Table of Content

18 August 2012, Volume 26 Issue 4

Previous Issue    Next Issue

Petrology

Petrogenesis of Volcanic Rocks from Sankeyushu Formation in Southern Jilin: Evidences from Zircon U-Pb Ages and Hf Isotopes

DUO Zhen-Min- , CHEN Ti-Jun

2012, 26(4):  627-634. 

Asbtract ( 11572 )   PDF (5506KB) ( 1639 )  

References | Related Articles | Metrics

Zircon U-Pb dating by LA-ICP-MS shows that Sankeyushu Formation trachyte in southern Jilin area formed in 118 Ma of late Early Cretaceous. Study of petrogeochemistry suggests that SiO₂ contents from Sankeyushu Formation trachyte are 6511%-6561%,rich in alkali(K₂O=6.29%-7.28%，Na₂O=3.71%-4.21%).It belongs to shoshonite series with weak peraluminous (A/CNK=1.05-1.12) and low Mg index (Mg＃=9-16).The total amount of rare earth elements is relatively high (∑REE=317.72×10^-6 -371.30×10^-6).Light and weight lanthanon differentiation evidence(LaN/YbN=1950-2280)is noticeable.Eu negative anomaly is weak(δEu=075-081).The trace elements Rb, Th, Zr and K enrichment, Nb,Ta and Sr obvious depletion, show the emblematical character of continent lithosphere.176Hf/177Hf from zircons range from 0.282,206 to 0.282,309, εHf(t) from-13.32 to-16.97, Hf model ages are 2.0-2.6 Ga, average is 2.2 Ga.The above characteristics indicate that the Early Cretaceous trachyte in the study area mainly came from Paleoproterozoic lithosphere partial melting and was formed in an extensional tectonic environment.

Petrogenesis and Crustmantle Mixing of Early Jurassic Granites in the Taipingling Mountains, Heilongjiang Province

LV Chang-Lu, XU Dong-Hai, LI Xin-Feng, HAO Xin-Zhong

2012, 26(4):  635-646. 

Asbtract ( 2409 )   PDF (14956KB) ( 1501 )  

References | Related Articles | Metrics

The Taipingling Mountains in Mudanjiang, Heilongjiang Province is an important component of the XinganMongolian Orogenic Belt. The granitic rocks are widely distributed in the area. Zircon SHRIMP U-Pb age of these granites ranges from 179 Ma to 204 Ma, which indicate that they formed in the Early Jurassic, rather than the Late Triassic by former traditional understanding. The main lithology of the batholith is granodiorite, which are abundant in finegrained dioritic enclaves. The finegrained dioritic enclaves are rarely found in the monzonitic granite and syenogranite. The petrologic, petrographic and geochemical studies in this paper show that the Taipingling granites are generated by magma mixing of crustal and mantle materials. The Early Jurassic Taipingling granites have homogeneous Sr, Nd, and Pb isotopic compositions, with εNd(t)ranging from -3.2 to+2.3, and (87Sr/86Sr)i ranging from 0.704 to 0.706. This further suggests that the rocks are strongly mantlerelated. The granites show volcanic arc granite characteristics, which implies it is related to the environment dominated by compression. The origin of the Taipingling granites is tectonically linked to the subduction of the paleoPacific plate.

Geochemical Characteristics and Zircon LA-ICP-MS U-Pb Ages of QuartzMonzonite Porphyry in Anji Polymetallic Ore District of Zhejiang and Their Geological Implications

TANG Yan-Wen, XIE Yu-Ling, LI Ying-Xu, QIU Li-Meng, LIU Bao-Shun, LI Yuan, ZHANG Xin-Xin, JIANG Xing-Cen, HAN Yu-Da, ZHOU Dun-Jie

2012, 26(4):  647-654. 

Asbtract ( 4393 )   PDF (9370KB) ( 1384 )  

References | Related Articles | Metrics

In order to get further understanding about the magmatism and its relationship with mineralization, the geochemical characteristics and zircon UPb age of quartzmonzonite porphyry in Anji polymetallic ore district in western Zhejiang have been studied. Quartzmonzonite porphyry is characterized by high SiO2(65.91%-66.72%), alkalirich (Na₂O+K₂O=7.82%-8.26%), potassiumhigh (K₂O/Na₂O=1.58-1.82) and A/CNK=0.86-0.91. Based on the results from A/CNKA/NK and SiO₂-K₂O diagrams, quartzmonzonite porphyry belongs to the quasialuminous rock and shoshonite series. In chondrite normalized REE distribution patterns, all the samples are LREEenriched and with weak negative anomaly in Eu (δEu=0.75-0.81). In primitive mantle normalized trace elements spider diagram, the largeion lithophile elements (e.g. Rb, Th and K) are high concentrations, but Ba, Sr and the high field strength elements (e.g. Nb, Ti and P) are relatively depleted. The aluminized indexes (A/CNK) of all the samples are less than 1.1 and all the differentiation indexes (DI) are about 77, so quartzmonzonite porphyry belongs to Itype granite. Zircon U-Pb dating by LA-ICP-MS shows this porphyry emplaced at (137.3±1.6) Ma of Early Cretaceous and has a similar age with the Wushanguan complex. Considering that quartzmonzonite porphyry exists along HuzhouXuechuan fault and is cut off by XiaofengSanmenwan fault, this age indicates that HuzhouXuechuan fault was activated in Early Cretaceous and also constrains the earliest time when XiaofengSanmenwan fault activated. The magmatism formed in the same time with mineralization, and mineralization also has a close relationship with the complex body in space, so it is believed that the mineralization is related to the magmatism in this study area.

