56 resultados para stratigraphy
Resumo:
Based on the study of sequence stratigraphy, modern sedimentary, basin analysis, and petroleum system in abrupt slop of depression, this paper builds sedimentary system and model, sandy bodies distribution, and pool-forming mechanism of subtle trap. There are some conclusions and views as follows. By a lot of well logging and seismic analysis, the author founded up the sequence stratigraphic of the abrupt slope, systematically illustrated the abrupt slope constructive framework, and pointed out that there was a special characteristics which was that south-north could be divided to several fault block and east-west could be carved up groove and the bridge in studying area. Based all these, the author divided the studying area to 3 fault block zone in which because of the groove became the basement rock channel down which ancient rivers breathed into the lake, the alluvial fan or fan delta were formed. In the paper, the author illustrated the depositional system and depositional model of abrupt slope zone, and distinguished 16 kinds of lithofacies and 3 kinds of depositional systems which were the alluvial fan and fan-delta system, lake system and the turbidite fan or turbidity current deposition. It is first time to expound completely the genetic pattern and distributing rule of the abrupt slope sandy-conglomeratic fan bodies. The abrupt slope sandy-conglomeratic fan bodies distribute around the heaves showing itself circularity shape. In studying area, the sandy-conglomeratic fan bodies mainly distribute up the southern slope of Binxian heave and Chenjiazhuang heave. There mainly are these sandy-conglomeratic fan body colony which distributes at a wide rage including the alluvial fan, sub-water fluvial and the turbidite fan or the other turbidity current deposition in the I fault block of the Wangzhuang area. In the II fault block there are fan-delta front and sub-water fluvial. And in the Binnan area, there mainly are those the alluvial fan (down the basement rock channel) and the sandy-conglomeratic fan body which formed as narrowband sub-water fluvial (the position of bridge of a nose) in the I fault block, the fan-delta front sandy-conglomeratic fan body in the H fault block and the fan-delta front and the turbidity current deposition sandy-conglomeratic fan body in the m fault block. Based on the reservoir outstanding characteristics of complex classic composition and the low texture maturity, the author comparted the reservoir micro-structure of the Sha-III and Sha-IV member to 4 types including the viscous crude cementation type, the pad cementation type, the calcite pore-funds type and the complex filling type, and hereby synthetically evaluated 4 types sandy- conglomeratic fan body reservoir. In the west-north abrupt slope zone of Dongying Depression, the crude oil source is belonging to the Sha-III and Sha-IV member, the deep oil of Lijin oilfield respectively come from the Sha-III and Sha-IV member, which belongs to the autogeny and original deposition type; and the more crude oil producing by Sha-IV member was migrated to the Wangzhuan area and Zhengjia area. The crude oil of Binnan oil-field and Shanjiasi oil-field belongs to mixed genetic. It is the first time to illustrate systematically the genetic of the viscous crude that largely being in the studying area, which are that the dissipation of the light component after pool-forming, the biological gradation action and the bath-oxidation action, these oil accumulation belonging to the secondary viscous crude accumulation. It is also the first time to compart the studying area to 5 pool-forming dynamical system that have the characteristic including the common pressure and abnormal pressure system, the self-fountain and other-fountain system and the closing and half-closing system etc. The 5 dynamical systems reciprocally interconnected via the disappearance or merger of the Ethology and the fluid pressure compartment zone, the fault and the unconformity surface, hereby formed duplicated pattern oil-gas collecting zone. Three oil-gas pool-forming pattern were founded, which included the self-fountain side-direction migrated collecting pattern, the self-fountain side-direction ladder-shape pool-forming pattern and the other-fountain pressure releasing zone migrated collecting pattern. A series of systemic sandy-conglomeratic fan bodies oil-gas predicting theory and method was founded, based on the groove-fan corresponding relation to confirm the favorable aim area, according as the characteristic of seismic-facies to identify qualitatively the sandy-conglomeratic fan bodies or its scale, used the temporal and frequency analysis technique to score the interior structure of the sandy- conglomeratic fan bodies, applied for coherent-data system analysis technology to describe the boundary of the sandy-conglomeratic fan bodies, and utilized the well logging restriction inversion technique to trace quantificational and forecast the sandy-conglomeratic fan bodies. Applied this technique, totally 15 beneficial sandy-conglomeratic fan bodies were predicted, in studying area the exploration was preferably guided, and the larger economic benefit and social benefit was acquired.
