, Volume 38 Issue 1
    

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    油气勘探
  • A history of hydrocarbon accumulations spanning important tectonic phases in marine sedimentary basins of China:Taking the Tarim Basin as an example
    Zhang Shuichang; Zhang Baomin; Li Benliang; Zhu Guangyou; Su Jin and Wang Xiaomei
    , 2011, 38(1): 1895-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Subaerial marine sedimentary basins in China have undergone three phases of important tectonic changes in the end of Early Paleozoic, Late Paleozoic-Early Mesozoic and Late Cenozoic. These tectonic changes have exerted strong impacts on the hydrocarbon generation, migration, accumulation and on the occurrence and distribution of hydrocarbon reservoirs. The Tarim Basin is a typical example of multiphase hydrocarbon accumulations in a marine basin of China. The Early Paleozoic tectonic framework laid a geological basis for the marine hydrocarbon formation of the Tarim Basin, but most of them were destroyed later due to frequent tectonic movements and only bitumen is left at present. In the Late Paleozoic, the Ordovician source rock located in the western Manjar Depression entered the peak generation and hydrocarbons successively accumulated at its southern and northern uplifted positions. The tectonic compressional deformation developed in the Early Mesozoic and the subsequent uplifted denudation allowed hydrocarbons accumulated at this phase to suffer from bacterial degradation. In the Late Cenozoic, the superimposition of basinal margin reconstruction and terrestrial molasse formation quickened the formation of secondary cracking gases in the platform of the basin, the influx of deep natural gases dissolved crude oils accumulated early and a unique large-scale condensate pool was then formed. The three tectonic changes controlled not only the formation of the marine basin, the sedimentary and evolution of source rocks, and the formation of reservoirs, but also the accumulation process and adjustment of hydrocarbons in marine sedimentary basins.
  • The significance of three reservoir profiles to risk exploration in Ordos Basin
    Zhao Zhenyu; Guo Yanru; Xu Wanglin; Zhang Yanlin; Gao Jianrong and Zhang Yueqiao
    , 2011, 38(1): 1896-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The Ordos Basin went through six main stages of geological evolution, developed three sets of soure rocks, two unconformities, several sets of reservoirs and caprocks, and had three typical petroleum systems, i.e. Lower Paleozoic Ordovician gas reservoirs, Upper Paleozoic Carboniferous-Permian gas reservoirs, and Mesozoic Triassic-Jurassic oil reservoirs. Three well profiles of oil and gas reservoirs in the basin are analyzed, which are the Wuzhong-Mizhi profile, Guyuan-Yichuan profile, and Baotou-Chengcheng profile. The size and distribution of the oil and gas reservoirs are controlled by the spatial distribution of soure rocks. Mesozoic oil reservoirs are located inside or near hydrocarbon depressions, where oil and gas had a short secondary migration. Paleozoic gas in the basin, after having a large-scale short migration in the range of source rocks, eventually gathered in the effective traps of the Ordovician weathering crust, and in the low permeability effective sand traps inside or near Carboniferous-Permian source rocks. The future risk exploration targets are: (1) for Mesozoic oil exploration, it will extend northward and explore unconventional reservoirs in source rocks; (2) for Upper Paleozoic gas exploration, it will extend southward and explore marine clastic gas reserviors; (3) for Lower Paleozoic gas exploration, it will search for lithologic-structural traps of carbonate weathering crust in the north-central and southeastern Yishan slope and those of carbonate reef flat.
  • Quantitative evaluation of hydrocarbon resource potential and its distribution in the Bozhong sag，Baohai Basin
    Jiang Fujie and Pang Xiongqi
    , 2011, 38(1): 1897-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The Bozhong sag is the biggest hydrocarbon rich sag in the Bohai Sea. However, hydrocarbon resource potential and its distribution are not clear, which restricts petroleum exploration. According to the material balance principle and the hydrocarbon accumulation threshold theory, the resource potential and distribution characteristics of hydrocarbons were evaluated quantitatively with hydrocarbon accumulation systems as evaluation units. The upper and lower plays in the Bozhong sag each can be divided into six hydrocarbon accumulation systems. The total afforded accumulation hydrocarbon quantity in the Bozhong sag is 60.27×108 t of oil (43.19×108 t in the upper play, 17.08×108 t in the lower play) and 27.02×1011 m3 of gas (17.75×1011 m3 in the upper play and 9.27×1011 m3 in the lower play). The Shijiutuo (Ⅰ) and Bodong (Ⅱ) accumulation systems are the further exploration areas with the greatest afforded accumulation hydrocarbon quantity.
