, Volume 35 Issue 1
    

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  • HU Wenrui
    , 2008, 35(1): 1555-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    This paper presents a new concept of redevelopment of mature fields and defines its object on the basis of the PetroChina’s field development status analysis, including development stage, remaining reserves, surface engineering, and average oil recovery factor. For mature field redevelopment, three conditions must be met. Firstly, the field producing is over 20 years (heavy oil fields over 12 years); secondly,the recovery factor of recoverable reserves is up to 70%; thirdly, the field water cut is up to 85%. PetroChina has developed special technologies and technical know-how in reservoir study, drilling and production engineering, and surface engineering since the national 11th five-year plan. Mature field redevelopment is complex system engineering and should follow three principles, which are integrative deployment, staged implementation, and pilot study first. Redevelopment of mature oilfields is a necessary way and the expected increase of oil recovery factor ranges from 10% to 20%.
  • 油气勘探
  • YIN Jinghong; LEI Angui; FANG Bingzhong; CANG Ruibo; CHEN Zhenyan and GONG Zhenchao
    , 2008, 35(1): 1556-0.
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    Small-scale and strip Mesozoic sags in the Liaohe Oilfield peripheral basin are strongly divided and close to massifs, so they are mainly proximal and polyenic deposits. Reservoirs in the sags have poor properties and multidirectional, intersected sources which form sand-shale alternating deposits. Low permeability in the reservoirs causes oil and gas to migrate in short distances horizontally and vertically, and be distributed close to or in hydrocarbon kitchens horizontally and close to oil source rocks vertically. The principle of "seeking for oil and gas deep down depressions" was proposed. Since its practice in 2004, good exploration results have been achieved. The next exploration targets in this area are the Wushijiazimiao, Jiaolige and Sanshifangdi subsags in the Lujiabao sag, the Hulihai subsag in the Qianjiadian sag, the Eertu subsag in the Longwantong sag, the Zhanggutai and Qijiazi subsags in the Zhangqiang sag, the central subsag in the Yuanbaoshan sag, and the central subsag in the Naiman sag.
  • WANG Zecheng; ZHENG Hongju; XU Anna and DONG Yue-xia
    , 2008, 35(1): 1557-0.
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    The above-source plays in the Nanpu Sag, including E3d1, Ng and Nm, are the main contribution to the present reserves and production increase in the PetroChina Jidong Oilfield Company. The reservoir-forming mechanism for the above-source plays is studied according to the analysis of structure and reservoirs, the determination of reservoir-forming period and the modeling of reservoir-forming processes. There are two stages of oil infilling: early Nm and late Nm. The key factor for the above-source plays is the oil-source fault along which oil and gas migrate upward under the high residual pressure difference between source rock and reservoirs providing sufficient oil source in forming reservoirs. The hydrocarbon accumulation in the above-source plays is controlled by the oil-source fault and the related structural traps. The conjugate shear belt which has huge oil and gas potential under compression and torsion stresses is an important exploration target.
  • GUAN Shuwei; LI Benliang; HOU Lianhua; HE Dengfa; SHI Xin and ZHANG Yueqian
    , 2008, 35(1): 1558-0.
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    The fold-and-thrust structure in the northwestern margin of the Junggar Basin is composed of the northern monocline belt, the middle syncline belt, the Ke-Wu faulted belt and the frontal slope belt, and is divided into the upper and lower structural layers in vertical. The upper structural layer preceded the lower one in terms of thrust sequence. Inferred from the restoration of unconformities, the motion of thrust faults started in late Triassic, activated in succession in Jurassic, and stopped in Cretaceous. The footwall venture exploration should aim at "cap brim" traps, especially in the triangular region, where the Dazhuluogou tear fault and the Ke-Wu thrust belt intersect and the exploration horizon imbeds moderately, and then aim at the deep anticlinal traps in duplex structures when obtaining the essential data of deep geology and velocity data.
  • YU Yixin; MA Baojun; TANG Liangjie; YANG Wenjing; LEI Ganglin; MA Yujie and WANG Pengwan
    , 2008, 35(1): 1559-0.
