914 resultados para Rio do Peixe Basin. Section devonian and diagenesis
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:
(1) I research on the relationship between elastic parameters, lithology and liquid. It is a physical base for pre-stack seismic inversion. I research all kinds of approximate expressions of Zoeppritz function. Then the relation of all kinds of approximate expressions can be confirmed. The geological model of water sand and gas sand in different depth was designed. Moreover I research on precision of all kinds of approximate expressions. (2) In process of seismic data which aim at amplitude recovery and apply in pre-stack seismic inversion, I advance to adopt double flow chart for different aim. Pre-stack noise elimination, real amplitude recovery and NMO correction of long offset are the key taches. (3) I made a systemic expatiate for the thinking and applicability about all kinds of expressions of elastic impedance. And mathematical model was applied to compare the precision with all kinds of expressions of elastic impedance. I propose a new pre-stack simultaneous inversion which is based on the Zoppritz function and simulated annealing algorithm. This method can ensure calculation precision of reflection coefficient from different incident angle and get a global optimum solution. Therefore this method improves the precision of pre-stack seismic inversion. (4) The object function of P-S wave pre-stack simultaneous inversion was established. I compared the precision and convergence between simultaneous inversion and P-wave inversion. And the results show that simultaneous inversion is superior to P-wave inversion. Through the study of AVO event of transformed wave, AVO characters of different kinds of gas sand were analyzed. (5) I carried out the study work of pre-stack seismic inversion for carbonate reservoir in middle of Tarim basin and sand shale reservoir in Sulige Area of Erdos Basin. The method and technology in this paper was applied to practical work. And I made a prediction for heterogeneous reservoir. Moreover it acquires a good application effect. Key Word: reflection coefficient, amplitude recovery, pre-stack seismic inversion, Heterogeneous reservoir,prediction.
Resumo:
The composition of the continental crust has long been a subject of interest to earth scientists as it can provide key information about the crustal growth and evolution of the continents. In this paper we make a comparative study on the lithological discrimination schemes featuring with the use of different seismic attributes, such as P-wave velocity, P- to S-wave velocity ratio, acoustic or elastic impedances, Lame impedances and high-sensitive identification factors. The results demonstrate that Lame impedances have more powerful constrains than other seismic attributes. In order to fully take the advantage of make the best of the different seismic response of crustal rock, we firstly use seismic attribute that have weak distinguish power to construct loose constrained lithological model, then use seismic attributes that have stronger distinguish power to tighten the constrains of lithological discrimination. We propose a joint scheme (chain constrain technique) by combing all available constrains to reduce the non-uniqueness in mapping rock distribution. We adopt chain constrain technique to construct lithological model beneath Tunxi-Wenzhou transect, Southeastern China, Manzhouli-Suifenhe transect, Northeastern China, and geophysical profile in Bohai Bay Basin, North China. The results can be suumarized as the follows: (1) We compare the sensitivity of different seismic factor constraints on rock types, and conclude that Lame impedances have tighter constrains than seismic velocity, Vp/Vs, density. (2) We propose chain constrains to construct lithological model from integrated geophysical data, and reduce the non-uniqueness in mapping rock distribution. (3) We reconstruct crustal lithological model beneath Tunxi-Wenzhou transect, Southeastern China. The results suggested that Jiangshan-Shaoxing fault is a crust-scale, and it is the boundary between Cathaysia and Yanthze blocks. (4) We construct crustal lithological model beneath Manzhouli-Suifenhe transect, Northeastern China. (5) We map the petrologic distribution along a geophysical profile in Bohai Bay Basin, North China, and construct a three-layered petrology model from the depth 2 km to about 10 km, consisted of basalt (the first layer), pelitic siltstone (the second layer), and silty mudstone and fine sandstone (the third layer).