Resumo:
The foundation of reservoir model and residual oil prediction have been the core of reservoir detailed description for improved oil production and enhanced oil recovery. The traditional way of sandstone correlation based on the geometrical similarity of well-logs which emphasizes "based on the cycle and correlating from larger to smaller" has shown its theoretical limits when explaining the correlating and the scale, geometry, continuity, connectivity of sandstones and the law of the reservoir property. It has been an urgent and difficult subject to find new theory and methods to solve the reservoir correlation and property prediction. It's a new way to correlate strata and found framework of reservoir through the process-response analysis in the base-level cycles. And it is also possible to analyze the reservoir property in reservoir framework. Taking the reservoir of zonation 6-10 in S3~2 of Pucheng Oil Field in Henan Province as an example, we founded the detailed reservoir stratigraphic framework through base-level correlation. In the strata frame, sediment distribution and its development are discussed based on sediment volume partitioning and facies differentiation analysis. Reservoir heterogeneities and its relation to base-level are also discussed. The analysis of primary oil distribution shows the base-level controlled oil distribution in reservoir. In this paper, subjects as following are discussed in detail. Based on the analysis of sedimentary structure and sedimentary energy, the facies model was founded. Founding stratigraphy framework through base level analysis In the studying zone, one long term cycle, 6 middle term cycles and 27 short term cycles was identified and correlated. 3 Predicting the property of reservoir for improving oil development The base level controlled the property of sandbody. The short and very short term cycle controlled the pattern of heterogeneities in sandbody, and the middle and long term cycle controlled the area and inter-layer heterogeneities. On the lower location of the middle and long term base level, the sandbody is well developed, with a wide area and large thickness, while on the high location of base level, there is an opposite reservoir character. 4 The studying of reservoir development response and oil distribution making a solid base for development adjustment Primary oil distribution is controlled by base level location. It tells that the sandbody on the high base level location was poor developed for its difficulty to develop. While on the low location of the base level, the sandbody is well developed for its relative easy to develop and dominant role in the development, but high residual oil for its high original oil content.
Resumo:
This dissertation tries to combine the new theories of high-resolution sequence stratigraphy and reservoir architecture with fine sedimentology to form a integral theory system -"high-resolution sequence sedimentology", which can be applied widely ranging from the early petroleum exploration to the tertiary recovery stage in marine and terrestrial basin. So the west slope area in south of Songliao basin, in which, early-fine exploration have been developed, and Xingnan area of Daqing placantictine in high water-bearing and tertiary recovery stage, are selected as target areas to research and analyze. By applying high-resolution sequence stratigraphy theory as well as analysis of source area-facies, the west slope area has been divided into two source areas and three drainage systems and the following conclusions have been drawn: three high values sandstone areas, two sandstone pinchout zones and one stratigraphic pinchout overlap; the facies between Baicheng-Tongyu drainage system is frist ascertained as large-scale argillaceous filled plain facies; fine-grained braided channel-delta depositional system has been found; plane sedimentary facies and microfacies maps of different-scale sequence have been completed, and then twenty-eight lithologic traps have been detected in the east of Taobao-Zhenlai reverse fault zone; In no exploration area of the west, large-scale stratigraiphic overlap heavy oil reservoirs has first been found, which has become an important prograss. In Xingnan area, in the view of high-resolution sequence stratigraphy, the surface of unconformity (the bottom of SSC13) in P I group has been identified, and the following method and technique have been advanced: the division and correlation methods of short-scale base-level cycle sequence (SSC); the comprehensive research methods of SSC plane microfacies; the division technique of hierarchy and type of flow unit, the origin of large-scale composite sandbody and flow unit; And ,on the basis of these, 103 monosandstone bodies and 87 flow units of the third levels have been identified, and four levels of flow units model of five sandstone-bodies types have been established. Because it is a very difficult task all over the world to research architecture in subsurface monosandstone body, brings forward a series of techniques as follows: technique of researching architecture of thin interbed in subsurface monosandstone body; classification, type and liquid-resisting mechanism of thin interbed; multiple-remember vertical subsequence model of remaining oil in monosadstone body. Models of heterogeneity and architecture of thin interbed in five types of monosandstone body have been established. Applying these techniques, type and distribution of remaining oil in different types of monosandstone bodies have been predicated.
