, Volume 36 Issue 6

    

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学术讨论
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  Evaluating maturity of source rocks by aromatic compounds：A case from Dongling Block, Songliao Basin

  Zhu Zhanjun; Jiang Yongjian and Cheng Zhe

  , 2009, 36(6): 1715-0.

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  The characteristics of the thermal evolution of aromatic maturity parameters, such as methyl phenanthrene, alkylated dibenzothiophene, dehydroxy-tocopherol and triaromatic-sterane series compounds were discussed on the basis of the molecular organic geochemistry and the GC-MS analysis of the source rocks in the Dongling area of Songliao Basin. The distribution characteristics of aromatic chromatography, MPI, the ratio of β/γ dehydroxy-tocopherol, 4-/1-MDBT, 4,6-/1,4-DMDBT, TASC27(20R)/C28 (20R), the content of triaromatic-sterane series and vitrinite reflectance all suggest that the Lower Cretaceous Quantou Formation source rock is in the middle stage of maturity, whereas the Lower Cretaceous Yingcheng Formation and the Upper Jurrasic Huoshiling Formation source rocks reach a high maturity stage.
油气勘探
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  Features of buried hill reservoirs in Hexiwu structural belt, Langgu Sag, Jizhong Depression

  Guo Jianhua; Guo Yuancao and Wang Lianshan

  , 2009, 36(6): 1723-0.

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  The buried hill reservoirs of the Hexiwu structure belt in Langgu Sag, Bohaiwan Basin are comprehensively studied by core and outcrop observation. The reservoir lithology is dominantly carbonate rock, and the reservoir spaces include dissolution pores, dissolution cavities, cracks and bedrock micropores, forming pore-cavity type, crack type, crack-cavity type and combination pore-cavity-crack type reservoirs. Multiple-phase fossil karstification is an important factor during reservoir formation. The fossil karst is developed in the leached belt, submerged current belt, fracture belt and bedding direction along buried hill unconformities. The cracks formed by tectonic movement increase porosity, improve connection of pores and cavities and permeability. The reservoirs developed in different lithologies and tectonic positions have different physical properties: dolomite reservoir is better than carbonate reservoir, and reservoir not overlapped by Permo-Carboniferous stratum is better than that overlapped by Permo-Carboniferous stratum, and reservoir in the fault-developed area is better than that in the non-fault-developed area. The buried hill reservoirs in the southwestern Hexiwu structure belt are well developed and are favorable areas for oil and gas exploration.
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  Global importance of “continuous” petroleum reservoirs: Accumulation, distribution and evaluation

  Zou Caineng; Tao Shizhen; Yuan Xuanjun; Zhu Rukai; Dong Dazhong; Li Wei; Wang Lan; Gao Xiaohui; Gong Yanjie; Jia Jinhua; Hou Lianhua; Zhang Guangya; Li Jianzhong; Xu Chunchun and Yang Hua

  , 2009, 36(6): 1769-0.

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  Based on distribution of oil and gas in the world, the connotation and characteristics of “continuous” petroleum reservoirs are elaborated in this paper. “Continuous” petroleum reservoirs refer to unconventional trap reservoirs existing in a large-scale unconventional reservoir system, and the distribution of oil and gas is continuous. The main geological characteristics of “continuous” petroleum reservoirs are as follows: located in the center and slope of a basin, large-scale distribution and rich locally; mainly of large-scale unconventional reservoirs; traps have no clear boundaries; mainly of self-generating and self-preserving; mainly of primary migration; accumulated by diffusion and buoyancy is limited; non-Darcy flow; poor oil-water differentiation and different saturation; oil, water and gas coexist and have no common interface and pressure system; resources abundance is low and reserves are calculated by well-control region; the mining technologies are special and tailored techniques are required. In this paper are discussed the cause of deep-water “sandy debris flow” and a few examples on “continuous” reservoirs, the shallow-water delta low or ultra-low porosity and permeability reservoirs, coal-bed methane and shale-cracked reservoirs and so on.
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  Theory on logging interpretation of igneous rocks and its application

  Li Ning; Qiao Dexin; Li Qingfeng; Wu Hongliang; Fu Yousheng; Dong Lixin; Feng Qingfu and Wang Kewen

  , 2009, 36(6): 1770-0.

