Most Down Articles

Published in last 1 year | In last 2 years| In last 3 years| All| Most Downloaded in Recent Month | Most Downloaded in Recent Year|

All

Please wait a minute...


For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails

Select

Characteristics and main controlling factors of tight sandstone reservoirs in the 8th member of the Yanchang Formation in Zhenjing area, Ordos Basin Xu Menglong, He Zhiliang, Yin wei, Wang Rui, Liu Chunyan Oil & Gas Geology    2015, 36 (2): 240-247.   DOI: 10.11743/ogg20150208 Abstract （308）      PDF（pc） （28449KB）（19009）       Knowledge map    Save The Yanchang Formation in Zhenjing area,southwestern Ordos Basin,contains typical low-porosity and low-permeability tight sandstone reservoirs.Core observation and logging data analyses of more than 20 wells drilled in the reservoirs were combined with experimental means like microscope and scanning electronic microscope to study the litho-logy and sedimentology of the reservoirs.Results show that the rocks are mainly lithic～arkoses with small amount of feldspathic litharenites.Sedimentary facies are dominated by the subfacie of braided fluvial delta,of which the microfacies-underwater distributary channel and mouth bar-have the best and second best petrophysical properties for hydrocarbon pooling.Analyses of relationship between reservoir physical properties and grain size of sandstone indicate that sandstone is the best in terms of reservoir physical properties.Diagenesis study of the area shows that three factors had played critical roles,namely compaction,cementation and dissolution.Compaction caused porosity(and permeability)of the rocks to decrease to less than 10% at a depth deeper than 2 400 m.Cementation was both destructive and constructive in that it reduced porosity of the rocks but meanwhile it also restrained further compaction and kept the particles apart.Dissolution was favorable for reservoir physical properties as the porosity was greatly improved during two stages of dissolution in deep reservoirs. Reference | Related Articles | Metrics | Comments（0）

Select

Quantitative identification of waterˉflooded zones in conglomerate reservoirs —an example from the Kexia Formation in the Liuzhong block of Karamay oilfield TAN Feng-Qi, LI Hong-Qi, WU Xin, FAN Xiao-Qin, YU Hong-Yan- Oil & Gas Geology    2010, 31 (2): 232-239.   DOI: 10.11743/ogg20100215 Abstract （3320）      PDF（pc） （4240KB）（11728）       Knowledge map    Save The conglomerate reservoirs inKaramay Oilfield have entered the development phase of high waterˉcut after forty years of water flooding. An accurate identification of waterˉflooded zones as well as a quantitative classification of wateringˉout level is the key and difficult issue to be considered in the adjustment of development strategy in this maturing oilfield. This paper documents a study that takes the conglomerate reservoirs in the Kexia Formation of the Liuzhong block as an example. It analyzes factors that affect the reservoir parameters by using the pressure coring data of three wells that were the focus of development adjustment in 2006 and by combining the actual geological characteristics of conglomerate reservoirs. It also selects logs that match well with the geoˉlogical characteristics and production pattern of the conglomerate reservoirs. Models for the interpretation of physical properties，lithology，water production rate，and water drive index of the Kexia Formation are established based on methods like cross plotting and multivariate linear regression. Three parameters，namely the water production rate，the oil saturation，and the water drive index，are chosen to be the main factors for aquantitative determination of wateringˉout level. Combining these factors with qualitative resistivityˉidentification chart for wateredˉout zones，the study offers rules and methods for qualitative identification of wateredˉout zones in this kind of reservoirs. The application of the method to the Kexia Formation yielded a coincidence rate of as high as 84.36%，well beyond the required accuracy. A set of technologies for quantitative identification of wateredˉout zones in conglomerate reservoirs is finally developed to improve the accuracy of wateredˉout zone identification. Reference | Related Articles | Metrics | Comments（0）

Select

Migration mechanism of the Permian hydrocarbon and shale oil accumulation in Malang Sag, the Santanghu Basin Liu Bo, Chi Yaao, Huang Zhilong, Luo Quansheng, Wu Hongzhu, Chen Xuan, Shen Ying Oil & Gas Geology    2013, 34 (6): 725-730.   DOI: 10.11743/ogg20130602 Abstract （344）      PDF（pc） （14034KB）（10577）       Knowledge map    Save The shale oil potential is high in the Permian Lucaogou Formation in Malang Sag,Santanghu Basin.Its genetic mechanism and accumulation patterns are greatly different from those of conventional reservoirs.Migration is a major component of genetic mechanism of shale oil.Based on core and thin section observation,and in combination with geochemical data and geological condition analysis,this paper studied the migration mechanism of shale oil,including dynamic force,pathway,direction,distance,efficiency and so on.Migration effect of shale oil within source rocks is insignificant,thus shale oil reservoirs are not the result of oil migration and accumulation within source rocks.In contrast,vertical migration effect of shale oil out of source rocks is significant.The existence of large active faults may lower the abundance of shale oil in source rock.High formation pressure caused by hydrocarbon generation is the main dynamic force of primary migration.After small scale migration through kerogen network,interlamination and microfractures,most of the oil generated retain in place,and the migration efficiency is very low.On the contrary,in areas where carrier faults are well developed,the oil can migrate vertically along the faults and accumulate in the overlying reservoirs of the Lucaogou Formation.This migration mechanism of shale oil determines the characteristics of shale oil play such as continuous distribution,no obvious oil-water contact,no influence of structure on oil accumulation,and low abundance of oil in areas with active faults. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(3)

Select

Major breakthrough of gas exploration in Yangchang blocks and its significance Wang Xiangzeng Oil & Gas Geology    2014, 35 (1): 1-9.   DOI: 10.11743/ogg20140101 Abstract （280）      PDF（pc） （11424KB）（9807）       Knowledge map    Save The natural gas exploration blocks of Yanchang Petroleum Group(Yanchang exploration blocks)are located in the southeast of Yishan slope of Ordos Basin.The basin has long been believed to be rich in oil in its south part and abundant in gas in its north-a mindset that resulted in pessimistic evaluation data of gas potential in the Upper Paleozoic exploration blocks of the Group.The first real exploratory well for gas was drilled in the area in 2003.Geological data gathered since then have revealed that the blocks sit in the eastern part of the northern Shanbei slope,which is rich in both oil and gas.The reservoirs are dominated by underwater distributary channels and barrier islands,source rocks are widely distributed,and mudstone seals are thick and stable.The gas resource was estimated to be over 750 bcm.Theoretical and technological innovation obtained during exploration in the blocks by the Group had led to the following achievements:(1)A new understanding of gas accumulation is proposed,i.e.gas accumulations are controlled by combination of reservoirs with paleo-fluid migration and accumulation space;(2)A new foam fracturing system(VES-CO2) was deve-loped and tested for the Upper Paleozoic tight gas reservoirs.A proven gas in place of more than 300 bcm and annual gas production capacity of 720 million cm3 were obtained. What's more,the Carboniferous Benxi Formation in the basin was found to be able to produce gas at an absolute open flow of over million cubic meters. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(12)

Select

DIAGENESIS AND PORE EVOLUTION OF UPPER PERMIAN REEFS, EASTERN SICHUAN PROVINCE Lei Bianjun, Qiang Zitong, Chen jigao Oil & Gas Geology    1991, 12 (4): 364-375.   DOI: 10.11743/ogg19910402 Abstract （2531）      PDF（pc） （11089KB）（9322）       Knowledge map    Save During the period of Late Permian, transgression from east to west occurred in Sichuan and its adjacent areas. The Upper Permian Changxing Formation reefs in East Sichuan were pinnacle and patch reefs which climbed on carbonate ramp with tragression. The Changxing reefs underwent five diagenetic environments, i. e. the sea floor,reef ialand tidal flat, subaerial, shallow to moderate burial and deep burial diagenetic environments. However, interreefs and non-reefS had never exposed and undergone meteoric diagenesis. They underwent from sea floor to shallow-moderate burial and deep burial diagenetjc environments. A lot of primary pores of reef rocks (shelter and growth framework voids, intrabiotic pores, interbreccia cavities, etc.) were almost filled by multi-phase cements of sea floor and burial diagenesis. Interreef biogenic debris and lime mud deposits had many micropores that were progressively vanished during burial compression process.Most of the dolomites of a reef body were formed by the replacement of compaction fluids which converged towards and through reefs in burial diagenetic environmemt and have good porosity and permeability. The main reservoir spaces are late solution pores and intercrystalline pores. Related Articles | Metrics | Comments（0） Cited: Baidu(11)

