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    20 August 2008, Volume 29 Issue 4
    专家论坛
    STUDY ON WELL LOGGING INTERPRETATION MODEL FOR HEAVYOIL RESERVOIR IN THE FOURTH MEMBER OF SHAHEJIE FORMATION OF BLOCK CAO4 IN LEAN OILFIELD
    LIN Cheng- yan XUE Jiu-huo WANG You-jing
    2008, 29(4):  1-5.  DOI: 10.3863/j.issn.1000-2634.2008.04.001
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    The target sections Es4 are located in the marginal area of the basin and with a shallow buried depth (about 1000m).The logging interpretation of heavyoil reservoir is very difficult because of the loose reservoir,heavy oil,complex rock texture,strong heterogeneity and clear differences between layers.Based on the core analysis,well test,production test and the oilfield production performance,the "four properties"(i.e.,lithology,physical property,electric property and hydrocarbon bearing)relationships among pebbly sandstone,coarse sandstone,fine sandstone,siltstone,conglomeratic argillaceous sandstone and pelitic siltstone formation are studied,the logging interpretation models of porosity,permeability and oil saturation for each sand group is set up.By using the interpretation models,51 wells in this area are reinterpreted,the result shows that the interpretation models based on different sand group have higher accuracy,and reliable parameters are provided for geologic modeling and remaining oil tapping.
    地质勘探
    SPATIAL PATTERN OF UNCONFORMITIES IN DEPOSITIONAL BASIN
    ZHOU Xiao-jun LIN Chang-song LI San-zhong PENG Li CHEN Qing-qing
    2008, 29(4):  6-10.  DOI: 10.3863/j.issn.1000-2634.2008.04.002
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    After multidisciplinary analysis of the sectional and planimetric characteristic of the unconformities in the Tazhong uplift,as an example,the spatial patterns and distribution characteristic are elucidated and the structural evolution in the Palaeozoic is probed.In overlapped basins,which usually undergo multiple superposition of tectonic movements,many unconformity interfaces are developed.There are some rules in the distribution and spatial pattern of the unconformities,from the uplifted area to the sunken area,the highangle and superimposed unconformities,lowangle truncated or onlayed triangle unconformities and parallel unconformities or conformities develop respectively.The differences between the spatial patterns of the unconformities are important to control the oilgas migration and accumulation.Considering the oilgas geologic conditions in the Tazhong uplift,the onlap unconformities traps in the Devonian are expected.

    STOCHASTIC MODELING STUDY ON INTERLAYERS IN 91 LAYER,SEGMENT 2 OF SHAHEJIE FORMATION,TUO 7 FAULT BLOCK,SHENGTUO OILFIELD
    LIN Bo; DAI Jun-sheng JI Guo-sheng FENG Jian-wei
    2008, 29(4):  11-14.  DOI: 10.3863/j.issn.1000-
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    The 91 layer,segment 2 of Shahejie Formation,Tuo 7 fault block,Shengtuo Oilfield is taken as an example,3D spatial distribution stochastic modeling of the interlayers is studied in order to find the relationship between interlayers distribution and remaining oil distribution.On the basis of geologic setting,an integrated study is conducted,with well drilling data and logging.Three interlayers types which include muddy interlayer,calcareous interlayer and physical property interlayer are confirmed.A 3D distribution modeling for interlayer is developed by sequential indicator simulation method.The model analysis reveals the distribution range of calcareous interlayer is the greatest,the distribution range of muddy interlayer is in the middle.The average thickness of muddy inter layers is 0.6m,the extending distance is 50-105m,and the distribution area is 0.01-0.05km 2.Interlayer distribution density is 0.11-0.63m/m,distribution frequency is 0.52-1.24layers/m.The average thickness of calcareous interlayers is 0.4m,the extending distance is 40-180m,and the distribution area is 0.01-0.08km2.Interlayer distribution density is 0.15-0.76m/m,distribution frequency is 0.61-1.39layers/m.There are many interlayers in 2-163,3-33,5-228,4-10,7-221,5-213 well areas,where

    remaining oil could be rich.

    MICROSCOPIC EXPERIMENT OF THERMAL TREATED ROCK 
    LIU Jun-rong WU Xiao-dong
    2008, 29(4):  15-18.  DOI: 10.3863/j.issn.1000-
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    An experimental study of high temperature treatment is carried out on three types of rock samples,which come from reservoir formation,to study the effect of thermal treatment on mineral composition and microfracture network,which were measured by Scanning Electron Microscope (SEM) and mineral compositions analysis under the atmospheric pressure and room temperature.Results indicate that the mineral compositions change with the increasing temperature at 100℃ to 800℃ and part of the crystal structure is destroyed.Some intergranular,intragranular and transgranular fractures are induced in the rock during thermal treatment and forms a good connection of fracture network,which results in the increase of rock permeability.The change of crystal structure and the mechanism of fracture creation and extension are discussed,and the mechanism of permeability increase of thermal treated rock is also analyzed.The result will be used for reference on how to improve the flow condition at the nearwellbore formation by formation heat treatment

    DIAGENESIS AND SECONDARY PORE ORIGIN OF SANDSTONE AND CONGLOMERATE RESERVOIR IN YONGBEI AREA
    WANG Shu-bao; ZHONG Jian-hua; WANG Yong XIA Jing-sheng
    2008, 29(4):  19-23.  DOI: 10.3863/j.issn.1000-
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    In order to understand the influence of pore evolution and diagenesis on sandstone and conglomerate reservoir petrophysical property of the third and fourth members of shahejie formation in yongbei area,reservoir rock property and diagenesis are studied by using the methods of core and rock tine section observation,electron microscope scanning and Xdiffraction analysis.It is revealed that cementation destroys the reservoir property and dissolution improves it.Compaction result in primary pore decreasing,on the other hand,high pressure result in mineral grain breaking,so physical properties of reservoirs are improved.The loss ratio of porosity from the cementation and filling is about 43.95%,and that from compaction is about 25.29%.The secondary pores account for a great proportion in the Es3-Es4 reservoirs.The mechanism of genesis includes thermal evolution of organic matter,experiment indicates that the thermal degradation makes kerogen produce a large amount of organic acid before it goes into the oil generation windows,eluviations at unconformities or fracture zones produce weathering crust secondary pores,the fluid thermal cycle convection leads to the formation of secondary pores.

