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    01 December 2014, Volume 36 Issue 6
    Significance of Discovery of Shale Gas From Well YQ-1 in Northern
    Yunnan-Guizhou Provinces,China
    Liang Xing, Ye Xi, Zhang Zhao, Zhang Jiehui, Shu Honglin
    2014, 36(6):  1-8.  DOI: 10.11885/j.issn.1674-5086.2014.04.30.04
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    The high quality shale of Wufeng-Longmaxi formations that was encountered by well YQ-1 during the drilling process
    is characterized by thick single layer,high TOC content,high organic matter maturity,and well developed microscopic
    pore and cracks. The analysis results reveal that the absorbed methane content of core shale from well YQ-1 increases with
    the rise of burial depth,formation pressure,content of organic matter and clay minerals. The gas in place(GIP)of the shale
    reservoirs ranges from 1.0 to 3.0 m3/t,indicating that the shale horizon of the basal of Longmaxi formation and Wufeng formation
    is the first target stratum with commercial development value. The marine gas shale in Southern China is characterized of
    “intensive reformation,and high maturity”,and because the occurrence of shale gas resources is characterized by the control
    factors on distribution,gas pool,and sweet pot that are controlled by tectonics,storage condition and physical properties of
    rocks respectively. The emergency mission on shale gas exploration is to identify the sweet spot areas that are characterized by
    organic richness,abnormal formation pressure,and good development of brittle microscopic pore and cracks. The sweet spots
    of marine shale gas often develop in broad syncline far from faults that reach the surface and is of weak tectonic deformation,
    good cap rock. The strategy of marine shale gas exploration and development in Southern China should follow the sequences
    of filtering sweet spots firstly,and then setting demonstration area,finally carrying out large-scale development.

    Hydrocarbon Geological Characteristics and Potential Prospect of Basins
    in Bengal Gulf West
    Ke Weli1, Tong Xiaoguang2, Wen Zhixin1, Zhang Guangya1, Wang Zhaoming1
    2014, 36(6):  9-17.  DOI: 10.11885/j.issn.1674-5086.2012.12.18.02
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    The analysis of plate evolution,stratigraphy development,factors of source,reservoir and seal of passive continental
    margin basins in Bengal Gulf West reveals that the basins have experienced three rift development phases,i.e. pre-rift,syn-rift
    and post-rift phases,and they developed into passive continual margin basins in the late post-rift phase with the India Plate
    drifting to north. According to plate evolution and stratigraphy sequence features,the basins could be subdivided into prerift,
    syn-rift and post-rift mega-sequences,seven third-level sequences and six reservoir accumulation associations. Current
    exploration activities are mainly concentrated on Tertiary sequences of onshore and shallow offshore area. Studies on evolution
    and geological features of passive continental margin basins in Bengal Gulf West result in conclusions that further petroleum
    exploration prospects should be Perm-Tri channel sandstone of Pre-rift sequence,Cretaceous delta and fluvial sandstone of
    Syn-rift sequence,sub-water channel sandstone of passive continental margin Tertiary and deep water turbidity sandstone of
    post-rift sequence.

    Play and Exploration Potential of the Llanos Basin in Colombia
    Liu Yaming, Xie Yinfu, Ma Zhongzhen, Wang Dandan, Yang Xiaofa
    2014, 36(6):  18-26.  DOI: 10.11885/j.issn.1674-5086.2013.06.23.03
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    The exploration potential of the Llanos Basin in Colombia was made clear by the method of play analysis. The
    geological evaluation of the basin was made firstly,secondly the play evaluation,then the petroleum geology features and
    the resource potential of each 2nd order play,and the exploration direction was pointed out lastly. The basin has excellent
    accumulation conditions and perfect accumulation model. According to the oil and gas bearing situation of each reservoir,
    the basin was divided into 3 sets of 1st order play,including the confirmed central play,the potential upper and lower plays.
    According to the six principles of the structure of the basin,generation-reservoir-seal,oil and gas enrichment characteristics
    and so on,the central play was further divided into 4 sets of 2nd order play:the upper Cretaceous,Paleocene,Eocene and
    Oligocene. The recoverable resources of all the plays are 3.06×108 tons of oil equivalent,and the upper Cretaceous play is of
    the largest resources volume. Upper Cretaceous and Eocene plays are the key exploration plays,and inner slope and foredeep
    are the key zones. The steps and rules of play analysis applied in this paper for the first time can be a reference to the study of
    plays in other basins.

