Xinjiang Petroleum Geology

Characteristics and Significance of Soil Oil-Gas Geochemistry in Ejina Qi Region

LU Jin-cai, WEI Xian-yang, LI Yu-hong, WEI Jian-she

2009, 30 (1): 6-8.

Abstract ( 127 )

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The geochemical research of soil hydrocarbon geochemical test profile in Ejina Qi region shows that the geochemical indices of acid hydrocarbon display higher hydrocarbon background value and stronger hydrocarbon anomaly, being characterized by heavier methane carbon isotope and bigger drying coefficient. The Carboniferous-Permian distribution and structures control the abundance changes of hydrocarbon indices on the profile. The background values of methane and heavy hydrocarbon are higher in the deep buried area of Carboniferous-Permian, and also the higher anomaly section corresponds well to the local structural highs of Carboniferous-Permian. It shows that the anomaly of soil acid hydrocarbon reflects the information of oil and gas accumulation related to Palaeozoic hydrocarbon source rocks.

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Establishment of Statistical Model for Oil Migration and Accumulation Coefficients of Rift Basins in East China

ZHOU Zong-ying

2009, 30 (1): 9-12.

Abstract ( 124 )

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According to the statistical data of oil migration and accumulation coefficients and related geological parameters in fifteen standard areas of rift basins in East China, the correlation analysis of various geological factors which affect oil migration and accumulation coefficients are conducted to determine their main controlling factors. The study shows that oil migration and accumulation coefficients are closely related with five kinds of geologic factors such as source rock generation hydrocarbon intensity, reservoir porosity, reservoir permeability, trap area coefficient and source rock-reservoir-cap rock assemblage number. The multi-element regression approach is used to establish the statistical model between oil migration and accumulation coefficients and main controlling geological factors of rift basins in East China and the mathematic model for forecast of the oil migration and accumulation coefficients, so as to make it more reasonable and more objective for determination of oil migration and accumulation coefficients, thus enhancing the reliability and comparability of hydrocarbon resources appraisal results.

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Tectonic Evolution and Hydrocarbon Potential in Heshituoluogai Basin in Northern Margin of Xinjiang

2009, 30 (1): 13-16.

Abstract ( 142 )

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According to the comparison and correction between latest and old seismic data, this paper presents the whole structural interpretation and evolution of Heshituoluogai basin using basin analysis theory, basin-mountain coupling idea and balanced cross section technique. it is concluded that: 1) Heshituoluogai basin originated from the collision and dip offset among Siberia plate, Kazakhstan micro-plate and Junggar micro-plate is a secondary compresso-shear basin situated on the hanging wall of major thrust belt; 2) the evolution of Heshituoluogai basin is subject to Junggar terrain, the double tectonic activities of its basement should be earlier than Late Triassic before which it was connected with Junggar basin as a boundary of it, and 3) the basin cover development can be divided into 4 stages: initial development stage (T 3--J 1 b), quick deposition stage (J 1 s-J 2 t), whole subsidence stage (K) and boundary faulting revival stage (E-Q), of which Jurassic is the main basin-formed period associated with largest structural deformation.

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The Buried Hill Structure and Oil-Gas Accumulation of Pre-Mesozoic in Yakela Fault Bulge, Tarim Basin

DAI Han-song, ZHAO Xi-kui, LIU Shu-gen, SUN Wei, LI Kun, YU Teng-fei, LIU Qing-song

2009, 30 (1): 17-20.

Abstract ( 184 )

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The development of buried hill of pre-Mesozoic in Yakela fault bulge was controlled mainly by Luntai and Yanan faults. The buried hill was formed in middle-late episode of Caledonian orogeny and lifted during Hercynian-Indosinian. Till the Early Cretaceous (mudstone deposit) in Yanshan movement, the buried hill-drape structure was formed completely. The multiple tectonic movements allowed shaping various buried-hill reservoirs here. The Sinian-Ordovician carbonate reservoir in it had undergone weathering and eluviation, karst process was well developed and most suitable for being as the reservoir rock. The studied area located between Kuche and Manjiaer depressions is the directing area for the long-term oil and gas migration. The unconformity and fracture system provided available passages for petroleum migration. However, the intense development of faults and the huge "scuttle" at the top of the buried hill prevent from the hydrocarbon accumulating in large scale. The study shows that the carbonate buried hill in northern Yakela structure belt (Sc2 Well) is good for re-exploration. Meanwhile, the carbonate buried hill in west section of Yakela fault bulge (Yongfengzhuang area) can be considered as the selective area for future exploration.