    APPLICATION OF LWD DATA IN LOG EVALUATION OF HORIZONTAL WELL
    SIMA Li-qiang FAN Ling WU Feng
    2008, 29(4):  24-26.  DOI: 10.3863/j.issn.1000-
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    The intrinsic difference between horizontal well and vertical well is that media don′t show radial symmetry around the wellbore.Therefore,such situations as aeolotropism,thin bed and inclined layer will become more difficulty in log interpretation of horizontal well.Stratum data acquired from LWD(loggingwhile drilling),because of the two characteristics of immediacy and uthenticity,have favorabe dominance in log evaluation of horizontal well,and can be used to effectively distinguish stratum,oil and gas reservoir(gas reservoir especially).The text describes some oftenused methods in layer interfaces recognition,reservoir evaluation and fluid contact recongnition,which can be used in log evaluation of horizontal well.In addition,taking a carbonate horizontal well drilling in Sichuan oil province as example,application of LWD data in this well is evaluated,to take a step further,some problems how LWD data will be better used in log evaluation of horizontal well are proposed.

    GEOCHEMICIAL CHARACTERISTICS OF NATURAL GAS OF XUJIAHE FORMATIONIN SOUTHERN AND MIDDLE SICHUAN
    XIAO Zhi-hua XIE Zeng-ye LI Zhi-sheng MA Cheng-hua SUN Qing-wu
    2008, 29(4):  27-30.  DOI: 10.3863/j.issn.1000-
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    In view of the natural gas of Xujiahe Formation in southern and middle Sichuan Basin,it is concluded that the proportion of CH4 is about 80%-96% in component of hydrocarbon,that of C2 is about 3%-18%,the ratio of C1/(C1-5) is less than 0.95,It is a typical wet gas and belongs to thermal degradation gas of kerogen.The gas isotope composition of δ13C1 ranges from 43‰ to 37‰,while that of δ13C2 from30‰ to 24‰,δDCH4 ranges from 190‰ to 150‰,δDC2H6 from 150‰ to 110‰.There is an fairly well positive correlation between δ13C1 and the absolute concentration of methane.The carbon isotope value of natural gas of Xujiahe Formation is obviously lighter than that of natural gas in the marine facies strata,it is of the coal related gas feature,which shows that the natural gas comes from Upper Triassic coalbed source rocks.

    FEATURE OF FLUID INCLUSIONS AND THE PERIOD OF PETROLEUM ACCUMULATION IN LINNAN SAG
    ZHU Zhi-qiang;ZENG Jian-hui;
    2008, 29(4):  31-34.  DOI: 10.3863/j.issn.1000-
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    In order to determine the period of hydrocarbon accumulation in Linnan Sag,study on fluid inclusions of different structural parts is done systematically in this paper.The history of hydrocarbon migration and accumulation in Linnan sag is discussed based on the data of fluid inclusions,homogenization temperature,burial history,thermal history and hydrocarbon generation analyses.There are mainly 3 types of fluid inclusions in sandstone reservoirs in Linnan Sag,i.e.,aqueous inclusion,liquid hydrocarbon inclusion and gas hydrocarbon inclusion.The homogenization temperatures of the aqueous inclusions coexisting with organic inclusions are 105-125℃.It is supposed that in different structural parts in Linnan Sag there are different periods of hydrocarbon accumulation.Hydrocarbon accumulation in the center of Linnan Sag occurred in two stages.They were late Oligocene Dongying Period and Miocene Guantao Period to Pliocene Minghuazhen Period.The latter is the main accumulation period.Hydrocarbon accumulation on the edge of Linnan Sag occurred in Miocene Guantao to Pliocene Minghuazhen Period.

    HYDROCARBON SOURCE AND THE ACCUMULATION IN JIANDING MOUNTAIN,NORTHWEST QAIDAM BASIN
    LU Jun-gang CHEN Shi-jia ZHANG Dao-wei FAN Xiao-jun WANG Min-fa
    2008, 29(4):  35-38.  DOI: 10.3863/j.issn.1000-
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    Jianding Mountain and Nanyi Mountain are the two adjacent structures in the northwest of Qaidam basin.Commercial oil and gas flow has been recovered in the shallow formation but nothing obtained in the deep formation of Jianding Mountain,so the accumulation model study of Jianding Mountain oil and gas structure is significant to the future exploration.In this paper,the authors apply the special geochemical characteristics of the different components of crude oil to identify the oil and gas source and explain successfully the reason why the oil maturity is higher than that of rock maturity,point out that the oil of N22 of Jianding Mountain comes from N1 matured hydrocarbon source rocks and mixed with low matured oil in the accumulation process,and the reservoir extracts of the deep formation is provided by the E32 matured hydrocarbon source rocks.It is recognized that the oil of Jianding Mountain is matured,and it comes from the hydrocarbon source rocks in the vicinity,not from the south of Qaidam Basin.Finally,the authors build the reservoir accumulation model of the Jianding Mountain reservoirs integration with hydrocarbon generation history and tectonic movement history.

    NATURAL GAS RESERVOIRING CONDITIONS OF SINIAN AND CAMBRIAN IN FROM WESTERN HUBEI TO EASTERN CHONGQING AREAS
    GUO Zhan-feng CHEN Mian-kun FU Yi-xing CHEN Xue-hui
    2008, 29(4):  39-42.  DOI: 10.3863/j.issn.1000-
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    The predicted Sinian and Cambrian gas resource amounts to about 1.42×1012 m3 in from western Hubei to eastern Chongqing areas,the prospect for the exploration is broad.Lower Cambrian mudstone is mostly hydrocarbon source rock and has good gas generating potential.Dengying Formation of Sinian and Shilongdong Formation of Lower Cambrian are two sets of high quality reservoirs attributed to favorable sedimentary facies,paleokarst action and fractures linkage.The sealing ability of the multi cap cocks is good,which is beneficial to the preservation condition of natural gas.According to hydrocarbon source rocks evolvement,tectonic evolvement and paleouplife evolvement,reservoiring course of Sinian and Cambrian natural gas in the areas is grouped into three phases:lithologic(paleokarst)stratum reservoirs during CaledonianHercynian,structural reservoirs during Indo Chinese epoch early Yanshanian,reservoirs adjustment and finality during ate Yanshanian Himalayan.Based on these facts and combined with the analysis of drilling date,it is indicated that there are excellent gas reservoir formation conditions in the areas and that Shizhu synclinorium is an important target in from western Hubei to eastern Chongqing areas for future Sinian and Cambrian natural gas exploration.Jiannan structure is a large scaled trap and has good trap style,so that it should be taken as the most favorable exploration target.