    Sedimentary Facies and Its Lateral Distribution of the
    Middle-lower Jurassic in Amu Darya Right Bank Area
    Zhang Ting1, Wang Qiang1, Liu Bin2
    2014, 36(6):  27-38.  DOI: 10.11885/j.issn.1674-5086.2014.03.23.01
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    The aim of this paper is to study the characteristics of sedimentary facies of the Middle-lower Jurassic in Amu
    Darya Right Bank Area according to the analysis of lithology,logging facies,seismic facies as well as regional structural and
    sedimentary background. The research shows that the Middle-Lower Jurassic stratum consists predominately of continental
    clastic deposits with small amount of marine-continental transitional sediments at the top. On this basis,four sedimentary
    subfacies including delta front,lakeshore,shallow lake,subtidal zone and twelve microfacies are identified. By studying
    the sedimentary evolution and lateral distribution characters,we identified two transgressive sequences in this stratum. The
    dominate sedimentary environment is shore-shallow lacustrine subfacies,while delta front subfacies are only present in limited
    areas of A block and the eastern B block in the early Middle-lower Jurassic. The lacustrine and deltaic environment contributes
    not only to the development of high quality source rocks,which are wide-spreading,but also to the development of reservoirs
    in the study area.

    Gas-bearing Reservoir Prediction of Braided River
    Hong Zhong, Liu Huaqing, Zhang Menggang
    2014, 36(6):  39-46.  DOI: 10.11885/j.issn.1674-5086.2013.07.18.02
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    The He 8 and Shan 1 members belonging to braided-river deposition are pay zones of Sulige western region,
    Ordos basin. The ranges of P-wave impedance of gas-bearing reservoir and surrounding rocks of these two members are
    overlapping. The gas reservoir could not be feasibly recognized by conventional post-stack seismic data. Also,due to the
    discontinuous mid-weak amplitude of seismic reflection,the seismic event of Shan1 member can′t be picked in the whole work
    area,leading to difficulty in obtaining the plane view of its sandstone distribution. Attempting to solve the problems above,
    we established the seismic response characterization of braided-river according to its sedimentary model. As the difference
    of Poisson ratio of gas-bearing reservoir and surrounding rocks are distinct,the AVO seismic data were utilized to identify
    gas-bearing reservoir. The conception of lithological converting has been proposed with reference to the theory of seismicsedimentology.
    The AVO attribute volume was converted to lithological volume,which provides convenience for the subsequent
    interpretation work. The isochronous surface of Shan1 member seismic reflection can be obtained with the aid of slicing method.
    The result shows that the feasibility of lithological converting of AVO attribute volume has been demonstrated by forward
    modeling and practical application. This series of method is capable of recognizing gas-bearing reservoir of He 8 and Shan 1
    members,and the evolutional history and plane distribution character of the gas-bearing reservoir are clearly delineated by the
    slices with isochronous significance.

    The Geological Characteristics and Hydrocarbon Accumulation Model
    of the Lower Paleozoic Clastic Play,Oman Basin,Middle East
    Li Haowu1, Tong Xiaoguang2, Wang Jianjun1, Wen Zhixin1, Zhang Yongjun3
    2014, 36(6):  47-59.  DOI: 10.11885/j.issn.1674-5086.2013.11.17.04
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    The lower Paleozoic clastic play is the most important gas play in Oman Basin,the sandstone reservoirs of Cambrian-
    Silurian Haima Group and its overlying thick mudstone being the basic reservoir-caprock combination,Huqf Group is the most
    important source rock. This paper analyzes the petroleum geological conditions,hydrocarbon accumulation models,exploration
    potential and risks. In the center of Ghaba sub Basin,Huqf source rock only generates gas today. The pores of early traps were
    mostly filled with the pyrobitumens formed by high formation temperatures. Attention should be paid to the traps formed after
    Cretaceous in exploration. The central palo-uplift of Ghaba Basin was a barrier for lateral migration,so the traps in east flank
    have risk of hydrocarbon charge. In the center of south Oman Sub Basin,it′s difficult for hydrocarbon to migrate vertically
    through the thick Ara salt to the upper Haima Group,so most of the traps lack potential. In the east flank of south Oman Basin,
    for the continued dissolution of Ara salt,which destroyed the seal of former oil pools,the oil released from them could recharge
    new traps of Haima Group,so there are chances for oil exploration.