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Hydrocarbon Generative Potentials of Middle and Lower Jurassic Source Rocks in Northern Margin of Qaidam Basin

CAO Jian, BIAN Li-zeng, LIU Yun-tian, HU Kai, YANG Shao-yong, WANG Li-qun, CHENYan, SUN Ping-an

2009, 30 (1): 21-24.

Abstract ( 170 )

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The Middle and Lower Jurassic coal-bearing mudstone source rocks occur widely in the northern margin of Qaidam basin. The depositional area in the Middle Jurassic is larger than that in the Lower Jurassic, with a relatively deeper water depth. This indicates that the lake boundary of the Middle Jurassic is wider. Also, the Middle Jurassic source rock has a higher abundance of algae and a lower abundance of cutinite than the Lower Jurassic source rock, showing that the Middle Jurassic source rock is better than the Lower Jurassic one in organic matter type. However, the distribution of present-day residual source rock and the total organic carbon abundance indicate that the hydrocarbon generative potential of the Lower Jurassic source rock is better than that of the Middle Jurassic one. Because the Lower Jurassic source rock has entered into highly maturated evolution stage (R _o >2.0%), the Middle Jurassic one is dominated by differential thermal evolution in different structural elements. Therefore, both the Lower and Middle Jurassic source rocks are all in good hydrocarbon generative potentials. This implies that not only the Lower Jurassic source rock, but also the Middle Jurassic ones should be equally placed enough importance for petroleum geological research and exploration in the future.

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Submarine Fan of Steep Slope Belt and Its Prospect for Petroleum Exploration in Shida Sag, Jiuxi Depression

WANG Bin-ting, XIAO Rong-ge, GOU Ying-chun, LIU Cai-yan, TIAN Duo-wen

2009, 30 (1): 25-28.

Abstract ( 125 )

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The Shida sag in Jiuxi depression is a Mesozoic-Cenozoic halfgraben-like basin with faulting in east and overlap in west. In the steep slope belt of Shida Sag, there deposited some submarine fan sandbodies. The sandbodies often sinked into the hemi/deep lacustrine dark mudstone and featured both source and reservoir in them. So, the hydrocarbon accumulation conditions are superior with great potentials for exploration.

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Structural Transform Zone and Its Control of Mesozoic Deposits in Northwestern Margin of Junggar Basin

QI Li-qi, BAO Zhi-dong, XIAN Ben-zhong, HUANG Zheng

2009, 30 (1): 29-32.

Abstract ( 137 )

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The foreland thrust zone in northwestern margin of Junggar basin could be divided into three fault zones: Hongshanzui-Chepaizi fault zone in the southwest, Karamay-Baikouquan fault zone in the central part and Wuerhe-Xiazijie fault zone in the northeast. There are two transform zones between neighboring fault zones which have the function of adjusting displacement and transferring deformation. The effects of the transform zones on Mesozoic sediments assume that compared with major fault zones, the sedimentary types developed in the transform zones are more abundant, characterized by more coarse sand grains, larger single-layer thickness, stable lateral distribution and far prograding distance. Hence, the sand bodies tend to enrichment along transfer slopes and transform faults, which could form large scale premium reservoirs.

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Sedimentary Characteristics of Upper Cambrian Dolomite in Eastern Tarim Basin

MA Feng, GU Jia-yu, XU Huai-xian, WU Guang-hui, LI Hong-hui, SHAO Long-yi, ZHU Chang-jian, LIU Yong-fu

2009, 30 (1): 33-37.