    TECTONIC EVOLUTION AND FORMATION OF RESERVOIRS IN QAIDAM BASIN
    CHEN Yan-peng LIU Zhen LI Wei-lian DANG Yu-qi MA Da-de
    2008, 29(4):  43-47.  DOI: 10.3863/j.issn.1000-
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    Tectonic evolution plays an important role in the formation,accumulation and distribution of petroleum pools.In view of the tectonic characteristic of the Qaidam Basin,the characteristic of the fault system is analyzed in detail,and then the control of tectonic on the pools are pointed out as following,1,discordogenic faults control the distribution of the petroliferous system,2,tectonic movement during the middle and late period of the Himalayan movement controlled the formation and evolvement of the structural trap,3,the fault system controls the distribution of the transforming system and migration,4,the fault activities during the late period of Himalayan movement were destructive,5,structural belts control distribution of the hydrocarbon accumulation belts and 6,the oil and gas enriched in the structural belts with palaeohighs which formed before the middle period of Himalayan movement in Qaidam Basin.So,the formation and distribution of petroleum pools are controlled by the tectonic activities.

    A STUDY ON STRATIGRAPHIC SEQUENCES AND LITHOFACIES OF THE IGNEOUS ROCKS IN KE WELL 92 REGION
    CHEN Qing QIAN Gen-bao DANG Yan YANG Zhi-guo YANG Kun
    2008, 29(4):  48-50.  DOI: 10.3863/j.issn.1000-
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    Volcanic eruption is layered and rhythmic,so,the stages of volcano activities are the basic units dividing and correlating volcanic rock formations.The determination of stages can be helpful to solve the problems of division and correlation of carboniferous volcanic rock formations in the northwest rim of Junggar Basin,Xingjiang.In this paper,the results of statistics of lithologic and electronic characteristics are probed to describe the law of stage change of volcanic rocks,and the characteristics of volcanic rock change in different stages are revealed.The method of lithologic texture division is used to study carboniferous volcanic lithology in Ke well 92 region,by researching the types of volcanic rocks,transporting means of volcanic materials,the products of volcanic action and the disposing relationship,the dividing ways and the distributing model of volcanic lithologic facies are set up,it is presented that volcanic lithologic facies are composed of crater subfacies,near crater subfaices,lava platform subfacies,volcanic sedimentary subfacies and secondary level mocrofacies,and the lithology and special distribution of different stages and different volcanic eruptive materials are described based on lithologic division.

    EVALUATION AND EXPLORATION PROPOSAL OF THE HYDROCARBON SOURCE ROCKS IN XIAOQUANGOU GROUP OF FUKANG SAG
    HE Kai;ZENG Liang-xiong LI Pei-jun ZHI Wen-dong LUO Ming-gao
    2008, 29(4):  51-54.  DOI: 10.3863/j.issn.1000-
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    It is generally acknowledged that there are three series of hydrocarbon source rocks in Jurassic,Permian and Carboniferous formations in the east of Junggar Basin.A great quantity of oil whether from the Xiaoquangou Group of Triassic or not is not confirmed in Fukang Sag.However,no agreement has reached whether the Xiaoquangou Group of Triassic in Zhundong exploration area is effective hydrocarbon source rocks.A systematic analysis of the oil generation potential of the hydrocarbons in the area is carried out in this paper.The analysis indicates that the organic matter is rich in abundance and relatively good in the type and that they have come to the peak of oil production at present in thermal evolution.It is suggested that they should be the reasonable source for the hydrocarbon.Previous research discovered that the oil from Well Fu 5 of the Triassic Xiaoquangou Group actually came from the hydrocarbon of Xiaoquangou Group in Fukang Sag,which indicates that the Xiaoquangou in Fukang Sag possesses hydrocarbongenerating potential.Hence,the evaluation of hydrocarbongenerating potential will be of great significance for the oil and gas exploration in the Junggar Basin.

    THE APPLICATION OF CASED HOLE FORMATION RESISTIVITY LOGGING IN KARAMAY LOWPERMEABLE RESERVOIR
    XU Chun-hua HOU Jia-gen ZHAO Xi-yuan WANG Xiao-guang ZHENG Sheng
    2008, 29(4):  55-59.  DOI: 10.3863/j.issn.1000-
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    Karamay Oilfield has been producing many years with water injection,by cased hole formation resistivity logging,the potential netpay reservoirs can be explored,improvement of reservoir recovery put forward.The authors analyze over 20 welllogging data of northwest and east oilfield of Junggar Basin,the main influencing factors of the cased hole formation resistivity logging application include vibrating of instrument while measuring,cementation quality,well bore waxing,case deformed,salinity of mud and injected water,the resolution on thinner layer,reservoir pollution etc..Based on the analysis of the application for lowpermeability sandstone and conglomerate reservoir,the authors give the conclusion,on the one hand,the heterogeneity of reservoir is key factor for evaluation on remaining oil,on the other hand,in general,measured interval should not be more than 400 meters.Although there are some shortness,it is believed that the casd hole formation resistivity logging application is prospective in Karamay Oilfield.

    APPLICATION OF MDT LOGGING IN HIGHLY DEVIATED WELL
    JIANG Zhi-ge;YIN Guo-qing
    2008, 29(4):  60-63.  DOI: 10.3863/j.issn.1000-
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    According to the characteristics of the fluidexpelling function of sampling tube acquired by cable formation modual,dynamic test(MDT),down hole oil and gas realtime testing and multipletime sampling and pressuretesting,considering MDT being widely used in quick recognition of formation fluid and correctly understanding the characteristics of formation,fluid property,types of reservoirs,MDT is tried to use in highly deviated wells,which provides a new field for the application of MDT.The application of MDT in highly deviated wells as deviated as 60 degree at designed testing spots is introduced in detail,the pretest design,logging operation and posttest analysis of MDT logging are clearly described,the fluid recognition,fluid sampling and pressure testing in the wells are successfully carried on,some design principles,practical steps and key technologies of the application in highlydeviated well are summed up.

    THE APPLICATION OF THE PROCESSING METHOD OF 3D-3C SEISMIC DATA IN SLG PROVINCE
    ZHANG Nian-chun;WANG Yu-chao;WANG Jian-hua
    2008, 29(4):  64-68.  DOI: 10.3863/j.issn.1000-2634.2008.04.016
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    Converted shear wave (P-SV) has lower velocity than P wave and its propagation is not influenced by pore fluid.The propagation regularity of converted wave is very different from that of P wave and this difference can be used to effectively identify oilgas.The reservoirs are mainly sandstone bodies of deltaic plain distribution channel in Ordos Basin and its distribution changes rapidly with low pore and low permeability laterally.Heterogeneity of reservoir physical property is apparent.In processing of real 3D converted wave seismic data in SLG gas province,researches are concluded in static sorting of common converted point (CCP) gathering,velocity analysis,NMO,etc..The 3C-3D seismic data processing flow chart is finally built and it is suggested that this processing flow chart may be widely used in converted shear wave seismic data processing.

