23 October 2015, Volume 42 Issue 5

    

• Select all
  |

油气勘探
• Select
  Major factors controlling the development of marine carbonate reservoirs

  Shen Anjiang; Zhao Wenzhi; Hu Anping; She Min; Chen Yana and Wang Xiaofang

  . 2015, 42(5): 545-554.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  Through case study of reef-shoal, karst and dolostone reservoirs in the Tarim and Sichuan Basins, the material base and the mechanisms of porosity creation, modification and preservation of carbonate reservoirs were examined carefully in order to figure out the major factors controlling the development of various types of carbonate reservoirs. Three factors control the development of carbonate reservoirs: (1) carbonate sediments of reef-shoal facies are the material base for not only reef-shoal reservoirs, but also dolostone and karst reservoirs; (2) epigenetic environment is crucial for porosity creation, i.e. reservoir space in ancient carbonates includes primary depositional porosity and/or secondary dissolution pores caused by epigenetic, freshwater dissolution; and (3) burial environment is the setting for porosity modification and preservation. There is no carbonate reservoirs of solely one origin, carbonate reservoirs are all the products of the combined effect of the above three factors. The four main controlling factors, reef-shoal sediments, epigenetic karstification, evaporation facies belt and burial-thermal fluid dissolution give rise to the reef-shoal, karst, sedimentary dolostone and burial-hydrothermal alteration dolostone reservoirs respectively.
• Select
  Formation conditions and “sweet spot ” evaluation of tight oil and shale oil

  Yang Zhi; Hou Lianhua; Tao Shizhen; Cui Jingwei; Wu Songtao; Lin Senhu and Pan Songqi

  . 2015, 42(5): 555-565.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  Liquid hydrocarbons in shale strata include two kinds of resources, i.e. tight oil and shale oil. Based on the exploration and research progress of liquid hydrocarbons in shale at home and abroad, their formation condition, accumulation mechanism, classification, and differences between lacustrine and marine shale systems are examined, and “sweet spots” are evaluated further. Analysis on the geological characteristics of the liquid hydrocarbons in the shale strata in North America and China shows the liquid hydrocarbons have two basic features: large-scale continuous distribution and no stable industrial production. The massive accumulation of the liquid hydrocarbons needs four fundamental formation conditions: stable tectonic background, widespread high quality source rocks, large-scale tight reservoirs with massive reservoir space, and co-existence of source and reservoir. The study reveals the formation mechanisms of the liquid hydrocarbons: source-reservoir coupling and porosity decrease during the diagenetic tightness; and identifies 24 kinds in 6 categories of the liquid hydrocarbons. It is concluded that the geological conditions of the lacustrine shales in China are characterized by lower thermal gradient and stronger heterogeneity than those of North America, so large scale “sweet spots” have to be picked out to push up industrial production steadily. “Sweet spots” evaluation should consider the three aspects of geology, engineering and economics comprehensively, and the maturity of source rocks is first and foremost factor controlling the “sweet spot” distribution. In China, prospective shale areas should meet the following conditions: the Ro between 0.8% and 1.3%, TOC higher than 2%, laminated shales or tight porous reservoirs, higher porosity (more than 8% for tight oil, and more than 3% for shale oil), higher content of brittle minerals (more than 70% for tight oil, and more than 40% for shale oil), oil saturation of 50%?90%, lower crude oil viscosity or higher formation pressure, and rich natural fractures. Liquid hydrocarbons in shale strata are huge in resource scale, so deepening the geological understanding on the formation and distribution of liquid hydrocarbons in marine and lacustrine shales constantly is of great significance for exploration and development of this important field.
• Select
  Seismic sedimentology characteristics of sub-clinoformal shallow-water meandering river delta: A case from the Suning area of Raoyang sag in Jizhong depression, Bohai Bay Basin, NE China

  Zeng Hongliu; Zhao Xianzheng; Zhu Xiaomin; Jin Fengming; Dong Yanlei; Wang Yuquan; Zhu Mao and Zheng Ronghua