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  Based on the summary of theories and methods of well logging interpretation for igneous rock at home and abroad, a complete interpretation process of well logging is formed, which includes lithology identification, quantitative matrix porosity calculation, quantitative saturation calculation, and fluid nature identification. This paper presents a theory and an application model of porosity and saturation calculation for heterogeneous and complex reservoirs, and establishes a framework for interpreting complex volcanic rock reservoirs; proposes a new method combining ECS with FMI logging for 3-D lithology identification of igneous rocks. Based on the study of the micro-fracture simulation well, this paper puts forward a practical quantitative calculation method for calculating the fracture porosity of heterogeneous reservoirs. By experimenting with core of whole diameter under high temperature and high pressure, the authors studied the influence of fracture on saturation calculation through numerical simulation, and proposed a new method of quantitative saturation calculation. The results of Xujiaweizi area in Daqing Oilfield and Ludong-Wucaiwan area in Xinjiang Oilfield show that the theory and method are correct and effective.
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  Geochemical characteristics and play targets of gas in eastern Qaidam Basin, NW China

  Zhang Ying; Li Zhisheng; Wang Dongliang and Wang Xiaobo

  , 2009, 36(6): 1771-0.

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  Natural gas exists extensively in the Sanhu region of eastern Qaidam Basin, NW China, where five gas fields and two gas-bearing structures have been discovered, and lots of gas shows have been found. The gas was identified as typical biogas with geochemical characteristics of light methane carbon isotope ratio and low content of heavy hydrocarbon gas. The generation of methane was mainly related to the CO2 reduction. The existence of C5-C8 hydrocarbons in gas samples and heavy carbon isotope values of ethane and propane in a few gas samples indicate that natural gas in this region may contain some thermal gas. It can be concluded that favorable source rock and conservation conditions exist for the formation of biogas reservoirs. Expanding exploration domain, especially paying more attention to reservoirs of shallow and ultra shallow biogas, deep biogas, and deep thermal hydrocarbon, was suggested for the future exploration activities.
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  Coupling of diagenesis and sedimentary facies of Shanxi Formation in An’sai-Shenmu, Ordos Basin

  Ji Hancheng; Weng Qingping and Yang Xiao

  , 2009, 36(6): 1772-0.

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  The type of rocks, diagenesis, distribution of Permian Shan 2 Member in the central-eastern Ordos Basin were studied based on core observation, thin section analysis, cathodoluminescence and scanning electron microprobe. The reservoir mainly consists of quartz and feldspathic quartz sandstones with subordinate lithic sandstones. The sandstones experienced all kinds of diagenetic processes, such as mechanical compaction, pressure solution, quartz overgrowth, carbonate cementation and replacement, kaolinite filling, dissolution. The dissolution turns out to be the essential control for the formation of effective reservoirs. Laterally, diagenetic features were analyzed in detail, with a conclusion that the regional variations of diagenesis are mostly controlled by facies in the given area. Along the dispersal system of sediments, pressure solution-siliceous cementation and dissolution become prominent whereas compaction, carbonate cementation and replacement decrease in intensity. From the center of the distributary channels to both flanks, compaction, carbonate cementation, and matrix dissolution increase in intensity and siliceous cementation and dissolution wane accordingly. Pores are well developed in the sandstones in the distributary channel of deltaic plain, the subaqueous distributary channel and mouth bar of deltaic front.
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  Acidity features and origin of crude oil in Tarim Basin

  Liu Jingjiang; Chen Guohong; Huang Chengyi; Cao Lei; Li Mei; Zhang Qiucha and Zhang Haizu

  , 2009, 36(6): 1773-0.