Deposit geology

⁴⁰Ar/³⁹Ar Dating for Kfeldspar from Duobuza Porphyry Coppergold Deposit in Tibet, China and Its Geological Significance

CHU Xiang-Beng, CHEN Hua-An, MA Dong-Fang, HUANG Han-Xiao, LI Guang-Meng, Liu-Chao-Jiang, WEI Lu-Jie

2012, 26(4):  656-662. 

Asbtract ( 3871 )   PDF (4848KB) ( 2008 )  

References | Related Articles | Metrics

Duobuza porphyry coppergold deposit is a newly discovered deposit, which is located in the middle of Tibet plateau and in the west of BangonghuNujiang metallogenic belt. K-feldspar from the potassic alteration zone was analyzed by ⁴⁰Ar/³⁹Ar dating technique, and these results yielded a plateau age of (118.31±0.60) Ma and a reverse isochron age of (118.30±0.79) Ma with initial 40Ar/36Ar=291±17, indicating that potassic alteration age in Duobuza porphyry deposit ranges from 119 to 118 Ma and coincide with the mineralization age (molybdenite Re-Os age, 119-118 Ma ). The magmatichydrothermal evolution of Duobuza deposit should be from magmatic stage (around 120 Ma) to potassic alteration and mineralization (119-118 Ma), then to phyllic alteration (118-115 Ma), and the duration of magmatichydrothermal evolution probably persisted 5 million years.

Deposits and Structure Geoglogy

Sources of the Oreforming Material of the Baiyangping Polymetallic Deposit in Lanping Basin, Northwestern Yunnan: Constraints from C, H, O, S and Pb Isotope Geochemistry

XUE Wei, XUE Chun-Ji, LI Hong-Jun, CHE Guo-Xiang, CENG Rong

2012, 26(4):  663-672. 

Asbtract ( 2754 )   PDF (4926KB) ( 1251 )  

References | Related Articles | Metrics

Baiyangping polymetallic deposit, located in the central, slightly north of the Lanping MesozoicCenozoic sedimentary basin, is one of important deposits in the famous Sanjiang metallogenic belt. C, H, O, S and Pb isotope geochemistry are discussed in this paper in order to find out sources of the oreforming material and characteristics of orefluids. The δ³⁴S value of polymetallic ore in Baiyangping deposit is between -5.6‰ and 11.2‰, with the property of thermalchemic reduction of Mesozoic to Cenozoic evaporite sulfate in Lanping Basin. Moreover, the composition of Pb isotope in ores and sedimentary rocks of Mesozoic to Cenozoic is also very similar, which illustrates that oreforming metal elements derive from the sedimentary rocks of the basin. The δDV-SMOW and δ18OV-SMOW of the oreforming fluids are between -122‰ to -86‰ and -4.52‰ to -15.34‰, respectively, showing that they come from basinal hot brine, supplied by precipitation. The δ13CV-PDB and δ18OV-SMOW value of dolomite formed in early hydrothermal oreforming stage are between -3.4‰ to 0.5‰ and 4.8‰ to 20.3‰, respectively, while the corresponding values in late hydrothermal oreforming stage are between -3.1‰ to 0.5‰ and 4.1‰ to 18.6‰, respectively, all of which indicate that CO₂ of the oreforming fluids derive from the solution of the limestone.

Deposit geology

Primary Study on the Sediment Structures in Blackshaleseries Deposits of the Basal Cambrian, Guizhou Province

WEI Fu-Rui, YANG Rui-Dong, GAO Jun-Bei, WANG Wei

2012, 26(4):  673-681. 

Asbtract ( 2518 )   PDF (11938KB) ( 988 )  

References | Related Articles | Metrics

Blackshaleseries deposits related to hydrothermal sedimentation were widely distributed in the basal Cambrian, southwest of China. According to the study on micro and macro structures of three different types of blackshaleseries deposit belts, namely NiMo ore deposit belt, V ore deposit belt and barite deposit belt, sedimentary structural features are concluded. Specifically, sedimentary structures and structures series that formed in extravasation, in pneumatohydrothermal process and in colloidalbiochemical process, as well as some penecontemporaneous sedimentary structures, were found and determined. As a result, comparison analysis was made on the differences and similarities of the sedimentary structures among those three deposit belts, which is of importance for mineralization theories related to deposits of this type.

Structural Geology

Differential Structural Deformation and Tectonic Evolution in the Middle Part of Kuqa Depression, Tarim Basin

XIE Hui-Wen, LI Yong, QI Jia-Fu, LI Jing, CHEN Yuan-Yong, MA Li-Ke, HU An-Meng

2012, 26(4):  682-690. 

