23 August 2015, Volume 42 Issue 4

    

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油气勘探
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  Contribution and significance of dispersed liquid hydrocarbons to reservoir formation

  Zhao Wenzhi; Wang Zhaoyun; Wang Dongliang; Li Jian; Li Yongxin and Hu Guoyi

  . 2015, 42(4): 401-413.

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  Oil expulsion rate of different types of source rock in geologic settings are estimated by modeling hydrocarbon generation and expulsion and examining the geological sections of different source-reservoir combinations. The major gas generation peak of oil-cracked gas kitchen is determined by study on the gas generation timing of dispersed liquid hydrocarbon inside and outside source rock and ancient oil reservoirs, and the factors affecting the gas generation timing. A “five-step method” based on the origin method is set up to quantitatively evaluate the cracked gas generated by dispersed liquid hydrocarbons. The hydrocarbon generation and expulsion experiment of different types of source rock, the study on oil expulsion rate of different source-reservoir combinations, analysis of rock pyrolysis parameters of reservoir rock all show that there is a large amount of liquid hydrocarbons retained in the source rock, and the feature on the whole is the oil expulsion rate decreases with the reducing of total organic carbon (TOC). The expulsion rate of source rock with TOC of less than 2% is below 50% in general during the liquid-window stage, while that of alternating sandstone and mudstone and of thick mudstone, with TOC of 2%?4%, are 60% and 30% respectively. Affected by the ancient landform, the expelled liquid hydrocarbons accumulated in different abundance in formations, with dispersed or semi-dispersed and semi-gathered form, and they are called dispersed liquid hydrocarbons outside source rock. When buried deeper, both dispersed liquid hydrocarbons inside and outside the source can be cracked into natural gas to form conventional and unconventional gas accumulations. Exploration practices in the Sichuan and Tarim basins have proven that the cracked gas generated by dispersed, semi-dispersed and semi-accumulated, and accumulated liquid hydrocarbons is an important source of deep natural gas in China, and takes an important position in gas exploration.
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  Innovation and prospect of geophysical technology in the exploration of deep oil and gas

  Sun Longde; Fang Chaoliang; Sa Liming; Yang Ping and Sun Zandong

  . 2015, 42(4): 414-424.

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  The global situation of distribution, reserves and production of deep oil and gas are examined systematically, the progress and exploration achievement of onshore China deep geophysical technology are summarized, and the challenges and developing direction of deep geophysical technology are pointed out. Aiming at the exploration of deep onshore strata in China, the article analyzes the key geophysical problems, such as low noise-to-signal ratio, low resolution, low imaging accuracy and low amplitude-preservation, in the exploration of deep clastic, carbonate, and volcanic reservoirs, and presents the corresponding technical countermeasures such as wide-line large-array 2-D acquisition, wide-azimuth and high-density 3-D acquisition, anisotropic pre-stack depth migration (PSDM),reverse-time migration (RTM), complex structure modeling, quantitative reservoir prediction, and pre-stack fracture prediction. The analysis from two aspects, imaging of deep complicated structures and prediction of deep complicated reservoirs, shows that wide-frequency, amplitude-preservation, high-accuracy and information integration are the challenges to and key issues in the geophysical technology. It is pointed out that wide-frequency acquisition, rock physical modeling of complex reservoirs, high-accuracy prestack amplitude-preservation imaging, comprehensive evaluation of complex reservoirs, non-seismic techniques, and drilling steering with seismic data are the key geophysical techniques needed to be developed in the future.
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  Features and origin of oil degraded gas of Santai field in Junggar Basin, NW China

  Lu Jungang; Wang Li; Chen Shijia; Han Hui; Zhang Huanxu; Huang Youlin; He Xiaobo; Zhan Pan; Zhou Shiying; Zhang Anran and Li Xiaotian

  . 2015, 42(4): 425-433.

