km, respectively. Since there exist a low viscosity layer about 3-5 km thickness, so it is reasonable that the decoupling between the crust and mantle occurred. So the effective thickness of the lithosphere can be estimated from the two elastic layers. Te is about 34 km. This is the maximum strength of the lithosphere. We can make an approximately estimation about the strength of the lithosphere beneath the Dabie Mts.: Te is about 20-30 km. The author believes that the following factors should be responsible for the low Te value: (1) the Dabie Mts. has elevated strongly since K_3-J_1. The north part of the Dabie Mts. elevates faster than the south part today; (2) there occur large active striking faults in this area. And in the east, the huge Tan-Lu striking fault anyway tends to decrease the lithosphere strength; (3) the lithosphere beneath the Dabie Mts. is heter-homogeneous in spatio-temporal; (4) the study area just locates in the adjacent region between the eastern China where the lithosphere thickness is significantly reduced and the normal western China. These factors will decrease the lithosphere strength.

各向同性与各向异性介质中地震波旅行时正演模拟与反演成像

By seismic tomography, interesting results have been achieved not only in the research of the geosphere with a large scale but also in the exploration of resources and projects with a small scale since 80'. Compared with traditional inversion methods, seismic tomography can offer more and detailed information about subsurface and has been being paid attention by more and more geophysicists. Since inversion based on forward modeling, we have studied and improved the methods to calculate seismic traveltimes and raypaths in isotropic and anisotropic media, and applied the improved forward methods to traveltime tomography. There are three main kinds of methods to calculate seismic traveltime field and its ray path distribution, which are ray-tracing theory, eikonal equation by the finite-difference and minimum traveltime tree algorithm. In ray tracing, five methods are introduced in the paper, including analytic ray tracing, ray shooting, ray bending, grid ray tracing and rectangle grid ray perturbation with three points. Finite-difference solution of eikonal equation is very efficient in calculation of seismic first-break, but is awkward in calculation of reflection traveltimes. We have put forward a idea to calculate traveltimes of reflected waves using a combining way of eikonal equation method and other one in order to improve its capability of dealing with reflection waves. The minimum traveltime tree algorithm has been studied with emphases. Three improved algorithms are put forward on the basis of basic algorithm of the minimum traveltime tree. The first improved algorithm is called raypath tracing backward minimum traveltime algorithm, in which not only wavelets from the current source but also wavelets from upper source points are all calculated. The algorithm can obviously improve the speed of calculating traveltimes and raypaths in layered or blocked homogeneous media and keep good accuracy. The second improved algorithm is raypath key point minimum traveltime algorithm in which traveltimes and raypaths are calculated with a view of key points of raypaths (key points of raypths mean the pivotal points which determine raypaths). The raypath key point method is developed on the basis of the first improved algorithm, and has better applicability. For example, it is very efficient even for inhomogeneous media. Another improved algorithm, double grid minimum traveltime tree algorithm, bases upon raypath key point scheme, in which a model is divided with two kinds of grids so that the unnecessary calculation can be left out. Violent undulation of curved interface often results in the phenomenon that there are no reflection points on some parts of interfaces where there should be. One efficacious scheme that curved interfaces are divided into segments, and these segments are treated respectively is presented to solve the problem. In addition, the approximation to interfaces with discrete grids leads to large errors in calculation of traveltimes and raypaths. Noting the point, we have thought a new method to remove the negative effect of mesh and to improve calculation accuracy by correcting the traveltimes with a little of additional calculation, and obtained better results.