Asbtract ( 1956 )   PDF (11960KB) ( 1072 )  

References | Related Articles | Metrics

Based on the field observation, interpretation of seismic, well data, and analysis of saltrelated structure styles, the research on the structural deformation characters in the middle of Kuqa depression was done. The result shows that: (1)The middle part of Kuqa depression can be separated into segments in westeast direction, belts in southnorth direction and layers in vertical. Four layers, overburden salt layer，salt layer, subsalt layer and basement layer, are divided in vertical. (2)The main structural styles in this area are contraction styles and salt tectonics. The distribution of structural styles are various in different segments. Different types of thrust and fold can be found in overburden layer. Saltrelated structural styles are mainly in salt layer and imbricate thrust fault and fold are in subsalt layer.(3)Distribution of fold belt in surface, salt tectonics and deformation in subsalt layer are three important factors which decide the differential deformation of Kuqa depression. It can be divided into four segmentations: BoziQuele segmentation, DabeiXiqiu segmentation, KeshenXiqiu segmentation and KL3Dongqiu segmentation.(4) The research on the balanced section and tectonic evolution history indicate that Kuqa depression experienced extensional depression stage in Mesozoic, bending depression stage from Paleogene to Miocene and intracontinental foreland basin from Pliocene to Quaternary. The present structures of the basins are mainly formed in the middlelate deposition period of Kuqa Formation.

Structural Characters and Evolution of the MidSouth Section at the West Margin of Ordos Basin

OU Yang-Zheng-Jian, CHEN Hong-De, FENG Juan-Ping

2012, 26(4):  691-695. 

Asbtract ( 1859 )   PDF (4892KB) ( 1876 )  

References | Related Articles | Metrics

 Main seismic sections in the west margin of the Ordos Basin are explained，depend on balanced section technology and 2D Move software. Nine firstlevel faults and four firstlevel structure units are confirmed，and the west margin of the Ordos Basin is divided into five sections.The structure distortion  is stronger  in the east than in the west. Majiatan section is thinskinned structure，but the others are thickskinned tectonics.The shortest compressed measure is different in different areas.Tianshuibu sections shortest compressed measure is up to 50.62%. Structure distortion came into being in Late Jurassic (146-135 Ma) mostly，ended in Cenozoic. Structure trap types are multiplex，which can supply a certain amount of space for the accumulation of oil and gas. Their forming matches with the period of accumulation of oil and gas. The structure character of the west margin of the Ordos Basin is different from east to west or from north to south. The relationship between the structure trap and accumulation of oil and gas is close.

Deformation Belt of Ductile Shear from Carbonate Platform in the TianeFengshan Area，Western Guangxi

ZHANG Nai, LEI Hai-Feng, YAN Yo-Tong, TUN Nian-Dong

2012, 26(4):  696-704. 

Asbtract ( 1710 )   PDF (7070KB) ( 911 )  

References | Related Articles | Metrics

Different degrees of ductile shear deformation have occured from Devonian to Permian in TianeFengshan area, western Guangxi. On the edge of carbonate platform, especially along the specific lithohorizon from Carboniferous and Permian, a set of deformation belt of calcareous ductile shear formed, with features of low metamorphism, strong deformation and stratiform. The ductile shear deformation belts consist in strong, low and middle deformation belts. Under the microscope, it is discovered that the metamorphic and deformation rocks from the the ductile shear deformation belt are charactered by mylonitic texture, and belong to mylonitic series. The deformation belt of the calcareous ductile shear shows the feature of thrust and concluded to form by the mechanism of arccontinent collision in late period of Middle Triassic in TianeFengshan area. The discovery may provide new evidence for the analysis of the formation and development of the Youjiang basin in western Guangxi.

Sedimentology

Genesis of the Unconsolidated Sandstones in the North Side of the Yellow River in Lanzhou, Gansu

XIE Yu-Jiang, LIU Gao, LI Gao-Yong

2012, 26(4):  705-711. 

Asbtract ( 2634 )   PDF (8900KB) ( 1097 )  

References | Related Articles | Metrics

The orangered unconsolidated sandstone which consists almost entirely of quartz is widely distributed from the east of Hongcheng to the west of Gaolan on the north side of the Yellow River in Lanzhou, Gansu Province. The research on unconsolidated sandstone not only has high economic value but also an extremely significance for the drought condition study in northwest China. For a long time, the genesis of this sandstone has attracted wide attention and dispute at home and abroad. By field observation of the sedimentary structure, indoor particle size analysis test and SEM scanning, the genesis of this sandstone were discussed in aspects of the sedimentary characteristics，the grainsize characteristics and the surface characteristics of the quartz in this  sandstone. The unconsolidated sandstone widely distributed from Shuifu to Caojiawan has the following characteristics of underwater sedimentary: the horizontal bedding is evident in the sedimentary structures; the change of cumulative grainsize distribution curves consists with the neptunian theory; the conchoidal fracture and scaly peeling caused by erosion on the quartz surface are developed. The unconsolidated sandstone distributed from Zhujiajing to Hongcheng has the following aeolian features: the tabular oblique bedding is evident in the sedimentary structures; the change of cumulative grainsize distribution curves meets the aeolian theory; the surface of the quartz in the unconsolidated sandstone possesses pockmarked face, butterfly pit, and so forth. These results indicate that the genesis of this sandstone is very complicated and is regionally different; it cannot be simply analyzed by aeolian theory or neptunian theory.

