Loading...

Table of Content

    01 October 2014, Volume 36 Issue 5
    Frontiers of the Oceanic Anoxic Events(OAEs),Terrestrial Deposits and
    Development of Source Rocks
    Hu Guang1,2, Cao Jian3, Hu Wenxuan3, Yao Suping3, Liu Wenhui2
    2014, 36(5):  1-15.  DOI: 10.11885/j.issn.1674-5086.2014.05.20.01
    Asbtract ( 260 )   HTML   PDF (1588KB) ( 635 )  
    References | Related Articles | Metrics

    Oceanic Anoxic Event(OAE)is the key to decipher the Cretaceous Earth System. The studies of the terrestrial
    deposits which were isochronous to OAE and impaction on source rocks are essential supplements for the researches on OAE.
    Take a reviewing look on this field,three trends can be drawn:(1)the scope of OAE researches become wider,and begin to
    concern the terrestrial deposits;(2)the work on OAE become more detailed,and more attention are paid to the geochemical
    characteristics of different types of organic matters;(3)the precisions of studies become higher,and high resolution and dense
    sampling strategy are begins to be carried out. However,the features and the triggers of the OAE are still disputed,and whether
    or not there are the terrestrial responses to OAE remains enigmatic. The research of terrestrial deposits which were isochronous
    to OAE is still very less,especially the correlation between marine and terrestrial systems under the precise chronological
    framworks. In addition,although the black shales that deposited during the OAE are important source rocks,but so far less
    attention paid to the impacts of OAE on the source rocks. The case study on the Lower Cretaceous terrestrial-transitional black
    shales(deposited during 113 ± 3 Ma to 109 ±2 Ma)indicated that these black shales not only are isochronous to the OAEs
    but also have similar negative carbon isotopic characteristics. The terrestrial-transitional Lower Cretaceous black shales in
    southeastern China might have relation with OAE. The OAE has active influence on the formation of terrestrial source rocks.

    The Reservoir Characteristics and Favorable Areas of Shale Gas
    in Northwestern Hunan Lower Cambrian Niutitang
    Jiang Wen1, Tang Shuheng2,Gong Yuhong3, Fan Erping2, Zhang Chenglong2
    2014, 36(5):  16-24.  DOI: 10.11885/j.issn.1674-5086.2014.04.16.06
    Asbtract ( 249 )   HTML   PDF (778KB) ( 583 )  
    References | Related Articles | Metrics

    Through outcrop observation and cross section measured,together with analytic results like microscope observation,
    geochemical parameters,pore structure,surface area and methane adsorption isotherm experiments,the geological
    accumulation characteristics and physical properties of the shale gas were investigated in detail in this article. Results show
    that the shale is characterized with wide distribution area,a great thickness,high organic content(an average of 1.87%),and
    high organic thermal evolution degree(above 1.0%). At the same time,a large variation in porosity(0.2%~25.9%),with an
    average size of 12.5±3.0 nm,and good sorting is conducive to shale reservoir reconstruction after migration. Pore structure is
    mainly dominated by tiny pores,but due to larger specific surface area and strong methane adsorption ability,a large amount
    of methane adsorbed on the shale surface. According to contrast with the shale constituency parameters of American 5 basins,
    we suggest that Yongshun–Sangzhi and Cili–Shimen Area are favorable shale gas accumulation zones.

    Characteristics of the Shale Gas Reservoir in the Lower Cambrian
    Hetang Formation,Northeastern Jiangxi,China
    Wang Ran1, Sang Shuxun1, Liu Shuigen2, Yu Kuankun2, Du Yi1
    2014, 36(5):  25-32.  DOI: 10.11885/j.issn.1674-5086.2013.08.29.08
    Asbtract ( 394 )   HTML   PDF (896KB) ( 555 )  
    References | Related Articles | Metrics