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    Salt structures are predominant in the western Kuqa Depression, and the mechanisms of salt flowage and deformation are complex and dominated by various factors during different evolution stages. Based on the mechanical properties of rock salt and overburden in the depression, an elastic-ductile bed model is established using the thin film theory to show the relationship of the rock salt and the overburden. The comparative analysis of the major factors controlling the salt flowage of different stages shows that differential loading was the major factor controlling the salt flowage and structure development in the early stage. Then, buoyancy exerted bigger influences than differential loading when salt pillows grew to a certain extent. Besides, the overburden flexural buckling resulted from compression stress played a greater role in the salt movement than buoyancy. The most important factor driving the salt flow is compression stress, followed by buoyancy and differential loading, in turn.
  • LI Wei; XIE Jun; GAO Xiaohui; ZHANG Longhai and YU Fang
    , 2008, 35(1): 1560-0.
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    The reservoirs discovered in the Turpan depression are mainly distributed in the Middle Jurassic, some distributed in the Upper Jurassic, Cretaceous and Tertiary. The characteristics of the mudstone overpressure are studied to reveal the relationship between reservoir distribution and mudstone overpressure. There are several overpressure mudstone cap-rocks in the depression, of which the most steady and the best one is in the Middle Jurassic Qiketai Formation. The distribution of reservoirs in the Jurassic and above sequences is controlled dominantly by mudstone overpressure. In the regions without mudstone overpressure, reservoirs are often destroyed because of frequent fault activities. Reservoirs have different dependence on the overpressure mudstone sealing. Overpressure mudstone seals oil reservoirs indirectly, while it seals gas reservoirs and gas-cap reservoirs directly. For the areas without rock salt or gypsum in the multi-cycle basins in West China, mudstone overpressure will play an important role in the hydrocarbon accumulation and reservoir preservation.
  • ZHAO Wanyou; WANG Zhensheng; SU Junqing and WANG Zhaohua
    , 2008, 35(1): 1561-0.
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    Chengbei fault-step zone is in condition of pool-forming, and has various traps and excellent petroleum exploration potential. The key pool-forming factors are as follows: enough oil and gas source; effective shallow traps; advantaged reservoir and seal combination; late activity faults linking source and traps of Neogene System, etc. Among the three sets of pool-forming sub-system, the Sha 3 member in the late depositional stage of Minghuazhen Formation has a late pool-forming stage, good conservation conditions, large distribution areas, good reservoir and high content of oil in the Neogene, and huge exploration potential in the Eogene System. The Sha 1 member pool-forming sub-system is characterized by hydrocarbon reservoirs of self-source and self-reservoir, but its oil-bearing area is limited. Prospective target areas are the Zhangdongdong structural, Zhangdong structural and Youyi structural belts in the Eogene System,and the Zhuanghai 12-Zhuanghai 9×3 well areas, Chenghai 4 well areas and the southern Liuguanzhuang structural belt in the Neogene System.
  • MENG Yuanlin; Li Bin; WANG Zhiguo; WANG Yuechuan; NIU Jiayu; YIN Xiulan; LI Jun and XIAO Lihua
    , 2008, 35(1): 1562-0.
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    There exist overpressures in the Paleogene of the central Huanghua Depression, Bohai Bay Basin, and the hydrocarbons of deep zones are dominantly accumulated in secondary pores of the overpressured formations. The diagenetic physical simulating experiments were done at different temperatures and under 25MPa and 55MPa respectively to study the relationships between overpressure and the organic acid generation in mudstones and the dissolution of reservoirs. The residual total organic acid contents in the samples under 25 MPa are lower than those under 55 MPa at the same temperatures, whereas the generated total organic acids under the 25 MPa are higher than those under 55 MPa, suggesting that pressure retards the organic acid generating. The porosity data from different pressure settings also supports the results. The main secondary porosity zone of Well GS48 with overpressure is 580m deeper than that of Well QN2 with no overpressure, overpressures retard the organic acids generation and result in the delay of reservoirs dissolution. The hydrocarbon exploration in deep basins should be focused on the over-pressured formations.
  • GUO Shaobin and WANG Hong-liang
    , 2008, 35(1): 1563-0.
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    According to the detailed analysis of drilling data, together with the interpretation of seismic section, the Mesozoic of Suibin Depression is divided into four second-order sequences and eight third-order sequences. The third-order sequences at the bottom of the second-order sequences develop low-stand systems tracts (LSTs), and the other sequences do not. The analysis result of the balanced section and Milankovitch cycle indicates that the Mesozoic sequences above third-order in the Suibin Depression are mainly controlled by structure, and that the Milankovitch cycle only controlls high frequency sequences (systems tracts). Base on the above analyses, the second-order sequence stratigraphy model of the Mesozoic of Suibin Depression is established. The model is of typical tripartition, the early basin fill (LST), the middle basin expansion (TST) and the late basin abortion (HST).The transgressive systems tracts (TSTs) overlying the LSTs in the second-order sequences may be good seal and source rock, so the LSTs have the potential for oil and gas.