Resumo:
Baijiahai uplift is an important hydrocarbon accumulation belt in eastern Jungger Basin, on which Cainan oilfield and lithologic hydrocarbon reservoir named Cai 43 have been discovered and both of them share the same target formation of Jurassic. However, in the subsequent exploration at this region, several wells that designed for lithologic traps of Jurassic were eventually failed, and that indicates the controlling factors of lithologic reservoir distribution are far more complicated than our previous expectation. This dissertation set the strata of the Jurassic in well Cai 43 region as the target, and based on the integrated analysis of structure evolution、fault sealing ability、simulations of sedimentary microfacies and reservoir beds、distribution analysis of high porosity-high permeability carrier beds、drive forces of hydrocarbons、preferential conduit system and conduit model as well as critical values of the reservoir physical properties for hydrocarbon charging, a special method that different from the conventional way to predict favorable lithologic traps was established. And with this method the controlling factors of the hydrocarbon reservoirs formation are figured out, and further more, the favorable exploration targets are point out. At Baijiahai uplift, fault plays as a crucial factor in the process of the hydrocarbon reservoir formation. In this study, it is found out that the availability of a fault that work as the seal for oil and gas are different. The critical value of the lateral mudstone smear factor (Kssf), which is used to measure the lateral sealing ability of fault, for oil is 3.9 while that for gas is 2.1; and the critical value of vertical sealing factor (F), which similarly a measurement for the vertical sealing ability of fault, for oil is 7.3 while that for gas is 5.1. Dongdaohaizi fault belt that possessed well lateral sealing ability since later Cretaceous have bad vertical sealing ability in later Cretaceous, however, it turns to be well now. Based on the comparison of the physical properties that respectively obtained from electronic log calculating、conventional laboratory rock analysis and the additive-pressure bearing laboratory rock analysis, we established the functions through which the porosity and permeability obtained though conventional method can be converted to the values of the subsurface conditions. With this method, the porosity and permeability of the Jurassic strata at the time of previous Tertiary and that in nowadays are reconstructed respectively, and then the characteristics of the distribution of high porosity-high permeability carrier beds in the evolution processes are determined. With the result of these works, it is found that both well Cai 43 region and Cainan oilfield are located on the preferential conduit direction of hydrocarbon migration. This conclusion is consistent with the result of the fluid potential analysis, in which fluid potential of nowadays and that of later Cretaceous are considered. At the same times, experiment of hydrocarbon injection into the addictive-pressure bearing rock is designed and conducted, from which it is found that, for mid-permeability cores of Jurassic, 0.03MPa is the threshold values for the hydrocarbon charging. And here, the conception of lateral pressure gradient is proposed to describe the lateral driving force for hydrocarbon migration. With this conception, it is found that hydrocarbons largely distributed in the areas where lateral pressure gradient is greater than 0. 03MPa/100m. Analysis of critical physical properties indicated that the value of the critical porosity and critical permeability varied with burial depth, and it is the throat radius of a certain reservoir bed that works as a key factor in controlling hydrocarbon content. Three parameters are proposed to describe the critical physical properties in this dissertation, which composite of effective oil-bearing porosity、effective oil-bearing permeability and preferential flow coefficient. And found that critical physical properties, at least to some extent, control the hydrocarbon distribution of Jurassic in Baijiahai uplift. Synthesize the content discussed above, this dissertation analyzed the key factors i.e., critical physical properties、driving force、conduit system and fluid potential, which controlled the formation of the lithologic reservoir in Baijiahai uplift. In all of which conduit system and fluid potential determined the direction of hydrocarbon migration, and substantially they are critical physical properties of reservoir bed and the lateral pressure gradient that controlled the eventually hydrocarbon distribution. At the same times, sand bodies in the major target formation that are recognized by reservoir bed simulation are appraised, then predict favorite direction of the next step exploration of lithologic reservoir.
Resumo:
Based on the theories of sequence stratigraphy and sedimentology, as well as comprehensive studies of seismic data, drilling data, core interpretation and setting of this area, the thesis presents an analysis for Mesozoic formation in Dinan uplift. By means of recognizing the boundary of the sequence, dividing and correlating the systems tract, Mesozoic of Dinan uplift is divided into ten sequences and twenty-five systems tracts during the establishment of the sequence framework. In the framework, some sequences are featured by mature systems of lowstand, water-transgression and highstand, while some undeveloped systems of lowstand or highstand. The main sedimentary facies in Mesozoic of Dinan uplift are braided river, meandering river, delta and lake. The braided river was divided into sandy river and rudaceous river by the lithology of the river channel and was divided into dry climate and wet climate condition by the color of the flood plain. Additionally, The concept of “wetland” is put forward for the first time and regarded as the consequence of wet climate. The analysis includes the classification of six types of traps: (1) stratigraphic overlap trap, (2) lithologic trap with updip pinchout, (3) stratigraphic unconformity trap, (4) fault-lithology trap, (5) fault trap, (6) anticlinal trap, and combining with the research of the characteristics and distribution rules for the known reservoir, it draws out that “fault control” is the petroleum accumulation pattern in this area, in which fault is the key element of the transporting system. Finally the thesis concludes the distribution characteristics and optimized some targets for the potential exploration zone.