    From geochemistry,petrology-physical properties and characteristics of the reservoir space,the shale reservoir
    characteristics are studied by microscopic section,scanning electron microscopy and X-ray diffraction experimental analysis of
    44 black shales from the lower Cambrian Hetang Formation in northeastern Jiangxi. The results show that the Hetang Formation
    shale ranging from 22.1 to 735.0 m,single layer thickness ranges from 19.59 to125.16 meters in the study area. Organic matter
    content is high,range from 3.32% to 11.40%,averaging 5.75%,The maturity is high,between 2.35%~4.90%,belonging to a
    mature stage. Mineral composition mainly includes quartz,clay minerals,calcite,pyrite and marcasite and its brittle mineral
    content is between 18.95%~51.84% with an average content of 40.97%. The microporosity is well developed. The Hetang
    Formation has some differences compared to five commercial shale gas producing areas in the U. S. It is thick and contains
    brittle mineral. Organic matter content and gas content is high. The adverse conditions is that it is buried deeply and the maturity
    is too high.

    Contrast of Shale Gas Reservoir Conditions in China and the
    United States
    Guan Xiaoxu1,2, Yi Xiangyi1, Yang Huohai1,2
    2014, 36(5):  33-39.  DOI: 10.11885/j.issn.1674-5086.2013.12.05.01
    Asbtract ( 270 )   HTML   PDF (423KB) ( 848 )  
    References | Related Articles | Metrics

    The exploitation of shale gas has been greatly successful in North America,while it is just starting out in China.
    Comparing the conditions of shale gas formation in China with those in America,it is of great significance to better exploit
    shale gas. This paper compared and analyzed 3 aspects in detail:the conditions for accumulation of shale gas,the properties
    of reservoir and reservoir evaluation factors. Through comparison,we get the following conclusions. The conditions for
    accumulation of shale gas in China are more complex,because the reservoir has properties great depth,high temperature,
    high thermal maturity and thin thickness. The mineral composition of shale gas in China is more complicated. The main clay
    minerals are andreattite and illite,both of which are fine grain migrating minerals. On the other hand,the shale contains more
    quartz,which leads to a higher brittleness index. Therefore,the fracture operation can be well applied,reservoir evaluation
    factors are also more complex in China. In order to evaluate the shale gas formation,it is necessary to take organic charcoal
    content,organic maturation,kerogen type,net pay thickness and lithological feature into consideration. In all,from the aspect
    of reservoir conditions,the shale gas reservoir in China,especially in Sichuan Basin,has already been equipped with the large
    scale exploitation conditions.

    Cenozoic Tectonic Characteristics and Evolution in Changdi Area
    of Jiyang Depression
    Li Xuemei, Wang Wei, Wang Pingping, Fan Jiulin, Liu Chaofei
    2014, 36(5):  40-48.  DOI: 10.11885/j.issn.1674-5086.2013.07.15.01
    Asbtract ( 287 )   HTML   PDF (1426KB) ( 445 )  
    References | Related Articles | Metrics

    The main fault and its associated structures in Changdi Area of the Bohai Basin are studied according to its 3D
    seismic data,drilling wells by using balanced section technique. The result shows that a variety of scales,shape and properties
    of the fault are developed in Changdi Area,the majority of which belong to growth fault. Fault activity has the characteristics
    of episodic by the influences of the Jiyang Movement and the Dongying Movement. The larger two unconformity interfaces are
    closely related to the fracture episodic activities in Changdi Area. The multi-phase unconformity interface reflects the tectonic
    evolution of the experience of polycyclic depression in the Cenozoic. According to the analysis of the major balanced cross
    section and identification of the important interface,and combined with regional subsidence history,the tectonic evolution of
    the Changdi Area can be divided into three stages:fold formation stage,fault depression stage and stable settlement stage.
    Fault depression stage can be further divided into episode I in Eocene(E2 s3—E2 s2)and episode II in Oligocene(E3 s1—E3d).
    Hydrocarbon trap are mainly controlled by fault activities,and meanwhile under the influence of its tectonic evolution.