小波域地震资料的处理方法（WSSP）研究

The modeling formula based on seismic wavelet can well simulate zero - phase wavelet and hybrid-phase wavelet, and approximate maximal - phase and minimal - phase wavelet in a certain sense. The modeling wavelet can be used as wavelet function after suitable modification item added to meet some conditions. On the basis of the modified Morlet wavelet, the derivative wavelet function has been derived. As a basic wavelet, it can be sued for high resolution frequency - division processing and instantaneous feature extraction, in acoordance with the signal expanding characters in time and scale domains by each wavelet structured. Finally, an application example proves the effectiveness and reasonability of the method. Based on the analysis of SVD (Singular Value Decomposition) filter, by taking wavelet as basic wavelet and combining SVD filter and wavelet transform, a new de - noising method, which is Based on multi - dimension and multi-space de - noising method, is proposed. The implementation of this method is discussed the detail. Theoretical analysis and modeling show that the method has strong capacity of de - noising and keeping attributes of effective wave. It is a good tool for de - noising when the S/N ratio is poor. To give prominence to high frequency information of reflection event of important layer and to take account of other frequency information under processing seismic data, it is difficult for deconvolution filter to realize this goal. A filter from Fourier Transform has some problems for realizing the goal. In this paper, a new method is put forward, that is a method of processing seismic data in frequency division from wavelet transform and reconstruction. In ordinary seismic processing methods for resolution improvement, deconvolution operator has poor part characteristics, thus influencing the operator frequency. In wavelet transform, wavelet function has very good part characteristics. Frequency - division data processing in wavelet transform also brings quite good high resolution data, but it needs more time than deconvolution method does. On the basis of frequency - division processing method in wavelet domain, a new technique is put forward, which involves 1) designing filter operators equivalent to deconvolution operator in time and frequency domains in wavelet transform, 2) obtaining derivative wavelet function that is suitable to high - resolution seismic data processing, and 3) processing high resolution seismic data by deconvolution method in time domain. In the method of producing some instantaneous characteristic signals by using Hilbert transform, Hilbert transform is very sensitive to high - frequency random noise. As a result, even though there exist weak high - frequency noises in seismic signals, the obtained instantaneous characteristics of seismic signals may be still submerged by the noises. One method for having instantaneous characteristics of seismic signals in wavelet domain is put forward, which obtains directly the instantaneous characteristics of seismic signals by taking the characteristics of both the real part (real signals, namely seismic signals) and the imaginary part (the Hilbert transfom of real signals) of wavelet transform. The method has the functions of frequency division and noise removal. What is more, the weak wave whose frequency is lower than that of high - frequency random noise is retained in the obtained instantaneous characteristics of seismic signals, and the weak wave may be seen in instantaneous characteristic sections (such as instantaneous frequency, instantaneous phase and instantaneous amplitude). Impedance inversion is one of tools in the description of oil reservoir. one of methods in impedance inversion is Generalized Linear Inversion. This method has higher precision of inversion. But, this method is sensitive to noise of seismic data, so that error results are got. The description of oil reservoir in researching important geological layer, in order to give prominence to geological characteristics of the important layer, not only high frequency impedance to research thin sand layer, but other frequency impedance are needed. It is difficult for some impedance inversion method to realize the goal. Wavelet transform is very good in denoising and processing in frequency division. Therefore, in the paper, a method of impedance inversion is put forward based on wavelet transform, that is impedance inversion in frequency division from wavelet transform and reconstruction. in this paper, based on wavelet transform, methods of time - frequency analysis is given. Fanally, methods above are in application on real oil field - Sansan oil field.

扩散波勘探方法基础及其在石油油气藏开发中的应用研究

As we know, the essence of exploration is objective body determined by getting the information. Such as seismic、electrical and electromagnetic prospecting, they are the common methods of the exploration. Therefore, They have a complete set of theory now. In fact, the effective information can also be got by the diffusion way, it is called diffusion prospecting. The diffusion way prospecting is necessary and important. The way of diffusion prospecting is studied in the paper and main works include below: (1) On the basis of studying basic law of the diffusion, the paper gives the idea of diffusion wave and the formulas of computing diffusion wave function. (2) The paper studies the way of the diffusion prospecting and the methods of data processing. At the same time, it also expounds the characteristics and the applied foreground of the diffusion prospecting. (3) The paper gives the tomography idea and the basic method of diffusion CT. Meanwhile, it also expounds the foreground that the diffusion CT is applied in oil development prospecting. (4) As the inversion of the diffusion equation is a part of the diffusion prospecting way, the methods of diffusion equation inversion are studied and the two formulas are deduced --Laplace transform and polynomial fitting inversion formulas. As the other important result of diffusion equation inversion, the inversion can offer a new analysis method for well Testing in oil development. In order to show a set of methods in the paper feasible, forward、inversion and CT numerical simulation are done in the paper.