  . 2015, 42(5): 566-576.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  The seismic sedimentology characteristics of sub-clinoformal shallow-water meandering river delta can be comprehensively analyzed by core, well logging and 3-D seismic data. This paper summarizes the sedimentary pattern of sub-clinoformal shallow-water meandering river delta of Suning area in Raoyang sag, Jizhong depression of Bohai Bay Basin. In Suning area, there are eight fourth-order sequences recognized from the upper part of Sha 1 Member (Es1s) to Dong 3 Member (Ed3), reflecting periodical change of lake level. From the central lake to the shore, and from the transgressive to highstand systems tracts, the color of mudstones varies from grey to red, showing a drop of lake-level. The seismic reflection pattern indicates the drop of lake level: the shingled reflections in Es1s (SQⅤ3) indicate water depth of 40?60 m in the lake center, followed by sub-parallel (SQＶ4-SQＶ6) with lower continuity reflections, and disappearance of shingled reflections, showing water depth no more than 30 m. Analysis of core, well logging, and seismic amplitude strata slices reveal that the sequences SQⅤ4-SQＶ6 of Es1s are sub-clinoformal shallow-water meandering river delta, different from the shingled reflection shallow-water meandering river delta in SQV3 of Es1s. The main seismic sedimentology characteristics are channel forms and lobate landforms advancing to the central lake by multiple zones, indicating numerous distributary channel and deltaic lobes depositions.
• Select
  Sedimentary characteristics and facies model of gravity flow deposits of Late Triassic Yanchang Formation in southwestern Ordos Basin, China

  Liu Fen; Zhu Xiaomin; Li Yang; Xu Liming; Niu Xiaobing; Zhu Shifa; Liang Xiaowei and Xue Mengge

  . 2015, 42(5): 577-588.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  Based on cores and logging data, and gravity flow theory, the sedimentary characteristics and facies model of gravity flow deposits in the Longdong area in southwestern Ordos Basin were analyzed. Five types of gravity flow deposits are recognized: slides, slumps, sandy debris flows, muddy debris flows and turbidity currents. Affected by multiple provenances, paleogeomorphology and triggering mechanisms jointly, the gravity flows resulted in sublacustrine fans and slump olistoliths in the basin center. Containing channels, the sublacustrine fans can be divided into three subfacies, inner fan, middle fan and outer fan and subdivided into six microfacies, main channel, main channel lateral margin, distributary channel, distributary channel lateral margin, inter-channel and sheeted turbidite sand. It is inferred that they are caused by seasonal floods. The slump olistoliths, with no channels, consist four parts: slide rock, slump rock, debris flow lobe and sheeted turbidite sand, and are inferred to be the product of collapse of break belts triggered by events like earthquakes. Combining facies models with types of gravity flow deposits can reveal the sedimentary characteristics and genetic models of gravity flow deposits in deep water more directly and provide theoretical basis for deep water oil and gas exploration. Key words: gravity flow deposit; genetic type; sedimentary system; sedimentary model; Yanchang Formation; Ordos Basin
• Select
  Distribution and controlling factors of tight sandstone oil in Fuyu oil layers of Da’an area, Songliao Basin, NE China

  Sun Yu; Deng Ming; Ma Shizhong; Chen Yuming; Yu Limin; Zhang Yan; Yan Baiquan and Zhang Yunfeng

  . 2015, 42(5): 589-597.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  By using core samples, thin section, scanning electron microscope and rate-controlled mercury penetration data etc, the reservoir characteristics, oil-bearing characteristics and main controlling factors of the tight sandstone oil in Fuyu oil layer of Da’an area, Songliao Basin are studied. The oil-bearing characteristics of Fuyu oil layers in Da’an area are as follows: (1) the extensive and continuous distribution, with “sweet spots” in local areas; (2) low oil abundance, and very complex distribution; (3) oil-bearing grade being oil immersion to oil spot, with very low lower-limit of oil-bearing porosity and permeability; and (4) poor differentiation of oil and water, no uniform oil-water contact. The above oil-bearing characteristics of the tight sandstone in Fuyu oil layers are mainly controlled by the spatial distribution of distributary channel sands, the differences in reservoir physical properties, the structure and size of pores and throats. The boundary of distributary channel sandbody is the boundary of tight sandstone oil distribution. The heterogeneity of tight sandstone oil is controlled by the single distributary channel sandbody and the contact relationship between different stages of distributary channel sandbody. Distribution of “sweet spots” and enrichment of tight sandstone oil are controlled by the differences in physical properties. The differentiation of oil and water in the tight sandstone is controlled by the pore structure and pore size. In-situ oil accumulation is controlled by the nano-pore throat structure system.
• Select
  Petrologic characteristics and genetic model of lacustrine lamellar fine-grained rock and its significance for shale oil exploration: A case study of Permian Lucaogou Formation in Malang sag, Santanghu Basin, NW China