    Differential Hydrocarbon Distribution and Its Main Controlling
    Factors of Plat Area in Western Tazhong
    Zhang Baotao1,2,3, Yu Bingsong3, Su Jin2, Yu Hongfeng4, Wang Xiangwei1,3
    2014, 36(5):  49-58.  DOI: 10.11885/j.issn.1674-5086.2012.08.30.09
    Asbtract ( 186 )   HTML   PDF (2565KB) ( 490 )  
    References | Related Articles | Metrics

    There is abundant hydrocarbon in the carbonatite of Tazhong northern slope of Tarim Basin,and there are complicated
    and multiple reservoir types in this area,which can be divided into three types by PVT and fluid component:oil reservoir,
    volatile oil reservoir and condensate reservoir. By analyzing production performances of mass wells,seismic data as well as
    testing data and discussing the distribution of fluids,faults and reservoir,oil/gas distribution difference and its main dominating
    factors were revealed. The weathered crust unconformity developed in the top of O1l3 controlled the reservoir depth and reservoir
    thickness vertically;the reservoir horizontal inhomogeneity is the important reason for the differential oil/gas distribution.
    The strike-slip faults as migration pathway have obvious reformation to reservoir,which decides the gas cutting intensity of
    different fossil reservoirs in late Himalayan and the different phase reservoirs distribution,and this is the immediate cause for
    the multiple reservoir types and the complicated fluid characteristics in this area.

    Interlayer Modeling with Sequential Indicator Simulation Method
    Pan Shaowei1, Luo Haining2, Guo Zhi3
    2014, 36(5):  59-66.  DOI: 10.11885/j.issn.1674-5086.2014.01.27.01
    Asbtract ( 181 )   HTML   PDF (930KB) ( 567 )  
    References | Related Articles | Metrics

    The interlayer has an important influence on the distribution of remaining oil in the late period of oilfield development.
    In order to find out the the distribution of remaining oil of the 1st-3rd sandstone in Es2,the 3D distribution modeling
    of interlayer is established with the different variation function range based on the fine description of the lithology,physical
    property and electrical property. Then,different random seeds are used to develop the 3D distribution modeling with the same
    variation function range. At last,all the models of interlayer are tested to find out the best model of which the predicted values
    of all indexes are the closest to the actual values. The results of interlayer modeling show that too big or too small variation
    function range will cause the uncontinuity of modeling with the same random seed and that the impact on modeling with different
    random seeds is very small in the case of denser well network. The interlayer modeling of the 1st –3rd sandstone in Es2
    has an important significance on the confirmation of its 3D distribution.

    Situation and Prospects of Offshore Seismic Survey Geometry
    Li Xin1, Yin Cheng2,Ge Zijian3, Zhang Peng1, Yang Kai1
    2014, 36(5):  67-80.  DOI: 10.11885/j.issn.1674-5086.2014.08.28.01
    Asbtract ( 219 )   HTML   PDF (1440KB) ( 736 )  
    References | Related Articles | Metrics

    With the increasing decline of onshore oil exploration potentiality,the key trend of petroleum industry is focused on
    marine oil exploration. At present,China´s marine oil exploration is mainly spread out at shallow water,and further geophysical
    exploration is also being devoted in deep water ocean. In order to meet the demand of geological structure imaging in deep ocean
    area and satisfy the need of reservoir evaluation,searching for favorable exploration target and improving explorative success
    rate in this area,it is necessary to enhance the study of survey evaluation and design of marine seismic acquisition. During recent
    two decades,a series of marine streamer survey techniques,such as NAZ,MAZ,WAZ,RAZ and FAZ appeared gradually. In
    order to analyze and summarize the merit and demerit of particular case,we take some typical associated acquisition geometries
    and acquisition patterns as example,and illustrate and describe the characteristic of each one in this paper. Furthermore,to
    prospect the development of marine streamer survey evaluation and design for multi-vessel,WAZ,we hope it to be further
    developed in the future.