Resumo:
The faulted slope zone of Biyang depression, a multiple hydrocarbon accumulation zone lying in a rich oil depression of Nanxiang basin, is a structural-sedimentary compounded slope, which is developed in Yanshanian period and has an area of 500 km2. From the ‘bottom up’, the developed strata may be divided into Yuhuangding formation in Neogene, Dacang Fang, Hetao-yuan plus Liaozhuang formations and Fenghuangzheng plus Pingyuan formation in Neogene, while Hetao-yuan formation is the main hydrocarbon-bearing target. Because of transtensional stress fields formed by persistent action of large-scale faulting in the south of the depression, sedimentary differential compaction in different stages, and tectonic inversion in later developing stage of the depression, a series of nose structure zones cut by different strike faults are developed. Therefore, the reservoir migration and accumulation are controlled by the complex faulted-nose structural zone, reservoir types are dominated by faulted-noses, faulted-blocks and fault-lithology, while lithology and stratigraphic unconformable reservoirs are locally developed. In combination with demands of practical production, applying with a new research approach of systematology and a combination with dynamic and static modes, guided by modern petroleum geologic theory, and based on previous data and studies, new techniques, methods of geophysical exploration, various computer simulation and forecasting techniques are applied in the new research of this paper. Starting from the structural features and formation mechanism, the forming mechanism of faulted structure, conditions and controlling factors of hydrocarbon accumulation, as well as various space-time allocation relationships in the process of accumulation are analyzed in the research. Besides that, the hydrocarbon migration, accumulation mechanism and dynamic evolution process are also discussed in the paper. Through the research, the accumulation rule of the faulted slope zone in faulted lake basin, the distribution and enrichment regularity of different reservoir controlling factors are systematically summarized. The summarizations indicate that the faulted slope is a favorable orientational zone, hydrocarbon is accumulated in nose structures and enriched in the main body of nose structures, faulted transformation zone and the ascent direction of laddering faulted blocks, the faults are the controlling factors, hydrocarbon accumulation zones controlled by fault-lithology are distributed along the faulting direcion. In the end, hydrocarbon migration and accumulation models of complex faulted-nose blocks are established. 1) Down cut model—‘flank-sheet’: the hydrocarbon is migrated like ‘sheet’ along a series of faults with parallel distribution and accumulated in the flank of nose structures; 2)Cross cut --‘axis-string’ model: the hydrocarbon cutting across the faults is migrated like ‘string’ and accumulated in the axis of nose structures. In view of different distribution models, reservoir forming combination patterns are divided and hydrocarbon reservoir evaluation exploration is carried out, which achieves good results in application. Key words: faulted slope zone; migration and accumulation model; reservoir controlling mechanism; reservoir-forming combination
Resumo:
Based on outcrop, borehole, seismic and regional geological data, the sequence stratigraphy, sedimentary facies of the Triassic in the western margin of the Zhugaer basin was studied, and favorable exploration target was forecasted. The major achievements include: (1) the Triassic in the western margin of the Zhugaer basin can be divided into 1 second-order sequence and 5 third-order sequences, which are, in ascending order, TSQ1, TSQ2, TSQ3, TSQ4, and TSQ5. TSQ1 is equivolent to Baikouquan formation, TSQ2 is equivolent to lower Kelamayi formation, TSQ3 is equivolent to upper Kelamai formation, TSQ4 is equivolent to lower and middle Baijiantan formation, and TSQ5 is equivolent to upper Baijiantan formation. Each sequence is divided into transgressive and regressive system tracts. Thus the sequence correlation framework is established. (2) The factors controlling development of sequences are analyzed, and it is believed that tectonic is the major controlling factor. Model of sequence development is summarized. (3)Through study on sedimentary facies, 6 types of facies are recognized: alluvial fan, fan delta, braided river, braided delta, delta and lake. Their microfacies are also recognized. In this study, it is proposed that the upper and lower Kelamayi formation(TSQ2、 TSQ3)is deposited by braided river instead of alluvial fan. This conclusion is of important theoretical and practical significance.(4) The sedimentary facies map of each sequence is compiled, and the sedimentary facies developed in each sequence is determined. In TSQ1, the sedimentary facies developed is alluvial fan and fan delta. In TSQ2, the sedimentary facies developed is mainly alluvial fan and fan delta in the north, and braided river and braided delta in the south. In TSQ3, the sedimentary facies developed is mainly braided river and braided delta. In TSQ4, the sedimentary facies developed is mainly braided delta in the north, and meandering delta in the south. In TSQ5, the sedimentary facies developed is mainly braided river and braided delta. (5) In the framework of sequence stratigrahpy, favorable areas for concealed traps are forecasted, and different types of traps are developed in different system tracts. (6) Favorable areas for future exploration are predicted.
Resumo:
Complex fault block reservoir is very important type in chinese oilfield.The reservoir have for many years and it has been the important issue of oil-gas exploration and development in china that how to increase reserves and production. Therefore,taking the Pucheng-oil field as an example, the article intensive study the geologic feature of oil pool, correctly recognize the rule of oil-gas accumulation and based on the fine representation of the characteristic of reservoir, research the remaining oil in high developed area,which is important for progressive exploratioon and development and taping the remaining oil. The article multipurpose uses the data of geology,drilling,wellloging, analysis and assay and so on, under the guidance multi-disciplinary theory, intensify the comprehension of the geologic feature of oil pool in high developed oil field. Based on the high-resolution sequence stratigraphic framework ,the article points out that Es_2 upper 2+3 reservoir in the south area of Pucheng oilfield is in the depositional environment of Terminal Fan, which has constant supply of sedimentary source ,and build the sedimentation model. Studies have shown that the major reservoir in work area is the distributary channel sandbody in central Sub-facies of Terminal Fan,secondary is both lateral accretion sandbodies of channel sands,nearby and far away from the channel overflowing sandbodies in front of the fan. The article analyze the effect of depth of burial of the reservoir, sandstone structure, strata pressure and bioturbate structure on control action of physical property for reservoir and indicate that deposition and diagenesis are major controlling factors.By building the model of reservoir heterogeneity, the article show the magnitude of reservoir heterogeneity ,the genesis and identification mark of Interlayer and build the the model of interlayer. in this area the vertical distribution of interlayer is complicated,but the intraed interlayer distribute steady. Thick interlayer is steady and the thin is relatively spreaded. By building models of fault sealing,stress field and fluid potential field of the south of the pucheng oil field, the regular pattern of fluid migration and accumulation runs out. By researching the elements of oil accumulation, migration pathway and accumulation period with quantification and semiquantitative methods,we bulit the oil-gas reservoir-forming mode of the south of the pucheng oil field,which will be the foundation of the rolling exploratory development in the future. We promulgated the master control element and the rule of distribution of the remaining oil with the upside 2+3 oil layer in shaer in the south of the pucheng oil field as an example.In this area, the formation and the distribution of the remaining oil is controled by the sedimentary microfacies, reservoir heterogeneity,fault and reservoir engineering. The remaining oil is concentrated in the vicinity of the gas cap, updip of the fault block and the area with incomplete flooding. Remaining oil saturation in some area can get 50%, so there are many places in which we can enhance oil recovery.