Accumulation Age and Rate of Peat in the Longli Alpine Meadow of Guizhou and Their Organic Carbon Isotope Records

WEN Xue-Feng, WEI Xiao, YANG Rui-Dong, TIAN Meng-Zhong

2012, 26(4):  712-715. 

Asbtract ( 1483 )   PDF (2196KB) ( 1517 )  

References | Related Articles | Metrics

On basis of radio carbon isotope and stable carbon isotope test on samples from the Longli alpine meadow, Guizhou, it is figured out that ages of the samples in 0.90 m and 0.55 m of the peat layer bottom are (7,933±33) a B P and (7,733±28) a B P , respectively and rate of peat layer accumulation is 1.75 mm/a. The δ¹³C of the peat layer, ranging from -28.9‰ to -26.6‰, with average value of -27.8‰，illustrates that C₃ plants are the primary vegetations, which is similar to the flourishing moss on the modern platform marsh. Compared with the climatic data of other areas, we infer that the peat here grew in relatively warm moist climatic environment,and the peat layer was the product formed in the first warm and humid period of the big warm period in Holocene.

Grain Size Characteristics and Deposit Environment of Strata in Hujiagang River Terrace in Yingxian, Shanxi Province

DIAO Dun-Xiang, XU Shen-E, LIU Zhi-Rong

2012, 26(4):  716-722. 

Asbtract ( 1835 )   PDF (6843KB) ( 1228 )  

References | Related Articles | Metrics

Hujiagang is located in Yingxian, Shanxi Province. The river terrace in Hujiagang was formed between 66.46 ka and 33.62 ka. The grainsize distribution characteristics were used to interpret the deposit environment of Hujiagang river terrace. The grainsize distribution characteristics show the following four aspects: (1)the grain sizes of strata in Hujiagang river terrace upwardly change from coarse to fine with a positive rhythm sedimentary characteristics，and the strata can be sorted into four sections, ie A, B, C and D;(2)sediments in section A which mainly consist of fine sands have similar grainsize distribution characteristics and were mainly transported in saltation, showing asymmetrical single hump and two parts in probability accumulation curves, and the sorting is good, indicating that the hydrodynamic activity is strong and the deposit environment is stable; (3)sediments in sections B and C which mainly consist of fine sands and silts have different grainsize distribution characteristics and are mainly transported in saltation, showing asymmetrical two humps and two parts in probability accumulation curves, and the sorting is bad, indicating that the hydrodynamic activity is strong and the deposit environment is instable; (4)sediments in section D which mainly consist of silts have similar grainsize distribution characteristics and are mainly transported in suspension, showing asymmetrical single hump and two parts in probability accumulation curves, and the sorting is good, indicating that the hydrodynamic activity is weak and the deposit environment is stable. The strata in Hujiagang river terrace in general are formed in fluvial facies and the top is alluvial plain sediments. The change of these grainsize distribution  characteristics is in accord with the oxygen isotope variation of Guliya ice core, thus the change of grain size and the deposit environment of Hujiagang river terrace are controlled by the climate change.

Petroleum geology

Hydrocarbon Generating Potential of Carboniferous Source Rocks in East Part  of North Margin of Qaidam Basin and Their Geological Significance

ZHANG Meng-Feng, TUO Jin-Cai, ZHANG Xiao-Jun, QIU Jun-Li, TUN Chen-Jun, GUO Li-Jun, JI Wen-Chao

2012, 26(4):  723-731. 

Asbtract ( 4879 )   PDF (5655KB) ( 1671 )  

References | Related Articles | Metrics

According to the basic geochemical data of organic abundance, organic type, organic maturity and biomarker,  the organic geochemical characters of the Carboniferous source rocks in east part of north margin of Qaidam Basin are analyzed. Results are as follows: (1)The darkcolored mudstone has an average organic carbon content of 1.26% and the organic matter is mainly of Ⅲ and Ⅱ types; (2)The carbonate rocks has a low organic carbon content with an average of 0.24%, and the organic matter is of ⅡandⅠtypes; (3)Hydrocarbon source rocks with a moderatehigh organic matter maturity, have larger hydrocarbongenerating potential. The darkcolored mudstone and carbonate rocks both reach the standards of good to moderate hydrocarbon source rock. The sedimentary organic matters are dominantly derived from lower hydrobiont and algae, and deposit in a strong reducing environment of saline water. The comparison study of discovered crude oils of north margin of Qaidam Basin indicates that the crude oils in Lenghu area and Nanbaxian oilfield have little contribution from Carboniferous source rocks. In Mabei oilfield, some crude oil samples are from the Carboniferous source rocks, indicating new petroleum exploration area in north margin of Qaidam Basin.

Clay Minerals of Black Shale and Their Effects on Physical Properties of Shale Gas Reservoirs in the Southeast of Chongqing: A Case Study from Lujiao Outcrop Section in Pengshui, Chongqing

LI Juan, XU Bing-Song, LIU Ce, SUN Meng-Di

2012, 26(4):  732-740. 