    Genesis of Low Resistivity Limestone Reservoirs in Oilfield A of Syria
    Xia Dongdong1, Sima Liqiang2, Zhang Qinghong1, Pang Wen1
    2014, 36(5):  81-89.  DOI: 10.11885/j.issn.1674-5086.2012.11.19.03
    Asbtract ( 250 )   HTML   PDF (784KB) ( 563 )  
    References | Related Articles | Metrics

    J Formation in Oilfield A of Syria is a rare low resistance limestone reservoir in the world,with high porosity,
    low permeable matrix reservoir and with resistance of 0.5∼5.0 Ω·m lower than water layer. Because few studies have been
    made on the causes for this low resistance reservoir before,to correctly evaluate the reservoir,this paper analyzes the forming
    mechanism and dominating factors of low resistance carbonate oil formation. We found that the special geological background
    is the basic of petrophysical origin in low-resistivity oil formation. The petrophysical origin uncovers the essence low-resistivity
    in carbonate oil formation. Low amplitude structures and weak hydrodynamic sediment are the geological background of lowresistivity
    oil formation. High irreducible water saturation,high formation water salinity,additive conductivity of clay minerals
    and conductive mineral are the internal causes for low-resistivity oil formation. The formation of low-resistivity reservoirs in
    carbonate rock is the result of macroscopic geological background and microscopic petrophysics characteristics.

    Seepage Numerical Model for Fractured Horizontal Well in Shale
    Gas Reservoir
    Guo Xiaozhe1, Zhou Changsha2
    2014, 36(5):  90-96.  DOI: 10.11885/j.issn.1674-5086.2013.09.11.07
    Asbtract ( 312 )   HTML   PDF (570KB) ( 535 )  
    References | Related Articles | Metrics

    After the hydraulic fracturing of horizontal wells,shale gas reservoir seepage areas show a complex fracture net- work
    morphology,single well flow numerical model considering desorption-adsorption mechanism has a strong theoretical value and
    practical significance for analyzing single well production factors. Based on Warren-Root dual media model guiding ideology,
    matrix flow mathematical model and fracture flow mathematical model are established considering desorption-adsorption.
    Methods of discrete differential equations is designed and IMPES seepage linear processing method is carried out,and finally
    iterative simulation programming is realized through the Gauss-Seidel. Field applications,based on the results of the microseismic
    for fractured horizontal wells in shale reservoir geological model was constructed,the established numerical model
    can analyze the impact of pressure,gas adsorption,permeability,formation properties and other characteristics on production
    parameters. The results are consistent with the law of shale gas production,so this simple model can effectively guide the field
    of engineering design and dynamic analysis.

    Influence of Shale Bedding Plane on Wellbore Stability for
    Horizontal Wells
    Ma Tianshou, Chen Ping
    2014, 36(5):  97-104.  DOI: 10.11885/j.issn.1674-5086.2013.06.30.03
    Asbtract ( 458 )   HTML   PDF (912KB) ( 952 )  
    References | Related Articles | Metrics

    Brittle shale formation developed a lot of bedding plane and microfissuring in marine shale gas region of South
    China. Borehole collapse problem of horizontal well in bedding plane formation has seriously hampers the development process.
    Therefore based on the linear elastic mechanics model of borehole stability and the single weak-plane strength theory,the
    borehole stability model for horizontal wells in bedding plane formationis is established. It considers influence of the attitude
    of bedding plane,strength of weak bedding plane,rock strength,horizontal azimuth,weakening of bedding plane(water
    cuts)and etc. Based on these,this paper quantitatively analyzed the effects of attitude of bedding plane and water cuts. The
    results show that collapse pressure is controlled by attitude of bedding plane and horizontal azimuth,and that the borehole
    stability of horizontal well is better when dip angle of bedding is 0°<θDIP<15° and 75°<θDIP<90°. Bedding weakening is one
    of the important factors,which lead to borehole collapse.No matter how attitude of bedding plane change,with water cuts of
    bedding increase,borehole collapse pressure increases rapidly,and the increase range of collapse pressure is about 12~18 MPa.
    When the water cuts is 20%,collapse pressure increases by 37.9%.