Resumo:
Xuanlong-type Hematite Deposits, distributed in Xuanhua and Longguang area in Hebei province and hosted in the Changchengian Chuanlinggou Formation of Mesoproterozoic, is an oldest depositional iron deposit characterized by oolitic and stromatolitic hematite and siderite. This thesis made an systematic study of its sedimentary, sedimentology, geochemistry, mineralogy and sequence stratigraphy. Based on above, the mechanism and background of biomineralization are discussed. There are four types of hematite ores including stromatolite, algal oolite, algal pisolite and oncolite. Based on detailed study on ore texture, the authors think both algal oolite and algal pisolite ores are organic texture ores, and related to the role of microorganisms. The process of blue-green algae and bacteria in the Xuanlong basin absorbing, adsorbing and sticking iron to build up stromatolite is the formation process of Xuanlong-type hematite deposit. Researches on ore-bearing series and ore geochemistry show that the enrichment of elements is closely related to the microorganism activities. Fe_2O_3 is enriched in dark laminations of stromatolite with much organic matter and SiO_2 in light laminations with detrital matters. The trace elements, especially biogenic elements, including V, P, Mo are enriched in ores but relatively low in country rocks. The paper also demonstrates on the sequence stratigraphy of hematite deposits and five sequences and twelve systems are divided. The characteristics of sequence stratigraphy show that the deposit-forming location has obviously selectivity and always exists under a transgressive setting. The oxygen isotope in hematite is about -2.2~5.7‰, which is similar to that of Hamlys iron formation of Australia but more negative than that of volcanic or hydrothermal iron deposits characterized by high positive values. The calculation by the result of oxygen isotope analysis shows that the temperature of ancient sea water was 48.53℃. The negative value of carbon isotope from siderite indicates its biogenic carbon source. Meanwhile, the occurrence of seismite in the ore-beds, which indicates the formation of hematite deposits is associated with frequent shock caused by structural movement such as distal volcano or ocean-bottom earthquake etc, show the occurrence of hematite deposits is eventual, not gradual. In shorts, Xuanlong-type hematite deposits were the result of interaction among geological setting of semi-isolated Xuanglong basin, favorable hot and humid climate condition, abundant iron source, microorganism such as algae and bateria as well as the fluctuation of the sea level.
Resumo:
Reformed basin is a basin that underwent multiple immense reformation after the sedimentary stage, the major geologic elements of the petroleum system in the prototyped basin are destroyed to a certain extent, and their petroleum system has been reconstructed. This type of basin is frequently found in the course of exploration both home and abroad. In China, especially in the western and southern part of China, the basins in which oil explorations have been conducted are mostly reformed basins. The reformed basins from Paleozoic, Late Mesozoic to Cenozoic are widely distributed in West and South China. They are, and moreover, will be a challenge for oil and gas exploration. The conventional investigation and exploration techniques used in the slightly reconstructed basin just don't work well when facing the reformed basin. Therefore, the study on the reformed basin, especially the study on the pool-forming mechanism and reservoir prediction becomes a focus and one of difficulties for the geologists overseas and domestic. Yingen-Ejinaqi Basin is a typical case of the Late Mesozoic and Cenozoic reformed basins in China. It locates in West China and is a exploration frontier with difficulties and no break through is made for years. A comprehensive research on it will be of significance for oil and gas exploration in similar basins of China. The late research for reformed basin in China now is mainly concentrated on basin classification, formation mechanism, geologic features, and survey technique, distribution regularity of oil accumulation and its dominating factors, assessment of oil exploration prospect and target zones, etc. On the other hand, the study on the pool-forming mechanism and reservoir prediction seems insufficient in systematization, and the research is deficient in methodology and combination of qualitative and quantitative studies, as well as the application of the new theory and techniques. The current efforts are mainly directed to structures (faults), sedimentation, the relationship between reservoir evolution and oil accumulation, and some other relevant fields. However, the application of the new theory and techniques seems to be insufficient such as petroleum system, pool-forming dynamics, fluid pressure compartment, and basin simulation, etc. So is the dynamic and integrated research. As a result, incomplete knowledge and understandings derived from the research on pool-forming mechanism and reservoir prediction often do not accord with rea-lity of the basin. The study and exploration under the guidance of this knowledge will inevitably lead to errors and failure. This paper, based on the previous study of the other geologists on reformed basins, with emphasis on "wholeness or systematic, dynamic and integrated" research, presents a reverse thinking of beginning from conserved units in the basin and the combination of qualitative and quantitative study with new theory and technique by building a geological model. The paper also puts forward a new thought for studying the oil & gas accumulation and reservoir prediction , and establishes a new research system for reformed basin. It is verified by the known reservoir and oil accumulation area in the basin and has a practical value for use and reference. The new ideas and achievements in this research are as following: 1.This is the first time that the system for studying the reformed basin and its pool-forming mechanism and reservoir prediction is presented. A reverse thinking and combination of qualitative & quantitative are applied here with emphasis on "wholeness or systematic, dynamic and integrated" research, new theory, techniques & methods comprehensive use and geologic models building. 