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01 June 2007, Volume 28 Issue 3 Previous Issue    Next Issue

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Conditions and Explorative Directions of Marine Giant Oil-Gas Fields of Paleozoic in China KANG Yu-zhu 2007, 28 (3):  263-265.  Abstract ( 209 )   PDF (222KB) ( 554 )   Save The first major breakthrough of marine oil-gas reservoir of Paleozoic discovered from Shacan-2 Well in northern Tarim basin was made since 1984 followed by that a number of large-middle scale fields has been found in Tarim, North China, Yangtze and Junggar blocks. In-depth researches of the conditions for forming large scale oil-gas fields are presented in view of source rocks, reservoir body, multiple reservoir-caprock assemblages, palaeohigh, palaeoslope-controlled oils, multistage hydrocarbon accumulation, multistage charging and sealing condition, etc. and the exploration directions are pointed out. These are of great significance for seeking more domestic large scale oil-gas fields of Paleozoic with very complex geologic structures. References | Related Articles | Metrics

The Important Factor for Petroleum Evaluation in Marine Provinces of South China: Organic Matter Matamorphism AN Zuo-xiang, MA Ji, PANG Qi-wei 2007, 28 (3):  266-268.  Abstract ( 119 )   PDF (579KB) ( 213 )   Save Since the founding of P.R.China, three geologic surveys and prospecting researches on petroleum Resources in marine sedimentary provinces of South China have been made, but the results are unsatisfied. The long-term overlooking of the organic matter metamorphism as one of important factors in hydrocarbon reservoir preservation condition and not taking it into consideration in the petroliferous prospect assessment system would be the major reasons. The study by means of the coal quality and fixed-carbon ratio shows that in Sichuan-Guizhou-Guangxi areas, gas fields could be possibly found in the lean coal or slight coaly metamorphism provinces with fixed-carbon ratio of less than 90%, in which the petroleum preservation conditions of Paleozoic were lost. References | Related Articles | Metrics

New Domains and Strategies for Offshore Oil-Gas Exploration in China ZHU Guang-hui, CAI Dong-sheng, LI Xu-xuan, TAO Wei-xiang, HU Xiao-lin 2007, 28 (3):  269-271.  Abstract ( 115 )   PDF (1155KB) ( 275 )   Save With the improvement of the exploration degree and the increase of the oil and gas demand, the oil and gas corporations in China emphasize on the exploration investment of new domains in order to increase the reserves. In recent years, the new domain exploration has made great progress, and the breakthrough of deep-water and lithological reservoirs has been made in offshore basins. However, the new domains are still insufficient in research and preparation, facing serious challenges. It is suggested that the exploration efforts should be strengthened at present, and the proper exploration strategies and investment combination should also be adopted in order to keep the sustainable development of the offshore exploration. References | Related Articles | Metrics

The Potential and Prospect Areas of Coalbed Gas ReSource in Junggar Basin LIU De-guang, WU Xiao-zhi, ZHAO Zheng-ya, LI Shi-hong, GONG Hong-yan 2007, 28 (3):  272-274.  Abstract ( 112 )   PDF (1002KB) ( 519 )   Save The study of the coalbed macro-and micro-features of Jurassic in Junggar basin shows that although the available resource quantity of it within depth of exploration is limited, there are abundant coalbed gas Resources in this basin. Shanan-Shazhang and Wutongwozi are selected as the preferable areas for coalbed gas prospecting, with target zones of Xishanyao formation and even deeper Badaowan formation (in Shanan-Shazhang area). These areas are in good condition for coalbed gas accumulation and high content of gas. Also, they are suitable for prospecting and development of the gas resource due to the moderate depth and simple subsurface structure and surface condition. References | Related Articles | Metrics

Formation Processes and Advantageous Models for High-Low-Rank Coalbed Methane Reservoirs CHEN Zhen-hong, SONG Yan 2007, 28 (3):  275-278.  Abstract ( 101 )   PDF (628KB) ( 559 )   Save The typical formation processes of high-low rank coalbed methane (CBM) reservoirs are presented based on tectonic evolution extents. The key factors controlling current accumulation and enrichment of CBM reservoirs are discussed. The study shows that the high rank CBM reservoir is of obvious episode for it normally undergoes multiple subsidence, uplift and modification with sufficient CBM and complex forming process; the CBM is not generated till reaching its highest evolution. So its current accumulation and enrichment mainly depend on conservation conditions. The formation process of low rank CBM reservoir is often simple, just undergoing single subsidence, single uplift and gentle modification, and controlled by underwater supply, migration, drainage and detention. According to these understandings, the advantageous model of high rank CBM reservoirs with closed system and the advantageous model of low rank CBM reservoir with basinal margin or gentle slope area are developed. References | Related Articles | Metrics