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  Crude oil in Tarim Basin belongs to mixed-type low and medium-acidity oil. Organic acids in the oil come mainly from biodegradation of the oil, and secondly from original organic acids. The oil has a lower acid number, below 3 mg/g in general, and the oil of Triassic and Jurassic reservoirs in the Lunnan area has a relatively high acid number, about 0.96-1.12 mg/g, only some local oil reaches the level of the high-acidity oil (1.0-5.0 mg/g); the oil in Ordovician and Carboniferous reservoirs has a lower acid number, mostly below 0.5 mg/g. The oil in Ordovician carbonate reservoirs experienced intense degradation, but the followed acid-rock reaction consumed almost all the early organic acids and depressed the oil acidity. The Jurassic, Trassic and Carboniferous oil acidity is related to the late-biodegradation due to active formation water.
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  Response of dual laterolog and fast correction for layer thickness and shoulder bed in horizontal wells

  Deng Shaogui; Li Zhuqiang and Li Zhiqiang

  , 2009, 36(6): 1774-0.

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  Based on horizontal well modeling with 3 layers, the 3D finite element method is used to simulate the response of dual laterolog in horizontal wells. The modeling results show that the response of the dual laterolog is obviously influenced by the borehole position in the target formation. When the borehole position varies, the dual laterolog response of non-thick formation changes. Under conditions of different layer thicknesses and/or different borehole positions, the responses of dual laterolog in horizontal wells are different from that in vertical wells. The deep and shallow resistivity of the dual laterolog exhibits an apparent amplitude difference for the non-invaded zone in horizontal wells. Based on the 3D numerical simulation results, the correction charts of dual laterolog responses for layer thickness and shoulder bed are generated, and a fast calculation method for resistivity correction in horizontal wells is proposed. The correction results from proposed method agree well with those from 3D numerical computation. The fast correction method is rapid and effective in layer thickness and shoulder bed correction.
油气田开发
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  Study on fine reservoir modeling and distribution of remaining oil with data of horizontal wells

  Hao Jianming; Wu Jian and Zhang Hongwei

  , 2009, 36(6): 1775-0.

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  The horizontal well-produced oil reservoir was taken as an example in No.8 substratum of the Guantao Formation, block Gao 104-5, Gaoshangpu Oilfield. Horizontal well drilling data, seismic data and other fundamental information, combined with the fine internal division and correlation of sedimentary cycles in a single sandbody, were used to establish a single-sandbody high-precision geological model for the target zone of horizontal well, with the currently popular phased stochastic modeling technology. On this basis, we carried out detailed reservoir numerical simulation and established a dynamic reservoir model, then verified the static model with history matching and dynamic method. The geological model has high accuracy, and meets the demand of further research. With the modified model, we researched and evaluated the development status of the horizontal wells, the characteristics and trend of water cut and the distribution characteristics of remaining oil.
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  Assessment of CO2 EOR and its geo-storage potential in mature oil reservoirs, Shengli Oilfield, China

  Zhang Liang; Wang Shu; Zhang Li; Ren Shaoran and Guo Qing

  , 2009, 36(6): 1776-0.

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  Most oil reservoirs in Shengli Oilfield have entered middle and late development stages after nearly 40-year production, and they are suitable for applying CO2 EOR and storage techniques. This study is aimed at assessing the potential of CO2 EOR and storage in 3 large oil fields in the region based on the data of 183 mature oil reservoirs. The assessments include regional geology assessment, storage site screening, reservoir screening for CO2 EOR, and EOR potential and storage capacity calculations. Many mature oil reservoirs are close to the main CO2 sources and have good geographical and geological conditions for CO2 storage. Of 41 reservoirs,18 are suitable both for EOR and storage and 23 suitable for storage as depleted oil reservoirs. The total EOR potential can be 999.72×104 t, and the CO2 storage can reach 9 553.92×104 t. The overall incremental oil recovery rate can be 5.76%. The greater OOIP the oil reservoir has, the greater potential of CO2 EOR and storage it will have, and the more suitable for large-scale storage projects it will be. Those oil reservoirs suitable for CO2 EOR with large OOIP will be the preferred sites for CO2 storage. Many nearly depleted oil reservoirs with large OOIP can be considered as main sites for CO2 storage in the near future.
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  Technique of enhancing recovery of remaining oil in heavy oil reservoirs by horizontal wells

  Qu Tongci and Li shuang

  , 2009, 36(6): 1777-0.

