23 October 2014, Volume 41 Issue 5
    

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    油气勘探
  • Origin, characteristics and significance of collapsed-paleocave systems in Sinian to Permian carbonate strata in Central Sichuan Basin, SW China
    Li Wenke; Zhang Yan; Zhang Baomin; Li Jinsong; Wang Jun and Ma Xiaoyu
    , 2014, 41(5): 513-522.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    The origin, characteristics and geological significance of the collapsed-paleocave systems in the Sinian to Permian carbonate strata in Central Sichuan Basin are studied based on 3D seismic interpretation and attributes analysis, as well as imaging logging and cores. Collapsed-paleocave systems are distributed in the Sinian to Permian carbonate strata vertically and along the ends, releasing offsets and intersections of faults horizontally. On profile, they occur as seismic events push-down. The collapsed-paleocave systems mainly originated from fault movements at three main structural phases, the first stage of Tongwan, the second and third stages of Tongwan and the Early Caledonian, and eventually got into shape at the end of the Permian. The collapsed-paleocave systems are featured by multi-layers, wide distribution and good reservoir quality, in which reservoir space is made up of pre-existing pores, structure genetic fractures and collapsed genetic fractures. According to seismic response characteristics, three types of collapsed-paleocave systems are identified in this area, including multi-layer cave system collapsed complex, multi-layer cave passage collapsed system and intra-bed cave collapsed system. The first two types, with complex and widespread fractures in the overlying deformed layers, are probably the favorable targets for gas exploration.
  • Genesis, source and charging of oil and gas in Lishui Sag, East China Sea Basin
    Su Ao; Chen Honghan; Cao Laisheng; Lei Mingzhu; Wang Cunwu; Liu Yanhua and Li Peijun
    , 2014, 41(5): 523-532.
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    Based on the results of components and stable carbon isotopic analysis of gas and oil from the Lishui Sag, East China Sea Basin, the oil and gas genesis, source and charge process are studied by combining the history of structural evolution, oil and gas generation and migration and accumulation. The study shows that there are two types of gases in the Lishui Sag now, one is the gas with high CO2 content and low oil-type pyrolysis gas content found in Well WZ13-1-1, the other is the gas with high content of the mixture of coal-type gas and oil-type pyrolysis gas and certain content of CO2 found in Well LS36-1-1, LS36-1-2 and LF-1. Hydrocarbon gases are all organic thermal gas, in which high maturity oil-type gas was from Paleocene Yueguifeng Formation and charged in middle-late Eocene-early Oligocene, and low maturity coal-type gas was from Paleocene Mingyuefeng Formation and was charged in late stage. The CO2 in Well LF-1 is of organic origin, while CO2 in other wells were derived from the deep inorganic mantle source gas charged variously in Oligocene. Oil in Well WZ6-1-1 is the high maturity sapropel type oil from Yueguifeng Formation which was charged in middle-late Eocene-early Oligocene. Condensate in Well LS36-1 is low maturity humus type oil from Mingyuefeng Formation charged in late stage. Oil in Well LF-1 may be of mixed source and greater proportion of oil likely from Paleocene Yueguifeng Formation.
  • Characteristics of noble gases in the large Gaoshiti-Moxi gas field in Sichuan Basin
    Wei Guoqi; Wang Dongliang; Wang Xiaobo; Li Jian; Li Zhisheng; Xie Zengye; Cui Huiying and Wang Zhihong
    , 2014, 41(5): 533-538.