Hydrocarbon Migration and Accumulation of Delingha Fault Depression in Qaidam Basin GAN Gui-yuan, YAO Xi-hai, CHEN Hai-tao 2007, 28 (3):  279-281.  Abstract ( 154 )   PDF (322KB) ( 397 )   Save By systematic analysis of Decan-1 Well is systematically analyzed integrated with information from the field outcrop reviews and the seismic prospecting, the hydrocarbon and accumulation of Delingha fault depression in Qaidam basin is studied. It is proved that the oil and gas in Decan-1 Well was originated from the underlying Middle-Lower Jurassic or Carboniferous, and the N1 to the upper E3 are the regional cap formation in depth of 3 000~3 860 m, but it is hard to form oil-gas pools in overlying strata due to lack of effective caprocks. Hence, the petroleum exploration targets should be in the underlying Middle-Lower E3 and Jurassic beds. The core analysis from depth of 4 000 m indicates that the sandstone reservoir is of better quality with porosity-developed sandstone, good storage capability and some asphaltic seepage, showing that petroleum migration had ever happened here. The existence of multi-fractural zones in 3 082~3 487 m suggests that the potential reservoir spaces could be shaped in them. The strata of 4 172~4 380 m is a combination of reservoircap formation of Upper Jurassic, within which natural gas could be found in its sandstone. References | Related Articles | Metrics

The Abnormal Pressure and Hydrocarbon Accumulation of Tertiary in Southwestern Qaidam Basin CAO Hai-fang, YAN Lin, XIA Bin, ZHOU Li 2007, 28 (3):  282-285.  Abstract ( 116 )   PDF (1054KB) ( 339 )   Save The analysis of tested pressure and the study of abnormal pressure characteristic in partial prospecting wells indicate that there exist various types of pressures in southwestern Qaidam basin and abnormal overpressure in certain depth. But different structural units have different characteristics in initial horizon, initial depth of abnormal pressure and their section features. According to oil-gas accumulation mechanism under abnormal pressure, the hydrocarbon accumulation phases are classified, and the effects of the abnormal overpressure on reservoir type and distribution are analyzed. The study shows that the mud fracture in overpressure zone and lithologic reservoir should be the target domains for petroleum exploration. References | Related Articles | Metrics

Condition and Explorative Direction of Lithologic Reservoir of Silurian in Northern Slope of Tazhong Uplift YANG Hai-jun, WU Guang-hui, SUN Li-xia, HUANG Guang-jian, HU Tai-ping 2007, 28 (3):  286-288.  Abstract ( 123 )   PDF (444KB) ( 518 )   Save Based on the integral evaluation and composite study of Silurian system in Tazhong uplift, it is indicated that the long-period and stable development of the northern slope setting is favorable for the development of stratigraphic and lithologic traps, and the thin interlayer of sandstone and mudstone in tidal flat sediments is the geologic foundation for forming the lithologic trap. The multistage hydrocarbon accumulation and migration/adjustment create the framework of extensive distribution of hydrocarbons. Hence, the Silurian system in Tazhong uplift possesses the geologic conditions for shaping large-scale and low-abundance lithologic oil reservoirs. The study suggests that exploration of the Silurian must break through the idea of local structure controlling hydrocarbon accumulation. Lithologic reservoirs are the main exploration targets. The updip lithologic pinchout zone is the favorable domain for hydrocarbon accumulation. The facies-varied zone and stratigraphic onlap zone of the Silurian in eastern Tazhong area are the main directions for petroleum prospecting. References | Related Articles | Metrics

The Control of Fractures on Karst in Ordovician Carbonate Reservoirs in Tazhong Area, Tarim Basin LIU Zhong-bao, SUN Hua, YU Bing-song, WANG Zeng-xiang, YANG Sheng-bin 2007, 28 (3):  289-291.  Abstract ( 171 )   PDF (471KB) ( 571 )   Save As controlled by sedimentation, diagenesis, structure and karst, carbonate reservoirs are strongly heterogeneous and it is important for fracture to rebuild carbonate reservoirs. Through observation over cores, dissolution caves with FMI logging, statistics of fractures, correlation analysis of the fractures vs. karstification, it is found that fractures are closely accreted with karstification and the high angle fractures under unconformity surface have a great promotion on the development of weathering crust-type karst, while low angle fractures have perfect correspondence to burial karstification. This affords a new revelation to evaluate and predict karst-fractures-type reservoirs by the characteristics of fractures in different occurrences. References | Related Articles | Metrics