  • Upper Palaeozoic gas accumulations of the Yimeng uplift, Ordos Basin
    Wang Mingjian; He Dengfa; Bao Hongping; Lu Renqi and Gui Baoling
    , 2011, 38(1): 1898-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    This paper analyzes the Upper Palaeozoic gas accumulations and conditions of the study area by using the definition and method of petroleum system, and concludes the natural gas accumulation pattern. The Upper Palaeozoic natural gas in the Yimeng uplift is mainly from the source rock of Taiyuan and Shanxi Formations in the southern part and Wushenqi area. Braided channel sandbodies of alluvial fan, river channel sandbodies and distributary channel sandbodies of delta plain in the Shanxi and Xiashihezi Formations are the most favorable reservoirs. The thick mudstone layers of the Shangshihezi and Shiqianfeng Formations which cover the whole region constitute the regional seal rock, and there are also many local seal rocks. Oil source, reservoir and seal rocks form a good relationship in time and space and they form two types of assemblage which are self-generating and self-preserving assemblage in the southern part of the Yimeng uplift and the lower-generating and upper-preserving assemblage in the southern and northern parts. Natural gas migrated to the north through the migration pathways composed by advantageous sandbody, unconformity, faults and cracks. Structural traps and the distal accumulation pattern dominate in the northern part, while the southern part is characterized by lithologic traps and the proximal accumulation pattern. The favorable gas accumulation zones are predicted in the study area.
  • Seismic sedimentologic research in shallow sea areas, DaGang
    Zang Xianguo; Lin Chengyan; Zhang Tao and Liu Wei
    , 2011, 38(1): 1899-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    In shallow sea areas with irregular well pattern and sparse well control, the accuracy of reservoir characterization based on well logging data is too low to satisfy the need of reservoir development research. A seismic sedimentologic studiew are made in the Block I of Chenghai Oilfield, Dagang. The architecture of braided bars is characterized finely by the inter-calibration and inter-restriction of vertical and horizontal information. Seismic data is processed with technologies of phasing and strata slicing and then the amplitude on slice is interpreted to obtain the planar distribution of bars. The evolution of braided bars is analyzed with research on slices of different depth. In this research, sand layer of the braided bar in NgI1-1 formation is subdivided into three parts, each of which is formed by a stage of flood deposition. The sedimentary characters and evolution revealed by strata slice interpretation is verified by fine research of vertical and horizontal wells. A sedimentary model is built and will play an important role in horizontal well production and in the architecture characterization of reservoirs without wells.
  • Tectonic compaction and its influence on reservoirs in the Kuqa foreland basin, Tarim
    Li Jun; Zhang Chaomo; Li Jinfu; Xiao Chenwen and Yuan Shijun
    , 2011, 38(1): 1900-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Tectonic compaction has great influence on reservoir properties in the Kuqa foreland basin. On the basis of logging responses to tectonic compaction, quantitative models were set up to determine the magnitude of palaeotectonic stress by logging data and analyze the influences of tectonic compaction on reservoirs. The influences showed dual nature: With intense tectonic compaction, both porosity and permeability become worse and worse, in particular, permeability is more sensitive to tectonic stress. On the other hand, with intense tectonic compaction, sandstone becomes densified and fractures occur, resulting in fractured reservoirs with high production. In addition, in this basin the fluid is characterized by high or hyper-high pressures. Sealing tectonic compaction contributes mainly to the abnormal fluid pressures. This provides a favorable foundation for reservoirs to keep higher porosity and permeability.