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  To excavate the remaining oil between the wells of super-heavy oil reservoirs in A Block of Liaohe Oilfield, the temperature field, pressure field and distribution of remaining oil are described by numerical simulation software where the horizontal wells were deployed. The employing degree is good around the production wells which have more steam stimulation cycles, the reservoir temperature attains 190-210 ℃, but the effective heating area around wellbore is 20-30 m, the majority region is still 45-65 ℃ between the wells. Because of steam channeling, the thermal channel is buildup between some wells. The reservoir pressure is 3.00 MPa where the employing degree is good, generally, 3.40-3.90 MPa. A large amount of remaining oil exists between the wells and the saturation of remaining oil is above 50%. Thirty horizontal wells are deployed in Ⅹ Ⅲ and Ⅻ2 formations where the effective thickness of individual bed is more than 5 m. The length of horizontal section is 250 to 400 m. According to the simulation, when the horizontal wells produce by eight steam stimulation cycles, the average cumulative oil production of a single horizontal well is 25 220 t, the oil-steam ratio is 0.42 and the degree of recovery is 31.5%. Compared with vertical wells, the infill horizontal wells can enhance oil recovery.
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  Reservoir fracture prediction by multi-parameter criteria method

  Yan Xiangzhen; Wang Zhigang; Liu Qinjie and Yang Xiujuan

  , 2009, 36(6): 1778-0.

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  The multi-parameter criteria method is proposed based on the in-situ stress distribution and properties of reservoir matrix to predict the fractures distribution. The in-situ stress of the study reservoir is obtained by inverse reliability-based approach. The reservoir fracture development degree is predicted by analyzing the relationship between stress state function and failure surface. The failure surface is established by utilizing several rock material parameters, serving as boundary conditions. The fracture density of reservoir is acquired using the measured fracture parameters of some key wells. A case study in Jiangsu Oilfield is investigated with the multi-parameter criteria method. The results show that there is a perfect linear relationship between fracture volume density and the common logarithm of fracture development index. The fracture volume density varies mainly from 0.23 to 1.20 m2/m3. The fault structure and tectonic geometry both have significant influence on the fracture development.
资源评价与管理
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  Geology and reserve of the Orinoco heavy oil belt, Venezuela

  Mu Longxin; Han Guoqing and Xu Baojun

  , 2009, 36(6): 1779-0.

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  Orinoco heavy oil belt is the largest heavy oil enriched area in the world, with the total area of 54 000 km2, heavy oil reserves of about 200 billion tons, and recoverable reserves of about 50 billion tons. It is located in the marginal uplift belt of East Venezuela Basin, and is a monocline dipping to the north. The main reservoir is Tertiary fluvial deltaic facies sandstone characterized by shallow depth of oil layer, large thickness, high porosity, high permeability, high oil saturation, poor consolidation, and strong heterogeneity. The main trap is lithologic trap, and locally controlled by faults. The belt is subdivided into 4 large areas with 32 blocks, and the proved reserves are mainly in the JUNIN and CARABOBO regions. Oil pools are characterized by "three highs and one low" in the fluidity of the heavy oil, that is, high gravity, high sulfur, high content of heavy metals vanadium and nickel, and low viscosity, and foamy oil can be formed. Under the conditions of cold production, the oil can flow and single well production is high, the production with horizontal well is up to 200 tons per day, and the oil recovery is relatively low (5%-10%).
油气田开发
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  Development of complex carbonate reservoir with condensate gas cap

  Song Heng; Fu Xiujuan; Fan Hailinag; Zhao Lun and Yu Lian

  , 2009, 36(6): 1780-0.