Division and Correlation of Middle-Lower Ordovician in Tazhong Area,Tarim Basin CAI Xi-yao, QIAN Yi-xiong, CHEN Yue, YOU Dong-hua 2007, 28 (3):  292-295.  Abstract ( 196 )   PDF (238KB) ( 557 )   Save According to the palaeontological feature, petrophysical and electric properties from the new wells, with combination of data from thin-section and scanning electron microscope, the Middle-Lower Ordovician in Tazhong aera can be divided into Yijianfang formation (Middle Ordovician),Yingshan formation (Middle-Lower Ordovician) and Penglaiba formation (Lower Ordovician), Yingshan and Penglaiba formations can be subdivided into 4 or 5 members, which are of good comparable behavior in the whole area. There existed an unified carbonate platform in Early-Middle Ordovician among Cardac uplift, Tangutsbas depression and Guchengxu uplift. In Cardac uplift, Yijianfang formation was lack, and Yingshan and even Penglaiba formations were incoordinately eroded, being an angular unconformity with Upper Ordovician or Lower Carboniferous. But in Tangutsbas depression and Buchengxu uplift, Yijianfang formation was existent, being successive deposition with Yingshan formation. References | Related Articles | Metrics

Petroleum Geology of Wuerxun Sag in Hailaer Basin MA Zhong-zhen, PANG Xiong-qi, WEI Jian-she, LI Ming-gang 2007, 28 (3):  296-299.  Abstract ( 122 )   PDF (1135KB) ( 510 )   Save Wuerxun sag is a second-rank structural unit with Lower Cretaceous in Beierhu depression in Harlaer basin, in which the source rocks are mainly distributed in its Nan-1 member, the reservoir rocks in its Nan-2 member and its well sealed regional cap rocks in Da-1 member, shaping a normal sequence's source-reservoir-caprock assemblage. The hydrocarbon accumulation-controlled factors analysis shows that the hydrocarbon distribution in this sag is controlled by effective hydrocarbon-generating center in plane and by major source rocks in vertical; the fan delta and sublacustrine fans around the fault belt are good reservoirs. Bayantala structural belt and Wudong area are the target areas for further exploration. References | Related Articles | Metrics

The Carbonate Reservoir Rocks of Jurassic in Qiangtang Basin XU Jian-hua, LV Shu-xin 2007, 28 (3):  300-303.  Abstract ( 124 )   PDF (207KB) ( 350 )   Save Based on the outcrop data, using such analytical techniques as rock thin section, cast section, SEM, conventional petrophysical property and capillary pressure curve, etc., the detailed studies are made in lithology, porosity-permeability distribution and pore structure. The carbonate reservoir rocks are dominated by granule limestone, including intraclast limestone, oolith limestone and bioclast limestone. The type of reservoir space includes pore (secondary solution pore) and fracture/fissure (structural fracture and solution fissure), with poor microstructure, belonging to a dense reservoir with low porosity and low permeability. The main factors are strong compaction and cementation. The late solution acted as a certain improvement on the reservoir quality. The tectonic action creates the fractures or fissures, increases the porosity/permeability of carbonate rocks and greatly improves the reservoir capacity in Qiangtang basin. References | Related Articles | Metrics

Formation of Deep Gas Pool in Dongpu Sag LI Ji-dong, WU Xiao-ling, LI Su-zhen, XIE Shu-qin 2007, 28 (3):  304-306.  Abstract ( 138 )   PDF (596KB) ( 407 )   Save Dongpu sag is of the superior geological conditions for forming deep gas pools, including two sets of premium source rocks, variety of sand bodies, well developed porosity and thick halite and mudstone as cap rocks. The deep gas of Dongpu sag can be divided into three types such as coal-formed gas, petroliferous gas and combination gas, which have different space distribution for each type. This paper presents the model for deep gas migration and accumulation in Dongpu sag by analyzing the histories of hydrocarbon generation, filling and injection, tectonic evolution and hydrocarbon migration and accumulation, using dynamic prediction method for oil-gas accumulation. References | Related Articles | Metrics