Select

Deposition and sequence stratigraphy of the Silurian Shiniulan Formation in southeastern Sichuan-northern Guizhou province Wang Zhenghe, Tan Qinyin, He Li, Cheng Jinxiang, Wang Ruihua Oil & Gas Geology    2013, 34 (4): 499-507.   DOI: 10.11743/ogg20130411 Abstract （426）      PDF（pc） （12893KB）（9318）       Knowledge map    Save Based on the integrated analysis of seismic,drilling and outcrop data,this paper studied the deposition and sequence stratigraphy characteristics of Shiniulan & Xiaoheba formations in southeastern Sichuan-northern Guizhou pro-vinces.The following results were obtained.The Shiniulan Fm and its underlying Longmaxi Formation compose a separate third-order sequence,and the Shiniulan Formation is part of a high-stand system tract.There are two sub-eustatic sea le-vel cycles in the Shiniulan Formation,so this formation can be further divided into an upper and a lower fourth-order sequence.There are one to two development phases of platform margin reef & bank facies in the high-stand system tract of each fourth-order sequence,but the best platform reef & bank facies lies in the upper one.The bioherms developed during the deposition of the Shiniulan Formation are generally small and in scattered or beaded distribution due to the non-exis-tence of obvious slope break between platform margin and slope as well as the dilution of terrigenous inputs.In the study area,the dolomitization of the Shiniulan Fm is very weak as a whole.It is assumed that the salinity was low in this stage mainly due to factors.The first is the input of fresh water from the central Guizhou Uplift in the south and Xuefeng Uplift in the east.The second is the low amplitude of uplift of platform margin reef & bank.The sedimentary environment of the Xiaoheba Formation in Nanchuan area should be a shallow water constructive delta with low river energy,non-well deve-loped provenance and predominant suspension transport. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(5)

Select

Distribution of large and giant coal-related gas fields in China and its significance Wang Tingbin, Dong Li, Zhang Yaxiong Oil & Gas Geology    2014, 35 (2): 167-182.   Abstract （208）      PDF（pc） （12966KB）（8783）       Knowledge map    Save The majority of gas reserves in China are stored in large and giant coal-related gas fields coal-related gas.Despite the fact of numerous coal-bearing basins in China,there are only a few large-and medium-sized such basins having the right geological conditions for forming large or giant gas fieds.The tectonic geological environments after deposition of coal-bearing strata are thought to be more closely linked to coal-related gas reservoirs:the later the peak gas-generation and reservoiring periods were,the more favorable it was for coal-bearing basins transforming into gas(oil)-bearing basins and forming larege and giant coal-related gas fields.Coal-bearing/gas(oil)-bearing basins of para-foreland type,intracratonic depressions type and marginal rift type are considered to be most promising in terms of exploration for gas.Basins including Ordos basin,central,western and north-eastern Sichuan basin,northern Tarim basin(Kucha depression),Xihu sag in East China Sea basin,Yingqiong basin and northern Chaidan basin as well as those in Sanhu area,northern and southern Junggar basin,the deeper part of Songliao basin,basins in deep water area of northern South China Sea,will still be the major hope for near and middle term gas reserve growth in China for the century. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

ESTABLISHMENT OF GEOLOGICAL MODEL FOR LABYRINTH DIFFLUENCE CHANNEL SAND BODIES IN YOUSHASHAN OILFIELD, QINGHAI Lin kexiang, Zhang Changmin, liu Huaibo, Lei Bianjun, Qu Pingyan, Ma Wenxiong, Let Bingzu, Tang Ruiying Oil & Gas Geology    1995, 16 (2): 98-109.   DOI: 10.11743/ogg19950202 Abstract （1027）      PDF（pc） （10652KB）（8199）       Knowledge map    Save The diffluence channel sand bodies of K2-K1-3 key horizones placed on the bottom of Pliocene lower Youshashan Formation in Youshashan Oilfield,Qinghai have developed into a deltaic labyrith reservoir frame. The frame prototype of outcropped sand bodies may be considered as the evidence in establishing underground prediction model.This means that data obtained from outcrops of the sand bodies including reservoir structure,the density and geometry(the ratio of width to thickness)of the sand bodies,regional paleocurrent direction,the ratio of total areas of prototype frame models of outcrops,the ratio of the area for sand bodies with different thickeness were used to establish the predictive transverse model, predictive plane model and permeabality model of the sand body frames.According to the prediction results.half of the reservoiring sand bodies have ever beed drilled yet. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

Overview of separate injection technique for polymer flooding in Daqing oilfield Li Haicheng Oil & Gas Geology    2012, 33 (2): 296-301.   DOI: 10.11743/ogg20120216 Abstract （2665）      PDF（pc） （2530KB）（7356）       Knowledge map    Save Three separate injection technologies for different stages of development are developed in Daqing oilfield,including concentric separate-injection,eccentric separate injection,and separate-layer molecular injection.The concentric separate-injection technology controls injection rate of each layer by using concentric injection allocator which regulates injection pressure.The eccentric separate injection technology controls injection rate of each layer by using eccentric injection allocator to generate enough differential choke pressure to regulate injection pressure.The separate-layer molecular injection weight technology controls injection rate of each layer by using molecular weight regulator or pressure regulator chosen according to reservoir property.This paper described in-detail their process principles,technical parameters,application scale and their effects et al.According to the actual stages of polymer injection in the oil field,this paper presents the rational timing and principles of separate injection as well as the corresponding test cycles.In addition,the principles for selection of separate injection technologies are also proposed according to the types of pay zones.Short clamping distance of the polymer injection technology and efficient measurement technology of separate injection wells in the polymer flood oilfield are the key research direction in Daqing oilfield. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(7)

Select

Form ing conditions and characteristics of shale gas in the Lower Paleozoic of the Upper Yangtze region，China DONG Da-Zhong, CHENG Ke-Ming, WANG Yu-Man, LI Xin-Jing, WANG She-Jiao, HUANG Jin-Liang Oil & Gas Geology    2010, 31 (3): 288-299,308.   DOI: 10.11743/ogg20100304 Abstract （2552）      PDF（pc） （10294KB）（5493）       Knowledge map    Save W ith focus on the sedimentary，geoˉchem istry，reservoir，and gas potential，a prelim inary study is perˉformed on the form ing conditions and characteristics of the shale gas in the Lower Silurian Longmaxi Formation and the Lower Cambrian Qiongzhu Formation in the Upper Yangtze region by using outcrop，drilling，and core data.The results indicate that an Early Paleozoic shallowˉdeep water shelf sedimentary environment controlled the development and distribution of the organicˉrich black shale in the formations.The black shale is the thickest in the depocenter on the deep water shelf.TheirTOC values are generally high.Horizontally，the distribution of organic rich black shale（TOC>2%）is in accordance with that of the shelf.In contrast，vertically，theymainly occur in the m iddleˉlower and bottom parts of the formations and have a continuous thickness of30-50m and a TOC value over4%.Being sim ilar to the gasˉbearing shale in America，the black shale is rich in brittlem ineˉrals，but unitary in clay m ineral type，and contains no smectite.The matrix contains wellˉdeveloped pores and m icroˉfissures，occurring in threadlike，netted and honeycomb shapes.The measured porosity of core samples ranges from2%to16%，indicatingmoderate poroperm characteristics.Active gas shows occur during drilling in the black shale.Gas content of core samples is above the industrial development threshold.Isothermal adsorption simulation of the samples also shows a high methane adsorption capacity.The overall gas potential is sim ilar to Related Articles | Metrics | Comments（0）