  • Formation of carbon dioxide and hydrocarbon gas reservoirs of the Changling fault depression, Songliao basin
    Yang Guang; Zhao Zhanyin and Shao Mingli
    , 2011, 38(1): 1901-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    On the basis of the research on the forming conditions and distribution of inorganic CO2 gas reservoirs and organic hydrocarbon gas reservoirs in the central uplift area of the Changling fault depression, the forming time, stage and sequence of the two gas reservoirs were studied and the pool-forming patterns were established by analyzing fluid inclusions and structural evolution. The organic gas is over-mature coal-derived gas, mainly from source rocks of the Yingcheng Formation, Shahezi Formation and Huoshiling Formation. Inorganic CO2 gas is mainly from mantle, secondarily from the degassing of volcanics. The distribution of gas-source fault systems and the degassing of mantle volcanos are the two main factors controlling the enrichment, migration and accumulation of inorganic CO2 gas reservoirs. The formation of hydrocarbon gas reservoirs is earlier than that of inorganic CO2 gas reservoirs, the former is 86Ma~81Ma at the early depositional period of the Yaojia and Nenjiang Formations, the latter is 28Ma in the late Paleogene. CO2 gas reservoirs mainly exist, alone or mixed with hydrocarbon gas, in the Yingcheng Formation volcanics, and the hydrocarbon gas reservoirs are on the top of the mixed gas reservoirs.
  • Application of fluid inclusion stratigraphy to petroleum exploration and production
    Zhou Zhenzhu; Zhou Yaoqi; Chen Yong and Ge Yunjin
    , 2011, 38(1): 1902-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    As an advantaged geochemical analyses tool, fluid inclusion stratigraphy (FIS) provides chemical information of formation fluids by rapid, automated bulk inclusions analyses. Some E&P problems, unsolvable with common methods, can be easily solved using the variable FIS response vs. depth. FIS can be used to: evaluate whether or not petroleum has moved through a dry hole with no shows that is adjacent to a prospect; assess the probability of encountering a deep, hydrocarbon-charged reservoir below a shallow boring; identify a failed seal; identify missed and low-resistivity oil layers; determine migration paths of hydrocarbons; delineate pay intervals and fluid contacts; study the connectivity of reservoirs; determine the type and quality of hydrocarbons and make rapid regional evaluation. FIS can help to select present and future prospects in a basin scale due to its rapid and economic analyses. This technology has been widely used abroad, but seldom in China, and should be paid attention to.
  • A review of the multi-component seismic data processing
    Sun Qifeng and Du Qizhen
    , 2011, 38(1): 1903-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Multi-wave and multi-component seismic exploration can fully utilize the signals of P-wave and S-wave. The technology of multi-component seismic data processing is based on the theory of elastic wave. According to processing steps, it can be classified into two kinds of techniques: (1) The wave field separation processing technology based on the scalar wave field theory. It has formed a complete processing steps and can be used into practice, with core technologies of decomposition of multi-wave field, static correction of converted wave, velocity analysis of converted wave, migration of converted wave, etc. (2) The multi-component joint processing technology based on the vector wave field theory. It has a better theoretical foundation and can maintain the original information of seismic data well. But it is still in the research and experimental stage, and cannot form a complete processing flow to meet the need of processing of actual multi-component seismic data. The related technologies still need improvement and development. Multi-wave multi-component technology is the effective solution for solving complex geological and geophysical problems and is the development trend of seismic exploration.
    • 油气田开发
  • Oil property changes during waterflooding for reservoirs with condensate gas cap
    Zhao Lun; Bian Dezhi; Fan Zifei; Song Heng; Li Jianxin and Zhao Xiaoliang
    , 2011, 38(1): 1904-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Zanarol oil field is a giant carbonate reservoir with condensate cap, weakly volatile oil, and bioclastic limestone of low porosity and permeability. During the waterflooding stage, formation pressure decreased step by step resulting from the former depleting development and the strong heterogeneity of carbonate reservoirs. The gas cap spread outwards with the formation pressure dropping, causing gas breakthrough in production wells near the oil and gas contact, GOR increased and oil density decreased. In the internal oil region far from the oil-gas contact, the dropping reservoir pressure led to dissolved gas separating out from oil, making crude oil change to black oil from weak volatile oil. With the separated solution gas, the oil density, produced gas oil ratio and oil viscosity increased, the oil well productivity decreased, all these make waterflooding more difficult. The main method for improving development response is to keep formation pressure and improve the utilization factor of water injection.