    Research on Wellbore Stability of Shale Gas Based on
    Hoek-Brown Criterion
    Liang Lixi, Liu Xiangjun
    2014, 36(5):  105-110.  DOI: 10.11885/j.issn.1674-5086.2014.03.26.06
    Asbtract ( 268 )   HTML   PDF (444KB) ( 802 )  
    References | Related Articles | Metrics

    The wellbore stability is one of the key technologies in order to achieve rule horizontal wellbore in shale with low cost.
    Due to the occurrence and the difficulty in obtaining mechanical parameters of the underground structural planes,the evaluation
    method of borehole stability by weak surface theory and Mohr-Coulomb criterion has not yet been applied in engineering,and
    was only studied in theory. In this paper,wellbore stability has been evaluated by using Hoek - Brown criterion. The core
    numerical model with different fractures has been created,and the tri-axial compression test with different confine pressures
    has been carried out by means of the numerical simulation. Relationship between the parameters mb,S and rock mass structure
    has been analyzed using the result of the numerical simulation. And the method to determine the parameters mb,S has been
    established with fracture development index. The analysis of engineering example shows that collapse pressure obtained with
    the theory are consistent with the actual drilling performance in shale formation and a new method for evaluating borehole
    stability of shale gas wells has been provided.

    Analysis of Gas Flow Behavior in Nano-scale Shale Gas Reservoir
    Ren Lan, Shu Liang, Hu Yongquan, Zhao Jinzhou
    2014, 36(5):  111-116.  DOI: 10.11885/j.issn.1674-5086.2014.01.07.06
    Asbtract ( 228 )   HTML   PDF (386KB) ( 686 )  
    References | Related Articles | Metrics

    Shale gas reservoir theory and field practices showed that the actual yield is higher than the predicted production
    of traditional seepage flow model,and that classic Darcy percolation law cannot fully describe the shale gas flow behavior
    of the shale media. Thus a calculation model for accurate description and calculation of gas flow of shale media needs to be
    established. Existing shale gas reservoir seepage flow models are the correction to traditional viscous flow by simply attached
    molecular flow,which ignored the middle flow state of the molecular flow and viscous flow,especially for characterization
    of transition flow. This paper considers different complex flow pattern in shale media to established gas flow analysis model
    of describing the shale reservoir. The calculation results show that the smaller the porosity of shale reservoir is,the smaller
    the gas molecular molar mass is and the lower formation pressure could be,the easier gas flow shows the micro flow regime,
    and the greater the ratio of the apparent permeability to Darcy permeability is. The model reveals the essential reason why the
    shale reservoir actual yield is higher than predicted yield of Darcy model,and the research has significant guiding importance
    to direct shale gas reservoir production.

    Large Scale Fracturing Technology of Well Pengye HF–1 Shale Gas
    Yang Huaicheng, Mao Guoyang, Song Qicang, Ji Zhijian, Liu Fangzhi
    2014, 36(5):  117-122.  DOI: 10.11885/j.issn.1674-5086.2012.08.30.04
    Asbtract ( 255 )   HTML   PDF (442KB) ( 779 )  
    References | Related Articles | Metrics

    Shale gas reservoir with low porosity,low permeability,and fractures development and other characteristics must
    be stimulated in order to achieve commercial development. Well Pengye HF–1 is one of the key shale gas exploratory wells of
    Sinopec. According to analysis of the reservoir conditions,the fracturing model of the well was determined. On the basis of
    this,we decided the fracturing crafts. Through experimental study,fluid and proppant selection were optimized. Well Pengye
    HF–1 was fractured according to the fracturing design,and the whole progression was divided into 12 sections. The treatment
    fluid is 16 211.6 m3,the accumulated proppant is 1 332.7 t. After the test,the well yields 20 000 m3/d. The well fracturing
    achieved great success and deliverability test obtained breakthrough,which not only proved the performance of shale containing
    gas and that the fracturing technology is suitable for the reservoir,but also provided a good references in other shale gas reservoir
    stimulation.