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  Zanarol Oilfield in Kazakstan is a big carbonate reservoir with condensate gas cap. Г North reservoir is the major reservoir of the field. The reservoir has a dual-porosity character. Fracture distribution changes on plane. Insufficient previous water injection results in decrease of formation pressure and increase of natural declining rate. The study of the developing characteristics and reasonable development technique policies for reservoirs with differently developed fractures reveals that development policies are different depending on the distribution of fractures. Sound formation pressure maintenance for reservoirs with well-developed fractures is 25-27 MPa, and the reasonable injection-withdrawal ratio is 1.1. Sound formation pressure maintenance for reservoirs with undeveloped fractures is 32 MPa, and the sound injection-withdrawal ratio is 1.3. When the flooding ratio of gas cap to oil rim is 2 to 8, energy of gas cap can be utilized well and the water flooding in oil rim can act more effectively.
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  Construction of a carbonate reservoir modelusing transient pressure data

  Seyed Sadegh Taheri Rudsari; Mohammad Bagher Ghanizadeh and Manuchehr Haghighi

  , 2009, 36(6): 1781-0.

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  A geological model is usually constructed using geophysical and petrophysical data by virtue of geological information. In this work, in order to achieve accurate model we built a carbonate reservoir model not only by seismic and well log data but also by the integration of 99 well test data available for this field. Many features such as sealing faults, aquifer, fracturing and layering systems were observed during the well test interpretation. Some of the above features were identified only by pressure transient data such as one sealing fault which was not observed in the seismic data. In addition to the identification of structural features, permeability data from well test were also used for the construction of iso-permeability map instead of depending on permeability data from core analysis. This is very significant assignment in a heterogeneous carbonate reservoir and when a single porosity model is used. Permeability obtained from well test is the effective permeability in the drainage area of each well while permeability from core analysis does not represent the property of a heterogeneous reservoir. This work proves that using transient pressure analysis results in construction of reservoir model can improve the accuracy of carbonate reservoirs models.
石油工程
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  Multilateral drilling technique based on Solid Expandable Tubular (SET) fixing system

  Zhang Yanping; Ren Rongquan; Wang Hui and Wang Jun

  , 2009, 36(6): 1782-0.

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  A new multilateral drilling technology is developed based on the Solid Expandable Tubular (SET) fixing system. By this new technology, every kind of tools in drilling, completion, well repair and oil formation improvement are located and operated according to down-hole SET fixing equipment. This SET fixing multilateral drilling technology reaches the international TAML 4 completion level and has such characteristics as simple procedure, big bore size after completion, and drilling several branches in small size casing. In this technology, whipstock is located reliably on downhole SET fixing equipment, which can stand great drill pressure and torque to meet implementation requirement such as windows cutting, side drilling, and washover. The successful application in 3 wells in offshore oil fields shows that the SET fixing multilateral technology has low difficulty job procedure and operation, high reliability of job security, and obvious implementation signal to make driller easy operation. Two series of SET fixing multilateral tools and technology have been developed with their respective main casings being 177.8 mm (7 in) and 244.5 mm（9 in).
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  Rig mode option for semi-submersible drilling platform

  Yue Jixiang; Qi Yaoguang; Xiao Wensheng; Yang Lei and Chen Jun

  , 2009, 36(6): 1783-0.

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  Mode option of deepwater rigs can affect the configuration and construction of the 6th generation semi-submersible drilling platform in China. This paper assesses the mode option of deepwater rigs through analyzing different kinds of rigs' offline operation ability and offline configuration, working efficiency, variable deck load (VDL) and patent influence. The analysis of design, application and offline configuration of three types of rigs-single rigs, offline rigs and dual derrick rigs, reveals the relation between offline configuration and work efficiency, that is, the more complete offline equipments are, the greater the work efficiency can be improved. The mechanism of dual derrick rigs is demonstrated by Gantt chart decomposing the whole drilling procedure of a deepwater exploration well, which is current operation and offline operation. Comparing the operation efficiency of the three-type deepwater rigs in drilling single wells, multiple wells and wells completion shows that dual derrick rigs are the most efficient. VDL, construction cost, patent of dual rigs influence the choice of dual rigs. The model of net present value considering all factors is built to assess three types of deepwater rigs and shows that dual derrick rigs are better than offline rigs on the whole.