  • Production features of steam and gas push: Comparative analysis with steam assisted gravity drainage
    Liu Zhibo; Cheng Linsong; Ji Youjun and Liu Qicheng
    , 2011, 38(1): 1905-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Using the numerical modeling method and the drafting software of Surfer, we charted the temperature fields and remainding oil saturation fields of steam assisted gravity drainage (SAGD) and steam and gas push (SAGP) in oil drainage periods, including beginning, peak stage and last stage of oil drainage. An intuitive and reliable comparative research was done about the formation and expanding process of steam chambers, the shape of steam chambers and flow features in different oil drainage periods. The recovery effectiveness of the two production methods was compared. The results show that: in the SAGP production process, the lateral expansion of the steam chamber is faster than that in SAGD and the vertical expansion slower than that in SAGD. By adding non-condensate gas in the steam of SAGD, it can reduce the amount of steam injection, increase thermal efficiency, improve the ratio of oil and steam, and ultimately improve the development effectiveness of SAGD.
  • Adsorption of hydrophobic nanoparticles in reservoir microchannels
    Gu Chunyuan; Di Qinfeng; Shen Chen; Wang Zhanghong; Shi Liyi and Wang Xinliang
    , 2011, 38(1): 1906-0.
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    Based on the analysis of the forces acting on a hydrophobic nanoparticle (HNP) in a reservoir microchannel, a model of the interacting energy was presented. The competition adsorption mechanism between HNPs and water molecules was investigated by the comparison of interacting energies on a HNP and on a water molecule from microchannel wall. The calculated results show that the combined force for the HNP is an attractive force toward the microchannel wall and the acting energy on the HNP from the wall is on the order of 10－18–10－17J, which is about 103 times that on the water molecule. Thus the HNP can penetrate hydrated layer and can be absorbed on the microchannel wall. To validate the model, an experiment was conducted using scanning electron microscope (SEM) and Energy Disperse Spectroscopy (EDS) to investigate the absorption of HNPs on the surface of the core which was treated with HNPs fluid. The results show that micro- and nano- structures of HNPs layer can be observed clearly on the core surface，which confirms that HNPs have broken through the hydrated layer and have formed a absorption layer on the core surface.
  • Flow fields in the blowout of natural gas wells containing carbon dioxide
    Liu Zhenyi; Zhang Ying’an; Zheng Yuanpan; Wang Feng; Qian Xinming; Zhang Deping; Huang Ping; Li Qing and Feng Changgen
    , 2011, 38(1): 1907-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The flow fields of the blowout of natural gas containing carbon dioxide were analyzed by using fluid dynamics theory and computational fluid dynamics (CFD) technology so as to provide scientific foundation for safe distance determination. Dispersion mechanisms of blowout flow field at each stage, boundary conditions and numerical algorithm for simulation were presented as well. The process of well blowout can be divided into six stages. They are critical flux, equal entropy expanding, compressible ejection, incompressible ejection, heavy gas dispersion, and normal dispersion. The distribution of gas velocity field was got via CFD simulation, and the flux velocity can be more than 700 m/s. The concentration of CO2 was analyzed, indicating that in the inner layer of the equal entropy expanding area, the concentration is uniform, while in the external layer, the concentration declines sharply. The correlation between mass concentration of CO2 and dispersion distance obeys the Gauss formula. The theoretical predictions were consistent with the results of simulation, It shows that the theoretical analysis of flow field and the CFD simulation method are practical.
    • 石油工程
  • Wellbore temperature and pressure coupling calculation of drilling with supercritical carbon dioxide
    Wang Haizhu; Shen Zhonghou and Li Gensheng
    , 2011, 38(1): 1908-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Wellbore temperature and pressure have great influence on CO2 density, viscosity, thermal conductivity, heat capacity and other physical properties, the change of these parameters will react against the wellbore temperature and pressure. The helmholtz free energy equation of gas put forward by Span and Wagner was adopted to build the pressure and temperature coupling calculation model, and coiled tubing drilling was done as an example for analyzing. The results indicated that the pressure of drill pipe and annular increases with the well depth increasing, and the state change point in the drill pipe is 50 meters deeper than that in the annular. The temperature in the drill pipe is a little lower than that in the annular. The density of CO2 decreases slowly with the well depth increasing, and the changing rate decreases . At the depth of 20 meters to the bottom hole, the density of CO2 in the annular increases abruptly, and the density of CO2 in the drill pipe increases too. The calculation error between this model and the P-R model is large, the main reason is that the referenced model doesn't consider the physical parameters change and its influence on the temperature and pressure, and this model has a high calculating precision.