    Modeling of Reservoir Characteristic and Its Application
    Jiang Ruizhong1, Wei Xihui2, Liu Mingming1, Shan Lijun1, Yao Zheng1
    2014, 36(5):  123-128.  DOI: 10.11885/j.issn.1674-5086.2012.06.28.01
    Asbtract ( 216 )   HTML   PDF (686KB) ( 504 )  
    References | Related Articles | Metrics

    Considering the disadvantages of reservoir concept model and real model,a reservoir characteristic model is proposed
    which can reflect the main reservoir geological characteristics,well pattern characteristics,production characteristics,
    percolation characteristics and distribution characteristics of remaining oil. The steps of establishing reservoir characteristic
    model are described in details. Its modeling process is simpler,and the effectiveness which reflects the geological and development
    characteristics lies somewhere in between those of the concept and real models. However,the model is able to present
    the main percolation characteristics and distribution characteristics of remaining oil. Based on this new model,development
    mechanism and actual water injection strategies are studied. Meanwhile,reservoir characteristic model provides a new method
    of modeling and expands the types of reservoir model. At last,Kongerbei Oilfield is taken as an example to describe the details
    of establishing the reservoir characteristic model and the cyclic water flooding strategies are studied on the model.

    Water-oil Displacing Modeling Experiment of Interlayer Heterogeneous
    Conglomerate Reservoir
    Tang Hongming1, Wen Xin2, Zhang Xuyang2, Ren Xiaocong3, Liu Hongxian4
    2014, 36(5):  129-135.  DOI: 10.11885/j.issn.1674-5086.2012.06.06.02
    Asbtract ( 310 )   HTML   PDF (691KB) ( 677 )  
    References | Related Articles | Metrics

    Aiming at the strong heterogeneity,the obvious contradiction between layers,the big producing difference of the
    profile and the low overall recovery rate of the reservoir. Taking the conglomerate reservoir of T2k2 formation in Block 7 of
    Xingjiang Oilfield as an example,a series of water-oil displacing experiments of different heterogeneous degree are conducted
    at constant pressure. The experiments show that in the same group of the parallel water-oil displacing experiments,the higher
    the permeability is,the faster the cores start while the water cut rises faster,the breakthrough recovery gets lower and the
    displacing efficiency becomes higher;the differential between the layers increases as the displacing efficiency falls and the
    parallel displacement with relative permeability differential bigger than 8 can not be launched;cores of single mode or dual
    mode pore structure have higher displacement efficiency,the complex mode of sandy conglomerate and conglomerate has lower
    displacement efficiency,the displacement efficiency of the low-medium permeability cores increases and the water cut rises
    faster after the displacement pressure of the parallel model is magnified.

    A Mechanism Model for Multiphase Flow in Gas Wells Using Foam
    Dewatering Technology
    Liu Tong1, Ren Guirong1, Zhong Haiquan1, Pan Guohua2, Deng Yuchuan3
    2014, 36(5):  136-140.  DOI: 10.11885/j.issn.1674-5086.2012.08.30.05
    Asbtract ( 269 )   HTML   PDF (447KB) ( 670 )  
    References | Related Articles | Metrics

    Based on the basic physics principle,this paper presents a mechanism model for multiphase flow in gas wells using
    foam dewatering technology,which can be applied to various flow patterns. Firstly,based on the experiments of Mitchell and
    Taitel,the model considers four distinct flow patterns(bubble,slug,homogenous foam,and mist)and formulates the transition
    boundaries among them. Then individual models for four flow patterns are developed. Bubble flow and slug flow are described
    by the drift flow models. Homogenous foam flow is treated as power-law fluid. Mist flow is simplified as no-slip model. The
    evaluation results using pressure test data in 39 foam lift gas wells indicate that the unified model shows an average error of
    -0.55%. Sensitivity study shows that foam lift gas well may experience bubble flow or slug flow while the gas-liquid ratio is
    low. Appropriately supplying gas can move the flow into the homogenous foam flow,which can improve the lifting efficiency.