Abstract ( 117 )

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By means of the core observation and thin section analysis, the dolomite of Cambrian in eastern Tarim basin is dominated by secondary dolomite which is divided into replacement dolomite and cemented dolomite. The development area of the dolomite is the Upper Cambrian Tuershaketage formation and the distribution area is in the east and west tectonic zones of Tarim basin. Geochemical analysis indicates that three dolomitization environments exist including extrasalinity, bury and hydrothermal fluid, and three dolomitization models are revealed including penetration reflux dolomitization, burial dolomitization and hydrothermal fluid dolomitization. The principal control factors for the high quality dolomite reservoir are carbonate sedimentary facies zones and dolomite genetic superimposed models. The seismic facies and the sedimentary facies analyses indicate that the facies of the west of eastern Tarim basin is carbonate platform margin-platform margin slope, the middle is deep-sea basin and the east is middle ramp-external ramp. The thickness of the dolomites in the west carbonate platform margin and the east middle ramp is big. The dolomite with high reservoir quality which is mainly formed by penetration reflux dolomitization superimposed with the burial dolomitization or hydrothermal fluid dolomitization.

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Stratigraphic Classification and Correlation of Cambrian in Bachu Uplift, Tarim Basin

CAI Xi-yao, MAO Shu-hua, QIAN Yi-xiong, CHEN Yue, YOU Dong-hua

2009, 30 (1): 38-42.

Abstract ( 161 )

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The Cambrian rocks commonly occured in the wells of Buchu uplift in Tarim basin could be divided into three series and seven members. They are clastic member, dolomite member and gypsum-bearing dolomite member in the lower series; subsalt carbonatite member, gypsum-salt member and gypsum-bearing dolomite member in the middle series, and pure dolomite member in the upper series, based on their obviously different electrical properties. The abundance fossils of small shell and algae found in the clastic member are discussed in space-time distribution in detail, and the age of the strata with small shell is determined as the early of Early Cambrian in wells of Bachu uplift. The outcrop section correlation shows that the clastic member and Yurtus formation belong to the relation of the same age but different facies. The subsalt carbonatite member corresponds to Shaylik formation, which can be considered as marker bed for formation correlation in this area. In addition, according to seismic sequence stratigraphy, the Cambrian strata can be divided into three super-sequences which correspond to three series; in terms of drilling sequence stratigraphy, it can be two and half super-sequences and five sequences. The classification and the correlation of the Cambrian strata in this area establish a stable stratigraphic foundation for further studies related to Bachu uplift.

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Diagenesis of Toutunhe Formation and Its Effect on Reservoir in Niuquanhu Area,Santanghu Oilfield

ZHU Yong-xian, SUN Wei, YU Feng

2009, 30 (1): 43-46.

Abstract ( 121 )

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The Toutunhe reservoir in Niuquanhu area of Santanghu oilfield is mainly composed of lithic sandstone, with an average porosity of 17.4% and average permeability of 13.1×10 ^-3 μm 2 . Its pore types include intergranular pore, intergranular dissolved pore, feldspar dissolved pore, a few cutting dissolved pore and few carbonate dissolved pore and matrix dissolved pore. The diagenesis appeared in the studied area is composed of compaction, cementation, metasomatism and dissolution. The target horizons are found in the late period of early diagenetic stage to the early period of late diagenetic stage. Differences of sedimentary facies, clastic constituents and burial conditions result in the difference of diagenesis in different areas. The cementation is the main reason for low permeability reservoir, followed by mechanical compaction.

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Characteristics of Igneous Rocks of Upper Sinian Profile in Xiaoerbulake of Akesu, Xinjiang

REN Kang-xu, ZHENG Yan, XIA Zhi-gang, YANG Hong-fei, HUANG Jin-hua, TIAN Xue-wen

2009, 30 (1): 47-48.

Abstract ( 130 )

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A suit of basic igneous rocks with accumulating thickness over 100 m developed in the Upper Sinian profile in Xiaoerbulake of Akesu, northwestern margin of Tarim basin. Nowadays, the lithofacies and forming age of them are still controversial. Based on field investigation, identification under microscope and K-Ar isotopic dating, it is confirmed they are a suit of diabases intruded along the bedding and have a K-Ar age of 452.56×10 ⁶ a±17.53×10 ⁶ a. The emplacement age corresponds to the Middle-Late Ordovician.

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Using Seismic Methods for Study of Volcanic Reservoir of Carboniferous in Dixi Area, Junggar Basin

WANG Ren-chong, XU Huai-min, SHAO Yu, YANG Di-sheng

2009, 30 (1): 49-52.