Resumo:
With the development of petroleum exploration, subtle reservoir has become the main exploration object in Dongying Depression, which requires some new technologies and methods to further reveal the geological characteristics in step with the mature exploration stage. In this paper, on the references to the studies of petroleum system and multiple oil-gas accumulation belt with flexible maneuverability, and the application of systematic theory, the concept of reservoir assemblage is initially defined as "the association of active source rock(s) and hydrocarbon reservoir(s) that are genetically related, with the bridge of pathway system in an oil and gas bearing basin". Compared with the theories of petroleum system and multiple oil-gas accumulation belts, it emphasizes on the processes of petroleum migration and accumulation and the correlation among active source rock, trapped hydrocarbon and migration pathway, and has been confirmed to be more suitably applied to high maturely explored basin. In the first study of this paper, sequence stratigraphy and subtle analytical technology of source rock have been employed to find that two categories of source rock with their characteristic types of organic matter and substantial states occurred in Dongying Depression. The first category, consisting of the oil shales within the third-order sequences of lacustrine expanding system tracts in the upper interval of the fourth Member of Shahejie Formation and both in the middle and lower intervals of the third Member of Shahejie Formation, is featured with the highest abundance of total organic matter (TOC) and the strongest abilities of hydrocarbon generation and expulsion, which is classified into the standard of good hydrocarbon source rock. Exploration assessment confirmed that about 70-80% of hydrocarbon in Dongying Depression came from this set of source rock for which the low sedimentary rate and strong oxygen-free environment would play the key role during its generation. The second category, composed of organic matter of dark mudstone in high stand system tracts in the upper and middle intervals of the third Member of Shahejie Formation, has been characterized by low content of total organic matter which mostly dispersedly distributes, and formed in the pre-delta to delta front environments. In classification, it belongs to the ordinary standard of source rocks. In the second research part, through the studies of high frequency sequence stratigraphy, fault geometry and active history combining with geochemistry of fluid inclusion and nitrogen compound and simulation test of hydrocarbon migration and accumulation, the faults have been thought to be the principal conduits, and the sandy bodies and unconformities might played the complementary pathways for hydrocarbon migration and accumulation in Dongying Depression of the continental faulted basin. Therefore, the fault activities may mainly constrain on the development of hydrocarbon pathways in space and time. Even more, using homogenization temperatures of fluid inclusion in digenetic minerals, three critical moments for hydrocarbon accumulation have been determined as well in Dongying Depression, which happened during the late stage of Dongying Formation (Ed), the early stage of Guantao Formation (Nig) and the early stage of Minghuazhen Formation (Nim), respectively. Comparatively, the last stage is looked as the main forming-reservoir period, which has also been supported by the results of geochemical analysis and simulation experiments of hydrocarbon generation and expulsion. Clearly, the times of hydrocarbon migration and accumulation are consistent with those of the fault activities in Dongying Depression, which indicate that tectonic activities would control the forming-reservoir. A conceptual model of faulting-episodic expulsion coupled with episodic forming-reservoir has then been established in this study. In the third part of this paper, some focusing areas were selected for the fine descriptions of pathway distribution and forming-reservoir, which has given four types of reservoir assemblage in terms of the main pathway and its correlation with the reservoir and trap: (1) mainly consisted of sandy bodies; (2) mainly consisted of faults; (3) mainly consisted of unconformities; and (4) their complex with two or three types of pathways. This classified criteria has also been applied to access the risk of some prospected traps in Dongying Depression. Finally, through the application of reservoir assemblage integrated with pathway distribution to all the prospective targets in Dongying Depression, the new favorably hydrocarbon accumulated belts have been figured out, and more subtle reservoirs have also been found. For examples, during 2000 and 2002, in the mature exploration areas, such as Liangjialou and Shengtuo structural closures etc., newly proved reserves were 2274 * 104t, and forecasted oil reserves 5660-5860xl04t; and in the predicted favorable areas, newly additional controlled oil reserves was 3355xl04t. Besides those, many other favorable exploration areas need to be further appraised.
Resumo:
Turbidity sandstone reservoirs have been an important field of hydrocarbon exploration and development in the basins all over the world, as well as in China. Lithologic pools are composed of turbidity sandstones and other sandstones are frequently found in the Jiyang Depression that is a Mesozoic-Cenozoic non-marine oil-bearing basin. The Dongying Sag lies in the sedimentary center of the basin. The subtle traps with turbidity reservoirs are generally difficult to be predicted and described by using current techniques. The studies on turbidity reservoirs plays thus an important theoretical and theoretical practical role in exploration and development in the Jiyang Depression. The attention is, in this thesis, focused on the petrologic properties and oil accumulating behaviors in lake turbidity sedimentary systems in the middle part of the third section of Shahejie Formation in the Dongying Sag, especially in Dongxin area, which lies on the central uplift of the Sag. The paper has disclosed the origin types of turbidity sandstones, distribution pattern and controlling factors of turbidity sandstones, and set up hydrocarbon accumulation patterns of the middle part of the third section of Shahejie Formation in Dongxin, based on