    Selective Water Control of a Relative Permeability Modifier
    Qi Ziyuan1, Wang Yefei1, Wang Tao2, Wang Guijie3, Yu Weizhao1
    2014, 36(5):  141-147.  DOI: 10.11885/j.issn.1674-5086.2012.07.25.03
    Asbtract ( 248 )   HTML   PDF (470KB) ( 741 )  
    References | Related Articles | Metrics

    The static adsorption and selective water shutoff performance of a cationic polymer type relative permeability modifier(
    RPM)were studied. The results show that the static adsorptions of RPM on quartz sands and oil sands are both langmuir
    adsorption,and the adsorption on quartz sands is twice of that on oil sands;the static adsorption is strongly affected by electrostatic
    attraction and the wettability of solid surface,and RPM can alter the oil wet surface(105°)to weakly water wet(72°);
    core flood tests are conducted to study the selective water shutoff of RPM,and it shows that the oil and water residual resistance
    factors decreases with the increase of permeability,temperature and brine salinity. The swelling/shrinking of polymer
    adsorption layer is a reasonable explanation for RPM selective water control.

    Single Step Online Acidizing Technology for Offshore Water
    Injection Wells
    Liu Pingli1, Zhang Lu1, Pan Yiyong2, Wang Tianhui2, Zhao Liqiang1
    2014, 36(5):  148-154.  DOI: 10.11885/j.issn.1674-5086.2014.02.17.05
    Asbtract ( 230 )   HTML   PDF (536KB) ( 711 )  
    References | Related Articles | Metrics

    To address the problems associated with conventional acidizing on offshore platforms,such as large equipment
    footprint,long operation time,difficulty in treatment coordination and negative impact on production caused by repetitive
    acidizing. A novel and simplified acidizing technology for horizontal wells is proposed and studied in this paper. Intelligent
    integrated acid-Inteacid,which is highly efficient in damage removal and precipitation inhibition,is used to substitute the
    conventional three stages of acid system and simplify the mixing and injection process. Acid is added into the injection pipeline
    system at predesigned ratio and conveyed to formation to achieve stimulation under the control of intelligent injection system
    CCS. Real-time injection pressure and flow rate are monitored to compute the corresponding skin factor and adjust treatment
    parameters automatically,ensuring the optimum result of acidizing. The application of this novel technology saves the operation
    time and footprint,maximizes human resource and improves the treatment safety significantly. Over 80 field cases show that
    the technology is effective in reducing injection pressure and enhancing productivity with high success ratio and efficiency.

    Corrosion Perforation of CaCl2 Produced Water to Bottom Plate of
    Crude Oil Storage Tank
    Liu Yucheng, Zhang Yinlong, Liao Sicheng, Xu Junzhong
    2014, 36(5):  155-159.  DOI: 10.11885/j.issn.1674-5086.2013.10.08.02
    Asbtract ( 192 )   HTML   PDF (452KB) ( 483 )  
    References | Related Articles | Metrics

    An analysis of process and influening factors in Tuha oilfield was made,aiming to solve the problems in oil production
    and safety issues caused by perforation leakage on tank bottom. After exposing coupons in the storage tank for 120 days,
    corrosion rate of weight loss was calculated. Scanning electron microscope(SEM)was employed to observe the microscopic
    corrosion morphology of coupons,and the composition of water and steel at the bottom of the storage tank were analyzed.
    The corrosion process was researched through electrochemical method and the influence of Ca2+ and Cl− on corrosion rate was
    tested. The results show that the irregular pitting corrosion appears on the surface of coupons hung at the bottom of the storage
    tank. The corrosion rate of weight loss is 0.22 mm/a and the corrosion rate tested by electrochemical method is 0.15 mm/a. The
    instantaneous corrosion rate presents a trend of gradual increase. Repetitive passivation and solubility of surface film occurs
    on carbon steel. Ca2+ and Cl− will accelerate corrosion in water solution in oil tank bottom. The research lays a foundation for
    analyzing and solving leakage of tank bottom.