Select

Mud debris flow fan deposits in Dainan Formation of the Subei Basin Liu Yurui Oil & Gas Geology    2017, 38 (3): 419-429.   DOI: 10.11743/ogg20170301 Abstract （234）      PDF（pc） （2046KB）（5419）       Knowledge map    Save Several features such as sedimentary system,lithology and lithofacies and sandbody distribution in the Dainan Formation of Subei half-graben fault basin neither follow the general patterns of the half-graben faulted basins in Eastern China,nor follow the common patterns that trench belts are the main locations where fans and sandbodies occur in continental basins.Through a large number of core data observation,it is found that there is a special type of sedimentary rock composed of sand grade coarse debris of mudstone,which shows a certain universality and regularity.The special lithologic section is comprehensively identified on the basis of core observation and description and in combination with the thin section observation,paleontological assemblage and some peculiar phenomena of logging responses.The study shows that this set of strata belongs to fans resulted from mud debris flow,a type of gravity flow.The fan bodies can be divided into 3 belts including root-fan,middle-fan and outer-fan.Laterally,this kind of fan develops in the slope break zone of faulted lake basins which is trench zone of lacustrine basin.Vertically,these fans are mainly found in LST of the Dainan Formation of Subei fault basin.No such fans occur in TST,and some occur in HST.Subei half-graben fault basin was formed in a special geological setting.A large complete depressed lake basin in the lower tectonic zone disintegrated into several mutually separated half graben fault depressions.Multi factors including confining of thick mudstone in the 4th Member of Funing Formation,old and new dual provenances,tectonic difference,various transportation flow patterns and mutiple types of slope break zones coupled together and controlled the sedimentary characteristics of Dainan Formation.The rules are found that the mud debris flow fans and mud-rich fans are developed in slope break zone on the concave side of fault depression and sand-rich fans occur in slope break zones on the convex side of the fault depression. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(2)

Select

Hydrocarbon pooling features and seismic recognizing technologies of small complex fault blocks in Subei basin Mao Fengming, Chen Anding, Liu Yurui, Yan Yuanfeng, Ye Saodong, Liu Qidong, Chen Liqiong, Tan Yan Oil & Gas Geology    2006, 27 (6): 827-840.   DOI: 10.11743/ogg20060614 Abstract （961）      PDF（pc） （15912KB）（4811）       Knowledge map    Save Subei basin is composed of small half grabens and features in closely-spaced faults,small traps,and homogeneous hydrocarbon abundance.Hydrocarbon pooling in Subei basin has the following characteristics:(1)The Late Eocene is the pooling period;(2)Hydrocarbon expulsion of source rocks is unilateral;(3)The migration and accumulation styles are different in the Eocene fault depression and the Palaeocene depression.The Eocene fault depression has small and isolated sandbodies,where hydrocarbons accumulate through vertical migration along the faults,the pools are distributed in the deep depression and occur vertically in multiple layers along the faults,and are dominated by structural-lithologic reservoirs.While the depression develops large delta sandbodies,hydrocarbon generation and accumulation occurring in the same layer and hydrocarbon migration is active.The pools mainly occur in the slope and uplift zones and are dominated by structural reservoirs.(4)Hydrocarbon enrichment is mainly controlled by source rock maturity,physical properties of sandbodies and sealing of the faults.The upper source-reservoir-cap rock combination is controlled by hydrocarbon migration,and the middle and lower combinations are controlled by the development of carrier beds and traps.To deal with the exploration of small complex fault block reservoirs,a set of technologies concerning seismic acquisition,processing,and interpretation,have been developed and improved. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(30)

Select

Accumulation conditions of tight sand gas in the 3rd member of the Shahejie Formation in Nanpu Sag, Bohai Bay Basin Guo Jigang, Dong Yuexia, Pang Xiongqi, Huang Hongxiang, Jiang Fujie, Xu Jing, Wang Pengwei, Peng Weilong Oil & Gas Geology    2015, 36 (1): 23-34.   DOI: 10.11743/ogg20150104 Abstract （290）      PDF（pc） （10947KB）（4712）       Knowledge map    Save Based on analyses of the source rocks and reservoirs in the Es3 (the 3rd member of Shahejie Fm), the hydrocarbon expulsion history was restored with the hydrocarbon generation potential method, and evolution history of reservoir porosity was established through numerical modeling.The results show that accumulation conditions of tight sand gas in the Es3 in the Nanpu Sag of the Bohai Bay Basin are pretty good: fair-good source rocks and widespread reservoirs were closely connected with each other, and the timing of gas accumulation and reservoir tightening was favorable.The peak gas expulsion occurred from the Guantao to early Minghuazhen, while the reservoir tightening was from the late Guantao to early Minghuazhen.These gases might accumulate in the lenticular sand body near the source rocks under the force of gas expansion, forming continuous tight sand gas reservoirs. Reference | Related Articles | Metrics | Comments（0）

Select

Tectonic-sedimentary characteristics and their influences on the forming of lithologic hydrocarbon reservoirs in the Shichang Subsag of the Nanpu Sag Liu Junrong, Wang Xiaowen, Zhao Zhongxin, Zhang Lei, Li Jie, Lu Pengfei Oil & Gas Geology    2014, 35 (5): 601-608.   DOI: 10.11743/ogg20140503 Abstract （315）      PDF（pc） （14279KB）（4670）       Knowledge map    Save Shichang Subsag of Nanpu Sag is an old exploration and development area of Jidong Oilfield,the its main structural reservoir has been proven,and put into development.The next is to find new areas torelay.In this paper,the lithologic reservoir accumulation mode is established through research and analysis of tectonic evolution,sedimentary system and their controlling role on lithologic traps.That provides a theoretical basis for future exploration.In the early Shahejie Formation(Es)period,the provenance was mainly from the bulge on the upthrown side of Baigezhuang fault in the east of subsag.There existed multiple fan-delta systems along the Baigezhuang downthrown side and they prograded far towards the subsag center.Meanwhile,small fan-delta,shallow lake and semi-deep lake sediments distributed along the downthrown side of Xinanzhuang faults in the west.In the late Es,the activity of Baigezhuang fault leaded to the inversion of early strata attitute.And the early downlap sandbody pinched on the slope, forming a updip pinchout type deposition mode.These sand bodies and sub-sag cooperated with west uplift tectonic introversion to form the updip pinchout trap,which formed the most important lithologic reservoirs in Shichang Subsag.These reservoirs have the characteristics of multi-strata-enrichment,large-scale and multi-oil-water systems. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(4)

Select

Tectonic-sedimentary constrains for hydrocarbon generating organism assemblage in the Lower Cambrian argillaceous source rocks, Tarim Basin Hu Guang, Liu Wenhui, Tengger, Cheng Qianglu, Xie Xiaomin, Wang Jie, Lu Longfei, Shen Baojian Oil & Gas Geology    2014, 35 (5): 685-695.   DOI: 10.11743/ogg20140514 Abstract （281）      PDF（pc） （13035KB）（4291）       Knowledge map    Save Hydrocarbon generating organism is an important object for the source rock research.The studies,so far,were focused on their hydrocarbon-generation potential via simulation experiments,and less attention was paid to the geological settings that affect development and distribution of hydrocarbon generating organisms.However,the development and distribution of hydrocarbon generating organisms is very important for predicting source rocks and guiding petroleum exploration.In this study,the Lower Cambrian Xishanbulake and Yuertus formations were selected from the Southern Yaerdangshan and Dongergou sections in Kuluketage and Keping districts,respectively.Researches on two formations demonstrate that the hydrocarbon generating organisms in the Xishanbulake Formation are dominated by benthic algae,and include some planktonic algae;whereas hydrocarbon generating organisms in the Yuertusi Formation are benthic algae.Anomaly of elements Ce and Eu and REE patterns of cherts in the two formations imply that the two sections were affected by hydrothermal fluid,and that the influence in the Southern Yaerdangshan section was stronger than that in the Dongergou section.Major and trace elements analyses of mudstones indicate that the Xishanbulake Formation have less reduction water,and more active volcano in the Kuluketage district which might be resulted in more undulating terrain than that in the Keping district during the Early Cambrian.Correlated with distribution of extant algae,it could be concluded that the difference in tectonic activity,water depth,and paleo-terrian may be the major cause for the difference in hydrocarbon generating organism assemblages between the Xishanbulake Formation in the Southern Yaerdangshan section and the Yuertus Formation the Dongergou section. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(20)