The Sequence Stratigraphic Division and Petroleum Geologic Condition of Lower Paleozoic in Jiyang Depression TAN Jun-min, LI Ming-juan 2007, 28 (3):  307-311.  Abstract ( 146 )   PDF (2350KB) ( 457 )   Save The Lower Paleozoic in Jiyang depression could be divided into two supper sequences (Sequence A and Sequence B) or two big datum-level cycles which were Cambrian Mantou group to Ordovician Yeli-Liangjiashang group and Ordovician Lower Majiagou group to Badou group. They correspond to eight sequences that are made up of transgressive system tract and high system tract for each one. The assembled relations among source-reservoir-cap rocks show that the source rocks in Sequence A are not developed as a whole, but the dolomite of its Liangjiashan group is an important buried hill reservoir rock. The multi-stage karstifications are found in the weathering crust in top of Sequence B, with superior reservoir condition, and can be as major reservoir rock in the buried hill reservoir. The argillaceous limestone and thick limestone of Majiagou group should be as potential source rocks for the reason of higher content of organic matter. The thick dark mudstone beneath the Upper Paleozoic acts as a preferable regional cap formation, forming a good sourcereservoir-cap rock assemblage along with underlying Cambrian and Ordovician systems. These are the favorable conditions for shaping original oil-gas reservoirs in this area. References | Related Articles | Metrics

Impact of Complex Structures on Seismic Wave Dynamics Characteristics in Underlying Strata ZENG Qing-cai, DU Yao-bin, WANG De-fa, YU Gong-ming, LI Chen 2007, 28 (3):  312-314.  Abstract ( 141 )   PDF (775KB) ( 235 )   Save The CRP ray path and amplitude variation characters in underlying strata of complex structure are of significance to the study of continuous seismic information such as the pre-stack inversion and AVO character analysis. In this paper, the ray tracing method is used for the seismic forward modeling, and the neighborhood well migration data are applied for the model design of complex structure. The analysis of the effect of the complex structure on underlying strata's seismic wave dynamics characteristics shows that the CRP from conventional methods for complex structural exploration has an asymmetric property, including CRP from actic region bottom boundary and the lateral reflection energy variation. It is shown that only local zones can reach full seismic coverage, which posts that complex structure has a big impact on underlying zone's reflecting dynamics characters. References | Related Articles | Metrics

The Age-Related Biomarkers Tested by GC-MS-MS Technologies and Their Geological Significances HAN Xia, TIAN Shi-cheng, ZHANG Zhan-wen, WANG Pei-rong, WU Tuo 2007, 28 (3):  315-319.  Abstract ( 180 )   PDF (913KB) ( 351 )   Save By means of GC-MS-MS method, the multiple series of age-related and taxon specific biomarkers are tested in source rocks and oil samples from Liaohe oilfield and Tarim basin, which are hard to be detected by conventional GC-MS method. They are steranes, methylsteranes, Tricyclic and tetracyclic diterpanes, methyl hopanoid alkanes and hexacyclic hopanoid alkanes, etc. High content of norsteranes and Dinosteranes that were found after Mesozoic broadly occurred in Cambrian source rocks in Tarim basin, postulating that the precursors might even exist in the period of Cambrian biologic explosions. These molecular evidences and age-related significance given by GC-MS-MS method have been used for distinguishing the crude oils of Middle-Upper Ordovician from Cambrian in Tarim basin, playing an important role in approach to Tarim oil sources that have disputed for a long time. References | Related Articles | Metrics

Geochemical Characteristic of Crude Oil in Eastern Part of South Slope of Dongying Sag WANG Jian-wei, SONG Shu-jun, LI Xiang-bo, LIU Jin-you, GAO Xia 2007, 28 (3):  320-323.  Abstract ( 115 )   PDF (1034KB) ( 361 )   Save The petroleum exploration indicates the complexity of the oil sources and origins of Palaeogene in eastern part, south slope of Dongying sag. The crude oil is characterized by the multi-source and the far-source in this area. The genetic classification and source identification are based on 61 oil and oil-bearing rock samples from different 45 points. The results show that there are three classes of crude oils in origin. Class-I oil is characterized by low m(Pr)/m(Ph) raito, low maturity and high gammacerane index, reflecting the oil may come from the Es4s source rock; Class-Ⅱoil by high m (Pr)/m (Ph) ratio, high maturity and low gammacerane index, showing it may derive from the Es3x source rock, while Class-Ⅲ oil by relatively high m(Pr)/m(Ph) ratio, relatively low maturity and extremely high gammacerane index, with high content of tricylic terpane and C29-αααsterane as well as little lighter of δ13C value, indicating that there existed a set of source rocks to be recognized here. The study shows that the multi-origin types of crude oil mean that in the ramp of this fault basin, there are multiple oil sources and complex processes of oil-gas migration and accumulation as well as much more oil potentials to be explored in the slope of Dongying sag. References | Related Articles | Metrics