nonmarine high resolution sequence stratigraphy, event sedimentology and new theories of hydrocarbon forming. By studying prediction method and technology of turbidity sandstone reservoirs, using precise geological model developing, new techniques of high resolution seismic inversion constrained by logging, the paper has forecast low permeability turbidity sandstone reservoirs and pointed out advantage exploration aims to progressive exploration and development. The paper has obtained mainly many productions and acknowledges as follows: 1.Turbidity sandstone reservoirs of the third section of Shahejie Formationin Dongying Sag are formed in such specifical geological background as rift and extension of basin. The inherited Dongying delta and transgression make up many turbidity distribution areas by overlaying and joining together. The hydrocarbon migrates from depression area to adjacent turbidity sandstone continuously. Accumulation area which is sufficient in oil is formed. 2.The paper has confirmed distinguishable sign of sequence boundary , established stratigraphic framework of Dongying Sag and realized isotime stratigraphic correlation. Es3 of Dongying delta is divided into eleven stages. Among them, the second period of the lower section in Es3, the sixth period of the middle section in Es3, the third period of the upper section in Es3 correspond to eleven sedimentary isotime surface in seismic profile, namely Es3 is classified into eleven Formations. 3.According to such the features of turbidity sandstone as deep in burial, small in area, strong in subtle property, overlaying and joining together and occurring in groups, management through fault and space variations of restriction quantum are realized and the forecast precision of turbidity sandstone by using precise geological model developing, new techniques of high resolution seismic inversion constrained by logging, based on the analysis of all kinds of interwell seismic inversion techniques. 4.According to the features of low permeable turbidity sandstone reservoirs, new method of log interpretation model is put forward. At the same time, distinguish technology of familiar low resistivity oil layer in the turbidity sandstone reservoirs is studied based on petrophysical laboratory work and "four properties" interrelationship between lithological physical Jogging and bearing hydrocarbon properties. Log interpretation model and reservoir index interpretation model of low resistivity oil layer are set up. So the log interpretation precision is improved. 5.The evolution law and its difference of the turbidity sandstone are embodies as follows: the source of sediments come from the south and east of the study area in the middle period of Es3. East source of sediments is pushed from west to east. However, the south source supply of sediments in the early and middle period of Es3 is in full, especially in Es3. subsequently, the supply is decreased gradually. Turbidity fan moves back toward the south and the size of fan is minished accordingly. The characteristic of turbidity sandstone in Dongying Sag is different in different structural positions. Dongxin in the middle-east of the central lift and Niuzhuang Sag He in Dongying delta front and prodelta deep lake subfacies. Although the turbidity sandstone of the two areas root in the Dongying delta sedimentary system, the sand body has different remarkably characteristic. 6.The sedimentary model of the turbiditys in study area have three types as follows: (1) collapse turbidity fan in respect of delta; (2) fault trench turbidity fan; (3) other types of microturbidity sandstone. Middle fan and outer fan, can be found mainly in sublacustrine fan. Middle fan includes braided channel microfacies, central microfacies and braided interchannel microfacies, which is main prospecting oil-bearing subfacies. The middle section of the third section of Shahejie Formation in study area (for example the central lift) can be divided into middle-lower and upper part. The middle-lower part is characteristic of turbidity fan. The upper part is sedimented mainly by delta-collapse fan. 7.The turbidity reservoirs of the middle part of the third section of Shahejie Formation in study area characterize by low maturity both in component and texture, strong in diagenesis and low in permeability. The reservoir can be classified into four types. Type III is the body of reservoir and comprises two types of H a and HI b. M a belongs to middle porosity - low permeability reservoir and distributes in the central lift. Hlb belongs to low porosity - low permeability and distributes in Haojia region. 8.A11 single sand body of lens turbidity reservoir of the middle part of the third section of Shahejie Formation in study area are surrounded by thick dark source rocks. The oil-water system is complex and behaves that every sandstone is single seal unit. The water body is 1/3-1-5 of the sand body. The edge water is not active. The gas exists in the top of reservoir in the form of mixed gas. For far-range turbidity fan with big scale channel, the area and volume of sand body is large and the gap is big in oil packing degree. There are lots of edge water and bottom water, and the latter increases rapidly during the course of development. 9.By exerting the modern hydrocarbon forming theories, the third section of Shahejie Formation in study area belongs to abnormally pressured fluid compartment. The lithological reservoir of the third section of Shahejie Formation is formed in the compartment. The reservoir-formed dynamic system belongs to lower self-source enclosed type. The result and the practice indicate that the form and accumulation of lithological oil reservoirs are controlled by the temperature and pressure of stratum, microfacies, thickness of sand body, fault and reservoir heterogeneity. 10. Based on studies above, the emphases focus on in south and north part of Dongying structure, west Dongxin region and south part Xinzhen structure in the application of production. The practice proves that the turbidity sandstone reservoirs in Ying 11 block and the fault-lithological reservoirs in Xin 133 block have been obtained significant breakthrough. The next target is still sandstone groups of the third section of Shahejie Formation in the bordering areas of Dongxin region for instance Xin 149 area, He 89 area, Ying 8 area etc.