Asbtract ( 2218 )   PDF (6431KB) ( 2106 )  

References | Related Articles | Metrics

In order to search after clay minerals of black shale and their effects on physical properties of shale gas reservoirs in the southeast of Chongqing, combination and distribution characteristic, formation mechanism and controlling factors of clay minerals and their effect on porosity and permeability are discussed in detail based on the knowledge of previous studies on clay minerals in petroliferous basins and taking Lujiao outcrop section in Pengshui County for example. Then it draws a conclusion that the combination of clay minerals in Lujiao section is I+C+I/S and the formation is controlled by palaeoenvironment and diagenesis which on one hand, the palaeosalinity is higher in the bottom and becomes lower in the up part, on the other hand, the black shale is in the B stage of late diagenesis. It has been discovered that type, quantity and distribution character of clay minerals are closely related to porosity and permeability of shale gas reservoirs. Exactly speaking, the growth of illite in the diagenesis can increase the porosity in some extent but will lose some permeability; chlorite has a positive correlation with porosity and permeability, which may be resulted from the detrital feldspars.

Geological and Geochemical Characteristics of Anoxic Event Bed in the Qingshankou Formation of Late Cretaceous in Songliao Basin

HAN Gang, ZHANG Wen-Jing, HUANG Qing-Hua, MENG Yuan-Lin

2012, 26(4):  741-746. 

Asbtract ( 3627 )   PDF (4118KB) ( 1486 )  

References | Related Articles | Metrics

The core from the drillinghole of Mao 206 in the Songliao Basin was obtained by the China Cretaceous Continental Scientific Drilling Project. The interval of the Qingshankou Formation is 497.02 meters long and is the material of present study. The formation is a group of dark mudstone and shale sediments rich in organic carbon. The organic carbonrich sediments are the marker beds of stratigraphic division and correlation in the basin. The organic geochemical characteristics identified from drillinghole Mao 206 are high organic carbon contents, positive excursion of kerogen isotopes and low diasteranes contents, and the biomarkers of gammacerane are ubiquitous. They are possibly the evidences of lacustrine anoxic records in the midCretaceous extreme greenhouse climate period. According to the biostratigraphic constrain, the present authors suggest that the anoxic event might be happened in the Songliao Basin and corresponds to the marine oceanic anoxic event occurred at the CenomanianTuronian boundary. Based on both biostratigraphy and chemostratigraphy, the age of the Qingshankou Formation should be Late Cenomanian to Turonian.

Late Ordovician Reservoir Petrology and Characteristics of Reservoir Space in Tazhong Area，Tarim Basin

XU Kang, XU Bing-Song, LIU Sai-Tong

2012, 26(4):  747-754. 

Asbtract ( 5164 )   PDF (7728KB) ( 1483 )  

References | Related Articles | Metrics

Combining field work with laboratory research, the reservoir petrology and pore characteristics of the Upper Ordovician Lianglitark Formation in Tazhong area have been studied in this paper. The results indicate that limestones in Lianglitark Formation in the study area are mainly framework reef limestone, grain limestone, argillaceous limestone, algae boundstone and karst breccia. Grain limestone mostly experienced multi periods of diagenetic transformation, in which fractures are relatively developed. The multistage pressure dissolution and dolomitization are common in micrite.The diagenetic transformation is the weakest in the algae boundstone. The types of pore space in the carbonate reservoirs are mainly large cavities, holes and cracks, of which holes most develop along the fracture and distributed sparsely and isolately, and crack is the main structural joints. Microscopic reservoir space mainly includes the dissolved pore and microfracture. Dissolution pores, which mainly develop in the grain limestone, can be subdivided into intragranular dissolved pore, intercrystalline dissolved pore, intercrystalline dissolved pore, moldic pore, dissolution skeleton hole, residual intergranular pore and dissolved microfracture pore, of which the intergranular dissolution pores have the highest proportion. Buried karstification is of large scale and widely distributed, which significantly influence the reservoir quality.

Characteristics and Formation Mechanism for Dolomite Reservoir of Permian Fengcheng Formation in Junggar Basin

XUE Jing-Jing, SUN Jing, SHU Xiao-Min, LIU Wei, SHU Shi-Fa

2012, 26(4):  755-761. 

Asbtract ( 5313 )   PDF (5768KB) ( 1856 )  

References | Related Articles | Metrics

Recently, dolomiticrock exploration of Junggar Basin has made a sustained breakthrough and opened a completely new exploration field. Definition of dolomiticrock is concluded, and the effective reservoir type, characteristics of occurrence and formation mechanism of dolomite are determined based on previous research conclusions, core observation, thin section, and so on. The dolomiticrock with special lithology and limited distribution mainly develops in Permian Fengcheng Formation of Wuxia district of the northwest margin. The dolomite has seven types of occurrence，including lameltate, uniform distribution, snow shape, irregular layered shape, crumb shape, fracture filling shape and exotic dolomite clastics. Corresponding, dolomite has five types of formation mechanism, including parasyngenetic dolomitization, mixed dolomitization, buried dolomitization, diagenetic dolomitization and weatheringtransportation of external dolostone. The effective dolomiticrock reservoirs whose space is microfissure, include dolomiticsiltstone, dolomiticmudstone, muddy dolomite, and so on. Development degree and dispositional relationship of fissure and karst cave have an important impact on the level of capacity. Overall, the microand macrodistribution characteristics of different types of dolomite are different, and their superimposed effect controls the whole features of the present dolomite.