沾化凹陷火成岩油气藏形成条件和分布规律研究

As a kind of special lithologic ones, Igneous rock oil and gas pool is more and more paid attention, and it has different forming condition and distribution from conventional ones, such as various terrane distribution types, serious reservoir anisotropy, complicated hydrocarbon-bearing, so there is not successful experience to follow for exploration and development of this complex subtle oil and gas pool at present. For an example of Igneous oil and gas pool of Luo151 area in Zhanhua seg, Eastern China, this article study the difficult problem, including petrologic nd lithofacies analysis, Origin, invasion age and times of Igneous rock, reservoir anisotropy, Geological Modeling, Igneous reservoir synthesis evaluation. forming condition and distribution are studied synthetically, and an integrated method to predict igneous rock oil and gas pool is formed, which is evaluated by using development data. The Igneous rock is mainly diabase construction in Luo151 area of Zhanhua Sag, and petrologic types include carbonaceous slate, hornfels, and diabases. Based on analyzing synthetically petrologic component, texture and construct, 4 lithofacies zones, such as carbonaceous slate subfacies, hornfels subfacies containing cordierite and grammite, border subfacies and central subfacies, are divided in the diabase and wall rock. By studying on isotopic chronology, terrane configuration and imaging logging data, the diabase intrusion in Zhanhua Sag is formed by tholeiite magma emplacing in Shahejie formation stratum on the rift tension background Lower Tertiary in North China. The diabase intrusion of Luo151 is composed possibly of three periods magma emplacement. There is serious anisotropy in the diabase reservoirs of Luo151 in Zhanhua Sag. Fracture is primary reservoir space, which dominated by tensile fracture in high obliquity, and the fracture zones are mainly developed round joint belt of igneous rock and wall rock and position of terrane thickness changing rapidly. The generation materials of the reservoirs in Luo151 igneous oil pools consist of Intergranular micropore hornfels, condensate blowhole-solution void diabase condensate edge, the edge and center of the condensate seam diabase, of which are divided into horizontal, vertical and reticulated cracks according fracture occurrence. Based on the above research, a conceptual model of igneous rock reservoir is generated, which is vertically divided into 4 belts and horizontally 3 areas. It is built for the first time that classification evaluation pattern of igneous rock reservoir in this area, and 3 key wells are evaluated. The diabase construction is divided into grammite hornfels micropore type and diabase porous-fracture type reservoirs. The heavy mudstone layers in Third Member of Shahejie formation (Es3) provide favorable hydrocarbon source rock and cap formation, diabase and hornfels belts serve as reservoirs, faults and microcracks in the wall rocks as type pathways for oil and gas migration. The time of diabase invasion was about in the later deposition period of Dongying Formation and the middle of that of Guantao Formation, the oil generated from oil source rock of Es3 in the period of the Minghuazhen formation and is earlier more than the period of diabase oil trap and porous space forming. Based on geological and seismic data, the horizon of igneous rocks is demarcated accurately by using VSP and synthetic seismogram, and the shape distribution and continuity of igneous rocks are determined by using cross-hole seismic technology. The reservoir capability is predicted by using logging constraining inversion and neural network technology. An integrated method to predict igneous rock oil and gas pool is formed. The study is appraised by using development data. The result show the reservoir conceptual model can guide the exploration and development of oil pool, and the integrated method yielded marked results in the production.

波动方程叠前深度偏移辛算法及速度建模

On 70~(th) SEG Annual meeting, many author have announced their result on the wave equation prestack depth migration. The methods of the wave-field imaging base on wave equation becomes mature and the main direction of seismic imaging. The direction of imaging the complex media has been the main one of the projects that the national "85" and "95" reservoir geophysics key projects and "Knowledge innovation key project of Chinese Academy of Science" have been supported. Furthermore, we began the study for special oil field situation of our nation with the international research groups. Under the background, the author combined the thoughts of symplectic with wave equation pre-stack depth migration, and develops and efficient wave equation pre-stack depth migration method. The purpose of this work is to find out a way to imaging the complex geological goals of Chinese oilfields and form a procedure of seismic data processing. The paper gives the approximation of one way wave equation operator, and shows the numerical results. The comparisons have been made between split-step phase method, Kirchhoff and Ray+FD methods on the pulse response, simple model and Marmousi model. The results shows that the method in this paper has an higher accuracy. Four field data examples have also be given in this paper. The results of field data demonstrate that the method can be usable. The velocity estimation is an important part of the wave equation pre-stack depth migration. A parallel velocity estimation program has been written and tested on the Beowulf clusters. The program can establish a velocity profile automatically. An example on Marmousi model has shown in the third part of the paper to demonstrate the method. Another field data was also given in the paper. Beowulf cluster is the converge of the high performance computer architecture. Today, Beowulf Cluster is a good choice for institutes and small companies to finish their task. The paper gives some comparison results the computation of the wave equation pre-stack migration on Beowulf cluster, IBM-SP2 (24 nodes) in Daqing and Shuguang 3000, and the comparison of their prize. The results show that the Beowulf cluster is an efficient way to finish the large amount computation of the wave equation pre-stack depth migration, especially for 3D.