    石油与天然气工程
    APPROXIMATE SOLUTION FOR NONSTEADY FLOW IN LOWPERMEABILITY RESERVOIR
    ZHU Chun-sheng CHENG Lin-song ZHANG Shu-juan
    2008, 29(4):  69-72.  DOI: 10.3863/j.issn.1000-
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    The two factors of TPR(threshold pressure gradient)and stress sensitivity should be considered in low permeability reservoir development.Because of strong nonlinear property of control equation and nonconstant boundary of fluid flow,the mathematical model used now is very tedious.In order to simplify calculation process,the characteristic of instability,low speed and nonlinear flow pressure distribution are obtained with reservoir pressure distribution approximate formula.Meanwhile,the motion law of flowing boundary and the distribution of formation pressure,as well as variation law of production rate are gained based on material balance principle under the condition of constant flow rate.Calculation results show that TPR increase flow resistance in porous media and media deformation decreases conductivity near the well bore formation,which result in formation energy can not be released and add to the difficulty of lowpermeability reservoir exploitation.

    EXPERIMENTAL STUDY ON THE FACTORS AFFECTING THE PRODUCTIVITY OF FRACTURED HORIZONTAL WELL
    GAO Hai-hong QU Zhan-qing ZHAO Mei
    2008, 29(4):  73-76.  DOI: 10.3863/j.issn.1000-
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    Fractures change the flow field near the well bore,and are the important factors affecting the performance of fractured horizontal wells.In order to successfully fracture horizontal wells,it is noted to study the relations between the fracturing parameters and the performances.The pressure distribution characters of fracturing horizontal wells are studied,in which,there are different inclinations between the fractures and the boreholes.Conclusions are drawn as following,firstly,the inclinations between the fractures and the boreholes change the shape of the pressure contour near the well bore,and the contour twists along the inclinations.The contour controls the bigger drainage area with the increasing angle,accordingly the productivity increases with the increasing angle α,and lines with the angle sinα.Secondly,there exits the optimal match including the inclinations,the fracture numbers,the fracture length,the horizontal section length and the fracture space.So the results are instructive for designing fracturing horizontal wells and forecasting productivity.

    EXPLOITATION COUNTERMEASURE OF DIFFICULTTO PRODUCE RESERVES IN TIGHT SAND GAS RESERVOIRS
    XIONG Xin-dong WANG Shi-ze LIU Ru-min TANG Bo
    2008, 29(4):  77-80.  DOI: 10.3863/j.issn.1000-
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    Complicated geologic characteristics and special flow mechanism of tight sand gas reservoirs make a lot of reserves difficult to be developed.The exploitation of difficulttoproduce reserves is an important subject.In this paper,based on a lot experiment,the flow mechanism of tight sand gas reservoirs of Js12 and Js32 in Xinchang gas field are studied,and the factors influencing the exploitation of difficulttoproduce reserves are analyzed.Accordingly,corresponding development strategies are put forward.As a result,water lock,stress sensitivity and threshold pressure effect are main influencing factors as to difficulttoproduce reserves.The present production pressure difference is 10MPa,much higher than reasonable pressure difference 7MPa,which results in severe stress sensitivity damage.Massive hydraulic fracturing technology with low harmful and high fracturing fluid back flow technology,multilayer fracturing technology and horizontal well technology are main exploitation strategies as to difficulttoproduce reserves in Xinchang Js21、Js23 gas reservoir.

    STUDY ON THE MATHEMATICAL MODEL OF THE RECOVERY OF POLYMER FLOODING BY USING THE SECOND THEOREM OF SIMILARITY THEORY
    GUO Wen-min QIN Ji-shun LV Ai-hua ZHANG Xing
    2008, 29(4):  81-85.  DOI: 10.3863/j.issn.1000-
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    In order to apply physical simulation results to oil fields properly and provide theoretic direction for the oilfield development,similar equation analysis method is used to get the similarity criterion of polymer flooding reservoir,similarity criterion is divided into dependent criterion and independent criterion according to variable relation,taking recovery of polymer flooding as example,numerical simulation is used,sensitivity analysis is carried out for the similarity criterion,and the Second Theorem is used to study the mathematical model of the recovery of polymer flooding.The results show that there exists a multiplication relationship between the recovery polymer flooding reservoir and the similarity criterion.Based on this relationship,the recovery model of polymer flooding is established,in which the relative permeability coefficient is applied to modify model.physical simulation is consistent with the numerical simulation,the model can meet the requirement of the actual oilfields.

    THE INFLUENCE OF FORMATION PRESSUER CHANGE OF DINA 2 RESERVOIRS IN PERMEABILITY
    GAO Wang-lai HE Shun-li
    2008, 29(4):  86-88.  DOI: 10.3863/j.issn.1000-
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    A lot research has been carried out in regard to the relationship between permeability and effective stress,but the final conclusions are different and enormous amount of controversy is caused.A new method is proposed in this paper.The permeability under original formation effective stress should be used as reference and the ratio of permeability under insitu stress to it should be used as evaluation criteria.The changes in permeability induced by the variation of formation pressure should include stress sensitivity and stress damage.According to the experimental data of core samples from DINA 2 gas reservoirs and the results of theory analysis,the stress sensitivity degree can be overestimated by using the permeability under conventional condition as reference than using the original insitu permeability.Both the stress ensitivity and stress damage of permeability can reflect the effect of elasticity and plasticity of core samples on permeability,the relationship between permeability and effective stress acquired by experiment under different stress path should be adopted in different developing stages.These conclusions can provide some useful help for evaluating the effect of changes in reservoir pressure on the gas well production correctly and designing the program of formation damage control.

    PROBE OF TARGET SELECTION TECHNOLOGY OF SULIGE GAS FIELD DEVELOPMENT
    LAN Chao-li HE Shun-li MEN Cheng-quan ZHANG Jun-feng LAN Yi-fei
    2008, 29(4):  89-92.  DOI: 10.3863/j.issn.1000-
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    Sulige gas field is characterized by narrow lateral extension,discontinuity,low permeability and prosity.Based on the research of reservoir sedimentary microfacies,synthesized reservoir predication and paleostructure in time of hydrocarbon generation and expulsion,three reasons for comparatively favorable target selection are brought forth.Based on these,the target selection technology for Sulige gas field is suggested.The application of this technology to the Taiyuan Formation at the east Ordos Basin is tested to be successful and shows it is applicable for the siliciclastic rocks gas field in the basin.