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    Taking the large Gaoshiti-Moxi gas field of Sichuan Basin as an example, the total composition contents and isotopes of noble gases in the natural gases from the Sinian Dengying Formation and Cambrian Longwangmiao Formation are analyzed, and then their geneses are identified. The content value of helium in the natural gases of the large Gaoshiti-Moxi gas field is generally 1-2 orders of magnitude higher than that of air, and the average content in the second member of the Dengying Formation is 512×10-6, reaching the industrial utilization standard. The content values of Neon, Argon, Krypton and Xenon are relative low, lower than the corresponding content value in air. The total composition contents of noble gases in the natural gas of the large Gaoshiti-Moxi gas field gradually reduce in the sequence of the second member of Dengying Formation, the fourth memeber of Dengying Formation, and Cambrian Longwangmiao Formation. The noble gases 3He/4He value in the natural gases of the large Gaoshiti-Moxi gas field is in 10-8 order of magnitude, the 40Ar/36Ar value is usual from 1 024 to 9 559, 132Xe is relatively surplus and 129Xe is relatively loss. The comprehensive genetic identification of Helium, Argon, Xenon indicates that the noble gases in the large Gaoshiti-Moxi gas field are typical crustal source genesis, and the study area has stable tectonic background and does not have active deep fractures or mantle connecting fractures.
  • Structural characteristics of the northern Longmenshan fold-thrust belt and the favorable exploration areas, Sichuan Basin, Southwest China
    Wang Lining; Chen Zhuxin; Li Benliang; Lei Yongliang and Yan Shuyu
    , 2014, 41(5): 539-545.
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    Based on the latest data from oil and gas exploration, the structural geometry features of the northern Longmenshan fold-thrust belt and its forming process were examined, and then favorable hydrocarbon prospecting areas were predicted. Two major orogenic events occurred in the Longmenshan belt since the Mesozoic: thrusts and folds were formed by a late Triassic compressional event, and later transformed by the late Cenozoic deformation featuring base-involved large folds. Due to the influence of the two events, thrust nappes, autochthonous thrusts and in-situ blind thrusts developed from the orogen to the foreland basin sequentially, and these structural units show different profile combination on profile from the north to south. Among these structural units, the autochthonous thrusts and folds under lower allochthonous nappes have high potential for oil and gas exploration.
  • 3D geometrical and kinematic characteristics of boundary faults in Minfeng subsag, Dongying Sag, Bohai Bay Basin
    Gao Liming; He Dengfa; Gui Baoling; Wang Junhui and Chen Weijia
    , 2014, 41(5): 546-553.
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    Under the constraint of high-precision 3D seismic data and well data, through 2D and 3D analysis, the geometrical and kinematic characteristics of the boundary faults of Minfeng subsag, Jiyang depression, Bohai Bay Basin were analyzed. According to the strike, dip and dip-angle, the boundary fault of the study area is divided into three segments, i.e. west, center and east. It is thought that the fault surface is a curved surface consisting of several inclined surfaces linked by axial plane (i.e. transversal axial plane and vertical axial plane), and a three-dimensional geometry model of the boundary fault was built. The Minfeng boundary fault surface is divided into 11 subzones by 6 transversal axial planes and 4 vertical axial planes. The kinematic characteristics of the Minfeng boundary fault were analyzed on the basis of the normal fault-bend folds theory, and the three balanced cross-sections in west, central and east segments are compared. It is concluded that the Minfeng boundary fault mainly experienced rotary motion in its early stage of development, and moved in the inclined shear fault-bend fold pattern in the late stage. There developed listric fault in the central segement, seat type normal faults in east and west segments of the Minfeng boundary fault. The activity intensity of west and central faults was affected by Shengbei fault, the rotation degree of Minfeng boundary fault weakens from west to east. The reverse degree of the Minfeng boundary fault increased from west to east at the end of the Paleogene Dongying Formation deposition.
  • Hydrocarbon migration system of Fulaerji oil field, Songliao Basin, NE China
    Xin Renchen; Yang Bo; Wang Shuheng; Liang Jiangping and Li Jin
    , 2014, 41(5): 554-562.