2. Identifying criterion and methods, classifying schemes, and denominating principles for the conserved units of reformed basins are presented in this paper. The geologic model of conserved units of Yingen-Ejinaqi Basin has been built. It is a practical method when combined with the traditional way for basin survey and the conserved units study. 3.The dynamic sources of basin deformation are believed to be stress, gravity and thermodynamics. The stress and gravity are key factors in basin deformation and pool forming, especially stress. Scientific proof is provided by classifying the functional type, style and range of the stress, gravity and thermodynamics. 4.The pool forming and reservoir distribution of Yingen-Ejinaqi Basin are controlled by multiple factors or geologic conditions or/and co-controlled by both of them. The qualitative and quantitative research on petroleum system and basin modeling will help us understand and determine the pool-forming period of the conserved unit (timing), the oil migrating direction (orientation), the oil accumulating region (location), the oil distributing border (bordering) and the size of oil accumulation (quantification). Thus the pool-forming and distribution zones can be predicted. 5.Three generating modes (reform-succession type, reform-destroyed type and reform-regenerating type or reform-newborn type) of pool forming for reformed basins are presented here, together with the inner relationships between basin deformation type, overlapping style and pool-forming modes. The pool-forming modes are determined by deformation type and overlapping style. Reservoir distribution will be predicted based on the modes and other concrete pool-forming conditions. 6.The evaluation methods of the conserved units and zones and the parameter selection are reliable in optimal selecting of target zones. The technical terms, new ideas and methods for the study of reformed basins, the pool-forming mechanism and reservoir prediction are presented in this paper. The concepts and terms, the identifying criterion, the denominating principles, the generating modes for pool forming, the methods of reservoir prediction, and the evaluation techniques for conserved units and zones can be used for reference in studies on the petroleum exploration of reformed basins in China and abroad. It serves as a typical example for further research of the reformed basins and the geologic regulations of oil accumulation. It has a practical value of use and reference. The future research in the field of pool-forming mechanism of the reformed basins may well be on the process simulation of pool-forming dynamics of the reformed basins. Experimental work has been conducted to simulate the processes by using quantitative and qualitative methods combined. The further study in this field calls for more efforts.
Resumo:
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.
Resumo:
Jiyang & Changwei depressions are two neighboring depressions in Bahai Bay Basin, the famous oil rich basin in East China. The exploration activities in the past 40 years has proved that, within the basins, there exists not only plentiful sandstone hydrocarbon reservoirs (conventional), but also abundant special reservoirs as igneous rock, mudstone and conglomerate ones which have been knowing as the unconventional in the past, and with the prospecting activity is getting more and more detailed, the unconventional reservoirs are also getting more and more important for further resources, among which, the igneous lithological reservoir be of significance as a new research and exploration area. The purpose of this paper is, with the historical researches and data as base, the System Theory, Practice Theory and Modern Comprehensive Petroleum Geology Theory as guide, the theoretical and practice break through as the goal, and the existing problems in the past as the break through direction, to explore and establish a valid reservoir formation and distribution models for igneous strata in the profile of the eastern faulted basins. After investigating the distribution of the igneous rocks and review the history of the igneous rocks reservoirs in basins, the author focused on the following issues and correspondingly the following progresses have been made: 1.Come to a new basin evolution and structure model named "Combined-Basin-bodies Model" for Jiyang even Eastern faulted basins based on the study on the origin and evolution of Jiyang & Changwei basins, depending on this model, every faulted basin in the Bo-hai Bay Basin is consisted of three Basin-Bodies including the Lower (Mesozoic), Middle (Early Tertiary) and the Upper (Late Tertiary) Bodies, each evolved in different geo-stress setting and with different basin trend, shape and igneous-sedimentary buildings system, and from this one to next one, the basin experienced a kind of process named "shape changing" and "Style changing". 