  Liu Bo; Lü Yanfang; Meng Yuanlin; Li Xinning; Guo Xiaobo; Ma Qiang and Zhao Wanchun

  . 2015, 42(5): 598-607.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  Taking the Permian Lucaogou Formation in the Malang sag, Santanghu Basin as an example, by using petrological methods such as high resolution core image scanning, conventional thin section, scanning electron microscope and energy spectrum analysis and geochemical tests such as trace elements and biomarker compounds, the petrologic features and sedimentary origin of the lamellar organic rich fine-grained rocks of lake facies were investigated, and its significance for shale oil and tight oil exploration was analyzed. The results of the study show that there are four types of laminae, siliciclastic enrichment laminae, carbonate enrichment laminae, tuffaceous enrichment laminae and organic matter enrichment laminae, which can form three kinds of layer combinations. Organic matter is laminar enrichment or dispersed in the carbonate laminae and tuff laminae. Stratification of ancient lake water was formed in the closed saline lake sedimentary systems with insufficient continental clast supply, and the activity of warm water at the lake bottom and the monsoon climate worked jointly to control enrichment of organic matter and formation of lacustrine lamina fine-grained rocks. This kind of fine-grained rocks have higher potential of hydrocarbon generation due to high abundance of organic matter, are rich in reservoir space due to the existence of micro-pores in carbonate laminae and micro-cracks between the laminae, and suitable for fracturing because of high brittle mineral content. They have favorable conditions for shale oil and tight oil accumulation, and are significant for exploration.
• Select
  Well logging evaluation of Triassic Chang 7 Member tight reservoirs, Yanchang Formation, Ordos Basin, NW China

  Li Chaoliu; Li Changxi; Hou Yuting; Shi Yujiang; Wang Changsheng; Hu Falong and Liu Mi

  . 2015, 42(5): 608-614.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  Taking the Triassic Chang 7 Member tight reservoirs of the Yanchang Formation in the Ordos Basin as study object, transverse relaxation simulation was made using nuclear magnetic resonance (NMR) experimental data, CT images and random-walker algorithm to evaluate microscopic pore-throats of the tight reservoirs. The smoothing degree of well logging curves was utilized to evaluate sand structure of the tight reservoirs; and through multi-well analysis and the calibration of well testing data, a grading chart of tight reservoir productivity was established based on sand structure. Reservoir quality was judged and analyzed by pore level: Transverse surface relaxivity ρ2 was obtained by comparing transverse relaxation time T2 of numerical simulation and that of NMR experiment, and the distribution of pore-throat radius was obtained according to the corrected NMR logging curves. The study shows there is an obvious correlation between productivity and sand structure of Chang 7 tight reservoirs. The more homogeneous the distribution of lithology, physical property and oiliness of the massive sand, and the smoother the well logging curves, the more likely the high oil yield will occur. Based on well logging evaluation and grading chart of productivity of tight reservoirs, sweet spots in well area W of Jiyuan Oilfield in Ordos Basin were identified, the comparison of the evaluation results and well testing data shows the accuracy rate is as high as 94.7%.
• Select
  Distribution of sedimentary formations in the Bornu Basin, Nigeria

  Solomon O. Olabode; John A. Adekoya and Peter S. Ola

  . 2015, 42(5): 615-623.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  By using drilling data and geophysical wireline logs of twenty-three wells in the Bornus Basin, the overall distribution of stratigraphic formations (Kerri-Kerri, Gombe, Fika, Gongila and Bima) in the basin have been simulated with software of Excel, Petrel and Surfer etc. Three major depressions, labeled A, C and D and a structural high B, have been identified. Depression A is located in the northeast, while depressions C and D are located in the southeast and southwest of the basin, respectively, structural high B separates depression A from depression C. All the existing stratigraphic formations (Kerri-Kerri, Gombe, Fika, Gongila and Bima) are widespread in the basin, but with variation in thickness. Drilling data of three deep wells (Kadaru - 1, Herwa - 1 and Kinasar - 1) showed that only the upper part of Bima Formation (middle to coarse grained arkose) have been penetrated, while the lower part of Bima Formation is not drilled yet, therefore, it is suggested that the deep formations in the depressions be drilled to find their hydrocarbon potential.
油气田开发
• Select
  Fluid interface moving for the concurrent production of gas cap and oil rim of gas cap reservoirs