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  Based on comprehensive analysis of the natural gas composition, carbon isotopes and associated oil carbon isotopes, saturated hydrocarbon chromatography, and gas chromatography-mass spectrography, the features and formation mechanisms of natural gas in Santai area, Junggar Basin are studied. The Jurassic natural gas in Santai area is characterized by light ethane carbon isotopes, and the features of associated oil are light carbon isotopes, low Pr/Ph ratio, high C29 and C28 sterane value and low C27 sterane value, which shows that the hydrocarbons were mainly derived from the sapropelic source rock of the Permian Pingdiquan Formation in Fukang sag. The natural gas composition is dominated by methane. The methane carbon isotope value of the natural gas is higher than that of biogenic gas, but it is lower than that of thermogenic gas. Natural gas reservoirs were buried shallowly and always associated with or close to heavy oil which was subjected to serious biodegradation, with occurrence of 25-norhopane. All above indicate that the natural gas in Santai area is typical oil degraded gas by bacteria. Biodegradation was a process of water-hydrocarbon reaction which was affected by the bacteria and thermodynamics. The methane bacteria made use of CO2 and H2 to reduce light carbon isotopes preferentially to generate methane of light carbon isotopic compositions. Biodegraded heavy oil and oil sand are widely distributed in the petroliferous basin, therefore, reservoir oil degradation gas has good exploration prospects.
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  Diagenesis and porosity-permeability evolution of low permeability reservoirs: A case study of Jurassic Sangonghe Formation in Block 1, central Junggar Basin, NW China

  Xi Kelai; Cao Yingchang; Wang Yanzhong; Haile Beyene Girma; Zhang Xiangxiang; Zhang Jianghua and Jin Jiehua

  . 2015, 42(4): 434-443.

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  Based on core observation, thin section examination, cathode luminescence analysis, scanning electron microscopy, fluid inclusions, carbon and oxygen isotope, mercury penetration, porosity-permeability test and other analytical methods, combined with the histories of burial evolution, organic matter thermal evolution and hydrocarbon charge, the diagenesis and porosity-permeability evolution are studied of low-permeability reservoirs of Jurassic Sangonghe Formation in Block 1 of central Junggar Basin. The matching relation between reservoir porosity-permeability evolution and hydrocarbon accumulation history is analyzed. The diagenetic environment evolution of the reservoir in the study area is early alkaline, interim acid and late alkaline, forming the diagenetic sequence of chlorite membrane precipitation, early calcite cementation, feldspar dissolution accompanied by quartz overgrowth and authigenic kaolinite precipitation, anhydrite cementation, late period ferrocalcite and ankerite cementation, a small amount of pyrite cementation. Generally, compaction occurs throughout the whole burial process. According to the matching relation between reservoir porosity-permeability evolution and hydrocarbon accumulation history, the Jurassic Sangonghe Formation has three genetic types of low permeability reservoirs: densification after hydrocarbon accumulation, with the best exploration potential; densification during the hydrocarbon accumulation, with medium exploration potential; densification before the hydrocarbon accumulation, with the poorest exploration potential.
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  Quantitative evaluation of fracture development for Triassic Yanchang Formation, Ordos Basin, NW China

  Liu Geyun; Huang Chenjun; Zhou Xingui; Zhang Linyan and Pan Yun

  . 2015, 42(4): 444-453.

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  To uniformly evaluate the fracture development of the Triassic Yanchang Formation in Ordos Basin, a set of evaluation method for fracture development degree is established by the observation and account of fractures developed in the sandstone cores of the Yanchang Formation in the blocks of Maling, Huaqing, Anbian, Wuqi and Yanhewan in the Shaanbei Slope. The method includes four aspects of qualitative and quantitative indices, fracture type, fracture strength, fracture grade and fracture assemblage, which are applicable to the fracture assorting, single well evaluation, block evaluation and belt evaluation of fracture development, respectively. Quantitative evaluation plates of block fracture development degree has been built and applied to evaluate the fracture development degree of the five blocks. The Chang 71 member in Maling block has high angle fractures of three grades (weak, moderate and strong) in similar development degree and low angle fractures in moderate-strong development degree; the Chang 72 member in Maling block has weakly to moderately developed high angle fractures and moderately to strongly developed low angle fractures; both the Chang 71 and Chang72 members in Anbian block have strongly developed high angle fractures, but undeveloped low angle fractures in thin-medium and thick sands; the Chang 63 member in Huaqing block has undeveloped high angle fractures and moderately to strongly developed low angle fractures locally; the Chang 6 members in Wuqi block and Yanhewan block have undeveloped high angle fractures and low angle fractures.
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  Fracture filling mechanisms in the carbonate buried-hill of Futai Oilfield in Bohai Bay Basin, East China

  Jin Qiang; Mao Jingjing; Du Yushan and Huang Xixi

  . 2015, 42(4): 454-462.