2. Supposed a serious of new realizations as follows (1) There were "multi-level magma sources" including Upper mantel and the Lower, Middle and even the Upper Shell magma Chambers in the historical Magma Processes in the basins; (2) There were "multi-magma accessing or pass" from the first level (Mantel faults) to the second, third and fourth levels (that is the different levels of fault in the basin sediment strata) worked in the geo-historical and magma processes; (3) Three tectonic magma cycles and more periods have been recognized those are matched with the "Basin -body-Model" and (4)The geo-historical magma processes were non-homogeneous in time and space scale and so the magma rocks distributed in "zones" or "belts". 3. The study of magma process's effect on basin petroleum conditions have been made and the following new conclusions were reached: (1) the eruptive rocks were tend to be matched with the "caped source rock", and the magma process were favorable to the maturing of the source rocks. (2) The magma process were fruitful to the accumulation of the non-hydrocarbon reservoirs however a over magma process may damage the grade of resource rock; (3) Eruptive activity provided a fruitful environment for the formation of such new reservoir rocks as "co-eruptive turbidity sandstones" and "thermal water carbonate rocks" and the intrusive process can lead to the origin of "metamorphism rock reservoir"; (4) even if the intrusive process may cause the cap rock broken, the late Tertiary intrusive rocks may indeed provide the lateral seal and act as the cap rock locally even regionally. All above progresses are valuable for reconstructing the magma-sedimentary process history and enriching the theory system of modem petroleum geology. 4. A systematic classification system has been provided and the dominating factors for the origin and distribution of igneous rock reservoirs have been worked out based on the systematic case studies, which are as follows: (1) The classification is given based on multi-factors as the origin type, litho-phase, type of reservoir pore, reservoir ability etc., (2) Each type of reservoir was characterized in a detailed way; (3) There are 7 factors dominated the intrusive reservoir's characteristics including depth of intrusion, litho-facies of surrounding rocks, thickness of intrusive rock, intrusive facies, frequency and size of the working faults, shape and tectonic deformation of rock, erosion strength of the rock and the time of the intrusion ect., in the contrast, 4 factors are for eruptive rocks as volcanic facies, frequency and size of the working faults, strength of erosion and the thermal water processing. 5. Several new concept including "reservoir litho-facies", "composite-volcanic facies" and "reservoir system" ect. Were suggested, based on which the following models were established: (1) A seven reservoir belts model for a intrusive unit profile and further more, (2) a three layers cubic model consisted of three layer as "metamorphic roe layer", "marginal layer" and "the core"; (3) A five zones vertical reservoir sequence model consisted of five litho-facies named A, B, C, D and E for a original lava unit and furthermore three models respectively for a erosion, subsidence and faulted lava unit; (4) A composite volcanic face model for a lava cone or a composite cone that is consisted of three facies as "crater and nearby face", "middle slope" and "far slope", among which, the middle slope face is the most potential reservoir area and producible for oil & gas. 6. The concept of "igneous reservoir" was redefined as the igneous, and then a new concept of "igneous reservoir system" was supposed which means the reservoir system consisted of igneous and associated non-igneous reservoirs, with non-hydrocarbon reservoir included. 7. The origin and distribution of igneous reservoir system were probed and generalized for the exploration applications, and origin models of the main reservoir sub-systems have been established including those of igneous, related non-igneous and non-hydrocarbon. For intrusive rocks, two reservoir formation models have been suggested, one is called "Original or Primary Model", and the another one is "Secondary Model"; Similarly, the eruptive rock reservoirs were divided in three types including "Highly Produced", "Moderately Produced" and "Lowly Produced" and accordingly their formation models were given off; the related non-igneous reservoir system was considered combination of eight reservoirs, among which some ones like the Above Anticline Trap are highly produced; Also, the non-hydrocarbon. Trap system including five kinds of traps was discussed. 8. The concept models for four reservoir systems were suggested, which include the intrusive system consisted of 7 kinds of traps, the land eruptive system with 6 traps, the under water eruptive system including 6 kinds of traps and the non-hydrocarbon system combined by 5 kinds of traps. In this part, the techniques for exploration of igneous reservoir system were also generalized and probed, and based on which and the geological progresses of this paper, the potential resources and distributions of every reservoir system was evaluated and about 186 millions of reserves and eight most potential non-hydrocarbon areas were predicted and outlined. The author believe that the igneous reservoir system is a very important exploration area and its study is only in its early stage, the framework of this paper should be filled with more detailed studies, and only along way, the exploration of igneous reservoir system can go into it's really effective stage.