    STUDY ON REASONABLE DEVELOPMENT LAYER COMBINATION LIMITS OF EXTREMELY HETEROGENEOUS RESERVOIRS
    ZHOU Qi JIANG Han-qiao CHEN Min-feng
    2008, 29(4):  93-97.  DOI: 10.3863/j.issn.1000-
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    The interlayer interference of extremely heterogeneous reservoirs becomes more serious as development.The layer series of development should be reconstructed.Reasonable selection is done for the permeability and the grading distribution of extremely heterogeneous reservoirs of Hu7 NanshaSanZhong on the basis of the dynamic and static reservoir data to design water displacing oil long core experiment for studying production pattern of different permeability cores.On the basis of experiment,production pattern of multilayers series of development is studied with the modified numerical simulator.An integrated contributory factor is presented to give fullscale reflection to the quantitative effect of heterogeneity on production characteristics and displacement effects of low permeability layers,and a reasonable technical limit is identified for combination of different permeable layers to give directions to practical development plan design of such extremely heterogeneous reservoirs.

    THE INFLUENCE DEGREE OF DIFFERENT FACTORS ON THE EFFECTIVENESS OF POLYMER FLOODING
    YUAN Fu-qing LI Zhen-quan
    2008, 29(4):  98-101.  DOI: 10.3863/j.issn.1000-
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    The displacement effectiveness of polymer flooding is influenced by numerous factors and different factor plays different role in controlling polymer flooding process.In this paper,the singlelayer and multilayer reservoir geological model are developed to investigate the influence of twelve parameters,such as polymer performance,injectionproduction parameters and large channel etc.,on the effectiveness of polymer flooding by the method of numerical simulation.The mathematical statistics method is used to analyze the different degree of effectiveness caused by various factors.The key factors controlling the displacement effectiveness of polymer flooding are obtained,and some suggestions are presented to ensure the effectiveness of polymer flooding.

    STUDY ON INTERPRETATIONAL METHODS ON FLUID PRODUCTION PROFILE OF IN ROD PUMPED WELL
    CHEN Hai-yuna QIU Chun-ning GUO Juan-jingb ZHAO Zhi-heng WANG Xue-lianc
    2008, 29(4):  101-103.  DOI: 10.3863/j.issn.1000-
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    Compared with the log plate interpretation,there is low accuracy in water quality interpretation chart and circulating rate of umbrella formation interval tester.To the log plate interpretation of umbrella formation interval tester in fluid profile of production log,there are more error in the interpretation of water content.In this paper,on the basis of interpretation and appreciation of plate and judgment on the bore hole fluid property and qualitative description in the pressure testing data of fluid profile,a new underground rod pumped well explanation is submitted.The method based on the successive approximation method in chart.By applying the interpretation theory of spondylolisthesis model,a correction on water holdup,water content and slippage velocity can be made.And by using the interpretation of down hole scale,the total flow rate and water content in the interpretation zone can be obtained.By comparing the interpretation of down hole scale with the plate method,the previous is more accurate in fact.

    THE DETERMINATION OF REASONABLE GAS WELL TUBE DIAMETER
    HE Zhi-xionga SUN Leib LI Tie-juna LIU Zhi-bina
    2008, 29(4):  104-106.  DOI: 10.3863/j.issn.1000-
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    Based on analyzing production system of gas wells,a result is obtained that utilizing the tube smaller than a certain diameter will restrain productivity of gas well during production.On the other hand,according to the analysis of the inflow dynamic curves and tube watercarrying curves,it is also demonstrated that there will be liquidaccumulated in well bore if the tube bigger than a certain diameter.In light of the two viewpoints above,the reasonable diameter of tube can be decided.Thereby,the calculation method that the energy supply and well bore rising abilities are considered in terms of formation energy,but also liquidcarrying ability of well bore,can be achieved and will guide the production of gas wells.With case study,it is pointed out that this method has its broad application prospect.

    RESEARCH ON FINE DIVISION OF STRATA IN LOW & ULTRALOW PERMEABILITY FAULTBLOCK RESEVOIRS OF W2
    ZHU Long-quan
    2008, 29(4):  107-110.  DOI: 10.3863/j.issn.1000-
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    Many problems occur such as reducing water flooding degree,interlayer inference and unbalanced vertical sweep in low and ultralow permeability faultblock reservoirs of W2.Based on the research on the limits of the number of perforated Strata,perforated thickness,permeability ratio,oilbearing area and reserve scale,the limits of oilbearing area and reserve scale for fine division of strata is proposed which suits for W2 faultblock reservoirs.The research on reasonable pressure,production rate and producer injector spacing is carried out and the effective limits for production are proposed.Thus,remarkable results,5.8% for recovery efficiency and 33.64×104t for recoverable reserves,have been achieved since fine division of strata in W2 faultblock reservoirs.

    PROPPANT FLOW BACK THEORY AND APPLICATION DURING FORCED FRACTURING FLUID FLOWBACK
    HU Jing-hong HE Shun-li LI Yong-ming ZHAO Jin-zhou LIU Guang-feng
    2008, 29(4):  111-114.  DOI: 10.3863/j.issn.1000-
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    To lowpermeability reservoirs,forced flowback technology is usually adopted after fracturing operation.Whether proppant flows back or not is the key evaluation criteria to forced flowback.The motion and start model is presented in the paper,which is based on the analysis of physical process of proppant backflow and the force on the last injected proppant.The calculation result shows that the last injected proppant stop immediately near fracture mouth and whether the proppant flow back or not is depended on flow velocity of fracturing fluid.Beginning with small choke and changing a bigger choke latter during forced flowback is not only discharge fracturing fluid in time but also can avoid proppant backflow.The results provide theoretical support to quantitative analysis of proppant flowback and optimize the flowback technology.