    Theoretical Analysis on Makeup Torque in Tubing and Casing
    Premium Threaded Connections
    Xu Honglin, Shi Taihe, Zhang Zhi
    2014, 36(5):  160-168.  DOI: 10.11885/j.issn.1674-5086.2014.04.30.03
    Asbtract ( 373 )   HTML   PDF (740KB) ( 813 )  
    References | Related Articles | Metrics

    The makeup torque and its composition of premium threaded connections are of great importance for improving
    mechanical and sealing integrity of tubing and casing. On the basis of analysis on typical makeup torque vs. turns curve,
    the theoretical calculation method of makeup torque for premium threaded connections has been established with the elasticity
    mechanics theory of thick-wall cylinder and rotary shoulder torque formula. The influences of different interferences and
    thread compound friction coefficient on the total torque and the ratio of torque acting on shoulder to total torque has also
    been investigated and the results show that the larger the interferences and thread compound friction coefficient,the higher the
    total makeup torque. The smaller the thread tooth radial interference,sealing surface radial interference and thread compound
    friction coefficient or the larger of the shoulder axial interference,the higher the ratio of torque acting on shoulder to total
    torque. Generally,the ratio is mainly influenced by thread tooth radial interference and shoulder axial interference,while the
    thread compound friction coefficient mainly affects the total torque. We suggest that enhancement of tolerance matching be
    optimized,processing precision be improved,makeup turns be strictly controlled and attention to thread compound optimized
    should be carried out. The study results provide theoretical basis for determining reasonable makeup torque of premium threaded
    connections and calculating its strength.

    Hierarchical Fault Diagnosis of Rod Pumping System Based on
    Fault Distinguishing
    Liang Hua
    2014, 36(5):  169-175.  DOI: 10.11885/j.issn.1674-5086.2012.11.19.09
    Asbtract ( 168 )   HTML   PDF (479KB) ( 467 )  
    References | Related Articles | Metrics

    There is higher fault probability under the bad work conditions of rod pumping system. Because of the large amount
    of sample and the long-time steady status,this paper proposes hierarchical fault diagnosis method. Fault distinguishing and
    fault identification are two phases in this method. In fault distinguishing,fault phase and normal phase are classified according
    to statistical rule of normal sample in dynamometer card. Combining statistical theory and search-tree,fault identification is
    processed in fault sample. Using this method,mechanical model of rod pumping system is not to be established and training
    set of fault sample is not necessary. Fault distinguishing process includes:fault taring phase and fault distinguishing phase.
    In fault training phase,stochastic distribution rule and parameters of samples are determined by X2 goodness-of-fit test after
    abnormal samples are rejected,then normal area and fault area is calculated. In fault distinguishing phase,classification of
    fault is estimated according to whether or not feature value of test sample is in fault area. Examples indicate fault samples can
    be selected from large number of samples in distinguish fault and correct rate of fault distinguishing is high. Statistical rule of
    training samples can reflect the actual production of oil well.

    Component Weight Factor Determination of the Nature Gas
    Compressor Integrity Assessment Based on AHP
    Liang Zheng1, Dong Chaoqun1, Tian Jialin1, Yu Dujun2, Ma Kedu2
    2014, 36(5):  176-184.  DOI: 10.11885/j.issn.1674-5086.2013.04.15.03
    Asbtract ( 295 )   HTML   PDF (477KB) ( 490 )  
    References | Related Articles | Metrics

    When natural gas compressors run into their full life cycle stage or extended service,there exist some hidden safety
    troubles in the operation process,so their safety life assessment is crucial to managers and users of the oil and gas field. For
    the units safety life assessment problem,research is carried out to clarify the relationship about the units integrity assessment
    and each component weight. The paper determines the natural gas compressor unit overall assessment index system based
    on components safety assessment. AHP is used to determine the components weights factor of the units. Aiming at security
    indicators and economic indicators of the weights,the high-level judgment matrixes are determined. The judgment eigenvectors
    and the largest eigenvalue were calculated by using the Matlab software. We must test the single-level consistency and the total
    level of the consistency. Several adjustments have done to meet the single-level consistency and the total level consistency.
    Finally the components of the compressor weights factor were determined and the theoretical basis was provided for the key
    components′ life assessment of compressor. So,it should be placed more emphasis on the higher weight components in the
    management and maintenance later days.