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  Genesis and distribution of fracture fillings of the Cambrian-Ordovician carbonate buried-hill in Futai Oilfield of Bohai Bay Basin were investigated based on observation of core samples and thin sections, analysis of inclusions in fracture fillings, stable isotopic compositions of carbon and oxygen as well as trace element compositions in the fillings and surrounding rocks. There are many kinds of fractures developed in Futai buried-hill structure. Generally, the fracture spaces are filled over 60% by calcite, mostly sparry calcite and formed once time in the fractures. The homogenization temperatures of inclusions in calcite fillings in the fractures are higher than those in the buried-hill reservoirs. Oil-bearing fluid inclusions were found in the calcite fillings in the fractures, which means that the fracture filling is at the same time as oil-pool formation. Analysis of compositions of stable carbon and oxygen isotopes and rare earth elements showed that calcite mother fluids (including oil-pool forming fluid) were hydrothermal fluids coming from deep strata in the basin, and the hydrothermal fluids dissolved the limestone and dolomite and then deposited calcite in the fracture networks in the shallow part of the buried-hill structure. The hydrothermal genesis of calcite fillings in the fractures is useful in understanding the distribution of the calcite filling contents in the buried-hill structure, that is, the fractures near Chengnan and Chengnan Ertaijie faults have higher filling contents, while the fractures far from these faults have fewer fillings.
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  Characteristics and identification of high quality deep-water gravity flow sandstone reservoirs in Baiyun sag, Pearl River Mouth Basin, South China Sea

  Chen Liang; Pang Xiong; Liu Jun; Han Jinyang; Feng Xuan; Hu Lian; Zheng Jinyun and Peng Guangrong

  . 2015, 42(4): 463-471.

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  The characteristics and identification methods of high quality deep-water gravity flow sandstone reservoirs in Baiyun sag of the Pearl River Mouth Basin are examined based on three-dimensional seismic and drilling data, and deep water sedimentary theory. The oil and gas discovered in the deep water of the Baiyun sag are dominantly from high quality gravity flow sandstones, including channel complexes, sheets, and channel-levee complexes. The analyses of the sediment supply, feeding channel, internal architecture of sedimentary bodies, depositional process and flow regime show that the development of three types of high quality reservoirs are controlled by sediment composition of the provenance (continental margin): Under the background of rich sand provenance, sandy debris flow is likely to form, giving rise to high quality reservoirs like channel complexes and sheets down dip the shelf-slope break. These reservoirs can be identified by seismic reflections such as incised valley, mound shape, and amplitude anomaly, and described by combining single sand body tracking with waveform recognition of sands and seismic attribute analysis. Under the background of sand-mud mixed provenance, gravity flow deposits are to occur below the shelf-slope break, where sedimentation differentiation is the key to the formation of high quality reservoirs. In the case that channel-levee complex is formed, high quality sandstone reservoirs, usually in the channel or the fan lobe below, can be identified and described by seismic features like U-shaped erosion on seismic profile, amplitude anomaly, bird-wing shaped seismic reflection, and waveform recognition.
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  Application of charging effects in evaluating storage space of tight reservoirs: A case study from Permian Lucaogou Formation in Jimusar sag, Junggar Basin, NW China

  Wang Xiaoqi; Sun Liang; Zhu Rukai; Jin Xu; Li Jianming; Wu Songtao; Bi Lina and Liu Xiaodan

  . 2015, 42(4): 472-480.

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  According to the study of the electron beam charging effects of the oil-bearing samples from tight reservoirs, a “Two-step Cross-section Back Scattered Electron (BSE) Imaging Method” is put forward, revealing the distribution of residual oil (the oil without loss in the vacuum conditions) in the tight reservoir. With the injection of charging agent, the connectivity of the pore system can also be characterized by the method, and a novel quantitative method of evaluating the effectiveness of reservoir space is established. For the tight reservoir samples from the Permian Lucaogou Formation in the Jimusar sag in the Junggar Basin, which was taken as an example, the strong charging effects mainly result from the residual oil in pores. The oil from pyrolysis of organic matter was widely stored in the pores nearby organic matter, or existing in poor organic matter area. Due to the super-large analyzing area, the Two-step Cross-section BSE Imaging Method can solve the weak representation of analysis area caused by the heterogeneity. The method of injection of charging agent works well in revealing the connectivity of the pore system. The total plane porosity of oil-bearing samples from the tight reservoir of the Lucaogou Formation is 12.56%, and the connectivity of the whole pore system in the sample reaches as high as 90%. The effectiveness of the reservoir space is very high.
油气田开发
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  A comprehensive review of polyacrylamide polymer gels for conformance control

  Bai Baojun; Zhou Jia and Yin Mingfei

  . 2015, 42(4): 481-487.