  • 油气田开发
  • Lü Aimin and YAO Jun
    , 2008, 35(1): 1564-0.
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    For the rational development of Block S48, Tahe Oilfield, which is a fractured carbonate reservoir with bottom water, a correlation equation of its perforating level and well density is derived based on the oil and gas fluid flow mechanics and the oilfield performance. The rational well spacing under certain perforating level and the rational open thickness under certain well density can be determined by this equation. The rational perforating level should be less than 50% and at this value the well spacing is largest. The rational open thickness decreases with the increase of water saturation during the development, and the open well sections should thus be closed gradually in oilfield production. Since the rational open thickness will increase and the rational well spacing will decline correspondingly as the ratio between vertical permeability and horizontal permeability increases, unevenly distributed well pattern should be adopted according to the fracture developments in different areas. In the later period of well pattern thickening, the location of new wells and their perforating thickness should be determined by the actual parameters of existing wells.
  • SUN Jianmeng; WANG Kewen and LI Wei
    , 2008, 35(1): 1565-0.
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    In order to understand the research situation of saturation interpretation models, and to offer some basic information for the well logging reservoir evaluation, this paper summarizes saturation interpretation models frequently used throughout the world, discusses the characteristics and development tendency of the saturation interpretation model research, and offers some advice for the future research. Based on theoretical background, the saturation interpretation models are divided into four types: classical Archie formula, saturation interpretation models considering shale effects, saturation interpretation models considering the effects of conductive mineral and multi-porosity, general saturation interpretation models based on the network conduction theory in heterogeneous rock. Except for the classical Archie formula, there are a variety of saturation models in the other types. The saturation interpretation models considering shale effects are subdivided into three kinds based on argillaceous equivalent volume, argillaceous cationic exchange capacity, and effective medium theory.
  • 油气勘探
  • LI Jingming; LIU Fei; WANG Hongyan; ZHOU Wen; LIU Honglin; ZHAO Qun; LI Guizhong and WANG Bo
    , 2008, 35(1): 1566-0.
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    The desorption characteristics of coal beds in China are affected by many factors. The desorption ratio of coalbed gas is about 40%, and mostly less than 70%, and it is affected by gas content and coal bed pressure. Most of the desorption time values are between 0.188 3 to 19.17d, and the time span of high rank coal is the biggest which can reach over 30d. The value has a positive correlation with coal rank. A great number of experimental data shows that temperature, coal dimension and shape, coal rank, ash content, gas content, cleat, sediment environment, and coal style are the main affecting factors of desorption time. According to the numerical simulation result, coal desorption volume affects the single well production, and the single well output has a positive correlation with the desorption. The variation of coal desorption time value can induce the change of output peak value of a single well and its occurring time.
  • DING Anna; LU Shuangfang; FENG Zihui; HUI Rongyao; FANG Wei and WANG Yuewen
    , 2008, 35(1): 1567-0.
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    The geochemical analyses of samples from both east Qaidam Basin and north Songliao Basin are implemented based on examining the influence of the activity of bacteria and archaea on the distribution of main biomarkers in saturated hydrocarbons and on the content of carbazole derivatives, with the aid of microbiological research results. Studies suggest that the regular sterane/17α(H)hopane value, C35αβ homohopane index, oleanane index, BNH/TNH ratio, and the abundance change of C28-C31 alkyl steranes can be used to appraise the activity of bacteria and archaea. In the strongly anaerobic environment from fresh water to saline water, the content of organic nitrogen in gas-generated materials is related to the nitrogen fixation of methanosarcina. Under the methane-producing condition, nitrogen-bearing heterocyclic compounds from protoplasm are degraded by methanogenesis partners. Thus, the contents of carbazole, methyl-carbazole and benzol-carbazole compounds are lower about 1 to 2 order of magnitude in excellent biogas source rocks than in other type samples.
  • LU Guiwu; LI Yingfeng; SONG Hui; YU Yinghui and WANG Chunlei
    , 2008, 35(1): 1568-0.