Select

Matching between sandstone tightening and hydrocarbon accumulation of the Xujiahe Formation,Guanyinchang area in southern Sichuan Basin Zhang Xiang, Tian Jingchun, Du Benqiang, Xia Jiwen, Gu Na, Lin Xiaobing, Deng Feiyong, Liang Yuchen Oil & Gas Geology    2014, 35 (2): 231-237.   Abstract （224）      PDF（pc） （19381KB）（4182）       Knowledge map    Save Tight sandstone reservoir of the Xujiahe Formation in Guanyinchang area mainly consists of delta plain distribu-tary channels sandbodies.Based on analyses of reservoir diagenesis and tightening,detailed study shows that the hydrodynamic conditions during sedimentation determine the storage capacity of reservoirs.Strong compaction is the major factor causing the decrease of inter-particle primary porosity,and quartz overgrowth in diagenetic stage is the key factor causing the tightening of reservoir.The temperatures of fluid inclusions in quartz overgrowth is between 82.5-125.1 ℃,accor-ding to which the tightening depth is estimated to be between 1 725-2 864 m.This depth interval corresponds to the period of Yanshan movement.According to analysis of the tightening process and hydrocarbon accumulation stages in the Xujiahe Formation sandstone reservoir,the following understandings were obtained.The sandstone reservoir was not tightened at the initial phase of gas accumulation,so gas could migrate long distance laterally.Before the peak gas accumulation,the sandstone reservoir had become tight,thus the gas could not migrate laterally for a long distance,instead,they migrated along the unconformity of channel and microfractures opened by high pressure.of the composite structural and lithologic gas reservoir got finalized during Himalayan epoch,and the gas reservoir was controlled by both lithology and structures,so their heterogeneity was strong. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(11)

Select

Hydrocarbon enrichment pattern and exploration potential of the Ordovician in Shunnan area, Tarim Basin Yun Lu, Cao Zicheng Oil & Gas Geology    2014, 35 (6): 788-797.   DOI: 10.11743/ogg20140606 Abstract （359）      PDF（pc） （19995KB）（4175）       Knowledge map    Save Shunnan area lies in the north slope to the down-thrown blocks of Tazhong No. 1 fault in Katake Uplift, and is adjacent to the hydrocarbon kitchen of Manjiaer Depression. The study area has regionally good cap rocks, and remains a slope for a long geological period, thus it is the main area where hydrocarbons migrate to and accumulate in. Multi-group NE-trending faults developed here were conducive to reservoir development and hydrocarbon accumulation, all such provide the favorable conditions for the formation of large oil and/or gas fields. Multi-period tectonic movements from the Caledonian to Hercynian controlled development of the multilayer and multiphase carbonate reservoirs. With tectonic movements and sea level fluctuations, the Ordovician carbonate rocks experienced multi-period exposure and led to the formation of karst reservoirs. The reservoirs were reconstructed by meteoric water and deep thermal fluids through faults, resulting in fractured-vuggy reservoirs. In brief, reservoirs determined the scale of hydrocarbon accumulation, and the strike-slip faults restricted the hydrocarbon accumulation zones. Geochemical analysis shows that the natural gas is dry gas with high maturity in Shunnan, and its accumulation period was the Himalayan. The natural gas in Shunnan area features in highly variable ln(C1/C2)value but low variable ln(C2/C3) value, a character obviously differing from that of cracked gas. The inclusions in several wells are dominated by methane gas inclusions, but rare bituminous gas phase inclusions and bitumen inclusions, indicating kerogen cracking origin. Analyses of drilling and test data reveal that the Ordovician carbonate gas accumulation is likely to be a large fractured-vuggy gas reservoir cluster featuring in vertical superimposition, lateral connection, high gas column and strong control of reservoir heterogeneity. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(28)

Select

Calibration method of shale petrological facies and its application in Fuling area,the Sichuan Basin Peng Yongmin, Long Shengxiang, Hu Zongquan, Du Wei, Gu Zhixiang, Fang Yu Oil & Gas Geology    2016, 37 (6): 964-970.   DOI: 10.11743/ogg20160618 Abstract （281）      PDF（pc） （1642KB）（4089）       Knowledge map    Save Petrological facies calibrations were performed on shale of horizontal wells in Fuling,Sichuan Basin,based on geological and well-logging characteristic marks,and specialized petrological facies.In accordance with the three key marks (lithological combination,calcareous content and siliceous content),the whole set of 89-meter-thick shale interval in the typical pilot wells of the Lower Silurian Longmaxi Formation in Fuling were divided into nine different types of petrological facies.The No 1,3 and 6 petrological facies were identified as specialized petrological facies based on geological marks like marker beds,carbon dyes and silty laminae as well as logging marks such as logging response anomaly,the types of logging curve shape,excavation effect and pseudo excavation effect.We compared the results of projected well-logging information through horizontal section-based vertical projection with characteristic marks and specialized petrological facies in typical pilot wells to determine the top and bottom boundaries of the petrological facies and accomplished the calibrations.The relationship between petrological facies and the post-fracturing tested productivity was used to identify the petrological facies in prolific horizontal wells.It was found that the petrological facies with high calcareous and silica contents (No.1 and 3 facies with) have the greatest productivity potential,thus were determined to be the best petrological facies.Based on the principle of the best petrological facies,we suggest the best trajectory of horizontal well or landing point of target window be between the No.1 and 3 facies.Application of the calibration method to Fuling shale gas field were positive,with the coincidence rate between the predicted and tested productivities being more than 80%,proving it a potential method for optimizing well trajectory design and increasing single-well production. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(2)

Select

Main control factors and distribution prediction of high-quality carbonate reservoirs in the Nanpu Sag, Bohai Bay Basin Cao Zhonghong, Zhang Hongchen, Liu Guoyong, Ren Miaosong, Fu Jiang, Wang Enze Oil & Gas Geology    2015, 36 (1): 103-110.   DOI: 10.11743/ogg20150113 Abstract （283）      PDF（pc） （19560KB）（4028）       Knowledge map    Save Hydrocarbon accumulation conditions of carbonate buried-hill are favorable in Nanpu Sag, and hydrocarbon enrichment is controlled by multiple factors like stratigraphy, structure and reservoir.Development and distribution of quality reservoir are the focus of the research.In-depth analysis of drilling, logging, core and other data reveals that the main reservoir type is fractured-vuggy carbonate reservoirs in Nanpu Sag, with dissolution pores and vugs as the dominant reservoir space and fractures as the main channels connecting the pores and vugs.Carbonate sedimentary facies zones, diagenesis (including karstification), and tectonic process are the main factors controlling on the development of high-quality carbonate buried-hill reservoirs.The favorable sedimentary facies are the basis of reservoir development, the favorable diagenetic epigenesis is the guarantee of reservoir development and the favorable tectonic process is the key to reservoir development.The precision of reservoir prediction is significantly improved through comprehensive seismic and geological reservoir prediction based on layer subdivision. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(10)