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  Polymer gels have been designed and successfully applied to improve sweep efficiency and to reduce excessive water production by minimizing reservoir heterogeneity. Based on their compositions and application conditions, polyacrylamide polymer gels can be classified into three types: in-situ monomer-based gel, in-situ polymer-based gels and preformed particle gels. Initially, in-situ monomer gels which are mainly composed of acrylamide were developed for water shutoff. Conventional in-situ polymer gels include metal-cross linked polyacrylamide gels and organic-cross linked polyacrylamide gels. Preformed gels include preformed particle gels, microgel, and bright water. A few directions are suggested for future research on novel gels, such as gels used for in-depth fluid diversion and gels for severe reservoir environments.
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  Quantitative characterization of interlayer interference and productivity prediction of directional wells in the multilayer commingled production of ordinary offshore heavy oil reservoirs

  Huang Shijun; Kang Botao; Cheng Linsong; Zhou Wensheng and Chang Shuping

  . 2015, 42(4): 488-495.

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  Based on the physical experiment of visible multi-tube water flooding, in combination with field production data, the interlayer interference in multilayer commingled production of ordinary offshore heavy oil reservoirs is quantitatively characterized and an appropriate productivity prediction method of directional wells is established for multilayer commingled production of ordinary heavy oil reservoirs. The interference coefficient formulae of fluid and oil production indexes are obtained for the multilayer commingled production of ordinary heavy oil reservoirs. The Vandervlis directional well productivity equation is revised by introducing interference coefficient with consideration of starting pressure gradient and a dynamic productivity prediction equation is finally established suitable for multilayer commingled production of ordinary heavy oil reservoirs. Interlayer interference is mainly controlled by vertical reservoir permeability difference, which can be comprehensively characterized by reservoir reference permeability, permeability contrast and permeability deviation. The productivity of wells with different water-cut stages is variously affected by interlayer interference. This influence will be intensified in high water-cut situation, which needs appropriate adjustment measures. The productivity can be more accurately predicted by considering interlayer interference, and the revised directional well deliverability equation can be well applied to field production.
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  A mathematical model and numerical simulation of waterflood induced dynamic fractures of low permeability reservoirs

  Fan Tianyi; Song Xinmin; Wu Shuhong; Li Qiaoyun; Wang Baohua; Li Xiaobo; Li Hua and Liu Hailong

  . 2015, 42(4): 496-501.

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  Based on abundant data of low permeability oilfields, dynamic fractures were conceptualized and their evolution, including cracking, extending and closing, were analyzed. A new model that describes the dynamic changes of fracture shape and properties was established and a software module was developed. The simulation results show that dynamic fractures cracked once the injection pressure was higher than the formation fracture pressure, and then extended continually, which showed a periodic variation relationship with the formation pressure and the injection volume. After the moderate injection, dynamic fractures remained the open status in a relatively long time, but then the whole fractures tended to close quickly, and these phenomena indicate that the dynamic fractures were significantly affected by the production condition. The presence of dynamic fractures provides a channel for the injection water. With the gradual extension of dynamic fractures, the injection water forms a narrow range of displacement, which leads to the severe imbalance of water flooding, aggravates the heterogeneity of low permeability reservoirs, and significantly affects the water cut rising rules of wells in all directions. However, dynamic fractures also show a positive effect on the establishment of an effective displacement system between the injection wells and the production wells.
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  Experimental analysis on reservoir blockage mechanism for CO-2 flooding

  Zhou Tuo; Liu Xuewei; Yang Zhengming; Li Xizhe and Wang Shuying

  . 2015, 42(4): 502-506.

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  The slim-tube experiment, component analysis experiment and microscopic simulation experiment are used jointly to analyze the phenomena of reservoir blockage and drop of oil production rate, and to find out reservoir?blockage?mechanism in the process of carbon dioxide flooding. The?slim-tube experiment shows that?the effect of carbon dioxide flooding is poor under low displacement?pressure, and the higher the displacement pressure,?the better the effect of?flooding. When the displacement pressure exceeds the minimum miscibility pressure, reservoir blockage could occur, affecting the reservoir productivity significantly. Component analysis and microscopic modeling experiments show that oil component differentiation could occur after oil contacts with carbon dioxide. Under low displacement pressure, component differentiation is not significant, so reservoir blockage will not occur; but when the displacement pressure is higher, aromatics in oil are extracted rapidly by carbon dioxide, resulting in quick deposition of non-hydrocarbons and asphalt and the blockage of pore-throats in reservoirs. Therefore, controlling the displacement pressure is the main measure to prevent reservoir blockage. The best pressure of carbon dioxide flooding should be near the minimum miscible pressure, pressure too high or too low is not good for carbon dioxide flooding.
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  Experiments of fluid diversion ability of a new waterproofing polymer solution

  Rogachev Mikhail and Kondrashev Artem

  . 2015, 42(4): 507-511.