    A PROBE INTO THE NEW TECHNOLOGY OF GAS PRODUCTION OF XUJIAHE GAS RESERVOIR IN WEST SICHUAN
    CHEN Zhao-guo;
    2008, 29(4):  115-118.  DOI: 10.3863/j.issn.1000-
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    Aiming at such production difficulties as deeply buried gas reservoirs,developed fractures,containing CO2,quick waterproducing in gas production and the production pipe string corrosion in Xujiahe reservoirs,west Sichuan,based on the factors that flow ability of formation fluid increase as the pressure difference increases,pipe string corrosion gets more severe as CO2 fractional pressure goes up,it is presented that in gas production,the critical productivity(maximum production pressure difference)can be used in proration to prolong the period of gas production without water,the down hole throttle technique used to decrease CO2 fractional pressure in gas production pipe string and the rate of the corrosion.The combination of the two ways can make both the proration reasonable,prolong the period of gas production without water,and ensure the control of production pressure difference,as well as decrease CO2 fractional pressure in well bore,the production efficiency will be increased.

    FRACTURE FORECAST AND REMAINING OIL OF BD OIL RESERVOIR
    HUANG Yan-mei XU Hong-liang WANG Ling-ge LIU Deng-ke WANG Yin-hu
    2008, 29(4):  119-122.  DOI: 10.3863/j.issn.1000-
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    Pu member 2 reservoir,Jiangsu BD,is a low permeability fractured one.Effectiveness of water flooding is relatively poor,the majority of the oil wells,because of high watercontaining,is stopped producing and injecting,awareness of the oil is very seldom duo to the fracture influence on the remaining oil.Aiming at the oilfield geological characteristics and waterproducing situation,the focus is to use seismic data fuzzy recognition technology to establish mathematical model of reservoir characteristics and fracture development scale by analyzing seismic characteristics,in the combination of sedimentary facies and fractures,the fine geological model is re-established,water drive characteristic curves and numerical simulation are applied to calculate and simulate the distribution of remaining oil,the insitu adjustment wells after operation verifies the recognition of remaining oil,some effects are achieved,and foundation is provided to followingup continuous adjustment.

    RESEARCH ON THE CHARACTERISTICS OF STEAM CHAMBER DEVELOPMENT OF STEAMASSISTED GRAVITY DRAINAGE
    ZHAO Qing-hui; LIU Qi-cheng YU Tao ZHANG Yong IU Bao-liang
    2008, 29(4):  123-126.  DOI: 10.3863/j.issn.1000-
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    Physical modeling experiment is carried out to facilitate the understanding of the development of the steam chamber and the corresponding production characteristics of verticalhorizontal SAGD well pairs.Selfmade large scale,multifunctional 3D highpressure,hightemperature physical model and 2D visual scale model are employed.The model can be used for the optimization of development method as well as the study of the influence to the production with different geological and injection/production parameters.Based on the similarity criterion established,scale model on Du 84 bitumen reservoir is constructed ,experimental scheme of SAGD following CSS is designed.The law of the evolution of 3D and 2D temperature and pressure fields are established based on the realtime temperature and pressure data collected from survey points.Based on the above,with reference to the field data,SAGD mechanism is analyzed with the development of steam chamber and the corresponding production performances studied.The result of the experiment can provide sound basis for the implementation and adjustment of SAGD commercial productions in the field.

    THE EXPERIMENT STUDY ON CHANGE MECHANISM OF ORIGINAL WATERCUT IN EXTRALOW PERMEABILITY SANDSTONE RESERVOIR
    GUO Long;
    2008, 29(4):  127-129.  DOI: 10.3863/j.issn.1000-
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    Through testing the change of water saturation and watercut,the experiment studies the characteristics of water flooding extralow permeability sandstone reservoir.The testing reveals that the change of watercut of low saturation sandstone reservoir consists of three phases,the rapid rising phase,stable fluctuating phase and slow rising phase.And the value of the rapid rising and stable fluctuating phases can be estimated by oil and water relative permeability curve.

    NEW RECOVERY TECHNOLOGY OF SUPER-DEEP AND SUPER-HEAVY OIL RESERVOIR DEVELOPMENT OF TAHE OILFIELD
    ZOU Guo-jun
    2008, 29(4):  130-134.  DOI: 10.3863/j.issn.1000-
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    Tahe Oilfield is the first superdeep and superheavy carbonate reservoir discovered in China so far,with a buried depth of 5350-6600m and 80% of the reserve is superheavy oil.There is a huge difficulty in developing such a kind of reservoir.Based on nearly 10 years′ developing experience,the influencing factors of the mechanism of light oil blending for viscosity reduction and the operating practices widely used in this field at present are analyzed in detail.Research indicates conventional thermal methods are not suitable for the Tahe Oilfield ,and light oil blending,largescaled operation,hot light oil blending,compound relay pump,chemical viscosity reducers are effective techniques proposed in practice.The development of Tahe oilfield provides adaptable experience in developing super deep and heavy oil reservoir.

    THE APPLICATION AND ALGORITHM OF AUTOMATIC TYPECURVE MATCHING IN WELL TESTING
    ZHANG Xiao-dong
    2008, 29(4):  135-137.  DOI: 10.3863/j.issn.1000-
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    Nowadays,many specialists and workers in well test analysis are all finding the methods that can get the parameters of well test effectively and automatically.In this paper,two automatic typecurve matching methods of modern well test analysis are presented after studying theories and algorithms of optimization.Based on the theory of least square method,combined with small residual sum of squares and large residual sum of squares,applied with the method of finite difference,a new algorithm can be concluded in well test analysis.Finally,compared with these two methods,the optimized algorithm in well testing can be obtained.

    OIL TUBIN DESIGN OF DEEP BRANCH WELL HYDRAUNICLLY CONTROLLED ON SURFACE
    LIANG Hai-bo ZHAO Jin-zhou
    2008, 29(4):  138-140.  DOI: 10.3863/j.issn.1000-
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    The feasibility of double column entering in the deep

    branch well is very low because of the high temperature and pressure,how to use the unitary column realizing intelligent control of commingled production of deep branch well is important research direction of study and unceasing improvement at home and abroad.The oil extraction is realized intelligent control of commingled production.This column has not only realized the branch selective mining from the branch well and the intelligent commingled production,but can also be used to effectively resolve the domestic oil extraction of the branch well that is confronted with several technology problems,i.e.,effectively resolve the problem of disturbance and channeling interbranch well,ensure that the productivity of every branch well is bought in full play and provide the technology hold for branch well to extract fracture and poretype reservoirs,no need to run a specialized test tool and blank off tool and find out the branch producing water,as to effectively blank off the branch,be able to meet the need of the high temperature and high pressure well,provide the technology hold for branch well to extract deeper oil.