    Characteristics Analysis of the Reservoir and Predominate
    Channel in Block Jin-16
    Liu Hongqi1, Li Baoying2, Wang Wanfu3, Dai Chunming4, Tang Dan3
    2014, 36(6):  60-68.  DOI: 10.11885/j.issn.1674-5086.2012.04.10.01
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    Block Jin-16 is an oilfield typical of high-porosity and high-permeability. In the process of water-flooding development,
    the injected water circulates along large pore channels,and the residual oil and water flooded zone scatter over the
    rocks,which increased the difficulty to extract remaining oil. This paper mainly discusses the lithology characteristics,reservoir
    space properties and the reasons for the formation of the advantaged channels based on the core data,casting lamella and
    other information. It illustrates that the reservoir has low compaction,low cement content,rich argillaceous cementation and
    poor rock cementation,which result in the formation of preferential channels in Block Jin-16. Another important aspect is that
    the high initial porosity and permeability are enlarged by injected water during the later stage of production. The influence of
    the pore space by water flushing and late physical and chemical reformation makes large channel seepage more obvious,and
    further exacerbates the formation of advantage channel.

    Application of Litho-stratigraphic Reservoirs Prediction by
    Three Seismic Methods
    Tong Minbo1, Gao Lidong2, Su Zhan3, Cao Qingrong1, Xu Xiaoqiang1
    2014, 36(6):  69-75.  DOI: 10.11885/j.issn.1674-5086.2012.12.24.04
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    In recent years,litho-stratigraphic reservoir exploration has become an important and difficult problem. The theory
    of“four basin types,three reservoir types”litho-stratigraphic reservoir play,trap,accumulation model,and the reseach model
    of“structure-sequence accumulation combination”have laid an important foundation for the exploration and exploitation of
    continental litho-stratigraphic reservoirs. The central depression in southern Songliao Basin belongs to“multi-slope break
    gentle slope-lake transgressive domain and high domain river delta combination”. The“structure-sequence”study alone is not
    enough for effective litho-stratigraphic reservoir prediction. Diversified geophysical methods for litho-stratigraphic reservoir
    exploration promotes the application of seismic technology in the field of litho-stratigraphic reservoir prediction,but the limited
    flexibility of seismic technology is also clear. This paper takes the research in central depression of southern Songliao Basin
    as an example,and explores application of vertical litho-stratigraphic combination,information of seismic trough,and multiwavelet
    decomposition technology,and we extract litho-stratigraphic information from seismic waveform. Applicability of the
    three seismic methods in litho-stratigraphic reservoir prediction of central depression in southern Songliao Basin is studied and
    has achieved good effect with reference to drilling and sedimentary rules constraint.

    Design of Multi-functional Ultrasonic Imaging Logging Tool
    Sun Zhifeng1,2, Chou Ao1, Chen Honghai1
    2014, 36(6):  76-82.  DOI: 10.11885/j.issn.1674-5086.2012.12.27.03
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    Based on the measurement principle of the ultrasonic impulse method,we designed a Multi-functional ultrasonic
    imaging logging tool,and explained how it works. It can conduct borehole wall imaging with the imaging mode of high
    resolution in open hole. It can also conduct casing inspection and cement bonding evaluation with the full wave mode in the
    cased hole. The proposed tool was tested in open hole and cased hole. Results shows that this tool can evaluate the geologic
    feature information,such as fracture,hole and bedding structure in open hole. The casing thickness imaging,inner and outer
    diameter imaging and cement impedance imaging can also be measured in the cased hole. This tool can provide quantitative
    evaluation of casing corrosion and cement bonding quality.