Carbon Isotopic Geochemistry of Crude Oil from Yingjisu Sag in Tarim Basin and Its Implication YUAN Fa-xiang, SUN Yong-ge 2007, 28 (3):  324-326.  Abstract ( 116 )   PDF (332KB) ( 289 )   Save A two-stage mode of stable carbon isotopic profile of n-alkanes from crude oil in the Yingjisu sag of Tarim basin has been revealed, featuring a two-phase hydrocarbon accumulation process to date in this region. The first phase is related to the peak oil generation and accumulation of Lower Ordovician source rocks and exemplified by Well Longkou-1. The second phase is characterized by the highly matured condensate reservoirs exemplified by Well Yingnan-2. The distribution of light hydrocarbons in condensates shows that it is possibly derived from the high evolution stage of kerogen rather than from crude cracking. References | Related Articles | Metrics

Jurassic Sedimentary Environment and Its Significance for Oil-Gas Accumulation in Kashi Depression, Tarim Basin ZENG Chang-min, MA De-min, FENG Xiao-jun, JIN Bin, ZHANG Chun-lian, MA Li-ke, LI Yong 2007, 28 (3):  327-331.  Abstract ( 130 )   PDF (906KB) ( 539 )   Save The analysis of Early-Middle Jurassic structural and lithofacies in Kashi sag shows that the Lower-Middle Jurassic strata developed respectively in two sedimentary systems, namely Kuzigongsu-Keziletao strike-slipping pull-apart faulted-depression and piedmont faulted-depression. Both of the sedimentary systems resulted in the different features of lithology, lithofacies, sedimentary thickness and distribution. The system of strike-slipping pull-apart faulted-depression of great thickness of Jurassic is controlled by the Talaso-Ferghana fault, with high-quality source rocks made up of coal-bearing strata and deep-semideep lake mudstone. The system of piedmont faulted-depression with relative thinner thickness of Jurassic possesses good source rocks formed by locally distributed coalmeasure strata in south Tianshan mountain and west Kunlun mountain. The oil and gas derived from the Lower-Middle Jurassic source rocks reach the key moments for hydrocarbon accumulation at end of Paleogene and Pliocene, respectively. It is concluded that the petroleum exploration in view of the Jurassic petroleum system should focus on the structural positions where the later structural transformation is relatively weak, or on the secondary oil-gas accumulation. References | Related Articles | Metrics

Fluid Inclusion and Hydrocarbon Accumulation in Longweihu Area of North Qiangtang Basin YANG Ping, JIA Bao-jiang, LIU Jian-qing, CHEN Yu-lu, PENG Bo 2007, 28 (3):  332-336.  Abstract ( 147 )   PDF (707KB) ( 390 )   Save The occurrence and homogenization temperature of fluid inclusion as well as the fluorescent indicator of organic inclusion from Xiali formation (Middle Jurassic) and Suowa formation (Upper Jurassic) in Longwei area of north Qiangtang basin are analyzed, indicating that the inclusion in this area is of multiple types with braded and banded distribution. The homogeneous temperature is of multiple peak values. The organic inclusion is of characters of blue-white and yellow-green fluorescence. It is believed by combination of the source rock's organic matter evolution and oil source studies that there existed two large-scale processes of hydrocarbon generation, migration and accumulation in late stage of Late Jurassic to early stage of Early Cretaceous and Kangtuo stage of Miocene, respectively. References | Related Articles | Metrics

Effect of Capillary Pressure in Deformable Media on Phase Behavior of Condensate Gas Reservoir YANG Xiao-song, SUN Lei, SUN Liang-tian, LIU Chuan-xi, WANG Wei-hong 2007, 28 (3):  337-340.  Abstract ( 119 )   PDF (465KB) ( 303 )   Save In the process of exploitation of low permeability condensate gas reservoir, the reservoir deformation will occur with the formation pressure decline; the average pore radius will decrease with the effective stress increase, and the capillary pressure effect will change with the pore radius variation. This paper quantitatively analyzes effect of the reservoir deformation on the average pore radius, develops the phase equilibrium mathematical model considering the effects of both the reservoir deformation and the capillary pressure, and then simulates the dew point pressure and phase behavior of constant composition expansion in a condensate gas reservoir. It is concluded that the effect of capillary pressure on phase behavior in distortional media is greater than that in porous media without distortion; the effects of capillary pressure on liquid phase pressure, retrograde condensed liquid saturation and liquid mole fraction in distortional media should be considered, especially, the effect capillary pressure on liquid phase pressure is prominent and should be considered. This paper also discusses the mechanism of the effect of capillary pressure on gas condensate phase equilibrium process, based on the analysis of the phase behavior and the composition. References | Related Articles | Metrics