  Fan Zifei; Cheng Linsong; Song Heng; Wu Xuelin and Zhang Angang

  . 2015, 42(5): 624-631.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  The pressure balance between gas cap and oil rim is likely to be broken during their concurrent production in gas cap reservoirs. In order to increase the whole development efficiency of the concurrent production of gas cap and oil rim, the Zhanzhol gas cap reservoir of Kazakhstan was taken as example to carry out the research, a three-dimensional visualization physical model was established based on the similarity criterion of oil phase, gas phase and water phase, and a reservoir engineering model of fluid interface moving rate was also set up according to the material balance principle. The calculation results of reservoir engineering model tally with the results of physical simulation experiment and reservoir dynamic test data. The moving rate template of fluid interface under three development modes, depletion development, barrier water injection development and barrier plus pattern water injection development have been also established by reservoir engineering method. The main controlling factors under different development modes have been figured out: for depletion development, the main controlling factors on the stabilization of oil-gas contact are oil recovery rate and gas recovery rate; for barrier water injection development, the main controlling factors are oil recovery rate, gas recovery rate and production-injection ratio; and for barrier plus pattern water injection development, the main controlling factors are oil recovery rate, gas recovery rate, production-injection ratio and the ratio of barrier water injection to pattern water injection.
• Select
  Development mechanisms and influence factors of dumpflooding

  Su Haiyang; Mu Longxin; Han Haiying; Liu Yongge and Li Bo

  . 2015, 42(5): 632-637.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  Aiming at the problem that the theory of dump flooding is not mature, this study examined the suitable reservoir conditions for dump flooding, defined the concept of “dump flooding threshold pressure” and its expression based on fluid mechanics and reservoir engineering fundamentals, and proposed the computing method of water injection rate, producing rate, water layer pressure, oil layer pressure, cumulative injection and cumulative production. It gave the corresponding computing program according to the proposed computing method, and made a case study and analyzed the factors affecting dump flooding using the program. The dump flooding computing methods are reasonable and applicable; when water reserve-oil reserve ratio is less than 60, production plateau extends with and oil recovery increases with the increase of water reserve-oil reserve ratio, when water reserve-oil reserve ratio is more than 60, the effect of the ratio of water reserve to oil reserve is negligible; the timing of dump flooding has a significant effect on production plateau and oil recovery, the later the dump flooding injection timing, the more completely the formation energy will be used, the longer the production plateau and the higher the recovery will be.
• Select
  Regionalized multiple-point stochastic geological modeling: A case from braided delta sedimentary reservoirs in Qaidam Basin, NW China

  Chen Gengxin; Cao Zhenglin; Zhao fan; Zheng Hongjun; Wang Aiping; Li Jiyong; Chang Lin and Hu Yunpeng

  . 2015, 42(5): 638-645.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  Research on the depositional model of a braided delta in Kunbei oilfield, Qaidam Basin, was conducted with a fine geologic study in a dense well network area by combining sedimentary physical simulation to obtain statistical characteristic parameters and allocation relations of plane sedimentary facies units. On this basis, training images in different sedimentary regions of the braided delta were developed for reservoir modeling. In each sub-region, sequential conditional simulation in adjacent regions used different training images with angle revolving and scaling. This simulation succeeded in finely modeling the sedimentary microfacies of the braided delta. This method relaxed the requirement for a stationary training image in multipoint simulation and improved channel continuity as well as portability of the training image. In the fine reservoir description of the Kunbei oilfield, the model results were consistent with practical production and have the potential to guide effective water-flooding development. Effective application demonstrated the feasibility and practicability of the method. This paper presents a new method for accurately characterizing the braided delta using stochastic simulation.
• Select
  Well spacing design for low and ultra-low permeability reservoirs developed by hydraulic fracturing