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    Through sedimentologic and petroleum geologic analysis of over 300 exploration wells in the north part of the west slope in the Songliao Basin, the conduit role the incised valley played in the oil and gas accumulation of the Fulaerji oil field is investigated. The major pays in the Fulaerji oil and gas field are the second and third members of the Cretaceous Yaojia Formation, where the hydrocarbon comes primarily from the Qijia-Gulong sag about 80 km east. The pathway of long distance hydrocarbon migration is the overlapping sandstone complex which fills the incised valley. The incised valley deposits overlapped on the delta deposits toward basin, and connected with shore-shallow lake sandy beach-bar formed during the highest lake flooding period toward the basin margin, constituting a sand rich sedimentary complex of delta - incised valley filling - shore sandy beach bar. Towards the basin, delta sand branches and pinches out in mudstone (mature source rock), transporting the hydrocarbon generated in the effective hydrocarbon kitchen to the incised valley filling body, the incised valley filling deposits transported hydrocarbon for a long distance to the updip pinching sandy beach bar lithologic trap, giving birth to the Fulaerji oil and gas reservoir. In the sand-rich sedimentary system related to the incised valley filling, the effective hydrocarbon transporting system is limited along Well Du 412 - Du 71 - Du 65 - Jiang 39 - Jiang 41 and Fulaerji oil and gas field. The pure hydrocarbon transporting layer is a water production layer with a high degree of hydrocarbon impregnation and low residual oil saturation. Baiyinnuole, Erzhan, Alaxin, Jiangqiao oil and gas fields distributed like a string of beads in NW are closely related to this effective hydrocarbon transporting system.
  • Geological features and exploration potential of Permian Tiaohu Formation tight oil, Santanghu Basin, NW China
    Liang Hao; Li Xinning; Ma Qiang; Liang Hui; Luo Quansheng; Chen Xuan; Bai Guojuan; Zhang Qi and Meng Yuanlin
    , 2014, 41(5): 563-572.
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    Based on seismic data, logging, mud logging and lab testing data, the geological features and exploration potential of Permian Tiaohu Formation tight oil were studied in Santanghu Basin, Hami Area, Xinjiang. The tight sedimentary tuff characterized as high porosity and low permeability is developed in the second member of Tiaohu Formation in Santanghu Basin, and its granularity is fine, nano-scale pores and throats account for 88.3%, its permeability is lower than 0.5×10-3 μm2. Because of high brittleness, the reservoir rocks are easy to be fractured, and its oil saturation and crude oil density are high. The oil in tight sedimentary tuff is mainly from the underlying Permian Lucaogou Formation high-quality source rocks with a 100-500 m interval between source rocks and reservoirs. The crude oil generated in source rocks migrated up to the second member of Tiaohu Formation along faults and fractures characterized as other-sourced charging and source-reservoir separating. Tight oil distribution is mainly controlled by Lucaogou Formation source rocks and second member of Tiaohu Formation sedimentary tuff reservoirs. The area of “sweet spots” in the second member of Tiaohu Formation of Malang-Tiaohu Sag is about 203 km2, and the oil resource is predicted to be 2.4×108 t.
  • Tight gas detection based on the reflectivity dispersion technology
    Yang Zhifang; Cao Hong; Yang Huizhu and Yan Xinfei
    , 2014, 41(5): 573-577.
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    The study focuses on the reflectivity dispersion caused by velocity dispersion related to pore fluid and its application to identify tight gas reservoirs. Seismic attenuation in viscoelastic media has two effects: (1) the change in frequency content and amplitude of a pulse propagating through attenuating media; (2) reflection coefficients are frequency dependent. Based on linear viscoelastic theory of velocity dispersion and the linearization of Zoeppritz equations, a new approximate reflection coefficient is presented considering P & S wave velocity dispersion, which adds the effects of frequencies and quality factors in reflection coefficient formula, representing the characteristics of reflection coefficient dependent by frequency, incident angle, quality factor etc. Based on the relationship between P-wave velocity and gas saturation, the reflected energy changes induced by reflectivity dispersion can be calculated and used to directly detect gas reservoirs, combining with seismic velocity, amplitude and energy attenuation mechanism caused by gas, such as squirt flow mechanism. This method has been successfully applied to characterize the distribution of tight gas sands in the GA101 well area of Sichuan Basin, and the results offer reliable foundations for seismic prospecting and well designing.