Abstract ( 122 )

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The reservoir characteristics of Carboniferous volcanic rocks in Dixi area of Junggar basin are analyzed from lithology, electrical property, lithofacies, pore types and reservoir physical property by core, thin section, conventional log and FMI imaging technique, including explorative methods of seismic facies and patterns of lithofacies characteristics for volcanic rocks as well as the pore volume type and affecting factors of the volcanic reservoir. The study shows that the volcanic reservoir rocks compose mainly of acidic rocks and volcanoclastic rocks, with pore types of secondary pores and fissures, vesicular and microfissure reservoir spaces. The main affecting factors to reservoir physical property are lithology, lithofacies, eruptive environment and late-stage erosion, eluviation and fault reconstruction.

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Effects of Triassic Yanchang Slope Break on Lithologic Reservior in Ordos Basin

LI Shu-tong, WANG Duo-yun, TAO Hui-fei, WANG Bin, QIAO Hua-wei, GUO Yong-kang, NAN Bei-jie

2009, 30 (1): 53-56.

Abstract ( 132 )

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The study on the sequence stratigraphy of Yanchang formation of Triassic in Ordos basin shows that there exist sedimentary slope break in margin of ramp belt of the basin. The slope break assumes NW-SE trending distribution. The slope break in the north is narrow and steep, toward the east, it becomes broad and gentle. This paper discusses the effects of the sedimentary slope break on the lithologic reservoir in Ordos basin in three aspects: 1)the control of the sand combination type, distribution and physical properties of the reservoir; 2)the control of the spatial distribution of the blocking stratum-flooding stratum, and 3)the control of the oil-gas migration directions and gathering spaces.

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Sequence Stratigraphy and Non-Structural Reservoir of Upper Part of the Third Member of Shahejie Formation in Dawangzhuang Area

ZHANG Da-zhi, JI You-liang, HAN Chun-yuan, CHU Li-lan

2009, 30 (1): 57-60.

Abstract ( 114 )

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The upper part of the third member of Shahejie formation in Dawangzhuang area in Raoyang sag is a third-order sequence and can be divided into the low stand system tract, the transgressive system tract and the high stand system tract. The low stand system tract is composed of two parasequence sets. Both the transgressive system tract and the high stand system tract are composed of one parasequence set, individually. Through the research of sedimentary microfacies and sandbody distribution of parasequence sets of the low stand system tract, it is found that there are three delta depositional systems in this period. The most favorable sandstone body is the subaqueous distributary channel and sheet bar of the delta front subfacies. According to the structural characteristics and sandbody distribution relationship, the future exploration targets non-structural reservoir in Dawangzhuang area is proposed.

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Satellite Gravity Anomaly Characters of Western China

JING Xiang-hui, CHENG Shun-you, XU Xiao-qiang, WANG Xiao-duo, QU Yan-wei, LU Xiao-fang

2009, 30 (1): 61-64.

Abstract ( 142 )

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Based on gravity field theory and the newest grace gravity model (GGM02C), the satellite gravity anomalies and characteristics in western China are presented, showing that the western China includes Xinjiang anomalous area and Qinghai-Tibet anomalous area. This paper focuses on the gravitational low belt in Tarim basin and the gravitational high and low belts in Tianshan Mountain. It is suggested that Tarim basin can be divided into two different anomaly areas by north latitude 40°, implying there exist different basement structures in southern and northern Tarim basin. Finally, it is concluded that there exist SN-strike structures in Tarim on the basis of the satellite gravity anomaly, and their dynamic sources are discussed.

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Origin of Formation Water of Upper Paleozoic in Hangjinqi Area in Ordos Basin

WANG Jian-hui, LI Zhong-dong, GUO Min, ZHANG Yue-hua

2009, 30 (1): 65-67.

Abstract ( 147 )

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The total salinity of formation water of Upper Paleozoic in Hangjinqi area in northern Ordos basin ranges from 2 333.55 mg/L to 89 445 mg/L, averaging 47 565.81 mg/L. It belongs to the category of brine water and bittern, with pH value of 4.37~7.3 and mild acid property. The type of formation water is of CaCl2 one. The geothermal gradient in Boerjianghaizi fault belt is the highest, in the south part of it is the next place, and in the north part is the lowest. The formation water salinity, pH value and geothermal gradient near the belt are abnormal due to mixing process according to this study. The interaction between the fluids and the rocks assumes the process of albitization in plagioclase.