Characteristics of Micropore Throat in High Pressure and LowPermeability Sandstone Reservoir of Deep Section: Taking the Middle of the Third Member  of Shahejie Formation in Wendong Oilfield, Dongpu Sag as an Example

WANG Rui-Fei, LV Xin-Hua, GUO Dian-Bin, SU Dao-Min

2012, 26(4):  762-768. 

Asbtract ( 1728 )   PDF (5362KB) ( 1240 )  

References | Related Articles | Metrics

The features of micropore throat in high pressure and lowpermeability sandstone reservoir of deep section were analyzed by using the constantrate mercury injection technology. The research shows there are little difference in the pores sizes and distribution, the pore radius is unimodal distribution, and the main peak is from 100 μm to 300 μm. Throat radius is the main factor that controls the reservoir property. The relation between the permeability and the throat radius is better than that between it and the pore radius. There is better correlation between the reservoir property and the pore throat parameters such as the effective throat radius, pore radius, throat volume, pore volume, and poretothroat radius ratio. When it comes to the high permeability sandstone sample, the effective poretothroat radius ratio is low, and its distribution frequency is high. The better the permeability is, the lower the poretothroat radius ratio is, and the more concentrated the distribution of the poretothroat radius ratio is. Its analyzed that in the pore throat parameters of the constantrate mercury injection, the numerical values such as the displacement pressure(pT), the median pressure(pc50), and the largest injection mercury saturation(SHgmax) are lower than that of the conventional mercury injection, and the largest continuous throat radius(Rmax), the median radius(r50) are larger than that of the conventional mercury injection. Compared with the conventional mercury injection, the pore throat feature parameters from the constantrate mercury injection are more accurate.

Diagenetic Facies and Micropore Structure of  Chang 6 Reservoir in  Yanchang Formation， Huaqing Area， Ordos Basin

SHI Diao-Diao, SUN Wei, ZHANG Chuang, LIANG Xiao-Wei, HE Sheng-Beng, LIN Da-Zhong, LI Chun-Xia

2012, 26(4):  769-777. 

Asbtract ( 6910 )   PDF (7412KB) ( 1277 )  

References | Related Articles | Metrics

The physical property of Chang 6 reservoir was poor with strong heterogeneity in Yanchang Formation, Huaqing area, Ordos Basin. In this paper, casting thin sections, SEM, Xray diffraction, physical properties, high pressure mercury injection and other analytical testing methods were used to analyze the diagenesis, diagenetic facies and micropore structure of the low permeability reservoir deeply. The results showed that: main reservior diagenetic facies were the hydromica cementationintegranular pore and feldspar dissolution diagenetic facies, feldspar dissolution and hydromica cementationintegranular pore facies, feldspar dissolution and chlorite cementationintegranular pore facies. The features of microscopic pore structures of various types of diagenetic phases were different. And the porethroat ratio and coordination number with mercury injection saturation and mercury withdrawal efficiency had a good correspondence. That is, the smaller the porethroat ratio was, the greater the coordination number was, and the greater the mercury injection saturation and mercury withdrawal efficiency were, such as the hydromica cementationintegranular pore and feldspar dissolution diagenetic facies; otherwise, the greater the porethroat ratio was, the smaller the coordination number was, and the smaller the mercury injection saturation and mercury withdrawal efficiency were, such as the feldspar dissolution and chlorite cementationintegranular pore facies.

Application of Gamma Curves Wavelet Transform to Calculate Grain Size Parameters

YANG Ning, WANG Gui-Wen, LAI Jin, LI Jian-Lun, CANG Dan, JIANG Ji-Jun

2012, 26(4):  778-783. 

Asbtract ( 3006 )   PDF (3702KB) ( 1468 )  

References | Related Articles | Metrics

The information on grain size of reservoirs from gamma logging curves can be obtained and the grain size parameter can be extracted based on the dyadic wavelet transform. Considering the influence of sampling intervals caused by the measurement rate of logging tools, an algorithm for solving the system of recurrence equations concerning volume fraction in different kinds of grain size distributions was presented through analyzing the content by volume in different kinds of grain size distribution and the relationship between range and frequency of signal which was extracted after gamma logging curves changed. On the basis of this algorithm, the absolute volume content in different kinds of grain size distribution can be transformed into the relative volume fraction. Then the grain size parameters can be calculated including the median grain diameter, the average particle size, the sorting coefficient, the skewness and the kurtosis according to Trask or FolkWard formulae. Four wells like DB101 in Dabei area of Tarim Basin were selected to verify the applicability and reliability of this method. Moreover, compared with the sieve method, all kinds of parameter errors are within an acceptable range. The advantage of this method is that it can reduce the demand for the source of information, timing consuming and cost in contrast to the similar methods at home and abroad.