A Probe to REV Theorem for Reservoir Upscaling QI Da-sheng, PING Rui 2007, 28 (3):  341-343.  Abstract ( 169 )   PDF (714KB) ( 251 )   Save Lasseter et al. (1986) proposed that scale-up of prtrophysical property should be done from the scale of a representative elementary volume (REV), a volume for which the measured property does not change with an increase in scale over a given limit of scale. The notion of REV has been a controversial concept because its definition is not clear-cut, and it didn't address how to obtain it in real reservoir system. There has even been some argument as to whether REV really exists. This paper, based on the REV concept, proposes the new idea of a REVG (Representative Elemental Volume Grid). The REVG is applied to best describe the heterogeneity of an original reservoir model for a given scale. Mathematically, in REVG system, the variance of properties will be smallest within each grid, and biggest between grids. REVG is the physical target for upscaling in reservoir simulation. References | Related Articles | Metrics

The Variation of Water Cut in Fractured-Vuggy Reservoir with Bottom Water LV Ai-min, YAO Jun 2007, 28 (3):  344-347.  Abstract ( 149 )   PDF (619KB) ( 347 )   Save The fractured-vuggy reservoir in Tahe oilfield is characterized by strong heterogeneity. This paper presents a geologic model for reservoirs with varied permeability in Tahe oilfield, including the water fractional flow equation for such a reservoir after partial perforation derived by oil-gas flow theory, and analyzes the impacting factors on the fractional flow curves. The study shows that the derived equation can be used to precisely describe the water cut variations under the different reservoir conditions and the different producing pressure differentials. The proposed theory could be as a guide for production performance analysis and prediction of other fractured-vuggy reservoirs with bottom water. References | Related Articles | Metrics

Method for Estimation of Gas Well Risk Productivity LAI Feng-peng, LI Zhi-ping, CEN Fang 2007, 28 (3):  348-349.  Abstract ( 133 )   PDF (212KB) ( 291 )   Save Gas well productivity estimation is an important method for determination of open flow potential and working system, prediction of production performance and study of related gas reservoir engineering. Using its probability statistical approach, this paper analyzes the uncertainty distribution of net pay thickness and permeability in the reservoir, researches the impact of geologic parameter uncertainty on gas well binomial productivity equation. Case study shows that considering the geologic parameter uncertainty allows the gas well productivity estimation to be more precise, thus decreasing the possible risks in gas pool development. References | Related Articles | Metrics

Predrilling Prediction of Formation Pressure in Shengke-1 Well, Dongying Sag ZHANG Jian-ning 2007, 28 (3):  350-352.  Abstract ( 122 )   PDF (534KB) ( 466 )   Save Shengke-1 Well is a key well for scientific probe of Sinopec, and its proper implementation or not is related to the understanding of deep reservoirs and prospecting courses in Dongying sag. This well is characterized by deep drilling horizon and varied formation lithology, so its predrilling prediction of abnormal pressure is the most significant. This paper presents the conceptual model for the formation pressure in this area based on the seismic-geology researched results. By analysis of the seismic velocity vs. the formation pressure, the seismic velocity is effectively picked up, and overlying formaiton pressure is properly estimated. The predicted result is well comparable to the testing result. References | Related Articles | Metrics

Using Reassemble Interval Acoustic Transit Time to Predict Formation Pressure SHEN Wen-long, PAN Ren-fang, LIU Peng-bo 2007, 28 (3):  353-354.  Abstract ( 106 )   PDF (247KB) ( 269 )   Save The normalization of logs in the same pressure area is made with the reassemble interval acoustic transit time logs from several wells. Some given formation pressures from partial wells are used to calculate the coefficients in Fillippone's formula and well pressures in studied area, and the planned well pressure is calculated by range weighted method. The proposed method for pressure calculation has been compiled into interactive software by using VC program. The pressure prediction of planned well in BS35 area is conducted, indicating that the software are quite helpful to the prediction of formation pressure in the area. References | Related Articles | Metrics