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  Low-permeability inhomogeneous reservoir displacement experiments were conducted using new waterproofing polymer solution GPS-1, and its fluid diversion ability was analyzed. There were three types of displacement experiments (nine experiments in total) in homogeneous cores, inhomogeneous oil- and water- saturated cores. Experimental results show that, compared with the initial polymer solution, the penetrating and water insulating abilities of the GPS-1 improve significantly, the pressure gradient of injection reduces by half, and both the water pressure gradient and the residual resistance factor increase considerably when water-isolating screen destructs. GPS-1 can create a durable waterproofing screen, thus increasing the oil displacement efficiency of water flooding for inhomogeneous layers. The water-isolating ability and oil displacement efficiency is increased greatly by injecting the GPS-1 with fringes of chloride calcium solution. The action selectivity of the GPS-1 is shown not only in formation of the water insulating screen mainly in water-saturated interlayers and effectively blocking high-permeability washed interlayer, but also in acceleration performance for injection wells due to the penetration of more injected water into highly productive intervals.
石油工程
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  A new concentric zonal water injection technique for highly-deviated wells

  Liu He; Xiao Guohua; Sun Fuchao; Pei Xiaohan; Hu Huili; Geng Haitao and Li Liangchuan

  . 2015, 42(4): 512-517.

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  Existing eccentric zonal water injection techniques cannot meet the requirements of separated layer water injection, testing and adjustment in highly-deviated wells, because of their low fishing success rate of down-hole nozzles, low efficiency of connection between instruments and nozzles, and low precision of zonal flow rate test. A new concentric zonal water injection technique is proposed for highly-deviated wells. This technique adopts concentric testing and adjustment, i.e., the test instrument is concentrically connected with the down-hole regulator, with high success rate of connection. The down-hole regulator uses bridge-type channel to effectively eliminate inter-layer interference and thereby improving testing and adjustment efficiency. Water flow rate is adjusted with an eccentric valve, which features small loss in full-off state, small adjustment torque and easier water adjustment. This technique is functional for both collected flow test and non-collected flow test, so it is workable for low flow rate test. It can achieve packer seal test on line by cable, the status of seal balls can be monitored and all seal test operations can be completed in one trip. This technique can obtain flow rate, pressure, temperature and other parameters of any layer on line and automatic testing and adjustment of injection allocation rate, without fishing, significantly improving testing and adjustment efficiency. Until now, this technique has been tested in 11 wells (maximum well deviation of 55°), with tested flow rate error of less than 5%, and three-layer seal check and adjustment time of less than one day. Compared with the existing techniques, this new technique has advantages such as high testing and adjustment efficiency, high precision and low cost.
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  Prediction of sustained annular pressure and the pressure control measures for high pressure gas wells

  Zhang Bo; Guan Zhichuan; Zhang Qi and Han Dong

  . 2015, 42(4): 518-522.

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  The sustained annular pressure caused by channeling threatens the casing safety significantly. Cement mantle composite permeability and one-dimension unstable seepage were used to describe the channeling of high pressure gas based on the analysis of the structure of the cement mantle containing micro-fractures and the seepage process of high pressure gas. According to the mass conservation law and volume accordance principle, a model was built to predict and analyze the pressure rising process when gas invades into the trapped annulus, and then this model was used to study the impacts of different factors on the annular pressure. The pressure rising process can be divided into rapid rising stage and stable rising stage, and the factors affecting annular pressure include the gas solubility and compressibility of annular liquid, height of cement return, composite permeability of cement mantle and annular volume; the rising velocity of annular pressure declines with the increase of annular liquid compressibility; the ultimate value and rising velocity of annular pressure increase with the increase of cement return height; the higher the composite permeability of the cement mantle, the faster the annular pressure increase; the increase of annular volume can prolong the rising time of pressure. From the viewpoint of engineering, high pressure gas wells should take annular liquid with proper compressibility, self-repairing cement should be used in high pressure gas wells cemented whole to improve cement quality, the composite permeability of cement mantle should be reduced by using proper measures if necessary, and annulus volume is properly increased to prevent the pressure from rising up too quickly.
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  Effects of laminated structure on hydraulic fracture propagation in shale

  Xu Dan; Hu Ruilin; Gao Wei and Xia Jiaguo

  . 2015, 42(4): 523-528.