    Studies on CO2 Injection Scenarios for Large Dip Angle Reservoir
    of Funing Group in ZJD Oilfield
    Chen Zuhua
    2014, 36(6):  83-87.  DOI: 10.11885/j.issn.1674-5086.2014.07.24.03
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    It is reported in domestic and foreign literatures that higher displacement efficiency and oil recovery will be achieved
    with gas injection by utilizing gravity in a tilt reservoir than in a reservoir with a little tilt. In this paper,by using numerical
    simulation,the effects of dip angle and injecting position on CO2 displacement efficiency is studied. The result of the simulation
    shows that with the increase of dip angle,recovery percentage by CO2 injection increases while the residual oil saturation in
    the high part of the reservoir decreases. Furthermore,oil recoveries by injecting CO2 in the high part are higher than that in
    the low part in all scenarios. And the larger dip angle,the better displacement effect can be obtained by injecting CO2 in the
    high part as CO2 can form a small CO2 cap which is helpful for flooding oil. Experiments of the effect of different injection
    scenarios with the practical geological model of large angle reservoir indicates that injecting CO2 in the high part can enhance
    oil recovery by 8.69% more than injecting in the low part,and it activates more reserves. Preliminary success has been made
    after the field application of injecting CO2 in the high part:half a year after injecting CO2 for,the central well in waist of the
    reservoir restores from producing no liquid to producing 9.3 t oil.

    Mechanism Study on Water Control and Enhanced Oil Recovery by CO2
    Huff-puff for Shallow Heavy Oil Reservoir
    Sun Lei, Pang Hui, Sun Yang, Hou Dali, Pan Yi
    2014, 36(6):  88-94.  DOI: 10.11885/j.issn.1674-5086.2014.03.26.01
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    To solve the problems of rapidly increase water cut and low oil recovery in the later water-flooding of low heavy
    oil and heavy oil reservoirs,we conducted laboratory physical simulation experiments and single well numerical simulation of
    CO2 huff and puff in water control and oil enhancement. To find out the mechanism and feasibility,CO2 and reservoir oil/water
    compatibility experiment and long core experiment of CO2 huff and puff are carried out respectively. The former has shown that
    CO2 has capacity expansion and viscosity reduction effects on the heavy oil. At a certain temperature,as the pressure decreases,
    the volume of reservoir water saturated with CO2 expands and the solubility of CO2 in reservoir water declines which indicates
    that in CO2 huff and puff,water is trapped by the small core thus causing Jamine Effect,and preventing the water from being
    produced. The long core experiment has also shown that CO2 huff and puff has a significant effect on controlling the water and
    enhancing the oil recovery. This has also been demonstrated by single well numerical simulation of CO2 huff and puff.

    Research on CO2 Flooding Parameters Optimization of Extra-low
    Permeability Reservoirs
    Wang Huan, Liao Xinwei, Zhao Xiaoliang
    2014, 36(6):  95-104.  DOI: 10.11885/j.issn.1674-5086.2012.08.30.03
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    The Chang-6 formation of Block Wangyao in Ansai Oilfield belongs to the extra-low permeability reservoir. Currently,
    it has entered the high water-cut stage. It is difficult to further enhance recovery by water flooding. However,CO2
    flooding is an important EOR approach in extra-low permeability reservoir,which can compensate for the disadvantages of water
    flooding. Taking the Chang-6 of Wangyao extra-low permeability reservoir for example,this paper analyzes the geological
    features of the block and the problems in water flooding development,and optimizes the CO2 flooding pattern fitting for the
    pilot area by applying geological modeling and reservoir numerical simulation techniques,and further optimizes the parameters
    of formation pressure,production rate,water alternating gas time,shut-in gas-oil ratio and total gas injection volume. The
    results of this study will offer basic parameters of CO2 miscible flooding to the construction and implementation of field test.
    It also provides reference to implement action of CO2 flooding technology to the entire Ansai Oilfield.