  Bian Xiaobing; Zhang Shicheng; Zhang Jingchen and Wang Daobing

  . 2015, 42(5): 646-651.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  In order to simulate non-Darcy flows in low and ultra-low permeability reservoirs, based on the black oil simulator, a three-dimensional, two-phase model was established considering two-phase start-up pressure, permeability sensibility and fracture conductivity decline. Then numerous simulations were run to analyze the elliptic drainage area induced by a fractured well, the results show that: for water fractured well, permeability is the dominant factor affecting the elliptic drainage area at the beginning, and pressure difference and start-up pressure have increasing effects as time goes by. However, no factor has a marked impact on the shape of elliptic drainage area. Parameters of elliptic drainage area can be calculated with GA-BP neural network improved by genetic algorithm. Aiming at acquiring maximum sweep efficiency, well spacing equations were deduced for rectangular pattern and diamond inverted nine-spot pattern. Field application demonstrated daily oil production enhanced 1.25 times after hydraulic fracturing, and the long time stimulation effect is substantial.
• Select
  Thermal stability of foam during steam drive

  Shen Dehuang; Wu Yongbin; Liang Shuxian and Luo Jianhua

  . 2015, 42(5): 652-655.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  A fine-long tube model was established for carrying out the thermal degradation experiments of steam foam to determine the foam stability in steam chamber. The real core sand from the Yulou oil layer of Block Jin45 of Liaohe Oilfield was packed in the model, and the experiment lasting for twenty days was conducted under the typical reservoir pressure and saturated steam temperature. The analysis on the experimental results and theoretical calculation results indicates that the thermal degradation reaction model of the added foam is the first-order reaction, and the degradation rate constants at the temperatures of 200 ℃, 250 ℃, and 300 ℃ are 9.35×10?8 s?1, 17.80×10?8 s?1, and 24.53×10?8 s?1 respectively. The foam thermal degradation rate kinetic model was deduced, which can be used to calculate the foam thermal degradation rate and half-life at any temperature condition. The half-lives of the added foam are 370 d, 160 d, 83 d, 49 d and 31 d at the temperatures of 100 ℃, 150 ℃, 200 ℃, 250 ℃ and 300 ℃ respectively, which indicates that the production performance of most of the heavy oil reservoirs developed by steam drive in China can be improved by injecting foam agent. But in terms of the deep and high-pressure heavy oil reservoirs, the foam stability is poor when the saturated steam temperature is over 300 ℃.
石油工程
• Select
  Sensitivity of self-elevating unit leg strength to different chord space

  Zhu Yazhou; Sun Chengmeng; Zhang Xiaoyu; Qi Xin; Qin Hongde and Jiang Bin

  . 2015, 42(5): 656-661.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  Aiming to optimize the truss leg structure of self-elevating unit, the sensitivity of leg strength to different chord space was analyzed, and the optimal value of chord space for legs was presented. The wind load under storm condition was obtained by wind tunnel test, and the wave and current loads were calculated based on theoretical and numerical methods. The natural vibration period and first order offset value were obtained by eigenvalue analysis, thus the inertial load considering the dynamic amplification factor and the inertial moment considering the geometric nonlinearity were obtained. It is found out through analysis that: the inertial load considering the dynamic amplification factor is more sensitive to chord space under a certain wave and current angle, and decreases with the increase of chord space in general; the inertial moment considering the geometric nonlinearity also decreases with the increase of chord space. According to the environment load, the strength of leg structures at different chord spaces were checked and the sensitivity of the structure strength to chord space was compared. Based on this, the optimal values of chord space for legs at three water depths were presented.
• Select
  Study of mechanical properties of shale based on micro-indentation test