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  Concrete samples with properties similar to the continental shale core of Well Yanke 1 in the Ordos Basin in the Shaanxi province, China, were made. The control effects of horizontal principal stress difference, the angle between perforated casing and lamina, the lamina thickness and space on hydraulic fracture propagation were modeled on a real tri-axial hydraulic fracturing experiment system, based on the design principle of four factors-three levels of orthogonal experiment. When the horizontal principal stress difference is small, the main fracture surface is parallel to the laminae strike, and the primary fractures will propagate as follows: propagate through the laminae, then deflect significantly at the surface of the laminae, continue along the laminae surface and finally change direction and propagate again through the laminae. When the horizontal principal stress difference is big, the main fracture surface is perpendicular to the laminae strike and the primary fractures will propagate as follows: run through the laminae, change their propagation direction dramatically on the laminar surface, and then run through the laminae. The smaller the difference of the horizontal principal stress, the bigger the angle of fracture deflection, and the better the fracturing result will be; the smaller the angle between perforated casing and laminae, the better the fracturing result will be; when the thickness of shale laminae is moderate, there will be more branching fractures and the fracturing result is better; tuff layers with smaller lamina thickness have better hydraulic fracturing effect. The hydraulic fracturing effect is most sensitive to horizontal principal stress difference, followed by the angle between perforated well casing and laminae.
综合研究
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  New understandings and exploration discovery of Paleogene reservoirs of Kunbei fault terrace belt, Qaidam Basin, NW China

  Ma Dade and Wang Yanqing

  . 2015, 42(4): 529-537.

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  The sedimentary facies distribution, sedimentary reservoir characteristics and main control factors of Paleogene Lulehe Formation and Lower Xiaganchaigou Formation were examined by studying on the Paleogene reservoir properties of Kunbei fault terrace belt in western Qaidam Basin, combined with well logging and seismic data. Because of the source control by Kunlun Mountains, the Lower Xiaganchaigou Formation developed braided river delta?lake sedimentary systems, mainly braided river delta front sediments, and the sand bodies distribution is SW-NE; the Lower Lulehe Formation mainly developed braided river delta plain, and braided river delta front mainly developed in the Upper Lulehe Formation. The reservoir physical properties of the braided river delta front in Lower Xiaganchaigou Formation are better, with favorable conditions of high-quality reservoirs. Tight reservoirs in Lulehe Formation have sweet spots. The oil and gas distribution of Lulehe Formation in Kunbei fault terrace belt is controlled by the content of argillaceous matrix. The new understandings of sedimentary reservoirs in Kunbei fault terrace belt play an important guiding role in oil and gas exploration of the area. Oil and gas exploration in the Qie 6, Qie 12 and Qie 16 structures achieves success, with almost one hundred million tons of proven geological reserves.
学术讨论
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  Three-dimensional physical modeling of waterflooding in metamorphic fractured reservoirs

  Tong Kaijun; Liu Huiqing; Zhang Yingchun; Wang Jing; Ge Lizhen; Dai Weihua; Hong Cheng and Meng Qingbang

  . 2015, 42(4): 538-544.

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  To understand the mechanism of water-oil displacement characteristics and how to improve waterflood efficiency in metamorphic fractured reservoirs, taking JZ251S oil field as an example, a large-scale physical simulating model which meets the geometric similarity, kinematic similarity, dynamic similarity and characteristic parameters similarity based on the theory of scaling criteria was designed to simulate the development of the actual reservoir. The mechanism of water displacing oil in dual media reservoirs, the factors affecting fluid flow and waterflood characteristics, and the EOR features of different water injection patterns were studied by experiments. The results show that: ⑴ Capillary imbibition is the main mechanism to enhance matrix oil recovery in a dual media reservoir which is controlled by waterflooding; ⑵ whether or not there is crude oil draining from matrix, the water cut trend after water breakthrough can be divided into two stages in fractured reservoir development, the first stage is quick rise stage of water cut in early water breakthrough period and the second stage is slow rise stage of water cut in mid-high water cut period; ⑶ displacement rate is the main factor controlling water-free production period, water cut trend and ultimate recovery; ⑷ compared with continuous injection, intermittent injection can give full play to the function of oil gravity segregation to reduce the water cut and improve the production rate of initial stages greatly.