    Research on Nitrogen Gas Lift Cleanup in Xingjiang Oilfield
    Wang Xiaolei, Yang Hai, Hong Jiangling, Li Yanling
    2014, 36(6):  105-109.  DOI: 10.11885/j.issn.1674-5086.2014.03.03.02
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    The gas reservoirs in Xingjiang Oilfield bear the following characteristics:great reservoir property differences,clay
    swelling ,water sensitivity and solid plugging. After perforation using the conventional strings,the perforating gun strings need
    to be replaced by the fracturing strings by killing the well. Repetitively killing the well causes secondary damage of reservoir,
    and makes it difficult for the flowback of the fracturing fluid due to the low-pressure-factor of reservoir. Therefore,the integrated
    string technology of perforation,fracturing and cleanup was developed. For the long-pocket gas wells without lower production
    layer,throw gun perforation technology is recommended. Otherwise,the full size perforation technique is adopted. The internal
    and tensile strength of stationary gas lifting barrel can reach 90.00 MPa and 70.00 MPa respectively;the loading capacity of
    gas lifting valve bellows can reach 35.00 MPa. The research result not only compensates for the shortages of the conventional
    completion strings,but also provides new technological approach to solve problems for similar gas reservoirs in unloading kill
    fluid,shortening cleanup time,reducing reservoir damage,etc. This research has high promotional and applicable value.

    Processing Method to the Data of Relative Permeability in Unsteady
    State Displacement
    Dong Dapeng
    2014, 36(6):  110-116.  DOI: 10.11885/j.issn.1674-5086.2012.08.30.07
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    JBN method is compared with Jones′ graphical technique by formula deriving and converting. It is concluded
    that the essential difference between the two methods is the different reference permeability of the rock. When calculating
    relative permeability,oil permeability at irreducible water saturation is a more suitable reference than the flowing ability of
    oil and water. The author made a comparison among Polynomial function,logarithmic function and exponential function
    when fitting average water saturation and total injection volume. The result shows that logarithmic function and exponential
    function have good fitting accuracy if piecewise fitting is carried out. Furthermore,oil ratio calculated by these two fitting
    function is more reasonable. We obtain similar oil relative permeability but quite different water relative permeability when
    using different functions to fit 1/Qi and 1/(IQi). Linear function,polynomial function and power function are compared,and
    the result calculated by power function is more reasonable.

    Effect of Well Completion on Acid Etched Wormhole Propagation
    Liu Ming1,2, Yang Peng1, Li Dequan3, Zhang Shicheng2, Mou Jianye2
    2014, 36(6):  117-122.  DOI: 10.11885/j.issn.1674-5086.2012.07.25.01
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    In carbonate acidizing,different completion methods have different effects on dissolution patterns caused by acidization.
    In this paper,we use a normal distribution function to generate initial porosity values and a two-scale continuum model
    to study the effects of perforation completion on dissolution patterns and analyze the effect of leakoff along the aperture. The
    results show that the dissolution pattern is very different from that of openhole completion. Acid flows into the formation
    through perforation tunnel,and the number of wormhole branches increases with the decrease of perforation length. Under the
    same injection velocity,the breakthrough volume of perforation completion without leakoff along the aperture is the least and
    that of open-hole completion is the most. Completion and leakoff rarely have effects on the optimum injection velocity. At
    small injection velocity,the inlet pressure declines sharply in the termination regime because of a very small distance between
    reaction front and spent acid front;at large injection velocity,the inlet pressure declines slowly due to the wide reaction front.

    Researches on Building Effective Displacement Pressure System of
    Advanced Water Injection in B239 Well-Block Reservoir
    Hu Shuyong1, Li Liang1, Wu Rui2, Wang Yujie3, Li Lei1
    2014, 36(6):  123-127.  DOI: 10.11885/j.issn.1674-5086.2013.11.07.03
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    The Chang 6 ultra-low permeability reservoirs test block of well-block B239 is developed with advanced water injection.
    However,the development effect has not reached expectations as planned. For this reason,we carryied out the research
    on the effectiveness of advanced water injection on improving development results. Based on the pattern of the infill wells
    adjustment,we designed the research plan by combining reservoir engineering and numerical simulation method. Researches
    show that the advanced water injection is more effective if the well spacing of the well network system reaches the effective
    distance. If the well spacing is too wide,advanced water injection cannot work or the effect is little. In that case high pressure
    will only appear at the bottom hole,without effective displacement. This study provides theoretical basis and technical support
    to advanced water injection development in other low permeability and ultra-low permeability oilfields,which has an important
    guiding significance for the exploitation of such oilfields.