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    The periodic molecular structure model of solvent-asphaltene system is constructed using molecular mechanical and molecular dynamical methods. The influences of six solvents (Nitrobenzene, Quinoline, Pyridine, 1-methylnaphthalene, Dibromomethane, Benzene) on the aggregate process of asphaltene molecules are investigated at normal temperature and higher temperatures. According to the analyses of structure and energy, the main interaction for the asphaltene aggregate is determined, and the influencing mechanism for the asphaltene stability in different solvents is discussed at 300K and 573K temperatures. It is found that VDW interaction plays an important role in the stability of the asphaltene aggregate. The electrostatic interaction is small compared to the VDW interaction. And the π-π interaction is the leading force for the aggregation of asphaltene molecules. The presence of heteroatom might be the major reason for the asphaltene polymerization. Benzene and nitrobenzene have a prominent inhibiting or disassociating effect on the asphaltene aggregation, and they can be chosen as inhibiting and scavenging agents.
  • ZHANG Jinchuan; TANG Xuan; BIAN Ruikang; XU Bo; XUE Hui; NIE Haikuan and JIANG Shengling
    , 2008, 35(1): 1569-0.
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    Nonassociated gas can be classified as conventional gas accumulation with displacement migration, source-contacting gas accumulation with piston-type migration, and shale gas accumulation with the displacement and piston-type migrations. Nonassociated gas accumulation can be described by using the continuous but universal dynamic equation. The accumulation of conventional trap gas is controlled by buoyancy and capillary pressure, and the accumulation dynamic equilibrium are influenced by the height of continuous gas column and the physical properties of seal rocks. Source-contacting gas accumulation is associated with gas generating intensity of source rocks, physical properties of reservoirs, and accumulation depth, and the accumulation dynamic equilibrium is constrained mainly by the effectiveness of gas generation and the physical properties of tight sand reservoirs. In complicated geological settings of shale gas accumulation, effectiveness of gas generation, physical properties of reservoirs, height of continuous gas column and buried depth are the conditions influencing the accumulation of nonassociated gas.
  • WU Chao; CHEN Mian and JIN Yan
    , 2008, 35(1): 1570-0.
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    Based on the close relationship between seismic and logging information, a real-time prediction model of borehole stability is established using seismic, logging and geological data to control borehole wall sloughing instability. Firstly, seismic attributes are extracted from borehole-side seismic traces of target wells and drilled offset wells respectively. Then mapping models of relationships between seismic attributes and logging data of various formation intervals in drilled wells are constructed using wavelet neural network. Using the seismic attributes of formation under bit and the corresponding mapping model, the acoustic and density logging data of the current undrilled formation can be predicted. On the basis of the prediction results, the mechanical model of borehole stability is employed to calculate pore pressure, collapse pressure and fracture pressure, thus predicting the safe drilling fluid density range. Practical application in Tarim Oilfield shows that real-time operation performance of the model is excellent and the prediction accuracy of parameters is satisfactory.
  • 油气田开发
  • LING Zongfa; WANG Lijuan; HU Yongle and LI Baozhu
    , 2008, 35(1): 1571-0.
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    To optimize well spacing and injection rate in horizontal well flood pattern, formulae of the reasonable injection rate and well spacing are derived under fraction and no-fraction conditions respectively using filtration theory. The formulae take into account the fluid flow in low-permeability and thin reservoirs, and assume that horizontal well injection is rigid water driving. According to these formulae, the influencing factors of pressure loss on the horizontal section are diameter of casing pipe, production rate, and length of horizontal section. For a well with fixed casing diameter and horizontal section length, the influencing factors of pressure loss on horizontal section is only production or injection rate; for a reservoir, the influencing factors of maximal well space are length of horizontal section, oil production rate and water injection rate. The research results are applied in the Hade 4 thin layer sandstone reservoir of Tarim Oilfield. The designed flood pattern decreases injection pressure, augments injection, and keeps field pressure.
  • LI Junshi; HOU Jianfeng; HU Yongle; LI Fanhua and QIN Qiang
    , 2008, 35(1): 1572-0.