Select

Dating of hydrocarbon accumulation by fluid inclusion characteristics in the Chang9 of Yanchang Formation in Jiyuan area, the Ordos Basin Shi Baohong, Zhang Yan, Zhang lei, HuangJing, Tang Chao Oil & Gas Geology    2015, 36 (1): 17-22.   DOI: 10.11743/ogg20150103 Abstract （331）      PDF（pc） （18922KB）（3855）       Knowledge map    Save Chang9 oil layer of the Triassic Yanchang Formation is a key horizon for reservoir development in Jiyuan area, Ordos Basin.The characteristics of fluid inclusions in Chang9 reservoir in Jiyuan area were analyzed systematically based on the measurements of Fourier transform infrared spectroscopy, fluorescence spectroscopy, and homogenization temperature to determine, in combination with the burial-thermal history, the phases and periods of hydrocarbon migration and accumulation.The results show that there are two types of hydrocarbon inclusions in the reservoir of Chang9, namely liquid hydrocarbon inclusions and gas liquid hydrocarbon inclusions with green or yellow-green fluorescence.The homogenization temperature of brine inclusions associated with the hydrocarbon inclusions has a continuous distribution with a 100-120 ℃ peak value.Salinity distribution is relatively concentrated with a peak value of 3-5 wt%NaCl.These cha-racteristics indicate that there is one major phase of oil migration and accumulation in the study area.Consistently, fluorescence spectroscopy and Fourier transform infrared spectroscopy data demonstrate that the Chang9 reservoir has undergone one phase of hydrocarbon charging with high organic matter maturity, with yellow-green and green fluorescence, corresponding to the fluorescence spectrum of 495nm.The analysis of burial and thermo-evolutionary history of Chang9 oil layer show that the hydrocarbon charging occurred mainly in mid-late stage of the Early Cretaceous. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(8)

Select

Models of contemporaneous fault controlling sandstone deposition：a case study of Es1 in southern Nanpu Sag Yang Xiaoli, Zhang Zili, Sun Ming, Shi Wenwu, Li Ruisheng Oil & Gas Geology    2014, 35 (4): 526-533.   DOI: 10.11743/ogg20140412 Abstract （298）      PDF（pc） （14493KB）（3766）       Knowledge map    Save Temporal-spatial differences of syndepositional tectonics have profound impact on accommodation space,sedimentation rate,types and distributional characteristics of provenance systems of a basin.Episodic tectonic movement of the Nanpu Sag is a major contributor to accommodation space.Several NE-SW-trending contemporaneous faults that were developed in the period of Es in the southern provenance enhanced the compartmentalization of lake basin.A series of echelon growth faults extending toward the basin controlled the distribution of the Shahejie Formation.The linear subsags with the same strike as the growth faults formed in the downthrown blocks are the main unloading areas for sediments.The main depositional system is the combination of braided river delta,infralittoral subaqueous fans,beach bar and lake system in the southern provenance.On this basis,a model of contemporaneous fault controlling sandstone distribution is established in southern Nanpu Sag.The contemporaneous faults stretching into the lake basin controlled the sandstone distribution of braid river delta,with lobate deposits occurring laterally along strikes on the downthrown blocks of faults and superimposing vertically in the shape of wedges.The favorable objectives for future exploration are braided river delta,infralittoral subaqueous fans at the distal end of these deltas,and the beach bars developed on the tilted blocks. Reference | Related Articles | Metrics | Comments（0）

Select

Fluid inclusion types and their geological significance in petroliferous basins Liu Dehan, Xiao Xianming, Tian Hui, Lu Jialan, Min Yushun Oil & Gas Geology    2008, 29 (4): 491-501,478,484.   DOI: 10.11743/ogg20080412 Abstract （1019）      PDF（pc） （10739KB）（3619）       Knowledge map    Save This paper presents a systematic nomenclature and taxonomy for fluid inclusions.Three groups of inclusions,namely the hydrocarbon inclusions,hydrocarbon-containing inclusions,and aqueous/non-hydrocarbon inclusions ,have been recognized based on microscopic fluorescence and transmitted light properties of inclusions.The hydrocarbon inclusions can be further divided into nine types based on their composition and phase characteristics :liquid hydrocarbon-liquid-gaseous hydrocarbon inclusions,gaseous hydrocarbon inclusions,bitumen-containing inclusions,hydrocarbon-bearing aqueous inclusions,hydrocarbon-bearing gaseous inclusions,liquid phase aqueous inclusions,two-phase aqueous inclusions,non-hydrocarbon gaseous inclusions,and childmineral-bearing aqueous inclusions.The liquid hydrocarbon-liquid-gaseous hydrocarbon inclusions can also be divided into four subclasses:heavy-oil inclusions,medium-oil inclusions,light-oil inclusions,and condensed oil inclusions.In addition,the paper also focuses on the distribution patterns of hydrocarbon inclusion in reservoirs, source rocks,and carrier beds,and the geological application of these fluid inclusions to the generation,migration,accumulation,and evolution of hydrocarbon. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(34)

Select

Seismic anisotropy of shale gas reservoirs in the 5th member of the Xujiahe Formation in western depression of Sichuan Basin Xu Tianji, Yan Lili, Cheng Bingjie, Tiang Jianming, Li Shuguang, Yang Zhenwu Oil & Gas Geology    2015, 36 (2): 319-329.   DOI: 10.11743/ogg20150218 Abstract （273）      PDF（pc） （13902KB）（3444）       Knowledge map    Save The huge gas potential in the 5th member of the Xujiahe Formation has made it one of the hottest exploration targets in China.However,the formation has not been well explored and many geological “mysteries” remained unsolved-anisotropy of the gas reservoirs there is one of them.A research was carried out on the anisotropy to better understand the reservoirs features and accumulation patterns,so as to improve the precision of reservoir prediction and success rate of well drilling.Previous study shows that the member had been controlled by sedimentary environment and formed lithologic assemblage dominated by thick mudstone and shale and thin tight sandstone.Looking horizontally,the shale varies drama-tically and shows strong anisotropy due to complicated mineral combination,directional alignment of detrital grains,cyclic veneer and other heterogeneous features.There have had no effective method for analyzing and predicting the anisotropy so far.Available methods are mostly based on seismic data to obtain anisotropy information of rocks through analyses of seismic reflection and the direct responses of azimuth attributes upon rock types,physical features and structure configurations.Comparatively speaking,anisotropy feature of shale formations is likely to be ignored by isotropy analyses based solely on stacked wide-azimuth seismic data.By combining both the azimuth and wide-azimuth stacked seismic data,we compared and analyzed the seismic reflection responses,curvature attributes,coherence attributes and impedances of the two sets of data,and then captured features of reservoir space under the guidance of the anisotropy information.A fine interpretation of sedimentary facies,lithology and fracture of the reservoirs and an accurate prediction of sweet spots in the member were then achieved by applying the above-mentioned method and data yield from it. Reference | Related Articles | Metrics | Comments（0）

Select

Main factors controlling hydrocarbon accumulation in northern subsag belt of the Zhu-1 Depression，Pearl River Mouth Basin Liu Zhifeng, Wu Keqiang, Ke Ling, Wang Shenglan, Yu Kaiping, Zhu Wenqi Oil & Gas Geology    2017, 38 (3): 561-569.   DOI: 10.11743/ogg20170316 Abstract （227）      PDF（pc） （1724KB）（3345）       Knowledge map    Save The dry wells in northern sub-sag belt of the Zhu-1 Depression,indicates that the "source" and "migration" account for a large proportion of well failure and are the two key controlling factors of hydrocarbon accumulation.For the source presence,based on seismic facies and geochemical analysis,five of the eight subsags,developing deep or semi-deep lacustrine source rocks,are identified to be favorable for hydrocarbon generation.For the migration,according to structural belt analysis on the plane view,five subsags in northern subsag belt feature gentle slope belt favorable for hydrocarbon enrichment.In vertical perspective,according to analysis of faults and Enping Formation mudstone sealing conditions of the five subsags,three of them belong to the shallow strata sealing type and the other two belong to the deep strata sealing type,favorable for shallow and deep accumulations respectively. Reference | Related Articles | Metrics | Comments（0）