Resumo:
Jiyang depression is one of the most important petroleum production basins in China. The petroleum pools, found easier, have been densely explored and developed. At present, the subtle traps are becoming the main exploring aims. A lot of Tertiary sand-conglomerate body petroleum pools, as one of the important subtle pools, have been discovered recently. It is necessary and urgent to study deeply the developing characteristics and petroleum pool distribution of Tertiary sand-conglomerate bodies in Jiyang Depression. The present dissertation has concluded the main developing characteristics of the Tertiary sand-conglomerate bodies in Jiyang Depression, and studied the sand-conglomerate bodies in Chengnan Fault Zone in detail. Depending on the synthesized studies of geology, geophysics and logging data, the following conclusions have been arrived at. Four criterion layers in Member 3 of Shahejie Formation, according to the depositional cycle analyses, have been established for the subdivision of different layers of sand-conglomerate bodies and the correlation of different sand-conglomerate bodies. It indicated that the alluvial delta, delta-fan, alluvial fan, shallow water fan , deep water turbidite , fan-front turbidite are the six kinds of sand-conglomerate bodies, which have been distinguished in Jiyang Depression with the study of genetic types, characteristics and distribution of sand-conglomerate bodies. The shallow water fan, steep slope deep water turbidite and fan-front turbidite were the main types of sand-conglomerate bodies developed in Chengnan steep slope. Their identification and distribution have been described in detail. The development and distribution of sand-conglomerate bodies were resulted by fault depressing, palco-climate change and channel or trough on the uplift. The fault depressing is the most important-factor to the episodic developing of sand-conglomerate bodies. An episodic developing genetic mode has been established by the contrast analyses between episodic fault depressing and climate change cycles. The hydrocarbon accumulation in the sand-conglomerate bodies in the steep slope was correlated with fan types, depositional phases, fault depressing and diagenesis. Sand-conglomerate wedge out (include up-oblique and onlap), lithological wedge out, mud screen (for anticline), fault plugging (by mud opposite sand, mud daubing) are the 5 possible mechanisms of oil accumulation. Lithological pool, stratigraphic pool and tectonic pool and lithologic-tectonic complex pool, and 9 subtypes of petroleum pools have been detected. It is easy for different pools to be combined as a complex reservoir, which was distributed along the syn-depositional fault slopes. The sand-conglomerate bodies in deep sag were usually evaluated as pore zone for hydrocarbon accumulation before. In fact, they are potential. Because of fan-front turbidite sands were especially developed in these zones, the sands have a close connection with the oil mud, and lithological pools can be expected to find in these zones. Chengnan fault slope was main channel of oil migration, and mud screen is the principle key for the oil accumulation in the sand-conglomerate bodies. If there was no mud between the sand-conglomerate bodies or on the top of sand-conglomerate bodies, the sand-conglomerate bodies would connect each other and there would be no dense material to hold up the oil migration along the slope. As the sand-conglomerate bodies could not been taken as a screen, the mud screen is the key for developing pool in this slope. According to this principle, about 6 potential traps, such as C915 block, C913 block, C916 block, south of Y109 well block, Y104 block and Y153 block, were selected for exploration and development.
Resumo:
Jurassic is an important hydrocarbon-bearing formation in Junggar Basin. Analyzing in strata sequence stratigraphy and hydrocarbon formation has both theoretical and practical values. First of all, strata sequence stratigraphy of continental facies is a new development and supplement in the theory of stratigraphic geology. Stratum of continental facies, unlike sea facies, has rich sup-plements, rapid facies changes, and was influenced slightly by sea level changes. The structural background and sedimentary environment of the basin in west China are greatly different from those of the basins in east China. So it is important to build the patterns of strata sequence stratigraphy in west China basins. Secondly, it is also of significance to find out all kinds of traps, for the dominant types are structural ones so far. After 50 years exploration, the stratigraphic or litholigic traps have become the main concern. This desertation is mainly focused on establishing the isochronal strtaum frame for Junggar Basin to show the evolvement characters of the basin sediment system and the regionalstuctrue background. By analyzing the conditions and patterns of the regional oil and gas bearing formations with typical cross-sections, we have established the patterns of sedimentary conditions for different reserviors. By authur's study, several fruitful results have been obtained in the following: Strata sequence frame and evolvement characteristics of Jurassic: By studing strata sequence, Jurassic has been divided into 2 second rank strata sequences and 3 third rank strata sequences based on the interface unconformities. Only 2 fourth rank strata sequences were grouped in BaDaoWan group. Also different seismic facies and sediment units have been recognized with the establishment of the of sediment system model. The oil-gas system characteristics in Jurassic: We conclude that hydrocar bon resources have the best oil potential. Potential of coal, carbonaceous and dark mudstone were reduced in turn. In this thesis we have made the evaluation of three hydrocarbon sources and the distribution oil-gas resource, and studied the potentials of hydrocarbon and evolvement for each kind of micro-component of the two main resource rocks. Prediction of paleo-temperature: In Junggar basin the evolvement of paleo-ground temperature can be divided into three stages. From Carboniferous to early Permian grads of ancient ground temperature was 8-5 ℃/100m, 5-3 ℃/100m from later period of Permian to end Trias, 3-2 ℃/100m from Jurassic to early Tertiary. Patterns of Jurassic hydrocarbon-bearing reserviors: There were two kinds of hydrocarbon source of Permian and Jurassic. They form different hydrocarbon - bearing systems. Six fundamental hydrocarbon - bearing trap modeS have been established. Directions for later exploration: There were two kinds of regional belts in Jurassic, One is structural belt caused by Yanshan and Ximalaya process, and the other was the stratum one caused by paleostructural rises.