    • 油气田开发
  • A study on remaining oil distribution in a carbonate oil reservoir based on reservoir flow units
    Fan Zifei; Li Kongchou; Li Jianxin; Song Heng; He Ling and Wu Xuelin
    , 2014, 41(5): 578-584.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Reservoir Г north, which belongs to Zhanzhol, Kazakhstan a fracture-pore typed carbonate oilfield, has a variety of reservoir types. According to the combination pattern of different voids and the relationship between porosity and permeability, carbonate reservoirs are classified into four types which are fracture-cavity-pore typed, fracture-pore typed, pore typed and fracture typed, and the identification of which by well logging data is realized. There is a little difference in the producing degree within the same reservoir type for fracture-cavity-pore typed and fracture typed reservoirs. However, there are large differences in the producing degree for fracture-pore typed and pore typed reservoirs. In order to appraise the producing degree of reservoirs more exactly, key parameters affecting the producing degree of fracture-pore typed and pore typed reservoirs are selected separately, which, for the fracture-pore typed are reservoir quality index (RQI), pore throat radius at mercury saturation of 50% (R50), total permeability (Kf+Km), and the ratio of fracture permeability to matrix permeability (Kf/Km), and for the pore typed are RQI, R50, and matrix permeability (Km). With the integrated consideration of matrix and fracture, a flow unit classification method for dual medium reservoir is established, and taking these parameters as clustering variants, four types of reservoirs are further divided into six kinds of reservoir flow units by the means of neural network clustering technology. Based on reservoir flow unit modeling, a numerical simulation model is built with each type of reservoir flow units adopting its corresponding relative permeability curve, based on which, the distribution regularity of remaining oil of reservoir Г north is studied and demonstrated. Eight new wells are designed according to the research result, and put into production in 2013 with the initial daily oil production rate being 2.3 times that of nearby old wells.
  • Forecast of fractured horizontal well productivity in dual permeability layers in volcanic gas reservoirs
    Wang Zhiping; Ran Bo; Tong Min; Wang Chunming and Yue Qingfeng
    , 2014, 41(5): 585-590.
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    In view of the flow particularity of fractured horizontal wells in dual permeability layers in volcanic gas reservoirs, based on the equivalent flowing resistance method and superposition principle, a new productivity forecasting method for fractured open-hole horizontal wells with multi-transverse fractures in volcanic gas reservoirs is established using a new pseudo-pressure function, with the comprehensive effect of gas slippage effect, starting pressure gradient, stress sensitivity effect and turbulence effect in fractures taken into consideration. The simulation results show that in the production process of fractured open-hole horizontal wells, and the starting pressure gradient has the most remarkable impact on gas well productivity, followed by pressure-sensitive effect and turbulence effect. The slippage effect has the lowest influence. Production pressure difference in gas reservoirs with strong pressure-sensitive effect should be reduced. Gas well production increases as the fracture half-length increases. With the increase of fracture number, the increase of gas production slows down, there exists an optimal number of cracks. The factor affecting gas well production most significantly is fracture conductivity capacity. Different gas reservoirs have different optimal fracture conductivity capacity.
  • An improved viscosity model for CO2-crude system
    Lian Liming; Qin Jishun; Yang Siyu; Yang Yongzhi; Li Shi and Chen Xinglong
    , 2014, 41(5): 591-596.
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    The existing viscosity models, including LBC (Lohrenz-Bray-Clark) Model, CS (Pedersen) Model and PR (based on PR Equation of State) Model, could not take into account accuracy, theory strictness and calculation convenience simultaneously. This study considers temperature, pressure, interaction between components and other affecting factors to improve the viscosity model based on PR EOS (equation of state) and finally establishes a new calculation model for CO2-crude system under high pressures and high temperatures. The accuracy of the PR model is improved by changing the dimensionless constant in the model into a function related to the system temperature. Furthermore, the mixing-rule in viscosity calculation of mixture is modified through introducing the binary interaction factor and effective mole fraction of CO2. Based on gas and liquid phase components of field oil samples from actual measurement, the calculation accuracy of models before and after improvement were compared, which shows that the new viscosity model is not only simple in computation, but also much more accurate, meets the industrial requirements.