Select

Characteristics of different types of glauconite and their classification systems Zhang Qin, Mei Xiaohan, Xie Yinfu, Wang Quanxin, Li Chenxi, Yang Xiaofa, Du Huiyao, Lu Jiajing Oil & Gas Geology    2016, 37 (6): 952-963.   DOI: 10.11743/ogg20160617 Abstract （478）      PDF（pc） （14218KB）（3258）       Knowledge map    Save Origin and classification of glauconite,a typical kind of sedimentary facies indicator,have long been the hot topics of mineralogy and sedimentology.This paper investigates the characteristics of autochthonous,parautochthonous and allochthonous glauconite,and documents its classification systems and genesis based on previous researches on the genesis of glauconite and a large number of case studies of glauconite worldwide.Several hypotheses have been proposed to interpret the genesis of autochthonous glauconite.The results suggest that the grain verdissement and pseudomorphic replacement hypotheses are applicable for the interpretation of the genesis of granular and autochthonous glauconite in the microscopic pores of shale,but are inapplicable for the interpretation of the formation of glauconite cement in intergranular pores in sandstones.Different types of glauconite show significant differences in elemental composition,maturity,morpho-logy and hosting environment.Autochthonous glauconite tends to accumulate in a thin layer of condensed section,and shows high maturity.Its element-composition features,thus,are symptomatic of depositional environment.Parautoch-thonous glauconite is characterized by multi-stage involucrums.Detrital glauconite generally accumulates in sandstones with large-scale bedding structure,and is commonly oval or granular.Its element-composition features cannot be used as the indicators of sedimentary environments.New classification systems are proposed to replace the current confused classification systems of glauconite.The glauconites are divided into "primary" vs."secondary" classes and "autochthonous" vs."allochthonous" categories,according to two main criteria (i.e.,genesis and whether removing from the initial formation place).An authigenic precipitation and cementation theory is proposed to interpret the genesis of glauconite that shows shapes of cement,halo edge and involucrum.Moreover,the existence of the authigenic glauconite cement is proved by a large number of case studies.Glauconite,therefore,plays a significant role in diagnosis sedimentary environment,rock dating and improving reservoir physical properties. Reference | Related Articles | Metrics | Comments（0）

Select

Influences of hydrocarbon charging and overpressure on reservoir porosity in Kela-2 gas field of the Kuqa Depression,Tarim Basin Guo Xiaowen, Liu Keyu, Song Yan, Zhao Mengjun, Liu Shaobo, Zhuo Qinggong, Lu Xuesong Oil & Gas Geology    2016, 37 (6): 935-943.   DOI: 10.11743/ogg20160615 Abstract （238）      PDF（pc） （4242KB）（3053）       Knowledge map    Save In order to investigate the factors controlling reservoir porosity in the Kela-2 gas field of the Kuqa Depression,Tarim Basin,the sandstone reservoir characteristics,the origin of overpressure,as well as the evolution of the reservoir charging history were studied by using quantitative grain fluorescence and fluid inclusion data.The research results indicate that horizontal tectonic compression played an important role in the overpressure generation in the Kela-2 gas field.The overpressured presalt sandstone reservoirs with the maximum paleoburial depth over 6 000 m have anomalously high primary porosities.The reason is that the cementation of the sandstone was influenced and even undercompaction occurred as the oil charged into the sandstone reservoirs was not expelled under the efective sealing of salt and gypsum cap rocks in the Kela-2 gas field.This is evidenced by that sandstone reservoirs with high intensities of Quantitative Grain Fluorescence (QGF) and QGF on extract (QGF-E) are associated with high porosity and permeability intervals,and sandstone units below the ancient oil-water contact have low porosity and permeability.Late oil charging occurred at the early period of the Kuqa Formation deposition and the corresponding sandstone reservoirs in the Kela-2 gas field had shallower burial depth and high primary porosities.This research suggests that the oil charging and overpressure played important roles in the development of reservoirs porosity. Reference | Related Articles | Metrics | Comments（0）

Select

Application of geostatistical inversion to thin reservoir prediction Wang Xiangwen, Liu Hong, Teng Binbin, Wang Lianyu Oil & Gas Geology    2012, 33 (5): 730-735.   DOI: 10.11743/ogg20120509 Abstract （1444）      PDF（pc） （599KB）（3037）       Knowledge map    Save Taking M1 thin reservoir in H-N oilfield,Southern Ecuador,as an example,this paper documents the challenges and problems of thin reservoir prediction and presents relevant techniques and methods to tackle these problems.Based on analysis of geophysical characteristics of reservoirs and surrounding rocks,a geostatistical inversion technique is applied in this case to identify the thin(1-25 ft)reservoirs with rapid lateral changes and strong concealment.Sand distribution is refined through correlation between different data volume including seismic interpretation,CSSI(Constrained Sparse Spike Inversion)and geostatistical inversion,and is further checked by non-well,random-wells and newly drilled wells.The accuracy of thin reservoir prediction is greatly enhanced to a vertical resolution up to 5 ft.This technique is successfully applied in H-N oilfield and the new drilling data show that all the prediceted thin sand layers are encountered and the drilling coincidence rate is 82%. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(37)

Select

Influence of tectonic movement on Cretaceous carbonate reservoirs in the Zagros Foreland Basin: A case study of Y oilfield Tang Ying, Fan Tailiang, Zhang Tao, Wang Zhe, Zheng Yuanchao Oil & Gas Geology    2016, 37 (6): 944-951.   DOI: 10.11743/ogg20160616 Abstract （266）      PDF（pc） （8710KB）（2941）       Knowledge map    Save On the basis of drilling cores,thin sections,imaging logging and 3D seismic data,the study discusses the effects of tectonic movement on diagenesis,fractures development and hydrothermal fluid activities of carbonate reservoirs in Y oilfield of the northeastern Zagros Foreland Basin.Tectonic movements from the late Cretaceous to the Holocene have most significant effect on the Cretaceous carbonate reservoirs in Y oilfield.During this period,because of compressional uplift,target strata were heavily eroded and weathered,which leads to development of an unconformity surface.Reservoirs below the surface suffered from severe dissolution.With the collision between Arabian plate and the Eurasian plate,and resultant folding and thrusting induced formation of fractures within reservoirs.Density and location of fractures were influenced by the intensity of folding and faulting,but also related to lithology.Fractures were mainly developed in the area around faults,and along fold axis or the lower end of fold limbs.In terms of lithology,fracture density in dolomite is obviously higher than that in limestone.Tectonic movements also controlled the hydrothermal fluid activities in Y oilfield.The faults are the main pathways of hydrothermal fluid into Y oilfield.Hydrothermal dolomitization occurred in grabens close to faults or fracture zones.Discussing the influence of tectonic movements on carbonate reservoir is beneficial for predicting and locating high-quality reservoirs in the study area,and optimizing production deployment of the oilfield. Reference | Related Articles | Metrics | Comments（0）