Logging Sequence Stratigraphic Division Based on Wavelet Time-Frequency Analysis CHEN Gang-hua, YU Jie, ZHANG Xiao-zhen 2007, 28 (3):  355-358.  Abstract ( 187 )   PDF (1806KB) ( 690 )   Save This paper introduces the basic principle and procedure of wavelet time-frequence analysis and discusses the geologic basis of sequence stratigraphic division with wavelet analysis. By analyzing the ideal model of sequence stratigraphy, the characteristics of sequence interface on the time-frequency energy chart and wavelet coefficient plot are summarized. Besides, with the wavelet transform of logging signals and selected proper scale, the sequences of different levels are classified, which provides a quantitative division method for sequence stratigraphic analysis, especially for high-resolution sequence stratigraphic analysis. References | Related Articles | Metrics

Application of Diplog to Microfacies Division of Donghe Sandstone JIAO Cui-hua, WANG Hai-geng, LIU Tai-xun, LIU Xiao-bing, CHANG Lun-jie, NIU Yu-jie 2007, 28 (3):  359-362.  Abstract ( 114 )   PDF (905KB) ( 360 )   Save The appropriate processing parameters of high resolution diplog are adjusted and selected by analyzing available core data. The accuracy of the processing result is fully improved for satisfying the need of fine interpretation of sedimentary structures. Based on the explained conclusion of sedimentary structures, the microfacies models are set up for detailed division of the microfacies. By this method the high resolution of diplog is fully exerted, with highly interpreting accuracy and good result, taking Donghe sandstone of HD4 oilfield in Tarim basin as an example. References | Related Articles | Metrics

Multiple Attenuation by Hyperbolic Radon Transform WANG Wei-hong, CUI Bao-wen 2007, 28 (3):  363-365.  Abstract ( 159 )   PDF (763KB) ( 434 )   Save Multiple is a coherent noise and exists in most seismic data. The residual moveout of multiples of common midpoint (CMP) following partial dynamic correction is more close to hyperbola. This paper presents the principle of multiple attenuation by time invariant hyperbolic Radon transform (TIHRT) in frequency-space domain and the TIHRT formula and the discrete sampling algorithm. The TIHRT approach is equivalent to parabolic Radon transform (PRT) in terms of computational efficiency because of the decoupling for any temporal frequency, but it is more accurate in separating multiples from primary sections than PRT. The multiple attenuation of horizontal layer media shows that TIPRT approach can attenuate multiples effectively in prestack of seismic data. The multiple attenuation of complex SMAART model indicates the validity and practicability of TIHRT approach. References | Related Articles | Metrics

Application of Seismic-Stratigraphic Method to Eroded Thickness Calculation of Superposition Basin—An example of Ackule swell in Tarim basin ZHANG Xiao-bing, ZHANG Shao-nan, ZHAO Xi-kui, HE Jian-jun, LI Kun, DAI Han-song, CHEN Yang 2007, 28 (3):  366-368.  Abstract ( 129 )   PDF (429KB) ( 286 )   Save Denudation is ubiquitous in superposition basin, and it is important for sedimentary basin study in buried history, tectonic evolution history and thermal history to choose the most proper method for calculation of resuming eroded thickness. Considering the localization of each method available, this paper presents the seismic-stratigraphic approach to do it and better results can be gained. The case study from application of this approach to the eroded thickness calculation of Middle-Upper Ordovician in Ackule swell in Tarim basin shows that its eroded thickness should be about 0~610 m. References | Related Articles | Metrics

Application of Seismic Attributes Analysis to Gas Reservoir Prediction WANG Li-tian, WANG Zhi-zhang, QIN Zhi-jun, ZHENG Jun-mao, QUAN Qin-fei 2007, 28 (3):  369-371.  Abstract ( 113 )   PDF (619KB) ( 330 )   Save The Shanxi sand layer of Permian in Ordos basin is a lithologic gas pool with strong heterogeneity and characterized by few well, big well spacing and difficult prediction of reservoir quality in its early stage of development. Through the seismic attributes analysis, combined with drilling/well data, the relationship between the reservoir parameters and the seismic attribute parameters is set up. By correction of the attribute inversion data from using the drilling/well data, the reliability of reservoir characterization in non-well area can be improved. The geologic statistical analysis shows that available coal-bed correction factor could be applied to more properly get back the sandstone sensitivity to the root-mean-square amplitude attribute. According to fitting relation between the adjusted root-mean-square amplitude attribute characteristic and the sandstone thickness, the plane distribution prediction and description of the reservoir can be directly conducted for the purpose of providing references for the sedimentary facies divition in this studied area. References | Related Articles | Metrics