  • Point bar configuration and residual oil analysis based on core and dense well pattern
    Yan Baiquan; Zhang Xinlei; Yu Limin; Zhang Dong; Jiang Guipu; Yang Yongjie; Sun Yu; Han Xiaolong and Xu Yagang
    , 2014, 41(5): 597-604.
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    Based on the dense well pattern and the core data of straight wells and horizontal wells of PI332 unit of Putaohua oil layer, Cretaceous Yaojia Formation in Xingbei area of Daqing Oilfield, according to the model of modern sediments and ancient outcrop, the configuration parameters of lateral interbeds configuration are acquired by rock-electricity combination, which are used to analyze the three-dimensional configuration characteristics of the point bar lateral accretion interbeds located in the meandering distributary channel of the delta distributary plain and the residual oil distribution. The results show that the lateral accretion interbeds of point bar are thin, slow, and dense in PI332 unit of Xingbei area. The thickness of interbeds is mainly 2-25 cm. The upper and lower dip angle of interbeds is smaller at 2°-5°. The middle of interbeds is steeper at 7°-10°. The plane distribution density is 0.11/m. The three-dimensional spatial configuration consists of the plane and profile features. The lateral accretion interbeds are in crescent arrangement on the plane, and in imbricate and echelon distribution on the profile. Under the influence of lateral accretion interbeds architecture and the physical difference of lateral accretions, the middle and lower parts of point bars are seriously flooded, and the residual oil is mainly distributed in the middle and upper parts. The horizontal section of a horizontal well should be designed in the middle and upper parts of point bars, and it should drill out the middle and upper parts of lateral accretion bodies to increase the supply unit and enhance oil recovery.
    • 石油工程
  • Coupling simulation of multistage pulse conflagration compression fracturing
    Wu Feipeng; Pu Chunsheng; Chen Dechun; Ren Shan and Liu Bin
    , 2014, 41(5): 605-611.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Due to the transient and multi-field coupling complexity of the multistage pulse conflagration compression fracturing, the coupling solution method for it was established, and the simulation calculation and field application analysis was conducted. The whole process of conflagration compression fracturing was divided into five subsystems: propellants conflagration loading, piezoresistive liquid column movement, perforation discharge, fracture initiation and dynamic extension. Based on the given assumptions, the kinetic model of each subsystem was built, and the coupling solution method of multistage pulse deflagration compression fracturing process was obtained using the node system analysis method. With the coupling solution method, a reasonable range of propellants charge can be calculated and the dynamic prediction of the conflagration pressure and fracture shape can be realized. Through simulation calculation, the changes of propellants conflagration pressure, piezoresistive gas-liquid interface displacement and fracture length were analyzed, and the whole process was divided into five phases by the time. The field application results indicate that the multistage pulse conflagration compression fracturing conducted based on the coupling solution method can fracture the reservoir successfully and reduce the breakdown pressure, making sure that the follow-up measures are carried out smoothly.
  • Division of coalbed methane desorption stages and its significance
    Meng Yanjun; Tang Dazhen; Xu Hao; Qu Yingjie; Li Yong and Zhang Wenzhong
    , 2014, 41(5): 612-617.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    To quantitatively analyze the effect of desorption characteristics on productivity, a division method of coalbed methane (CBM) desorption stages was established based on the Langmuir adsorption isothermal theory, and the indicating significance of the method was analyzed with cases of CBM production. The desorbed efficiency was used to quantitatively characterize the CBM desorbed rate under different reservoir pressures. On the basis of key nodes on mathematical curves, the starting pressure, turning pressure and sensitive pressure were defined. For different coal samples, the corresponding desorbed efficiencies of the three nodes were always constants, therefore the CBM desorption process was divided into four stages, i.e., inefficient, slow, fast and sensitive desorption stages. Studies reveal that, fast and sensitive desorption stages contribute a lot to CBM productivity, while inefficient and slow desorption stages have very little contribution; absorption capacity, gas-bearing property and reservoir pressure are the key factors for the desorption characteristics. The production status of southern Qinshui Basin and Liulin area in Ordos Basin in Northwest China demonstrates that the method can guide the CBM development effectively.