    A Fast Solution to the Mathematical Model of Cross-linked
    Polymer Flooding
    Yuan Fuqing1,2, Mu Tinghua3, Wei Cuihua2
    2014, 36(6):  128-134.  DOI: 10.11885/j.issn.1674-5086.2012.08.30.12
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    To solve the problem of the poor computational efficiency in solving reservoir mathematical model,we studied a
    fast solution. A three-dimension,two-phase(oleic,aqueous)and five-component(oil,water,polymer,cross-linked polymer,
    cross-linker)mathematical model was presented according to the profile control and flooding mechanism of cross-linked polymer
    flooding. Based on IMPES method,a more efficient and more stable Douglas difference scheme was proposed which uses
    the step-by-step reduced-order idea to solve a model. The simulation result shows that compared with commercial simulator
    CMG,the Douglas difference scheme in combination with chase method can greatly improve the solution efficiency,which
    provides an effective way to solve a reservoir mathematical model.

    The Research on Corrosion in High-Sulfur Gas Purification Plants
    Zeng Dezhi1, Shang Jianfeng2, Long Decai3, Liu Yuanzhi2, Wang Tuanliang2
    2014, 36(6):  135-142.  DOI: 10.11885/j.issn.1674-5086.2013.10.20.02
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    A high-sulfur natural gas purification plant can process 120×108 m3 feed gas,in which the mole fraction of H2S and
    CO2 reach 14% and 8%,respectively. Production facilities and equipment in the high-sulfur natural gas purification plant are
    at severe risk of corrosion for the high content of acidic components and large capacity load. Considering the characteristics of
    the plant,we adopted the inductors(DG–9500)to monitor the corrosion in 14 detection points distributed in desulfurization,
    dehydration,sulfur recovery,tail gas treatment,sour water stripping unit. Through a one-year corrosion detection,we obtained
    the degree of corrosion in the process nodes,combined which with the corrosion coupon results,we found the corrosion weaknesses
    of this gas purification plant. The results showed that the corrosion mainly occurred in the amine regeneration system,
    sulfur recovery systems and chilled water cooling systems. The corrosion types include general corrosion,localized corrosion
    and pitting. It was also found that the results obtained from inductive probes and corrosion coupons were almost the same,
    which indicates that the former detective method can be used to monitor the corrosion conditions effectively in the high-sulfur
    natural gas plants. The research provides an important basis for corrosion detection in the high-sulfur purification plants.

    Synthesis of Imidazoline Modified Acrylamide-based Copolymer as
    EOR Chemical
    Jiang Wenchao1, Ye Zhongbin1,2**, Gou Shaohua1,2, Liu Xiangjun1,3, Song Zewen2
    2014, 36(6):  143-149.  DOI: 10.11885/j.issn.1674-5086.2013.10.31.03
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    A novel copolymer was synthesized using acrylamide,acrylic acid,N–allylimidazole and N,N–diallyl oleamide.
    The optimal conditions for synthesis such as temperature,pH,initiator and monomer loadings were studied. The viscosity
    measurements,and rheological measurement of the obtained copolymer were characterized by Infrared(IR)spectroscopy,H
    nuclear magnetic resonance spectrometer(1H NMR),scanning electron microscope(SEM). X-ray diffractometer(XRD)were
    also conducted to investigate the clay stabilization property of the obtained copolymer. The results indicated that the copolymer
    was of good temperature tolerance,and anti-shear abilities and salt resistance. Core flooding result revealed that the enhanced
    oil recovery could be up to 13.8%. The result of X-ray diffractometer revealed a good clay stablility of sodium montmorillonite.