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Sedimentary Facies of Triassic in Hong-Che Area in Junggar Basin

WANG Ya-ning, ZHANG Shang-feng, ZHAO Wei-jun, LIANG Ze-liang

2009, 30 (1): 68-72.

Abstract ( 168 )

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The Triassic in Hongshanzui-Chepaizi area is one of the important petroleum enrichment zones in northwestern margin of Junggar basin. The favorable exploration play assessment is primarily based on the studies of the sedimentary facies of the Triassic. This study identifies multiple sedimentary facies types in this area through core description and analysis, integrated with the log information and seismic data, including alluvial fan, braided river, delta, lake, etc. The braided river deposit in Lower Karamay formation in Hongshanzui area is the favorable facies belt for lithologic reservoir exploration.

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Fault System and Oil-Gas Accumulation in Yaha Structural Belt of Tabei Uplift

CUI Hai-feng, ZHENG Duo-ming, DONG Xue-hua, ZHANG Nian-chun

2009, 30 (1): 73-76.

Abstract ( 163 )

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The detailed interpretation of 3D seismic data of Yaha structural belt shows that there exist obvious differences of fault activity between the Cambrian and the Meso-Cenozoic. Its plane distribution mainly occurs in four directions: near EW, NWW, SN and NE, of which near EW Yaha fault is dominant fault and has undergone such tectonism stages as thrust nappe, negative inversion and left-lateral strike-slip process from compresso-shear to transtension, and along its strike developed a series of faulted anticlines. These fault activities control the distribution of Cambrian buried hill, the development of favorable reservoirs and the migration of oil and gas. Also, they are pathways for hydrocarbon migration and accumulation in Paleogene in this area.

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Stable Productivity Formula for Horizontal Well with Improvement

YUAN Ying-zhong, ZHANG Lie-hui, WANG Jian

2009, 30 (1): 77-80.

Abstract ( 180 )

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Horizontal well productivity equations of Borisov's, Joshi's, Giger's and Renard-Dupuy's formulae are analyzed comprehensively, and then their differences and similarities are compared. Actually, there are some problems to be improved in Joshi's formula. 3-D analytical productivity equation of horizontal well in infinite-acting reservoir with sealed boundary is derived. For the problem of Joshi's formula without π in the denominator of vertical seepage resistance term and the treatment of eccentricity as well as the differences between 2-D and 3-D seepage flow field, the corresponding improvement method is proposed. The study indicates that the error caused by the simplification of seepage flow field is not obvious. However, the problem of Joshi's formula without π and the treatment of eccentricity should be improved.

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Distribution Rules of Ground Stress in Different Blocks in Hailaer Oilfield

CHENG Yu-qi, WANG Shu-li, ZHOU Zhi-jun, WANG Hong-wei, MA Ying-zhuo, GU Ming-zhi

2009, 30 (1): 81-84.

Abstract ( 156 )

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The Xing'anling group's tuffaceous sedimentary rock and the Budate group's epimetamorphic rock in Hailaer oilfield belong to low porosity and extra-low permeability reservoir, being characterized by poor physical property, low natural productivity and sensitive hydraulic fracturing effectiveness. A thorough understanding of the current ground stress of the reservoirs can help to determine such parameters as occurrence, length and width of fractures in fracturing design, reducing blindness of hydraulic fracturing operation. Analysis of the existed stress calculation model considering both tectonic stress and thermal stress is made in combination with real well logging data from this oilfield, and the ground stress interpretations of Bei-28, Bei-16 and Su-131 blocks are given, obtaining the stress profiles and the lithomechanics parameters along depth, and mathematical models for stress calculations in different blocks. The calculated vertical and plane stress distribution rules indicate that Xing'anling group's sedimentary reservoir is in lower ground stress and preferable linear distribution feature in different depths, while Budate group's epimetamorphic reservoir appears in big difference of stress, with unclean the linear distribution rule. Applying wave velocity's anisotropy, viscous remanence method, the wellbore caving method and thermal strain recovery method, it is determined that the maximal plane major stress direction ranges from 99° to 107° and the minimal plane major stress direction is from 9°and 17°.