Division of Flow Units in Fractured Reservoirs：Taking the First Oil Layer in the Eighth Member of the Yanchang Formation in Jiyuan Area of Ordos Basin as an Example

JIANG Beng, DIAO Ying-Cheng, CHEN Kai-Yuan, LI Jia-Hong, HU Xiao-Meng

2012, 26(4):  784-791. 

Asbtract ( 4343 )   PDF (7555KB) ( 1254 )  

References | Related Articles | Metrics

Previous studies showed that R/S analysis of well logs can effectively characterize the degree of reservoir fractures. But R/S calculation only using acoustic curves cannot avoid the influence of lithology changes. In this paper, R/S calculation using the reconstructed curves (AC-GR) could remove the influence of lithology changes on acoustic curves and could reserve the response of fractures. In this way, R/S analysis of reconstructed curves (AC-GR) can much effectively characterized the development and location of fractures. Statistics showed that the relationship between fracture density and fractal dimension (D) of reconstructed curves (AC-GR) was good. In this study on dividing the flow units, in addition to the commonly used parameters, ie. porosity, permeability and effective thickness, the fractal dimension (D) of reconstructed curves (AC-GR) was also used in the method of cluster analysis. Taking the first oil layer in the eighth member of the Yanchang Formation in Jiyuan area of Ordos basin as an example, four types of flow units were defined according to the comprehensive flow ability. The first type was located in the confluence of main channel where the reservoir property and the effective thickness were high and the fractures were developed. The second was located in the main channel where the effective thickness was high and fractures were developed moderately. The third was located in the river flank where the effective thickness was low and fractures were developed. The fourth was sporadically distributed along the northeasttosouthwest direction in the areas where the reservoir property was not good and fractures were not developed.

Accumulative Conditions and Distribution Characteristics of Hydrocarbon in Huanghekou Depression, Offshore Bohai Bay Basin

JIANG Hun-Sheng, LV Xiu-Xiang, ZHOU Xin-Fu, XU Chang-Gui, SHU Xiu-Xiang, DIAO Xu-E

2012, 26(4):  792-800. 

Asbtract ( 4264 )   PDF (9738KB) ( 1107 )  

References | Related Articles | Metrics

The hydrocarbon accumulation conditions in the Huanghekou depression are analyzed in this paper, using the latest highresolution 3D seismic and well logging, combined with the core observation information, from the source rock, reservoirs, reservoirseal assemblage, traps type and carrier systems. The results show that source rocks are general in the Huanghekou depression, and there develop three sets of hydrocarbon source rocks, and the 3rd Member of the Shahejie Formation and the 3rd Member of the Dongying Formation are the major source rocks. The main reservoir includes Cenozoic clastic reservoir and bedrock reservoir. The main types of sourcereservoircap rock assemblages include lowergeneration middleaccumulation and uppercap rock, uppergeneration loweraccumulation and uppercap rock, indigenous generation and accumulation. The trap types are mainly fault block traps, and faults dominate the carrier system in the vertical direction. The influence of Neotectonic Movement on the Huanghekou depression brings favorable conditions for the Neogene hydrocarbon accumulation, and the late fault activity plays roles of preservation and secondary distribution of the formed reservoirs. Major reservoirs in the plane are around oilgenerating depressions with a zonal distribution in the structural belt. Paleogene reservoirs are in zonated distribution around the eastern sag. The Neogene majorly is in “T”shaped distribution. Hydrocarbon accumulates from the periphery to the center, from south to north, from the Paleogene to the Neogene in the Huanghekou depression.

Formation Stages of Oilgas Reservoirs in Hailaer Basin，Inner Mongolia

CUI Jun-Beng, ZHONG Gao-Run, LIN Zhan-Li

2012, 26(4):  801-807. 

Asbtract ( 2426 )   PDF (4910KB) ( 1535 )  

References | Related Articles | Metrics

On the basis of illite dating method，hydrocarbon generated and hydrocarbon expulsed process and  homogenization temperatures of fluid inclusion, the formation stages of oilgas reservoirs in Hailaer basin were studied. The results show that there are two main formation stages of oilgas reservoirs in Hailaer basin. The first stage is about 120-80 Ma, which is corresponding to the sedimentary period of Yimin Formationearly sedimentary period of Qingyuangang Formation, and it is the main formation time of oilgas reservoirs in Hailaer basin. The great majority of formation period of oil and gas is 105-90 Ma, which is corresponding to the secondthird segment sedimentary period of Yinmin Formation, and it is the abundant period of hydrocarbon generated and expulsed processes, in which the sufficient migration force is helpful to the formation of oil and gas reservoirs. The second stage is from the time that Qinyuangang Formation was deposited to now. During the second stage, the oilgas reservoirs formed in the first stage was adjusted, and at the same time the second formation process occurred in the oilgas reservoirs. The fine hydrocarbon，faults and sustained thick mudstone control the formation and distribution of oilgas reservoirs in the study area.

Engineering Geology and Environmental Geology

Compliance of Drillingrod System for Hydrofracturing in Situ Stress Measurement and Its Effect on Measurements at Great Depth

WANG Cheng-Hu, SONG Cheng-Ke, GENG Bo-Rui

2012, 26(4):  808-816. 