    The Simulation and Analysis of Drillstring Stick-slip Vibration
    Lü Miaorong, Shen Shigang
    2014, 36(6):  150-159.  DOI: 10.11885/j.issn.1674-5086.2013.02.22.02
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    In this paper,based on dynamical equation of the drillstring of four degrees of freedom and bit-rock interaction law,
    we analyzed the dynamic characteristics of drillstring in straight borehole. And the systemic simulation software of a multi-DOF
    drillstring stick-slip vibration is developed. Using this software,we made the simulation research on the influence of single
    factor on the dynamic behavior of the drillstring. And we also derived the influence of the stiffness and the moment of inertia
    of the drillstring,the bit and the rotary table,and WOB,speed,etc. on the dynamic behavior of the drillstring. In addition,
    the four state characteristics of the movement of the drillstring are obtained. Further practical dynamic parameter simulation
    of the drillstring,reveals that the longer the drillpipes are,or the shorter the drillcollars,the more likely the drillstring is in a
    stick-slip vibration state. In addition,changing the inner and outer diameters of the drillstring is unlikely to effectively suppress
    the stick-slip effect. Obviously,these results have very practical significance for on-site drilling process.

    Numerical Simulation Analysis of Rock Breaking Mechanism for
    Oscillation Impacter
    Dong Xuecheng1,2, Xiong Jiyou1,2**, Wang Guohua1,2, Qin Dawei1,2
    2014, 36(6):  160-167.  DOI: 10.11885/j.issn.1674-5086.2014.08.15.01
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    A model was built to simulate the process of rock breaking,under the action of oscillation impacter.In this model,
    influences of different parameters on rock breaking efficiency were considered.Moreover,a quantitative analysis was proposed
    for different parameters,such as different frequencies,different cyclic dynamic loads and different kinds of rocks.Through
    the modelling and simulation using ABAQUS/Explicit,rock breaking efficiency was investigated in detail.The results indicate
    that the connected face of rock and bit appears in three distinct zones:the broken zone,damage zone and undamaged zone.
    Rock breaking process can be divided into three stages:center cutters of bit crushing rock,surrounding cutters of bit crush
    rock and rotary cutting.When the frequency is about 16 Hz,rock breaking efficiency gets the maximum value.Along with the
    increase of dynamic load,the depth of broken pit increased,when the dynamic load was larger than 10 kN,the rising trend
    of rock breaking efficiency slowed down.Different rock had different rock breaking efficiency.It is very helpful to the field
    application.

    Oil and Gas Accumulation Conditions and Accumulation Mode in
    Llanos Basin,South America
    Xu Guosheng1, Liu Wenjun1, Xu Shenghui2, Qian Jin1, Yu Qing1
    2014, 36(6):  168-180.  DOI: 10.11885/j.issn.1674-5086.2014.06.15.01
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    Llanos Basin is an important oil and gas rich basin in south America and even in the world which is located in the
    north of south American plate. Based on analysis of the Llanos Basin hydrocarbon accumulation,with condition,consideration
    of the tectonic evolution and sedimentation impact,the article reveals the hydrocarbon accumulation characteristics of Llanos
    Basin and establishes hydrocarbon accumulation mode. Llanos Basin has experienced three tectonic evolution stages of Paleozoic
    passive continental margin,Mesozoic back arc rift and Cenozoic foreland basins. There have developed multiple sets of
    hydrocarbon source rocks and reservoir cap combinations,various types of traps and complicated oil and gas distribution in the
    basin,and have good prospects for exploration and development. The hydrocarbon accumulation of the basin is characteristics
    of remote migration,mixed-source charging,broken sand-dimensional,continuous transporting and stepped-trapping accumulation;
    the oil and gas distribution of main production layer of Oligocene Carbonera Formation is characterized by large and
    medium-sized deep oil and gas fields formed by preferred trap of near hydrocarbon source rocks,and shallow-small-composite
    oil and gas fields formed by trap of far hydrocarbon source rocks. This knowledge obtained has important reference significance
    in further oil and gas discoveries of Llanos Basin.