    THE INFLUENCE OF PERFORATION IN FRACTURING PRESSURE AND FRACTURE GEOMETRY BY NUMERICAL SIMULATION
    ZHUANG Zhao-feng ZHANG Shi-cheng WANG Bo-jun ZHANG Jin
    2008, 29(4):  141-144.  DOI: 10.3863/j.issn.1000-
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    In terms of extensive literature review on influence of perforation in fracturing pressure and fracture geometry in hydraulic fracturing,DDM(Displacement Discontinuity Method)is applied for mechanics analysis in hydraulic fracturing by establishing propagation model under different perforation orientations and different farfield principal stress.Meanwhile,corrected G Criteria and F Criteria are used to study the propagation orientation.According to the simulation results under different perforation orientation and farfield principal stress ,fracturing pressure increases with the rise of the perforating angle and the fracture geometry is reversed at the same time.Meanwhile,uneven surface enlarges the friction of the fracturing fluid.Conclusions of the study offer reference to optimization of perforation parameters and fracturing implementation.

    A SIMPLIFIED METHOD OF FLUIDSOLID COUPLING SIMULATION TO STRESSSENSITIVE RESERVOIR
    BU Tao; DAI Ping
    2008, 29(4):  145-147.  DOI: 10.3863/j.issn.1000-
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    Fluidsolid coupling is used to consider the stresssensitivity in simulation,but it needs a lot data and computing time as the progress of simulation will be impacted.Introducing the poroelasticity and double effective stress theory,the authors of this paper get the relationship of the fluid pressure and the permeability,and the laboratory data is transformed to the insitu data.The relationship ia applicated in the simulation,the results show that the reduction of accumulative production and days of stable production resulting from stresssensitivity is small; and the difference of simplified model and fluidsolid coupling model is small.

    THE NUMERICAL SIMULATION OF THE TWO PHASES NONEQUILIBRIUM THERMODYNAMIC PROCESS IN PVT CELL
    LIANG Ping TIAN Yuan REN Dong-xing YUE Cong-hai TANG Ke
    2008, 29(4):  148-150.  DOI: 10.3863/j.issn.1000-
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    The currently used methods for determining the thermodynamic equilibrium of the mixed two phases substances is to judge the equality of the coefficient of each component in two phases,and with this analysis,each component mole fraction can be got at the equilibrium state.But this method can not be used in analyzing the process from the initial two phases nonequilibrium state to the final equilibrium state.To address this issue,diffusion equation to describe various gas and liquid components from exposure to the stabilization process is introduced in this paper,a mathematical model to describe the two phases nonequilibrium diffusion process established.By using the method,a gasliquid two phases system that changes from contact to steady status in the PVTcanister is analyzed.The whole process pressure change rule of the system is obtained.The methane concentration distributing rule that changes with altitude in the balance state got,too.The results compared with the experimental data proved the feasibility of the method,thus the nonequilibrium phase transition analysis of the issue gives a new train of thought.

    油气化学工程与化工
    INFLUENCE OF GH COMPOUNDED VISCOSITY STABILIZER ON OIL DISPLACEMENT PROPERTIES OF ALKALI/POLYMER SYSTEM
    XU Wei-dong SUN Lin PU Wan-fen ZHAO JIN-zhou XIN Jun
    2008, 29(4):  151-153.  DOI: 10.3863/j.issn.1000
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    Aiming at the serious viscosity loss occurring during Alkali/Polymer (AP) flooding of Dagang Yangsanmu Oilfield,GH viscosity stabilizer is formulated and developed.In order to research whether this viscosity stabilizer is useful to ultimate displacement characteristics of AP flooding,its effectiveness on displacement properties of AP system is analyzed one by one.Thermaloxygen aging experiment,interfacial tensiometer and rheometer measurement,as well as SEM observation are applied to study longterm thermaloxygen stability,IFT,rheological properties,viscoelastic properties and microscopic shape of AP system when GH viscosity stabilizer is added and not.The result shows that GH can keep the pseudoplasticity rheologic property and ultralow interfacial tension of AP system and improve its longterm thermaloxygen stability and viscoelastic properties through strengthening its micromechanism.GH viscosity stabilizer contributes to improve the stability of AP system,and possesses favorable field practice prospect in EOR.

    APPLICABILITY OF PYRROLIC NITROGEN COMPOUND MIGRATION PARAMETER IN CRUDE OIL
    LIU Jun-hai YANG Xiang-hua
    2008, 29(4):  154-158.  DOI: TE133
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    Pyrrolic nitrogen compound parameters are important indicators to study petroleum migration,but they are always not effective in different geological conditions.Based on the test data of the crude oil in Huzhuangji oilfield with gas chromatographmass spectrometry technology,the influence of sedimentary environment,maturity and biodegradation on pyrrolic nitrogen compounds distribution is analyzed,and applicability of pyrrolic nitrogen compound parameters on petroleum migration is discussed.The results show that maturity plays a significant role on pyrrolic nitrogen compounds distribution,while biodegradation plays little role on the pyrrolic nitrogen compounds distribution.The concentration of pyrrolic nitrogen compounds,the ratio of Alkylcarbazole/Benzocarbazole and the Benzocarbazole ratio show an apparently positive correlation with maturity and a negative correlation with Gammacerane index,so they are not suitable to be the indicators of the petroleum migration.Maturity and sedimentary environment have little influence on the isomer ratio of Dimethycarbazole,so it is still a good petroleum migration indicator.
    THE APPLICATION OF THE HIGHLY EFFCTIVE LOST CIRCULATION ADDITIVE IN THE PERMIAN IN TAHE OILFIELD
    HUANG Xian-jie DONG Yun
    2008, 29(4):  159-162.  DOI: 10.3863/j.issn.1000-
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    The pressure sealing test is carried out to the Carboniferous reservoirs of well S119-3 at the depth of 5115 meters,after four times of unsuccessful inert material bridge plug sealing,highly effective loss circulation additive HHH combining with fresh water is applied to seal.The additive is of the characteristic of high effect,high water loss and strong leakagesealing,the analysis of high density sealing slurry indicates that its suspending property is poor,water loss is fast and the slurry is easy to deposit to the bottom of tanks,pipelines or in drilling pipes while resting,when the slurry contacts the well bore wall,water loss occurs quickly,mud cake increases in thickness,chunks are formed and the drilling pipes are easily stuck.By experimental adjustment,the amount of CMC is increased 0.15%,the suspending property of sealing slurry is enhanced and the full water loss time is delayed.The time for full water loss is longer,40~60 min more,in 2 hours,water is not completely lost,the requirement for operative time in leakage sealing design is met.The 1.46g/cm3 leakage sealing slurry does not precipitate and plug pipes,the operation is successful.