地震波场模拟及叠前深度偏移的李群方法

The processes of seismic wave propagation in phase space and one way wave extrapolation in frequency-space domain, if without dissipation, are essentially transformation under the action of one parameter Lie groups. Consequently, the numerical calculation methods of the propagation ought to be Lie group transformation too, which is known as Lie group method. After a fruitful study on the fast methods in matrix inversion, some of the Lie group methods in seismic numerical modeling and depth migration are presented here. Firstly the Lie group description and method of seismic wave propagation in phase space is proposed, which is, in other words, symplectic group description and method for seismic wave propagation, since symplectic group is a Lie subgroup and symplectic method is a special Lie group method. Under the frame of Hamiltonian, the propagation of seismic wave is a symplectic group transformation with one parameter and consequently, the numerical calculation methods of the propagation ought to be symplectic method. After discrete the wave field in time and phase space, many explicit, implicit and leap-frog symplectic schemes are deduced for numerical modeling. Compared to symplectic schemes, Finite difference (FD) method is an approximate of symplectic method. Consequently, explicit, implicit and leap-frog symplectic schemes and FD method are applied in the same conditions to get a wave field in constant velocity model, a synthetic model and Marmousi model. The result illustrates the potential power of the symplectic methods. As an application, symplectic method is employed to give synthetic seismic record of Qinghai foothills model. Another application is the development of Ray+symplectic reverse-time migration method. To make a reasonable balance between the computational efficiency and accuracy, we combine the multi-valued wave field & Green function algorithm with symplectic reverse time migration and thus develop a new ray+wave equation prestack depth migration method. Marmousi model data and Qinghai foothills model data are processed here. The result shows that our method is a better alternative to ray migration for complex structure imaging. Similarly, the extrapolation of one way wave in frequency-space domain is a Lie group transformation with one parameter Z and consequently, the numerical calculation methods of the extrapolation ought to be Lie group methods. After discrete the wave field in depth and space, the Lie group transformation has the form of matrix exponential and each approximation of it gives a Lie group algorithm. Though Pade symmetrical series approximation of matrix exponential gives a extrapolation method which is traditionally regarded as implicit FD migration, it benefits the theoretic and applying study of seismic imaging for it represent the depth extrapolation and migration method in a entirely different way. While, the technique of coordinates of second kind for the approximation of the matrix exponential begins a new way to develop migration operator. The inversion of matrix plays a vital role in the numerical migration method given by Pade symmetrical series approximation. The matrix has a Toepelitz structure with a helical boundary condition and is easy to inverse with LU decomposition. A efficient LU decomposition method is spectral factorization. That is, after the minimum phase correlative function of each array of matrix had be given by a spectral factorization method, all of the functions are arranged in a position according to its former location to get a lower triangular matrix. The major merit of LU decomposition with spectral factorization (SF Decomposition) is its efficiency in dealing with a large number of matrixes. After the setup of a table of the spectral factorization results of each array of matrix, the SF decomposition can give the lower triangular matrix by reading the table. However, the relationship among arrays is ignored in this method, which brings errors in decomposition method. Especially for numerical calculation in complex model, the errors is fatal. Direct elimination method can give the exact LU decomposition But even it is simplified in our case, the large number of decomposition cost unendurable computer time. A hybrid method is proposed here, which combines spectral factorization with direct elimination. Its decomposition errors is 10 times little than that of spectral factorization, and its decomposition speed is quite faster than that of direct elimination, especially in dealing with a large number of matrix. With the hybrid method, the 3D implicit migration can be expected to apply on real seismic data. Finally, the impulse response of 3D implicit migration operator is presented.