  • Design and calculation of a MPD model with constant bottom hole pressure
    Wang Guo; Fan Honghai and Liu Gang
    , 2011, 38(1): 1909-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Bottom hole pressure can be maintained in a reasonable range by using the managed pressure drilling (MPD) technique with the special equipment. A calculation model is established for the back pressure and drilling fluid density of constant bottom hole pressure MPD, which are calculated by iterative method. The calculation model is applied to the well Kela 201. In the comparison of the annulus pressures at 3 314 m in the well, and the conventional drilling method cannot provide the appropriate drilling fluid density, but the constant bottom hole pressure MPD technique can make the annulus pressure within the pressure window. The design result of back pressure and mud weight of the narrow pressure window illustrated that the well can drill the target zone directly by using the MPD technique. It can simplify casing program and save drilling cost. The calculation example demonstrates that this technique not only reduces mud density, but also meets the demand of annulus pressure control. Narrow pressure window can be drilled. It provides a technical basis for optimizing well profile.
  • Accurate extraction of valve opening and closing points based on the physical meaning of surface dynamometer
    Liang Hua and Li Xunming
    , 2011, 38(1): 1910-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The extraction of valve opening and closing points is the basis for the identification and quantitative analysis of pumping well dynamometer cards, and it is important for the failure diagnosis and production evaluation of pumping wells. In light of the working principle of sucker rod pump and the physical meaning of surface dynamometer card, this paper discusses theoretically valve opening and closing points and presents an accurate method of extracting the valve opening and closing points of surface dynamometer cards. Top and the bottom dead centers are determined by the polished rod displacement, and the closing points of travel valve and set valve and the opening points of the valves are determined by the polished rod load. We find the optimization opening points by partition de-noising, smoothing de-noising, curve fitting and iteration de-noising of the load curve. A corresponding computer program is developed and analyses of 1000 examples indicate that this approach is effective.
    • 综合研究
  • Expression of hydrocarbon on sea surface and its remote sensing detection: Taking the South China Sea area as an example
    Liu Yang; Shao Yun; Yu Wuyi; Qi Xiaoping; Tian Wei; Wang Shiang and Yuan Junna
    , 2011, 38(1): 1911-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    To timely acquire the distribution conditions of hydrocarbon on the sea surface and track the generation and evolution of oil slick, the satellite-earth simultaneous SAR observation experiment has been conducted in South China Sea. The oil slick was generated at regular intervals. The Cosmo X-SAR with high resolution was used to study the features of spatial-time evolution of oil slick spread on the sea surface. Through two satellite imaging (half an hour interval) on hydrocarbon slick on the sea surface, the inversion analysis of SAR backscatter features has been conducted and it is thought that the damping effect of oil slick on sea surface waves changes with the trend from increasing to decreasing during the period of oil spreading. Oil slicks break at weak link locations with relative low backscatter features along the main spreading axis. Drifting speed of oil slick is stable under the conditions of low wind speed on the sea surface. Remote sensing has been proven to be a powerful tool for oil slick detection due to its fast acquisition, low-cost and regional observation capability, which has great significance for the potential prospect evaluation in the early stage of offshore petroleum exploration and for the safe monitoring in the offshore petroleum development.
    • 学术讨论
  • Evaluation methodology of lithologic exploration areas in a rift basins: A case from the Bohai Bay basin
    Wang Yuman; Huang Xu’nan and Cheng Kunfang
    , 2011, 38(1): 1912-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Based on the analysis about the main controlling factors of the formation and enrichment of lithologic hydrocarbon reservoirs of sandy conglomerate in the Bohai Bay basin, and combined with qualitative and quantitative analysis, a classified evaluation mode was established including four factors that are tectonic setting, sedimentary environment, reservoirs and hydrocarbon source rocks. In the evaluation of geologic settings of one rift basin, the authors analyzed and compared the geologic conditions, hydrocarbon bearing and exploratory results of five types of structural zones and three types of sedimentary systems. In the reservoir evaluation, a evaluation item of the reservoir structure was added including six styles and evaluation grades. Combining the classified evaluation of the four factors with the routine analysis of exploration target areas, an evaluation standard of lithologic traps in rift basins was constructed, which is useful to evaluate lithologic targets in rift basins of eastern China.
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