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A Single Point Deliverability Forecasting Formula for Water-Producing Gas Well

WANG Fu-ping, HUANG Quan-hua

2009, 30 (1): 85-86.

Abstract ( 111 )

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Based on the steady deliverability equation for water-producing gas wells, a single point deliverability forecasting formula for them is derived. The result shows that compared with conventional gas wells, the empirical parameter in the formula for water-producing gas wells is also related to the water production from gas well, and with the increasing of water/gas mass ratio (RWG), the empirical parameter will decrease gradually and the predicted open flow potential decreases too. In the case study, the single point deliverability forecasting formula for water-producing gas reservoir is established. It is shown that the formula is more reliable and practicable.

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Transformation from Turbidity Current to Contour Current

DING Hai-jun, XU Huan-hua

2009, 30 (1): 87-91.

Abstract ( 151 )

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The small cross lamination, the large vertical cross-bed and the glutinous cross-bed dould not exist in the sedimentary system. The conclusion from all the sedimentary characters of B, C, D and E segments is that the grains for forming these segments are transported by the tractive current in the last stage or before the sedimentation, not formed by turbidity current. The turbidite deposit is simply gravity current deposit in A segment, which is converted into contour current in B, C, D and E segments, hence being widely developed and dominant in the late stage of the turbidity current. In this paper, the clastic sediments and types of Lashizhong formation of Middle Ordovician in Zhuozishan area in Inner Mogolia are presented in view of sedimentary facies, facies family, paleo-current direction and the ecologic features of fossil ichnocoenosis. And the identified clastic contourite indicates that no Bouma sequence occurs in this formation.

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Study of Injection-Production Well Patterns for Herringbone Branch Horizontal Well

ZHANG Shi-ming, XU Qiang, ZHOU Ying-jie, DONG Ya-juan, TIAN Tong-hui

2009, 30 (1): 92-95.

Abstract ( 149 )

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This paper presents the micro well group conception to describe the typical injection-production well patterns for herringbone branch horizontal well. The analysis of the injection-production relation, flow behavior of the micro well group is made and its injectionproduction relation is optimized using numerical simulation method. Based on these, the sensitivity of angle of injection-production well, branch length and branch location of the herringbone well is studied. The adjusting strategies are proposed, and the result shows that the efficiency of the new well pattern is effectively improved.

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Flow Units of Conglomerate Reservoir—An example from Badaowan formation in Midwest of District 2 in Karamay oilfield

HE Hui, PENG Shi-mi, YUANG Shu-wang, ZHANG Hua

2009, 30 (1): 96-99.

Abstract ( 125 )

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Based on the keystone of flow unit, a quantitative classification method is proposed for conglomerate reservoir with high water cut of Badaowan formation in Midwest of District 2 in Karamay oilfield. After optimizing the parameters from cored holes, the reservoir flow units are classified into four types using cluster analysis and the discriminant functions for each type of flow units are set up for discriminant analysis and classifying the flow units of non-cored holes. The flow unit 3D geologic model is developed using sequential indication simulation method, in order to more properly reflect the flowing characteristics of in-situ fluids. This model could be as a guide for forecasting the distribution of remained crude oil, modification of this high water-cut oilfield development and enhancing the oil recovery in this area.

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Determination of Economic Limit Oil-Bearing Area in Complex-Fault-Block Oil Field

LUO Dong-kun, XIA Liang-yu

2009, 30 (1): 100-102.

Abstract ( 128 )

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New oil-bearing fault block in a complex fault block oilfield needs more detailed prospecting wells to prove its reserves for development. For a given oil-bearing fault block with homogeneous reservoir rocks, its oil-bearing area and reservoir depth are the key factors for deciding results from investment. Under given reservoir depth, ground communication and hydroelectricity conditions, this paper presents the economic limit oil-bearing area model based on discounted cash flow method, using available data from discovery wells in the fault block integrated with characteristics of complex fault block oilfields. The comparison of prospective oil-bearing area with economic limit oil-bearing area could quickly eliminate the investment projects to be obviously unfeasible, so as to shun related risk and increase decision-making efficiency.