Select

Characteristics and genesis of Mid-Triassic Leikoupo Formation reservoirs, Northeastern Sichuan Basin Qin Weijun, Zou Wei Oil & Gas Geology    2012, 33 (5): 785-790,795.   DOI: 10.11743/ogg20120516 Abstract （1290）      PDF（pc） （718KB）（2938）       Knowledge map    Save The overall sedimentary environment of the Mid-Triassic Leikoupo Formation in the Northeastern Sichuan Basin is dominated by evaporite platforms where a set of thick and wide-spreading evaporites predominantly of gypsums and dolomites were deposited.The Leikoupo Formation can be subdivided into four members.The seismic responses of the fourth member feature in weak amplitude,low frequency and relatively continuous reflection configuration.Most reservoir rocks within the fourth member are type-III of low permeability,some of them show characters of type-II.Their pore spaces are dominated by caverns,dissolution-widened fractures and structural fissures.The development and distribution of the reservoir rocks in the member were controlled by both sedimentary facies and weathered crust.Dolomites of platform evaporate facies and lagoon facies in the study area were exposed and eroded into weathered crust during the last period of the Leikoupo Formation deposition.In addition,the dolomites also experienced leaching and corrosion of meteoric water along unconformities and fractures,resulting in a set of high-quality reservoir rocks. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(4)

Select

Productivity index prediction of alluvial fan coarse-grained clastic reservoirs with low porosity and low permeability：a case from Triassic Baikouquan Formation reservoir in Y-region at northwestern margin of Junggar Basin Ren Tao, Wang Yanchun, Wang Renchong Oil & Gas Geology    2014, 35 (4): 556-561.   DOI: 10.11743/ogg20140416 Abstract （272）      PDF（pc） （3036KB）（2924）       Knowledge map    Save In order to use 3D seismic data for productivity index prediction of alluvial fan coarse-grained clastic reservoirs with low porosity and low permeability,we chose the Triassic Baikouquan Formation reservoir in Y-region at the northwestern margin of Junggar Basin as a case.Based on traditional reservoir prediction such as thickness and porosity of coarse-grained clastic reservoirs,we analyzed in detail factors influencing permeability and oil-bearing properties,and introduced the average monthly production data at the early stage of development into 3D seismic inversion to predict the productivity index.The following work flow was established:‘finding coarse-grained clastic reservoirs through typical curve inversion,finding high quality coarse-grained clastic reservoirs through porosity inversion,finding permeable coarse-grained clastic reservoirs through spontaneous potential inversion,finding oil-bearing coarse-grained clastic reservoirs through resistivity inversion,and predicting reservoir productivity index with the combination of several methods’.A productivity index cube was finally generated through Neural Network modeling by using the monthly productivity as hard data and wave impedance,porosity,resistivity,spontaneous potential inversion data cube and time domain structure as trai-ning samples.The result shows that there is a positive correlation(R2=0.948 7)between the predicted monthly productivity and initial average monthly production.For wells with an initial monthly average production more than 300 ton,the error of prediction is less than 10%.The data cube contains various information controlling hydrocarbon distribution,such as lithology,reservoir property,oil-bearing property and permeability.The oil production of three appraisal wells deployed based on this research in Y-region reached more than 5 ton per day,which verified the accuracy and practicability of this productivity index prediction technology. Reference | Related Articles | Metrics | Comments（0）

Select

Characterization of the pore space in tight sandstone reservoirs from macroscopic and microscopic perspectives: A case study of Gaotaizi reservoir in Qijia area,the Songliao Basin Li Yilin, Zhang Yunfeng, Yin Shuli, Cong Lin, Yan Ming, Tian Xiaoxiong Oil & Gas Geology    2016, 37 (6): 915-922.   DOI: 10.11743/ogg20160613 Abstract （243）      PDF（pc） （27327KB）（2919）       Knowledge map    Save Comprehensive analyses are conducted to characterize the Gaotaizi tight reservoir in Qijia area from macroscopic and microscopic perspectives,through Nano Micron CT,automatic mineral identification system (QEMSCAN),MAPS image mosaic technology,and environmental scanning electron microscopy (ESEM).From the macroscopic perspective,lithologies are mainly siltstone and argillaceous siltstone.The sedimentary bedding structures are diversified-massive bedding are the majority but cross-bedding,wedge bedding and lenticular bedding are also present.The obvious sand-shale interlayer and complicated sedimentary beddings commonly contribute to the heterogeneity of the tight reservoirs,even though the massive bedding is the most favorable for the enrichment of tight oil.The microscopic perspective reveals more interesting characteristics.Pores are continuously distributed in the micro to nano meter level,with the peak of micro pore sizes concentrated in the range of 2-3 μm,and that of nano pores around 200-300 nm.Microscopic heterogeneity can be obviously displayed in the pore-throat spatial distribution and connectivity features of different 3D modeling areas.The main pore spaces are intergranular dissolved pore,intragranular dissolved pore and micro cracks.Moreover,high porosity generally corresponds to high concentration of organic acids,indicating the controlling of porosity by dissolution. Reference | Related Articles | Metrics | Comments（0）

Select

SINOPEC’s coalbed methane development potential Oil & Gas Geology    2011, 32 (3): 481-488.   DOI: 10.11743/ogg20110321 Abstract （2101）      PDF（pc） （2990KB）（2858）       Knowledge map    Save Abstract: Large amount of coalbed methane(CBM)is produced in the US,Canada,and Australia.From the development of CBM industry at home and abroad,we can see that 1)the development of CBM industry is a long and rough road;2)favorable policies will help to promote the development of CBM industry;3)rapid development of CBM industry needs the involvement of big oil companies.SINOPEC has more than 8 trillion cubic meters of CBM resources.Analysis of geology and block screening reveal that the Heshun block in the Qinshui basin,the southern margin and the northern part of Ordos Basin and the eastern Yunnanwestern Guizhou region are the key areas for developing CBM in the near term.We suggest Sinopec see CBM as important as conventional oil/gas and adopt positive investment strategies.First,get access to as many as CBM resources both at home and abroad through block leasing,acquisition and cooperation with other companies.Second,treat existing blocks differently.For the Yanchuannan,Heshun and Zhijin blocks which have already found CBM,pilot production and further appraisal should be conducted in order to realize commercial production.For blocks in the northern part and the southern margin of Ordos Basin and in the eastern Yunnanwestern Guizhou region,exploration should be deepened in order to make a breakthrough.For blocks in southern North China Basin and Northwest China,exploratory work should be carried out in order to appraise their CBM potential.Third,intensify investment in R&D and build an integrated team of management,production and scientific research to ensure the fast and healthy development of SINOPEC’s CBM exploration and production. Related Articles | Metrics | Comments（0）

Select

Oil & Gas Geology    2017, 38 (1): 0-0.   Abstract （99）      PDF（pc） （340KB）（2827）       Knowledge map    Save Related Articles | Metrics | Comments（0）

Select

Characteristics of the Lower Cretaceous source rocks and shale gas exploration potential of eastern basin group,NE China Meng Yuanlin, Shen Wanqi, Zhou Xingui, Li Shizhen, Wang Dandan, Zhang Wenhao, Qu Guohui, Cui Cunxiao Oil & Gas Geology    2016, 37 (6): 893-902.   DOI: 10.11743/ogg20160611 Abstract （268）      PDF（pc） （19816KB）（2766）       Knowledge map    Save In order to study the characteristics of Lower Cretaceous source rocks and shale gas exploration potential of the eastern basin group in Northeast China,field sampling,geochemical analysis and rock-mineral tests of source rocks were performed and geochemical parameters were measured in the Sanjiang Basin,Jixi Basin,Tonghua Basin,Liuhe Basin and Hongmiaozi Basin.The results indicate that the abundance and type of organic matter in the Lower Cretaceous source rocks are mainly controlled by sedimentary facies,while the maturity of source rocks is influenced by the depth of Moho surface.The Lower Cretaceous source rocks in the north of the study area were deposited in shallow water environment that results in large cumulative thickness of mudstones and higher silt content.These source rocks contain type Ⅱ2 kerogen and Ⅲ kerogen and are graded as poor-moderate source rocks at mature to over-mature stages.The Lower Cretaceous source rocks in the south of the study area were deposited in deeper water environment that results in thick mudstone deposition (with thickness of 233 m to 446 m) and high organic content.These source rocks mainly contain type Ⅰ-Ⅱ2 kerogen at low-mature to mature stages.Moreover,the Lower Cretaceous hydrocarbon source rocks are characterized by high content of brittle minerals,important content for development of pores and fractures between clay minerals,intergranular pores as well as organic pores with pore throat structure of micro- and meso-pore.Therefore,there exists favorable exploration prospects for both conventional hydrocarbon and shale gas in Lower Cretaceous of eastern basin group in Northeast China. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(2)