Application of Boron-Neutron Life Logging—An example of Xianhezhuang field ZHAO Wei, WANG Hai-wen, LIU Yan-mei, CHEN Shi, TAN Guang-ming 2007, 28 (3):  372-374.  Abstract ( 157 )   PDF (230KB) ( 430 )   Save Xianhezhuang field of Shengli oilfield, which is composed of several small complicated fault blocks, has been developed for over 30 years. It is characterized by obvious interlayer contradictions, high water cut in most of the blocks and severe water out behavior. Boron-Neutron Life Logging (BNLL) is an important radioactive logging technology developed in recent years with peculiar advantages compared with other logging technologies. It is especially applied to the reservoir production with high water cut. The study presents this technology and elaborates the application of BNLL to Xianhezhuang field, taking several typical wells as examples. This study can be as a guide or reference for application in other similar oil fields. References | Related Articles | Metrics

Identification and Evaluation Technologies of Lithologic Trap of Triassic in Tahe Oilfield SHI Yu, LI Zong-jie 2007, 28 (3):  375-378.  Abstract ( 162 )   PDF (698KB) ( 459 )   Save The great breakthrough has been made in Tahe oilfield in recent years for Triassic lithologic reservoir exploration. The complex trap of upper oil measure in Akeyasu-2 well and the lithologic trap of channel sand body of middle oil measure in southern Tahe oilfield were found, on which Well AT2 and Well YT2, etc. were drilled and commercial oil-gas flows were gained, revealing a good prospect for Triassic lithologic reservoir exploration. This paper presents the identification and evaluation of the Triassic lithologic traps in Tahe oilfield based on the combination technologies such as sequence stratigraphy, sedimentary microfacies study, petrophysical properties, forward modeling, seismic attribute, waveform analysis, 3D visual seismic interpretation, seismic inversion, sand thickness prediction and oil-gas detection, etc. References | Related Articles | Metrics

A Review of Indicators of Thermal Evolution of Source Rocks LI Xin, SHANG Hong-qun, LIi Ji-hong, CHAI Xian-ping, DING Lei, LI Jing-bo 2007, 28 (3):  379-384.  Abstract ( 144 )   PDF (290KB) ( 450 )   Save The review of available indicators of all organic matters in source rocks is based on collecting literatures published at home and abroad, and their advantages and disadvantages as well as the problems existed in practical application are listed. The study shows that a number of indicators should be applied for appraisal of the extent of thermal evolution of organic matters, thus establishing the relationship among the indicators and the vitrinite reflectance in order to properly confirm the extent of thermal evolution. References | Related Articles | Metrics

A Discussion about A New Model for Forecasting Production of Oil and Gas Fields XU Yi, DU Ying 2007, 28 (3):  385-386.  Abstract ( 152 )   PDF (63KB) ( 264 )   Save Production Prediction is one of key problems for reservoir engineering research, and an easy, practical and reliable method for it becomes the seeking target. The Wang-Li's model for production forecast was proposed in paper A New Model for Forecasting Production of Oil and Gas Fields and successively introduced in his treatise. However, this study shows that it can not be established for errors in mathematic principle existed in this model, hence the given case study results are incredible. This paper presents some opinions for them for the purpose of correct development of such production forecast researches by further attentions and discussions. References | Related Articles | Metrics

Structures and Hydrocarbon Accumulation in Fula Sag of Muglad Basin in Central Africa WANG Wang-quan, DOU Li-rong, FAN Tai-liang, LI Zhi, ZHANG Zhan-min 2007, 28 (3):  387-390.  Abstract ( 153 )   PDF (1622KB) ( 446 )   Save Fula sag is located in northwestern Muglad basin of Sudan Republic in Central Africa. The rift sag dominated by Mesozoic deposits was formed under the setting of shear stress field in Central African shear belt. Its fault activity can be divided into three phases, namely Early Cretaceous, Late Cretaceous and Paleogene, which form two groups of faults in trends of N-S and NW-SE. The frame of Fula structure is controlled by N-S fault and the growth of second-rank structural belt within this sag by NW-SE fault. It is indicated from the structural controlling effects in Fula sag on its oil-gas reservoirs that the structural trans-zone could be as the hydrocarbon enrichment zone, the multi-cycle structural subsidence may shape the favorable reservoir-caprock assembages and the structural slope could be the favorable area of hydrocarbon accumulation. References | Related Articles | Metrics