  • Equipment and technique for improving penetration rate by the transformation of drill string vibration to hydraulic pulsating jet
    Guan Zhichuan; Zhang Hongning; Zhang Wei; Liu Yongwang and Liang Deyang
    , 2014, 41(5): 618-622.
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    To improve the down-hole drilling fluid energy and its utilization efficiency, a drilling string absorption and hydraulic pulsed jet generator was designed, its simulation model was established and simulation analysis was conducted, and its performance was tested in field application. Based on the idea of translating the energy of the drill string vibration into high pressure hydraulic pulsating jet energy, the structure of the device was designed and its working principle was analyzed, and then its simulation model was established. The simulation analysis results demonstrate that the device can produce the jet pressure 2 to 6 MPa higher than the nozzle pressure drop in conventional drilling. Field test results show that the device can improve the drilling speed significantly and extend the service life of the bit effectively; the device itself has steady performance and long service life, and can satisfy the drilling requirements.
    • 综合研究
  • Early Silurian paleogeography and source-reservoir-cap rocks of the Middle-Upper Yangtze region in South China
    Zhou Kenken; Mou Chuanlong; Xu Xiaosong; Ge Xiangying and Liang Wei
    , 2014, 41(5): 623-632.
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    The lithofacies paleogeography for the three successive ages (Rhuddanian, Aeronian and Telychian) in the Middle-Upper Yangtze region of South China in the Early Silurian (Llandoverian Epoch) is reconstructed according to the concept that structures control a basin, a basin controls facies, which, in turn, control the basic geology of oil and gas. The time-space distribution and sedimentology of source-reservoir-cap rocks are summarized. In the Rhuddanian age, the study area inherited and developed a semi-confinement stagnant basin resulting from tectonic compression started on Late Ordovician. The widely-covered organic-rich muddy shales occurred on deep-water shelves in a global-scale transgression after the Hirnantian glaciation and subsequent relatively slow regression. The sagged areas, formed mainly by tectonic tilting and plugging effect of rigid continental nucleus, are sedimentary centers of favorable source rocks. At the intermittent stage of tectonic compression during the Aeronian age, a mix-sedimented “carbonate ramp” formed by global sea-level drop, warm-humid climate and slight clastic sources. The reef-bank type carbonate reservoir rocks within Shiniulan Formation occurred in subtidal high-energy environments within inner ramp. In the subsequent Telychian stage, tectonic compression intensified, resulting in regression and overall uplifting of the basin, terminated the development of carbonate depositional environments. The eastern region was then dominated by shoreface and tide-dominated deltas where sand barrier type reservoir rocks in the Xiaoheba Formation occurred. The widespread muddy sediments of the Hanjiadian Formation could be cap rocks for the underlying potential oil-bearing layers.
    • 学术讨论
  • A Lattice Boltzmann model for multi-component vapor-liquid two phase flow
    Gong Bin; Liu Xuan and Qin Guan
    , 2014, 41(5): 633-640.
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    In traditional multi-phase multi-component Lattice Boltzmann (LB) models, the phase properties especially the vapor-liquid equilibrium calculations failed to model the actual flow realistically. A new multi-component vapor-liquid two phase LB model that involves a four-parameter (critical temperature, critical pressure, acentric factor and volume shift factor) equation of state (EOS) is proposed. The new model employs a four-parameter EOS to calculate the force on each lattice and then to determine the force between different fluid phases accurately. An accurate difference method is proposed to integrate the interaction force into the evolution functions of each component. Moreover, the Lorentz-Bray-Clark viscosity model is implemented to calculate the viscosity of lattice fluid according to the component density. The new model is validated and applied to forecast the phase behavior of methane, ethane, and propane mixture at multiple temperatures and pressures. The simulation results show a good agreement with experimental data and theoretical predictions.
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