Resumo:
River is a major component of the global surface water and CO2 cycles. The chemistry of river waters reveals the nature of weathering on a basin-wide scale and helps us understand the exogenic cycles of elements in the continent-river-ocean system. In particular, geochemical investigation of large river gives important information on the biogeochemical cycles of the elements, chemical weathering rates, physical erosion rates and CO2 consumption during the weathering of the rocks within the drainage basin. Its importance has led to a number of detailed geochemical studies on some of the world's large and medium-size river systems. Flowing in the south of China, the Xijiang River is the second largest river in the China with respect to its discharge, after the Yangtze River. Its headwaters drain the YunGui Plateau, where altitude is approximately 2000 meters. Geologically, the carbonate rocks are widely spread in the river drainage basin, which covers an area of about 0.17xl06 km2, i.e., 39% of the whole drainage basin. This study focuses on the chemistry of the Xijiang river system and constitutes the first geochemical investigation into major and trace elements concentrations for both suspended and dissolved loads of this river and its main tributaries, and Sr isotopic composition of the dissolved load is also investigated, in order to determine both chemical weathering and mechanical erosion rates. As compared with the other large rivers of the world, the Xijiang River is characterized by higher major element concentration. The dissolved major cations average 1.17, 0.33, 0.15, and 0.04 mmol I"1 for Ca, Mg, Na, and K, respectively. The total cation concentrations (TZ+) in these rivers vary between 2.2 and 4.4 meq I'1. The high concentration of Ca and Mg, high (Ca+Mg)/(Na+K) ratio (7.9), enormous alkalinity and low dissolved SiO2/HCO3 ratio (0.05) in river waters reveal the importance of carbonate weathering and relatively weak silicate weathering over the river drainage basin. The major elements in river water, such as the alkalis and alkaline-earths, are of different origins: from rain water, silicate weathering, carbonate and evaporite weathering. A mixing model based on mass budget equation is used in this study, which allows the proportions of each element derived from the different source to be calculated. The carbonate weathering is the main source of these elements in the Xijiang drainage basin. The contribution of rainwater, especially for Na, reaches to approximately 50% in some tributaries. Dissolved elemental concentration of the river waters are corrected for rain inputs (mainly oceanic salts), the elemental concentrations derived from the different rock weathering are calculated. As a consequence, silicate, carbonate and total rock weathering rates, together with the consumption rates of atmospheric CO2 by weathering of each of these lithologies have been estimated. They provide specific chemical erosion rates varying between 5.1~17.8 t/km2/yr for silicate, 95.5~157.2 t/km2/yr for carbonate, and 100.6-169.1 t/km2/yr for total rock, respectively. CO2 consumptions by silicate and carbonate weathering approach 13><109and 270.5x10 mol/yr. Mechanical denudation rates deduced from the multi-year average of suspended load concentrations range from 92-874 t/km2/yr. The high denudation rates are mainly attributable to high relief and heavy rainfall, and acid rain is very frequent in the drainage basin, may exceed 50% and the pH value of rainwater may be <4.0, result from SO2 pollution in the atmosphere, results in the dissolution of carbonates and aluminosilicates and hence accelerates the chemical erosion rate. The compositions of minerals and elements of suspended particulate matter are also investigated. The most soluble elements (e.g. Ca, Na, Sr, Mg) are strongly depleted in the suspended phase with respect to upper continent crust, which reflects the high intensity of rock weathering in the drainage basin. Some elements (e.g. Pb, Cu, Co, Cr) show positive anomalies, Pb/Th ratios in suspended matter approach 7 times (Liu Jiang) to 10 times (Nanpan Jiang) the crustal value. The enrichment of these elements in suspended matter reflects the intensity both of anthropogenic pollution and adsorption processes onto particles. The contents of the soluble fraction of rare earth elements (REE) in the river are low, and REE mainly reside in particulate phase. In dissolved phase, the PAAS-normalized distribution patterns show significant HREE enrichment with (La/Yb) SN=0.26~0.94 and Ce depletion with (Ce/Ce*) SN=0.31-0.98, and the most pronounced negative Ce anomalies occur in rivers of high pH. In the suspended phase, the rivers have LREE-enriched patterns relative to PAAS, with (La/Yb) SN=1 -00-1 .40. The results suggest that pH is a major factor controlling both the absolute abundances of REE in solution and the fractionation of REE of dissolved phase. Ce depletion in river waters with high pH values results probably from both preferential removal of Ce onto Fe-Mn oxide coating of particles and CeC^ sedimentation. This process is known to occur in the marine environment and may also occur in high pH rivers. Positive correlations are also observed between La/Yb ratio and DOC, HCO3", PO4", suggesting that colloids and (or) adsorption processes play an important role in the control of these elements.