Resumo:
The Nihewan Basin is a key area for research into human occupation at high northern latitudes in northeast Asia after the initial expansion of early humans out of Africa. Well-developed late Cenozoic lacustrine deposit sequence in this basin offers a unique opportunity to address this issue. In this thesis, detailed magnetostratigraphic investigation coupled with mineral magnetism was conducted on the Donggutuo and Cenjiawan sections in the eastern basin, where lacustrine deposits sequences containing the Donggutuo, Maliang and Cenjiawan Paleolithic sites are well developed. The sequences are mainly composed of grayish-white clays, grayish-green clayey silts, grayish-yellow silts and fine-grained brown sands, which have recorded reliable polarity variations of geomagnetic field.Characteristics of the anisotropy of magnetic susceptibility show that the sediments have preserved typical original magnetic fabric for sediments, indicating that the strata were developed in a low-energy lake environment and were never perturbed by tectonic stress since deposition. High-temperature magnetic susceptibility measurements (x-T) of representative specimens and demagnetization experiments indicate that the dominant magnetic mineral and remanent carrier at the two sections is magnetite. In addition, hematite and possibly minor maghemite exists in some portions of the sequences. The majority of the samples have relatively simple demagnetization behaviors. After removal of soft magnetic components, the stable characteristic remanent magnetizations (ChRMs) are isolated, which can represent the original remanences.The Donggutuo section mainly records the Brunhes chron, the Matuyama chron and the Jaramillo subchron. The Maliang stone artifact layer occurs just below the Brunhes/Matuyama boundary; and the Donggutuo artifact layer, just below the Jaramillo onset. Accordingly, the Maliang and Donggutuo sites can be dated at about 0.78 Ma and 1.1 Ma, respectively. The Cenjiawan section has recorded a portion of the Matuyama chron. After correlations with the magnetic polarity sequence of the Majuangou section adjacent to this section, the Cenjiawan stone artifact layer is determined below the Jaramillo onset, with an estimated age of 1.1 Ma.To establish the magnetic stratigraphy framework for the lacustrine sediments in the eastern Nihewan Basin, this thesis draws on the magnetic polarity sequences of the Donggutuo and Cenjiawan sections as well as previously obtained results from the Majuangou, Haojiatai, Xiaochangliang and Donggou sections for magnetostratigraphic correlations. The accumulation of the lacustrine sequences at the east margin of the basin commenced from about 2.0 Ma. These sequences record not only the coarse magnetostratigraphy of the Brunhes normal chron and the middle to late Matuyama reverse chron (that is, the Jaramillo and Olduvai subchrons) but also some of the fine structure (that is, the Kamikatsura, Santa Rosa, Punaruu and Cobb Mountain geomagnetic events). The development of the Nihewan paleolake experienced at least twice large expansion periods, split by a large-scale shrinking event in the middle period of the paleolake development. The accumulation of the lacustrine strata was controlled by fault activities.After temporal control for the Donggutuo, Maliang and Cenjiawan Paleolithic sites were established, the three sites along with other well-dated Paleolithic/hominin sites of the Early Pleistocene in North China were combined to construct a chronological sequence of early human occupation in northeastern Asia. Furthermore, after incorporation of paleoclimate changes retrieved from Chinese loess/paleosol sequences and marine sediments, it could be possibly proposed that human groups of the Early Pleistocene in North China might have survived repeated warm/humid interglacials and cold/dry glacials, which were paced by earth orbital variations of the Eastern paleomonsoon.
Resumo:
Observation of the Miocene aeolian dust deposits in Qin'an area provide a long-timescale, almost continuous geological record for understanding significant environmental changes, such as the environmental evolution of Asian monsoons and the inland Asian aridification, and make possible new explorations of global and regional environmental evolutions and other relevant studies. However, the QA-I and QA-II sections that are previously investigated are near to each other, and there is a lack in understanding the spatial characteristics of changes in paleoenvironment. Therefore, new sections of Miocene aeolian dust deposits are needed to complete the present spatial framework. Meanwhile, it is necessary to carry out in-depth studies, which are already belated, on the depositional characteristics of these Miocene aeolian dust deposits.This thesis choose the Miziwan section and Shaogou section that are west to Liupan Mountain for magnetostratigraphic studies, results of which are compared with the QA-I section with respect to the lithology, magnetic susceptibility and paleomagnetic polarity stratigraphy. Quartz-fraction grain size of 300 samples from the QA-I section was analyzed. In addition, 30 out of these samples were determined in terms of the quartz morphological characteristics by using scanning electronic microscopy. On the basis of these data and the correlation with the Xifeng sequence of aeolian dust deposits, the following 3 conclusions are drawn as below:The upper and the lower boundary age of the Miziwan section are 11.6 Ma B.Rand 18.5 Ma B.R, respectively. The Shaogou section spans from 15.1 Ma B.P, to20.8 Ma B.R The lower boundary age of both sections is no older than that of theQA-I section. The Miziwan and the Shaogou sections can be well correlated withthe QA-I section in terms of the field lithological features, magnetic susceptibilityand magnetic polarity stratigraphy.Sedimentological evidence of the QA-I quartz grain size and quartz morphologicalcharacteristics further supports the previous conclusion that the QA-Iloess-paleosol sequence is of aeolian origin, and also verifies the accretionalfeatures in paleosols of this sequence in terms of the grain-size composition.Modifications of the grain-size composition of the original dusts due to later-stageweathering and pedogenesis are common characteristic of Miocene and Quaternary aeolian dust depositions. The above-mentioned processes further rework and refine the bulk grain size, which is more evident in paleosol layers. 3, Like the hipparion Red-Earth and the Quaternary aeolian deposits, the Miocene loess deposits are transported by near-ground winter monsoons. However, the average wind intensity evidenced by the quartz median grain size of Miocene loess, together with the maximum wind intensity by the quartz maximum grain size, is weaker than those of the Quaternary.