    石油机械工程及其它
    PERFORMANCE ANALYSIS FOR UNIFORM WALL THICKNESS BUSHING OF PDM
    HAN Chuan-jun QIU Ya-ling LIU Qing-you WANG Guo-rong
    2008, 29(4):  163-165.  DOI: 10.3863/j.issn.1000-
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    PDM(Positive displacement motor) is suitable for drilling directional wells because of its advantages,But it still could not be used for deep wells,highdensity mud wells and smallcurvature wells widely.The PDM′s conventional bushing is a screw surface,it is a variablethickness elastomer stator.It has poor capability to withstand the high mud pressure and a soft mechanism characteristic,is easy to leak,wear and tear,and expand unevenly,its efficiency descends continually.Therefore,the short,highpower,highpressuredrop and lowrotatespeed PDM are developed and applied to improve the drilling efficiency and save cost.In this paper,the mechanics experiment of NBR is carried out,the FEA models of uniform wall thickness and the conventional one are established for calculating.The results indicates,under the same mud pressure when compared with the conventional one,the uniform wall thickness is of less deformation,with the same interference,it has a better seal capability.The equidistant PDM can gain the same torque with less length than the he conventional one.
    HYBRID GENETIC ALGORITHM FOR TOPOLOGY OPTIMIZATION OF STELLATED OIL GATHERING AND TRANSPORTATION PIPELINE NETWORK
    YANG Jian-jun ZHAN Hong LIU Yang ZENG Wen
    2008, 29(4):  166-169.  DOI: 10.3863/j.issn.1000-
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    An optimized mathematical model of topology optimization for stellated oil gathering and transportation pipeline network is established,in which the minimum investment is taken as objective function.According to the model characteristics,the subjection relations of wells and stations are optimized with improved integercoded genetic algorithm,optimal location of metering station is optimized by nonlinear method.Aiming at the limitation of genetic algorithm,the operational process is improved,simulated annealing algorithm is combined with,fitness function is adjusted,the method of determining initial temperature is given,selecting operation is improved,then the hybrid genetic algorithm formed,random parentnumber fitnessweighted cross and multiple mutation methods are adopted.Processing methods of constraint conditions are proposed,so the number of infeasible solutions is reduced,and the computational efficiency is improved.Case study shows that the algorithm is efficient.
    APPLICATION OF WAVELET TRANSFORM IN DETECTING LEAKAGE IN PIPELINES
    LIU Tao LIU An-xin PENG Shan-bi WANG Ming-jun
    2008, 29(4):  170-172.  DOI: 10.3863/j.issn.1000-
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    The oil pipeline leaking accident occurs for many reasons.In order to reduce the loss which the accident results in,the leakage and leaking position should be discovered promptly.In this paper,the basic theory of applying negative wave to detect leakage is introduced,then the characteristic of pressure signals singularity and the different characteristics between signals and noises are analyzed based on their wavelet transform,the sudden change signal wavelet transformation mold maximum value increases along with the criterion increases,but the noise wavelet transformation mold maximum value reduces along with the criterion increases.Therefore,the leaking point position can be figured out by using the time difference and propagation velocity of the negative pressure wave,which may arrive at the both ends of the oil pipeline.The case study indicates that,the wavelet transform method of transformation can be used to accurately withdraw the sudden change value of the transient negative pressure wave,thus the leakage location can be detected.
    EXPERIMENT ON GAS ANCHOR SEPARATION EFFICIENCY
    CHEN Qin WU Xiao-dong WU Fu-rang
    2008, 29(4):  173-175.  DOI: 10.3863/j.issn.1000-
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    The separation efficiency of gas anchor is a very important index to evaluate the performance of gas anchor.Because it works in high temperature and high pressure environment,no apparatus can measure its separation efficiency.In order to study the influence of flow parameter on gas anchor separation efficiency quantitatively,a gas anchor and related experiment apparatus are designed and two important parameters,flow velocity and gas oil ratio,that influence separation efficiency studied.The experimental results show separation efficiency increases with gasliquid ratio,when gasliquid ratio is greater than 0.75,the influence of gasliquid ratio is not so important.The separation efficiency increases with flow velocity,when flow velocity is low,the different separation efficiency caused by gasliquid ratio is distinct.When flow velocity increases,the trend of difference reduces.At last,theoretical method is used to verify the result of experiment.This research can give some insight on gas anchor quantitative separation efficiency analysis.
    THE OIL PUMP FAULT DIAGNOSIS BASED ON THE WAVELET NEURAL NETWORK
    ZHAO Peng-cheng ZHU Huan-qin MENG Fan-qin QIN Yong
    2008, 29(4):  176-180.  DOI: 10.3863/j.issn.1000-
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    The oil pump is the important equipment of the oil deport.It′s very significant to assert and diagnose the pump fault.Adopting the fault diagnosis technology to examine the pump,finding out the fault and deal with it are the important aspects to the oil depot′s safety.According to the advantage of the wavelet neural network,in the paper,the three layers BP wavelet neural network is used to set up the fault diagnosis model and to diagnose the pump fault.This method can abstract the feature and selfstudy and selfadoption.It is easy to assert and diagnose the pump fault.It can realize the database management of the neural network study fault feature abstraction and the output of the neural network,the good effect is acquired in the oil pump fault diagnosis.As a result,a new way is provided to supervise and diagnose the pump fault by combining the wavelet analysis and the neural network.It is very significant to the oil deport.
    博导论评
    A FUNCTIONAL SIMULATION FOR OILFIELD OUTPUT FORECAST BASED ON TIMEVARYING SYSTEM
    LIU Zhi-bin REN Bao-sheng ZHAO Ming
    2008, 29(4):  181-184.  DOI: 10.3863/j.issn.1000-
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    One advantage of neural network forecast is the good historical matching between forecast indices and influence factors indices,while the differential simulation forecast pays more attention to the change trend of forecast indices.In this paper,these tow methods are organically combined.At first,the inputoutput relation between oilfield output and their influence factors is viewed as a timevarying system,then the BP neural network is introduced to parameter identification of differential simulation to obtain a new forecast method of functional simulation based on timevarying system.This new forecast model owns good selfadaptability since its parameters change with time.Moreover,it has better effect in midlong term forecast because the nonconvergence problem appeared in the coupling process between it and differential simulation can be overcome in the training process of neural network by variable learning rate.In the end,a practical output forecast case in a certain oilfield in China is given.The computational results show that the forecast is in good agreement with the reality,even much better than the results obtained by other forecast methods.