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Study of Stratigraphic Denudation Recovery by Seismic Data in New Exploration Area

LIANG Quan-sheng, LIU Zhen, HE Xiao-hu, HAN Jun

2009, 30 (1): 103-105.

Abstract ( 137 )

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Because the erosion interface here is the same with the sequence boundary, this paper introduces a point of view of sequence stratigraphy, improves the traditional trend thickness method in erosion interface pattern, erosion boundary and thickness and proposes a composite method of sequence stratigraphy integrated with trend thickness. Applying to Baijiahai swell in eastern Jungger basin has obtained good result.

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Improvement and Application of Reservoir Size Sequential Method

LI Xiao-guang, LU Gang, SHAN Jun-feng

2009, 30 (1): 106-108.

Abstract ( 162 )

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The reservoir size sequential method is an important method for petroleum resource estimation. However, with this method irrational predicted results are often gained by selecting value k in terms of minimum standard error as principle. This paper proposes an improved algorithm in terms of k-line chart concept and "1-2-2 principle" for determine value k. The numerous testing results indicate that "1-2-2 principle" combined with k-line chart will be more reasonable to give value k, and more helpful to improve the predicted precision.

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Application of Geophysical Prospecting Technologies to Volcanic Rock Identification and Reservoir Prediction———Examples from Songliao basin and Junggar basin

LIU Deng-ming

2009, 30 (1): 109-113.

Abstract ( 137 )

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Volcanic rock is one of important petroliferous reservoir rocks. The reservoir space of volcanic reservoir has a certain correlation with volcanic lithofacies. The research of the measured data from outcrop and cores shows that there exist differences of the density, magnetic, electrical and some other petrophysical properties between volcanic rocks and surrounding sedimentary strata and among various lithologies of volcanic rocks. In this paper, the volcanic rock identification and reservoir prediction are mainly based on seismic data and combined with drilling, gravity-magnetic-electrical prospecting data. Such a method is applied to the research of Songliao basin and Junggar basin, and improved that it is simple, practical and effective for application, being one of the effective means for volcanic rock identification and reservoir prediction at present.

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Application of High-Precision Gravity-Magnetic-Electric Prospectings to Study of Geologic Structures in Gumudi Area in Southern Margin of Junggar Basin

SUO Xiao-dong, WU Jian, LI De-chun

2009, 30 (1): 114-116.

Abstract ( 126 )

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Because of the blind area existed in middle-deep seismic images, the understanding of the structural characters in Gumudi area is still unclear up to now. In view of obvious differences of density and resistivity of strata in different ages in southern margin of Junggar basin, there are good geophysical conditions for gravity-magnetic-electric prospectings. The study shows that Gumudi structure belongs to front structure of piedmont folded thrust belt in Bogda mountain. Controlled by step fractures, it is characterized by vertical multi-strata structures: the shallow strata assume tight overthrust inverted anticline; the middle strata appear in roof-like fault block controlled by step overthrust faults, and the deep strata are buried hill drape-like thrust anticline. The gravity anomaly displays that the west pericline of Gumudi anticline could be a complete anticline. It is concluded that the middle-deep structures and the west pericline in Gumudi area are favorable targets for petroleum exploration.

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Application of Absorption Filter on Seismic Signals to Gas Reservoir Identification

XU Tian-ji, CHENG Bing-jie, LI Xian-gui, GAN Qi-gang, TANG Jian-Ming

2009, 30 (1): 117-120.

Abstract ( 116 )

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When seismic wave propagates in hydrocarbon-bearing reservoirs, its reflecting frequency in response of absorption and attenuation is difficult to be detected in original seismic data. The absorption filter technology of seismic signals is based on autoregressive moving average (ARMA) analysis method and Prony transforming theory to decompose seismic signals into damping waves which are different in amplitude, frequency, phase and absorption coefficients. These decomposed signals comprise of the signal storage. We can analyze, select, reconstruct and optimize the seismic signals, combined with the information of well logging, petrophysics and geology, etc. Comparing with original seismic signals, the absorption-filtered data can depict various seismic responses more effectively, thus predicting hydrocarbon-bearing reservoirs more intuitionisticly, more effectively than using the original signals. The case study indicates that good applied result has been obtained using this method in test of model data and in gas reservoir identification.