Resumo:
Gaochentou region is located in the southwest direction of Gaochentou village in Huanghua city of Hebei province. In regionally structural position, It lies in Qikou sag In the middle part of Huanghua depression, which belongs to the east part of the south Dagang structure zone in the middle part of Huanghua depression. Its' very beneficial at regional structure in Gaochentou , and It becomes the advantage area for oil and gas gathered and preserved, Sandstone reservoir of Dongying Formation is main bearing bed .Dongying Formation in Gaochentou region of Huanghua depression is consisted of set of mudstone and sandstone interbeds by deposited delta fades . Dongying Formation can be divided into 3 members from above to below: the first member of Dongying Formation (FMDF), the second member of Dongying Formation (SMDF), and third member of Dongying Formation (TMDF). The lithology of the upper part of FMDF was consisted of mostly middle-grained and fine-grained sandstone, and it is small for the oil-bearing area of the sand bodies .The lithology of the lower part is coarse-grained sandstone bodies which are well connected between sandstone bodies of wells, and the lower part was main bed of oil production in Dongying Formation; SMDF and TMDF are consisted of larger scale set of mudstone, in which the sandbodies are lenticular and pinch out quickly, and the lithology was mostly fine sandstone and silt stone, in which there are little oil and gas .Because the reservoirs in this area are largely influenced by the factors such as lithology, fault and others, and the reservoirs have the strong,heterogeneity , there exists the problem of oil-down and water-up for vertical distribution of oil and gas bearing. It is not very clearly for the three dimension distribution of sandstone , and the geology researchs is not enough. So, it can't satisfy the need of further development and production for Gaochentou oilfield.Having the key problem of oil-down and water-up and the mechanism of the reservoir for Gaochentou area, There are as follow study works, the first, is study of the high-resolution correlation of sequence stratigraphy and sedimentary microfacies. Dongying Formation was divided into three parasequence sets and each parasequence set was divided into different amount of parasequences. FMDF, as the main oil and gas producing bed, can be divided into seven parasequences. Oil and gas are discovered in six parasequences except the seventh. On the basis of study of sedimentary microfacies, the sediments of Dongying Formation are considered deposited mainly in delta front subfacies. The microfacies types of Dongying Formation are sub-water distirbutary channel, sub-water natural bank, inter distributary channel bay, distributary channel mouth dam, and delta front mat sand.Seismic facies analysis and logging-constrained inversion technique were applied by Author for transverse prediction of sandstone reservoir. Having 4 modes of interwell single sandbodies correlation technique, Author have described distribution characteristics of sandbodies, and established geological reservoir model of Gaochentou reservoir.Author presented that the reservoirs characteristic have very strong heterogeneity ,and In the section of sandstone interlayed with mudstone,the folium sandstone interlayed with each other, and the wedge shaped sandbodies pinched out in the mudstone. So the pinch-out up sandstone trap and lenticular sandstone trap are easily formed. They are most small scale overlying pinches out in the place of slope. This article applies the concept of deep basin oil to resolve reasonably the problem of which the oil is below the water in Gaochentou area. Combined with the study of sedimentary facies, reservoir and other aspects, the mechanism and patterns of deep basin oil are studied on the basis of characteristics in Gaochentou area.On the basis of the above study, the mechanism of the oil and gas' migration and accumulation in isotropic sandstone and heterogeneous sandstone are thoroughly analyzed through experiments on physical modeling. Experiments on physical modeling show that the discrepancy between sand layers with different permeability and thickness has important influence on the direction, path, and injection layer of oil's migration. At the beginning of the injection of oil and gas in high permeability sand layer, the pressure is low, the migration resistance is small, and the oil and gas are more easily displacing the water in sand. So it can act as good transformation layer or reservoir. But at the beginning of the injection of oil and gas in sand layer with low permeability, the pressure is high, the migration resistance is big, and the oil and gas are more difficultly displacing the water in sand. So it can only act as bad or worse transformation layer or reservoir. Even if it cannot act as transformation layer or reservoir, it can act as water layer or dry layer. The discrepancy between sand layers on permeability and thickness can make discrepancy in injection of oil and gas between different layers. Consequently it leads to small amount of oil and gas injection in sand layers with low permeability. Ultimately it affects the oil's accumulation and distribution in different sand layers.At Last, combining analysis of the structure and pool forming condition, The thesis has established models of reservoir formation to predict the advantage distribution of oil and gas bearing , and put forward the prospective target It is not only of theoretical signification for explosion and importance, but also has realistic value in guiding the progressive petroleum exploration and exploitation.