南海北部大陆边缘盆地热演化史及其与油气关系

This thesis focuses on the present-day thermal field features, evolution and their connections to hydrocarbon generation of the three continental margin basins-the Yinggehai (Yingge Sea), Qiongdongnan(southeast Qiong), and Pear River Mouth basins-in northern South China Sea, based on available data from drillings, loggings, seismic cross-sections, BHTs, thermal indicators (Ro%, inclusion, etc) and geopressure measurements. After studying of present-day distribution of geothermal field and thermal disturbance of fluid in the sedimentary strata, the author discovered that the distribution of gas fields in Yinggehai Basin are closely related to the distribution of anomalously high thermal gradient area, whereas it is not the case for the Pear River Mouse Basin. And detailed processing of the fluid inclusion data indicates that geothermal fluids activated frequently in this area, and they may mainly be derived upward from the overpressure and hydrocarbon-generating beds, 3000-4500 m in depth. Therefore, the abnormal gradients in sedimentary beds were mainly caused by the active geothermal fluids related to hydrocarbon migrating and accumulating in this area. Because of the effect of overpressure retarding on vitrinite reflectance, the thermal indicators for thermal history reconstruction should be assessed before put into use. Although some factors, such as different types of kerogen, heating ratio, activities of thermal fluids and overpressure, may have effects on the vitrinite reflectance, under the circumstance that thermal fluids and overpressure co-exist, overpressure retarding is dominant. And the depth and correction method of overpressure retarding were also determined in this paper. On the basis of reviewing the methods of thermal history studies as well as existing problems, the author believes that the combination of thermal-indicator-inversion and tectono-thermal modeling is an effective method of the thermal history reconstruction for sedimentary basins. Also, a software BaTherMod for modeling thermal history of basins was successfully developed in this work. The Yinggehai Basin has been active since Tertiary, and this was obviously due to its tectonic position-the plate transition zone. Under the background of high thermal flow, long-term quick subsidence and fluid activities were the main reasons that lead to high temperature and overpressure in this basin. The Zhujiangkou Basin, a Tertiary fault-basin within the circum-Pacific tectonic realm, was tectonically controlled by the motion of the Pacific Plate and resembles the other petroliferous basins in eastern China. This basin developed early, and characterized intensive extension in the early stage and weak activity in the later stage of its development. Whereas the Qiongdongnan Basin was in a weak extension early and intensity of extension increased gradually. The relative geographical locations and the extensional histories of three basins ilustrate that the northern continental margin of South China Sea spread from south to north. On the other hand, the Qiongdongnan and Yinggehai Basins may have been controlled by the same tectonic regime since later Tertiary, whereas the Zhujiangkou Basin was not meaningfully influenced. So, the tectono-thermal evolution character of the Qiongdonnan basin should be closely to the other two. It may be concluded that the three basins have been developed within the active continental margin since Tertiary, and the local lithosphere might undergo intensive extension-perhaps two or three times of episodic extension occurred. Extension lead to large tectonoc subsidence and extreme thick Tertiary sediments for hydrocarbon generation in the basins. In response to the periodic extension of the basins, the palaeothermal flow were also periodical. The three basins all have the characteristics of multi-phase thermal evolutions that is good for oil-gas generation. And the overpressure expands the depth range of oil-gas habitat, which is meaningful to petroleum exploration in this region.

华南地壳岩石弹性和变形性质的高温高压实验研究

The South continent of China lies to southeast of Eurasia block. It is an active area from the view of crust growth and continent spread and is a transition zone between continental crust and oceanic crust. The compressional wave velocities and anisotropies of typical crustal metamorphic rocks were determined at high temperature (up to 1000 ℃) and high pressure(up to 800MPa). The experimental results show that the velocities generally increase with pressure, and is unaffected by temperature up to around 550 ℃. But the velocities of all experimental samples start to drop above a temperature point. For an example, this greatly reduce the speed of wave propagation in amphibolite and serpentinite above 760 ℃ and above 550 ℃ respectively, which may be due to dehydrate of amphibole and serpentine. P-wave anisotropy coefficients of those rocks range from 2% to 10% at 800MPa and 500 ℃. The anisotropies decrease with increasing pressure at room temperature, but hardly change as function of temperature at constant 800MPa or 600MPa pressure. The average velocity of the six crustal rocks is 6.28km/s under the condition of 800MPa and 550 ℃, which is consistent with the result of deep seismic sounding data. Based on this experimental result, we deduce there may exist a lot of felsic granulites and amphibolites at the depth of 15-25km underground. With increasing temperature and pressure, the deformation behavior of the rocks undergoes from localized brittle fracture, semi-brittle deformation (cataclastic flow or semi-brittle faulting, semi-brittle flow) to homogeneous crystal-plastic flow. This transition is associated with mechanical behavior and micro-mechanism. It is very important to understanding earthquake source mechanics, the strength of the lithosphere and the style of deformation. The experiments were conducted at temperature of 600-1000 ℃, confining pressure of 500MPa, and stain rates of 10~(-4)-10~(-6) S~(-1). For fine-grained natural amphibolite, the results of experiments show that brittle faulting is major failure mode at temperature <600 ℃, but crystal-plastic deformation is dominate at temperature >800 ℃, and there is a transition with increasing temperature from sembrittle faulting to cataclastic flow and sembrittle flow at temperature of 670-750 ℃. For medium-grained natural Felsic granulite, the results of experiments show that brittle faulting is major failure mode at temperature <500 ℃, but crystal-plastic deformation is dominate at temperature >700 ℃, and there is a transition with increasing temperature from semibrittle faulting to cataclastic flow and sembrittle flow at temperature of 500-600 ℃.