  Chen Ping; Han Qiang; Ma Tianshou and Lin Dong

  . 2015, 42(5): 662-670.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  In view of the difficulty to get mechanical characteristics of shale reservoirs, a quantitative evaluation method based on micro-indentation test technology was proposed to research the meso-mechanical properties of shale. Through micro-indentation test of shale outcrop samples from the Cambrian Longmaxi Formation in the Changning area, Sichuan Basin, the meso-mechanical properties of shale were analyzed, and the relationship between the macro-scale and meso-scale shale mechanical properties was evaluated. The analysis results of micro-indentation tests show that the mesoscopic elastic modulus and indentation hardness are heterogeneous in distribution. The comparison of macro and meso experiments shows that the statistical mean value of meso-elastic modulus is approximate to the value of the macro-elastic modulus. The relationship between composition and mechanical properties of shale was obtained based on the packing density model theory. The result shows that mesoscopic elastic modulus and indentation hardness increase nonlinearly with the increase of the packing density. Based on the hardness-packing density model, the reverse analysis of cohesion and friction angles shows that the mesoscopic value is slightly smaller than the macroscopic value. The micro-indentation test technology can evaluate shale meso-mechanical properties and predict the macro-mechanical properties effectively.
综合研究
• Select
  Structural architecture difference and petroleum exploration of passive continental margin basins in East Africa

  Wen Zhixin; Wang Zhaoming; Song Chengpeng; He Zhengjun and Liu Xiaobing

  . 2015, 42(5): 671-680.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  Based on the plate tectonic theory, and by studying seismic, geologic data and related documents, this study restored the proto-type basins and lithofacies paleogeography of East African passive margin basins in the major geological periods, and carried out analysis on the basin architecture characteristics and sedimentary filling variance. Based on the dissection of fifteen reservoirs, three hydrocarbon accumulation models were identified to find out favorable plays and the further exploration direction in this region. The East African passive continental margin basins experienced three prototype stages, Late Carboniferous-Triassic Karoo intercontinental failed rifts, Jurassic intercontinental-intracontinental rifts, and passive continental margins since the Cretaceous. The rift sequences are developed in all the basins, forming the “rift type”, “rift depression type” and “delta reconstruction type” passive continental margin basins in line with the different thicknesses of the sediment fillings during the depression period. In the “rift type” basins, the sediment thickness during the depression period was less than 3 000 m, forming “single source - structure type” hydrocarbon accumulation model, where the exploration direction will mainly focus on giant structural traps on the top of the rift sequences. In the “fault-depression type” basins, the sediment thickness during the depression period was more than 5 000 m, forming “double sources - double combinations type” hydrocarbon accumulation model, where the exploration direction will mainly focus on giant slip-collapse-debris flow deposits on the top and middle of the slope. In the “delta-reconstruction type” sediment basins, the thickness is more than 6 000 m, forming constructional delta deposits with four structural belts from onshore to offshore, unique growth faults, mud diapirs, thrust faults and fore deep gentle slope, which are named as “three sources - multi-combinations type” hydrocarbon accumulation model, and all the four structural belts can form giant oil and gas fields.
学术讨论
• Select
  Low limit of tight oil flowing porosity: Application of high-pressure mercury intrusion in the fourth Member of Cretaceous Quantou Formation in southern Songliao Basin, NE China

  Gong Yanjie; Liu Shaobo; Zhu Rukai; Liu Keyu; Tang Zhenxing and Jiang Lin

  . 2015, 42(5): 681-688.

  Abstract ( ) Download PDF ( ) Knowledge map Save

  According to porosity measured by high-pressure mercury intrusion experiments and helium, and analysis of oil saturation data of 30 samples of tight formations of Member 4 of Cretaceous Quantou Formation in Rangzijing slope zone, southern Songliao Basin, the low limit of flowing porosity of tight oil and its controlling factors of the samples are determined. By conversion between capillary pressure in reservoir conditions and capillary pressure from high-pressure mercury intrusion experiments, flowing porosity in various injection pressures in reservoir condition can be calculated. By calculating the minimum flowing porosity of oil-bearing samples and the maximum flowing porosity of the samples without oil, it is confirmed that 3.2% is the low limit of flowing porosity in the oil-bearing samples in the study area; and the corresponding injection pressure in reservoir conditions is 0.35 MPa. If the injection pressure is higher than 0.35 MPa, tight oil can effectively flow and accumulate. The flowing porosity of tight formations and pore-throat ratio are negatively related. When the connectivity of pore-throat in reservoirs becomes poorer, higher injection pressure is needed for flowing porosity to be 3.2%. The injection pressure needed for flowing porosity to be 3.2% have a negative correlation to reservoir quality coefficient. With the reservoir quality coefficient increasing, the injection pressure needed for flowing porosity to be 3.2% has a decreasing tendency. Based on the tight oil low limit of flowing porosity and injection pressure in reservoir conditions, the discriminant chart of effective accumulation of tight oil is set up.