Asbtract ( 1322 )   PDF (7537KB) ( 1388 )  

References | Related Articles | Metrics

The widelyaccepted hydrofracturing system in China mainland consists of six parts, iecontrol system for hydraulic fluid, highpressure pump, power supply system, data recording system, straddle packers, and watertight drilling rods. This whole testing system can be divided into two kinds: one is the  shallow testing system for boreholes with depth less than 100 m, the other is the deep testing system for boreholes with depth more than 100 m.As for the drillingrod hydrofracturing measurement system, the elastic deformations of drilling rods, connection highpressure hoses and rock mass around testing interval have little effects on the compliance of testing system, and the elastic deformation of packers and the compressibility of fracturing fluids are two major factors. When testing interval is less than 100 m in depth, the compliance of testing system is controlled by the elastic deformation of packers and the compressibility of fracturing fluid, and when testing interval is greater than 100 m in depth, the compliance of testing system is controlled by the compressibility of fracturing fluids. For the testing at great depth, due to the large compliance of testing system, it is very difficult to determine the reopening pressure Pr0 In order to eliminate the negative effects from the compliance of testing system during the measurement campaign in deep boreholes, it is recommended to adopt other methods to determine Tfh, the tensile strength of rock mass around the testing interval so as to determine the maximum horizontal principal stress SH, or utilize other techniques to estimate  SH. In the future research, the potential feasible way is to develop new downwell pressure gauges and flow meters in order to completely eliminate the negative effects from the compliance of testing system.

Formation Mechanism of the “20110606” Debris Flows within Wangmo, Guizhou

MA Yu, TU Bin, QI Xing, WANG Chao

2012, 26(4):  817-822. 

Asbtract ( 5240 )   PDF (5376KB) ( 1993 )  

References | Related Articles | Metrics

The “20110606” rainstorm(105.9 mm/h)triggered many debris flows in Wangmo County, Guizhou Province. During the hazards, thirtyseven people were killed and fifteen people were lost，and many houses were seriously destroyed. In order to improve the result accuracy of the forecasting and early warning system, based on field investigation and analysis, this paper analysis formation and mechanism of debris flows. The results reveal the following aspects: (1)the tense outbreak of debris flow is an inevitable coupling result of topography, material sources and rainstorms， and the rainfall breaking the 50year record is the main factor for the outbreak of those debris flows, but the steep terrain and soft rock layers, such as sandstones and shales etc., are the important causes;(2) the formation mechanism of debris flows, including bedfailuretriggered debris flow, outbursttriggered debris flow and landslidetriggered debris flow were main types in this area, and the initiation of bedfailuretriggered debris flow was surface flow→erosion gradually→transformed into debris flow, and the initiation of outbursttriggered debris flow was collapse→block→burst→transformed into debris flow, the initiation of landslidetriggered debris flow was rainwater infiltration→failure→fluidization→transformed into debris flow.

Investigation of Sorption and Migration Effect Factors of Uranium on Granites in Beishan

WEI Honggang

2012, 26(4):  823-828. 

Asbtract ( 2067 )   PDF (4024KB) ( 1457 )  

References | Related Articles | Metrics

The paper simulates and predicts the conditions after the uranium entered into the groundwater in a disposal site  of preselected high level radioactive waste in China by using hydrologic modeling software PHREEQCⅡ. The paper also analyzes the different roles of the various influential factors such as pH, dispersity，diffusion coefficient and temperature in the simulation. The behaviors of sorption and migration of uranium on granites in Beishan have been investigated by using the batch method. The distribution coefficient of uranium is determined. The effects of granite particle size, pH,concentration and temperature of  uranium in simulated groundwater are studied. The results show that the ability of granites in Beishan to adsorb uranium is rather weak and influenced by some influential factors. The results of simulation by software is similar to the experimental results. Therefore, the study will provide an important basis for the safety research on the site.

Soil Heavy Metal Pollution in a Industrial Site of North China

FU Qian-Qian, WANG An-Cai

2012, 26(4):  829-836. 

Asbtract ( 1940 )   PDF (8696KB) ( 1212 )  

References | Related Articles | Metrics

The analytical methods of mathematical statistics and geostatistics are used to explore the spatial distribution features and the correlation between different soil heavy metal elements in a industrial site of North China in this paper. The results indicate that these heavy metal elements are of certain degree of accumulation in the study area, and the average concentration of Hg is higher than the level three standard value of national Environmental Guality Standard for Soil and local soil background value. It suggests that the pollution of Hg is the most serious, and it is considered as a dominant element causing soil heavy metal pollution in the site. In general, according to pollution degree, the heavy metal elements are orderly Hg，Zn，Cd，Mn，Pb，Cu，Cr and As, of which the average concentration of As is closing to the local soil background value. In addition, Hg, Cd, Mn, Fe and Co have the moderate degree of spatial correlation, it provides the basis on pollutants and pollution source identification. The soil heavy metal pollutions of the 1, 4, 8 and 9 plants are the most serious, and the types of contaminants have a certain relationship with their special operating processes, which provides an important basis for the work of prevention and controlling in the future.