Resumo:
The foreland basin on the northern margin of the lower reach of the Yangtze river (the lower Yangtze foreland basin) is tectonically situated in the basin-mountain transitional area along the southeastern flank of the Dabie mountains. The early formation and development of the basin is closely related to the open-up of the Mian-Lue paleo-oceanic basin on the southern margin of the Central Orogenic System represented by Qinling-Dabei orogenic belt, while the tectonic evolution of the middle-late stage of the basin is mainly related to development of the Mian-Lue tectonic zone that occurred on the basis of the previous Mian-Lue paleo-suture. The foreland basin of the northern rim of the lower reach of the Yangtze river was formed during the middle-Triassic collision between the Yangtze and North China plates and experienced an evolution of occuirence-development-extinction characterized by marine facies to continental facies and continental margin to intracontinent in terms of tectonic setting.The foreland basin (T2-J2) was developed on the basis of the passive continental marginal basin on the south side of the Mian-Lue paleo-ocean and superimposed by late Jurassic-Tertiary fault basin. The tectonic setting underwent a multiple transformation of rifting-collisional clososing-tensional faulting and depression, which resulted in changes of the property for the basin and the final formation of the superposed compose basin in a fashion of 3-story-building. According to the tectonic position and evolution stages of plate collision happening on the southeastern margin of the Dabie mountains, and tectono-tratigraphic features shown by the foreland basin in its main formational period, the evolution of the foreland basin can be divided into four stages: 1) pre-orogenic passive margin (P2-Ti). As the Mian-Lue ocean commenced subduction in the late-Permian, the approaching of the Yangtze and North China plates to each other led to long-periodical and large-scale marine regression in early Triassic which was 22 Ma earlier than the global one and generated I-type mixed strata of the clastic rocks and carbonate, and I-type carbonate platform. These represent the passive stratigraphy formed before formation of the foreland basin. 2) Foreland basin on continental margin during main orogenic episode (T2.3). The stage includes the sub-stage of marine foreland basin (T2X remain basin), which formed I-type stratigrphy of carbonate tidal flat-lagoon, the sub-stage of marine-continental transition-molasse showing II-type stratigraphy of marine-continental facies lake - continental facies lake. 3) Intracontinental foreland basin during intracontinental orogeny (Ji-2)- It is characterized by continental facies coal-bearing molasses. 4) Tensional fault and depression during post-orogeny (J3-E). It formed tectono-stratigraphy post formation of the foreland basin, marking the end of the foreland evolution. Fold-thrust deformation of the lower Yangtze foreland basin mainly happened in late middle-Jurassic, forming ramp structures along the Yangtze river that display thrusting, with deformation strength weakening toward the river from both the Dabie mountains and the Jiangnan rise. This exhibits as three zones in a pattern of thick-skinned structure involved the basement of the orogenic belt to decollement thin-skinned structure of fold-thrust from north to south: thrust zone of foreland basin on northern rim of the lower reach of the Yangtze river, foreland basin zone and Jiannan compose uplift zone. Due to the superposed tensional deformation on the earlier compressional deformation, the structural geometric stratification has occurred vertically: the upper part exhibits late tensional deformation, the middle portion is characterized by ramp fault -fold deformation on the base of the Silurian decollement and weak deformation in the lower portion consisting of Silurian and Neo-Proterozoic separated by the two decollements. These portions constitutes a three-layered structural assemblage in a 3-D geometric model.From the succession of the lower reach of the Yangtze river and combined with characteristics of hydrocarbon-bearing rocks and oil-gas system, it can be seen that the succession of the continental facies foreland basin overlies the marine facies stratigraphy on the passive continental margin, which formed upper continental facies and lower marine facies hydrocarbon-bearing rock system and oil-gas forming system possessing the basic conditions for oil-gas occurrence. Among the conditions, the key for oil-gas accumulation is development and preservation of the marine hydrocarbon-bearing rocks underlying the foreland basin. The synthetic study that in the lower Yangtze foreland basin (including the Wangjiang-Qianshan basin), the generation-reservoir-cover association with the Permian marine facies hydrocarbon-bearing rocks as the critical portion can be a prospective oil-gas accumulation.Therefore, it should aim at the upper Paleozoic marine hydrocarbon-bearing rock system and oil-gas forming system in oil-gas evaluation and exploration. Also, fining excellent reservoir phase and well-preserved oil-gas accumulation units is extremely important for a breakthrough in oil-gas exploration.