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    According to reasonable hypothesis and simplification of fluid flow through fractured horizontal wells in a three-dimensional reservoir, this paper presents a physical model and an unsteady porous flow model. A half analytical coupling method is used to get the bottom pressure and flow rate distribution of the horizontal wells. The flow regime analysis is done for horizontal bottom pressure curves. The fluid flow in the fractured horizontal wells has 4 flow regimes, including radial flow in fractures, double linear flow in fractures and reservoirs, linear flow in reservoirs, and spheroid flow in reservoirs. The flow rate distribution in fractures is affected by flowing time and fracture conductivity, and tends to get more and more uniform as they increase. The pressure curve is influenced by top and bottom reservoir boundaries, the pseudo pressure differential is a constant in an infinite reservoir with closed top and bottom boundaries, and the pseudo pressure differential curve has a declining trend in an infinite reservoir with constant-pressure top and bottom boundaries.
  • SONG Fan; XIAO Chengwen; BIAN Shutao; SU Xiaojun and WANG Huanzeng
    , 2008, 35(1): 1573-0.
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    Recently, low resistivity oil reservoirs of Jurassic, Cretaceous, and Early Tertiary in Lunnan Oilfield have been discovered successively. The statistics for 57 oil and gas layers of 22 oilfields in the Tarim Basin shows that reservoirs of poor physical properties are prone to have low resistivity and those condensate gas reservoirs of moderate fluid density or light oil reservoirs are prone to form low resistivity oil layers. High immovable water saturation is the main reason for the formation of the low resistivity oil layers. The origin analysis of the low resistivity oil reservoirs shows that low angle drape structures with the background of being major reservoirs or paleo-reservoirs have the favorable conditions of forming low resistivity oil layers. The matching of reservoir space and hydrocarbon types is the key reason for part of the oil reservoirs having low resistivity.
  • 石油工程
  • Bill Heins; XIE Xiao and YAN Deng-chao
    , 2008, 35(1): 1574-0.
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    Steam Assisted Gravity Drainage (SAGD) or non-SAGD heavy oil recovery process uses a large amount of high-pressure steam and produces a significant amount of oily wastewater. Conventional water treatment and steam generation process is very complex, producing poor quality water for reuse and low energy efficiency etc. Using evaporation process to replace those conventional treatment processes was first emerging in North Albert, Canada. This eventually resulted in introducing conventional drum boilers to replace once-through steam generators to produce steam. This paper introduces the evaporation technology used to treat heavy oil wastewater and produce high quality boiler feed water. It also provides comparison data between evaporation and conventional processes (warm lime softening and weak acid cation ion exchange) from technical and operational aspects. Evaporation provides an alternate approach to produced water treatment, which is simpler, more cost effective, reliable, and reduces complexity of the steam generation system. Additional steps can be taken to recover all liquid waste streams for reuse in the plant, resulting in zero liquid discharge.
  • 国际交流与合作
  • CHENG Dingsheng; PAN Xiaohua; LEI Zhenyu; WAN Lunkun; DUAN Haigang and LI Zhi
    , 2008, 35(1): 1575-0.
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    China National Oil & Gas Exploration and Development Corporation (CNODC), CNPC, farmed in four blocks in Myanmar in 2001 and 2002. They are situated in central Myanmar with a total area of 3514 km2. Due to the low exploration degree and high exploration risk in these blocks, it is necessary that the synthetic analyses of petroleum geology and resource potential be done as soon as possible. Twelve oil samples are picked up from different blocks and formations and the oil-oil correlation is carried out by biomarker analyses. Based on the oil-oil correlation by biomarker differences in different oils, three oil families in the Salin Basin are identified, and the studied areas are divided into three possible petroleum systems. The biomarker lupanes and bicadinanes have also been detected from all oil samples, suggesting these oils should be sourced from the Late Cretaceous or Tertiary terrestrial source rocks.
  • 学术讨论
  • ZHANG Jinglian
    , 2008, 35(1): 1576-0.
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    This paper discusses the Mr. Wang Lansheng's arguments about the origin of petroleum. It is well known that metal elements and their isotopes can be combined with organic compounds to form coordinating ions or complex compounds, which can be applied to petroleum tracing and isotopic dating. The Fischer-Tropsch reaction can synthesize different kinds of hydrocarbons, including crude oils, under different catalysts, temperatures and pressures. Daqing's exploration shows that abiogenic gas not only is existent, but also can form big gas reservoirs, such as the Xincheng Gas Pool. In the Tarim Basin, the Silurian bitumen whose reserves are 917.8×108 t was generated by inorganic reaction rather than by organic matter. Abiogenic oil and gas were also found in meteorites and in continental scientific drillings. Some other topics related to the origin of petroleum are also discussed. According to the inorganic origin theory of petroleum, some exploration targets are presented in this paper.