辛格式波动方程叠前深度偏移及速度建模

On 70~(th) SEG Annual meeting, many author have announced their result on the wave equation pre-stack depth migration. The methods of the wave-field imaging base on wave equation becomes mature and the main direction of seismic imaging. The direction of imaging the complex media has been the main one of the projects that the national "85" and "95" reservoir geophysics key projects and "Knowledge innovation key project of Chinese Academy of Science" have been supported. Furthermore, we began the study for special oil field situation of our nation with the international research groups. Under the background, the author combined the thoughts of symplectic with wave equation pre-stack depth migration, and develops and efficient wave equation pre-stack depth migration method. The purpose of this work is to find out a way to imaging the complex geological goals of Chinese oilfields and form a procedure of seismic data processing. The paper gives the approximation of one way wave equation operator, and shows the numerical results. The comparisons have been made between split-step phase method, Kirchhoff and Ray+FD methods on the pulse response, simple model and Marmousi model. The result shows that the method in this paper has an higher accuracy. Four field data examples have also be given in this paper. The results of field data demonstrate that the method can be usable. The velocity estimation is an important part of the wave equation pre-stack depth migration. A. parallel velocity estimation program has been written and tested on the Beowulf clusters. The program can establish a velocity profile automatically. An example on Marmousi model has shown in the third part of the paper to demonstrate the method. Another field data was also given in the paper. Beowulf cluster is the converge of the high performance computer architecture. Today, Beowulf Cluster is a good choice for institutes and small companies to finish their task. The paper gives some comparison results the computation of the wave equation pre-stack migration on Beowulf cluster, IBM-SP2 (24 nodes) in Daqing and Shuguang3000, and the comparison of their prize. The results show that the Beowulf cluster is an efficient way to finish the large amount computation of the wave equation pre-stack depth migration, especially for 3D.

地质规律约束下的波阻抗反演

Impedance inversion is very important in seismic technology. It is based on seismic profile. Good inversion result is derived from high quality seismic profile, which is formed using high resolution imaging resolution. High-resolution process demands that signal/noise ratio is high. It is very important for seismic inversion to improve signal/noise ratio. the main idea is that the physical parameter (wave impedance), which describes the stratigraphy directly, is achieved from seismic data expressing structural style indirectly. The solution of impedance inversion technology, which is based on convolution model, is arbitrary. It is a good way to apply the priori information as the restricted condition in inversion. An updated impedance inversion technology is presented which overcome the flaw of traditional model and highlight the influence of structure. Considering impedance inversion restricted by sedimentary model, layer filling style and congruence relation, the impedance model is built. So the impedance inversion restricted by geological rule could be realized. there are some innovations in this dissertation: 1. The best migration aperture is achieved from the included angle of time surface of diffracted wave and reflected wave. Restricted by structural model, the dip of time surface of reflected wave and diffracted wave is given. 2. The conventional method of FXY forcasting noise is updated, and the signal/noise ratio is improved. 3. Considering the characteristic of probability distribution of seismic data and geological events fully, an object function is constructed using the theory of Bayes estimation as the criterion. The mathematics is used here to describe the content of practice theory. 4. Considering the influence of structure, the seismic profile is interpreted to build the model of structure. A series of structure model is built. So as the impedance model. The high frequency of inversion is controlled by the geological rule. 5. Conjugate gradient method is selected to improve resolving process for it fit the demands of geophysics, and the efficiency of algorithm is enhanced. As the geological information is used fully, the result of impedance inversion is reasonable and complex reservoir could be forecasted further perfectly.