Resumo:
Ordos Basin is a typical cratonic petroliferous basin with 40 oil-gas bearing bed sets. It is featured as stable multicycle sedimentation, gentle formation, and less structures. The reservoir beds in Upper Paleozoic and Mesozoicare are mainly low density, low permeability, strong lateral change, and strong vertical heterogeneous. The well-known Loess Plateau in the southern area and Maowusu Desert, Kubuqi Desert and Ordos Grasslands in the northern area cover the basin, so seismic data acquisition in this area is very difficult and the data often takes on inadequate precision, strong interference, low signal-noise ratio, and low resolution. Because of the complicated condition of the surface and the underground, it is very difficult to distinguish the thin beds and study the land facies high-resolution lithologic sequence stratigraphy according to routine seismic profile. Therefore, a method, which have clearly physical significance, based on advanced mathematical physics theory and algorithmic and can improve the precision of the detection on the thin sand-peat interbed configurations of land facies, is in demand to put forward.Generalized S Transform (GST) processing method provides a new method of phase space analysis for seismic data. Compared with wavelet transform, both of them have very good localization characteristics; however, directly related to the Fourier spectra, GST has clearer physical significance, moreover, GST adopts a technology to best approach seismic wavelets and transforms the seismic data into time-scale domain, and breaks through the limit of the fixed wavelet in S transform, so GST has extensive adaptability. Based on tracing the development of the ideas and theories from wavelet transform, S transform to GST, we studied how to improve the precision of the detection on the thin stratum by GST.Noise has strong influence on sequence detecting in GST, especially in the low signal-noise ratio data. We studied the distribution rule of colored noise in GST domain, and proposed a technology to distinguish the signal and noise in GST domain. We discussed two types of noises: white noise and red noise, in which noise satisfy statistical autoregression model. For these two model, the noise-signal detection technology based on GST all get good result. It proved that the GST domain noise-signal detection technology could be used to real seismic data, and could effectively avoid noise influence on seismic sequence detecting.On the seismic profile after GST processing, high amplitude energy intensive zone, schollen, strip and lentoid dead zone and disarray zone maybe represent specifically geologic meanings according to given geologic background. Using seismic sequence detection profile and combining other seismic interpretation technologies, we can elaborate depict the shape of palaeo-geomorphology, effectively estimate sand stretch, distinguish sedimentary facies, determine target area, and directly guide oil-gas exploration.In the lateral reservoir prediction in XF oilfield of Ordos Basin, it played very important role in the estimation of sand stretch that the study of palaeo-geomorphology of Triassic System and the partition of inner sequence of the stratum group. According to the high-resolution seismic profile after GST processing, we pointed out that the C8 Member of Yanchang Formation in DZ area and C8 Member in BM area are the same deposit. It provided the foundation for getting 430 million tons predicting reserves and unite building 3 million tons off-take potential.In tackling key problem study for SLG gas-field, according to the high-resolution seismic sequence profile, we determined that the deposit direction of H8 member is approximately N-S or NNE-SS W. Using the seismic sequence profile, combining with layer-level profile, we can interpret the shape of entrenched stream. The sunken lenticle indicates the high-energy stream channel, which has stronger hydropower. By this way we drew out three high-energy stream channels' outline, and determined the target areas for exploitation. Finding high-energy braided river by high-resolution sequence processing is the key technology in SLG area.In ZZ area, we studied the distribution of the main reservoir bed-S23, which is shallow delta thin sand bed, by GST processing. From the seismic sequence profile, we discovered that the schollen thick sand beds are only local distributed, and most of them are distributary channel sand and distributary bar deposit. Then we determined that the S23 sand deposit direction is NW-SE in west, N-S in central and NE-SW in east. The high detecting seismic sequence interpretation profiles have been tested by 14 wells, 2 wells mismatch and the coincidence rate is 85.7%. Based on the profiles we suggested 3 predicted wells, one well (Yu54) completed and the other two is still drilling. The completed on Is coincident with the forecastThe paper testified that GST is a effective technology to get high- resolution seismic sequence profile, compartmentalize deposit microfacies, confirm strike direction of sandstone and make sure of the distribution range of oil-gas bearing sandstone, and is the gordian technique for the exploration of lithologic gas-oil pool in complicated areas.
Resumo:
Paleointensity changes of geomagnetic field help us to understand the evolutionprocess of earth completely and provide further constraints for earth interior process and geodynamo model. Marine sediments are good carriers for relative paleointensity of geomagnetic field. But in most cases, deep sea sediments that conform with magnetic "uniformity" usually have low sedimentation rate about l-2cm/ka and lie under the Carbonate Compensate Depth with little carbonate content. Therefore, the number of relative paleointensity records with detailed oxygen stratigraphy is still rare. This thesis focus on four cores from east of Ryukyu Trench which have foraminiferal content of 5-30% and sedimentation rate of lOcm/ka and wish to get centennial -millennial changes of relative paleointensity.The sediments from east of Ryukyu Trench conform with magnetic "uniformity" and remanences of four cores all show single component with stable direction and faithfully record the magnetic field. The NRM301T1T/ARM and NRMsomT/ x are still affected by grain size and concentration changes although the sediments are "uniform" , indicating the uniformity might not enough for relative paleointensity. After renomalized by grain size parameter MDF, the intensities remove the effect of grain size changes to different degrees and show coherency in 1-1 Oka scale with results from ODP983/984. The characteristics of paleointensity of geomagnetic field arefrom 32-24kaBP, paleointensity of geomagnetic field is low;24-12kaBP, paleointensity of geomagnetic field is high and shows two peaks boundary with 19kaBP.3) 12-5.3ka, paleointensity is low. Then increase from 5,3kaBP until a small trough at 2.7kaBP, then increase till now.