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A Method for Automatic Residual Static Corrections Based on Uniform Design

LI Li, CHEN Xiu-juan, JING Xi-li

2009, 30 (1): 121-123.

Abstract ( 110 )

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The uniform design-based algorithm developed for dealing with residual static corrections is used to determine the candidate solution in huge resolving space, integrated with simulated annealing approach, in order to increase the speed of searching for the global optimized solution through more uniform distribution of candidate solution in the model space. Also, selecting the temperature parameters and the annealing processes of different model components allows the annealing process to be of adaptive feature. This new algorithm overcomes the shortcomings of the conventional simulated annealing method, such as non-uniform optimizing space and same annealing process in different model components. The case study from seismic data shows that the algorithm proposed in this paper is more reasonable and efficient than the conventional simulated annealing method.

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Some Geologic Questions About Wenchuan Violent Earthquake

SUN Wei, LUO Zhi-li, YANG Rong-jun, LIU Shu-gen, YONG Zi-quan, DAI Han-song

2009, 30 (1): 124-128.

Abstract ( 162 )

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The analysis of the geologic tectonic background and structural units division of Longmenshan fault belt where the Wenchuan violent earthquake happened in May 2008 replies the questions about tectonic earthquakes, combined with sallow and deep structural characters of Longmenshan fault belt. It is indicated that Wenchuan violent earthquake belongs to tectonic earthquake resulted from intracontinental subduction (C-subduction), probably being the type of double major shocks plus aftershocks. Hence, it has high magnitude and intensive destruction. By comparison of the geologic conditions causing the earthquake of Longmenshan fault belt with Chengdu plain, it is believed that a big earthquake could not take place in Chendu plain for it locates within the stable ancient Yangtze plate.

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Enlightenment of Petroleum Exploration in Songliao Basin to That in Junggar Basin

YONG Zi-quan, ZHONG Tao, LIU Qing-song, YANG Suo

2009, 30 (1): 129-132.

Abstract ( 135 )

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This paper expounds the likelihoods between Junggar basin and Songliao basin in geotectonic unit, evolution and petroliferous geological condition. It is shown that Junggar basin has large exploration potential and the theories and methods for the basins' exploration can be used for reference mutually. It is concluded that petroleum exploration of Junggar basin should focus on the study of paleo-uplift, relationship between faults and hydrocarbon accumulation, simultaneous exploration of gas and oil, and Carboniferous volcanic reservoirs.

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Discussion on Genesis of Red Beds of Jurassic in Yongjin Area in Junggar Basin

HE Zhen-jian

2009, 30 (1): 133-135.

Abstract ( 211 )

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The red sandy mudstone deposit (red beds) occurs in the top of Jurassic in Yongjin area of Junggar basin. Based on the core observation, change of clay mineral composition, oxide ratio and chemical alteration index analysis, the red beds are normal sedimentary rocks formed in the shore-shallow lake or braided delta front environment, followed by being oxidized while migration and deposition under the semiarid-subhumid climate. The result shows that the red beds are in weak chemical weathering and leaching process without weathering crust. It is suggested that the red beds should belong to Toutunhe formation of Middle Jurassic. The Che-Mo palaeohigh developed in late of Middle Jurassic is of short-term subsidence and then uplift features.

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The Plutonic Oil-Gas Fields

V. A. Krayushkin

2009, 30 (1): 136-141.

Abstract ( 176 )

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The geologic characteristics of giant oil-gas fields, more than 1 000 deep oil-gas fields and continental shelf oil-gas fields as well as natural gas hydrate pools in MidEast, South-North America are analyzed. These oil-gas fields may not be rationally explained by organic origin theory whether in oil-gas reserves and occurrences or in geologic characteristics of hydrocarbon distribution. Numerous measured data prove that a mass of hydrocarbons have been found in volcanic products, commercial gas flow found in crystal basement of Precambian and a series of hydrocarbon compounds found in cosmic stars and extraterrestrial spaces. All these indicate the possibility of inorganic origin for hydrocarbons. The inorganic origin theory for hydrocarbons provides a wide prospect for deep oil-gas development.

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