Select

Migration system types and their control on hydrocarbon accumulation in central fault depressions of Hailar-Tamtsag Basin Li Mingyi, Yue Xiang’an, Jiang Qingchun, Wang Hongwei, Wu Yulin Oil & Gas Geology    2012, 33 (3): 407-416,423.   DOI: 10.11743/ogg20120310 Abstract （1684）      PDF（pc） （958KB）（2678）       Knowledge map    Save The types of source-reservoir-cap rock assemblages,migration systems and their control on hydrocarbon accumulation in the main central fault depressions in Hailar-Tamtsag Basin(Haita Basin)were investigated by analyzing spatial combinations of hydrocarbon accumulation elements and processes.Three types of source-reservoir-cap rock assemblages were recognized,including self-source and self-reservoir,up-source and down-reservoir,and down-source and up-reservoir.Different source-reservoir-cap assemblages have different hydrocarbon migration and accomulation systems.For the self-source and self-reservoir type,hydrocarbon migration pathways are pore-fracture and comb-like systems.Subsags connected by the pore-fracture system and tilting uplifts and uplifts within sag connected by the comb-like system are favorable for development of lithologic reservoirs.For the up-source and down-reservoirs type,the migration system is flower-like.The reverse structures connected by the flower-like system are favorable for hydrocarbon accumulation.For the down-source and up-reservoir type,the migration systems are step-like or inverted U-shaped.The palaeouplifts connected by unconformities are favorable for hydrocarbon accumulation. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(7)

Select

Applications of petrography and isotope analysis of micro-drill samples to the study of genesis of grape-like dolomite of the Dengying Formation in the Sichuan Basin Qian Yixiong, Feng Jufang, He Zhiliang, Zhang Keyin, Jin Ting, Dong Shaofeng, You Donghua, Zhang Yongdong Oil & Gas Geology    2017, 38 (4): 665-676.   DOI: 10.11743/ogg20170404 Abstract （281）      PDF（pc） （1814KB）（2539）       Knowledge map    Save The shell-comb and grape-like dolomite of the Dengying Formation in the Sichuan Basin has an unusual textures.The petrographic data,carbon,oxygen and strontium isotope analysis on matrix and grape-like dolomites microdrill-samples have been used to investigate the origin of shell comb and grape-like dolomite.The grape-like dolomite is characterized by length-fast fascicular-optic fibrous aragonite cement,and bladed radial slow high-Mg calcites as well as granular calcites.The micritic dolomite in opposite direction growth,which consists of different size of either spherical and dumbbell forms or rhombic shape,has formed in pattern rhythm layers of banding or laminated along the terrace of C-axis of crystal.The zonation,which consists of microcrystalline,fine crystalline dolomite,has generally a more distinctive negative values of δ13C(PDB) and δ18O(PDB) than that of the black and white fibrous dolomite of grape-like dolomite.The black or dull fibrous dolomite has a positive δ13C(PDB) and δ18O(PDB),compared with that of white fibrous dolomite.It may mainly indicate a marine origin for shell comb and grape-like dolomite.At least three different fluid environment oscillation to generate the banding of shell comb grape-like dolomite:① One of them is characteristic of lower negative of δ13C(PDB)and δ18O(PDB) and much higher 87Sr/86Sr compared to that of matrix dolomite or seawater.The wide medium bright orange luminescent bands with interval of dull bright zones is supposed to form in seawater overprinted with fresh water,indicate an periodic environment changes between weak oxidation and weak reduction;② The second has a sharp variation of sequences,with slow decrease of δ13C(PDB) and increase of δ18O(PDB) from its centre to rim of zonation.Normal seawater value of 87Sr/86Sr,medium bright orange luminescent in the centre to dull or non-luminescent in outer zones indicates it generated in a seawater with continuous recharge of fresh water,and weak reduction in the center shifted to weak oxidation in the outer of zone;③ The third one does not have very clear zonation,and negative 18O(PDB) in the rim with a slow increase of δ13C(PDB) and increasing and later decreasing of δ18O(PDB).It also shows a cathodoluminescence feature similar to that of matrix dolomite,which has been interpreted as a weak reduction and later oxidation environment.The environment first developed in condense seawater and was ventilated by fresh water in later diagenesis periods.In conclusion,the shell comb and grape-like dolomite has been developed in an unusual Neoproterzoic seawater characterized by very high Mg/Ca.It is coeval with the precipitation of algal laminated stromatolite and thrombolite,in forms of the microbial mat,mound,biofilms and reef.The environment model can most likely account for rapid growth of isopachous,fibrous aragonite and bladed high-Mg calcites cement,and growth of later granular calcites induced or promoted by bacterial microbial modulation,and para-contemporaneous dolomitization in condense seawater.The fluid is oversaturated seawater at the beginning,and later superimposed by a cyclic subaerial exposure of fresh water. Reference | Related Articles | Metrics | Comments（0）

Select

Definition and application of tight oil and shale oil terms Zhou Qingfan, Yang Guofeng Oil & Gas Geology    2012, 33 (4): 541-544,570.   DOI: 10.11743/ogg20120407 Abstract （3377）      PDF（pc） （435KB）（2536）       Knowledge map    Save Based on a thorough literature investigation and a detailed analysis of the meanings and applications of the tight oil and shale oil terms,this paper compares their similarities and differences,and presents suggestions for a better understanding and application of the two terms.Though shale oil also refers to the crude generated through processing kerogen from shale rocks,both terms bear broad and narrow senses when used to indicate the oil from shale or shale-like formations.The current usage of the two terms can be summarized and described in the following three scenarios:(1)They refer to different kinds of unconventional resources,therefore are regarded as totally different from each other;(2)They are thought to be identical and are used alternatively;(3)They are different but also inherently connected.It is suggested that when using the terms,we shall follow the rule of "showing respect to customs and facilitating communications" and try to understand fully their connotations and extensions instead of only reading the lines.To tackle problems encountered during using or understanding the terms,we also shall adapt the policy of "continuous perfecting and timely modification" so as to achieve a more objective definition of the terms.Meanwhile,their international applicability shall also be taken into consideration. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(68)

Select

SEM observation of organic matters in the Eopaleozoic shale in South China Zhang Hui, Jiao Shujing, Pang Qifa, Li Ning, Lin Bowei Oil & Gas Geology    2015, 36 (4): 675-680.   DOI: 10.11743/ogg20150418 Abstract （279）      PDF（pc） （8276KB）（2509）       Knowledge map    Save The Eopaleozoic shale in South China is assessed as the preferred target for shale gas exploration and development in China, and the research on its organic matters is imperative.Some shale samples are taken from the Eopaleozoic such as the Lower Cambrian, Upper Ordovician and Lower Silurian in Anhui, Guizhou and Sichuan provinces in South China.The naturally fractured surfaces(perpendicular to or parallel to the beddings)and the argon ion milled surface are prepared from these shale samples.Under the scanning electron microscope(SEM)with field emission, the maceral, che-mical composition, occurrences of the organic matters and pore types are systematically observed and studied.The results show that the organic maceral types are dominated by bituminite and bacteria and algae body with strong potential of hydrocarbon generation.The bituminite is composed of spherulites with several to dozens of nanometers in diameter with stripped, interstitial, thin films and amorphous occurrences.The bacteria and algae body has obvious characteristics of biological morphology, mainly in clastic form and dozens of micrometers in diameter.On the basis of identification of maceral, the genetic types of the organic pores are classified into biological pore, vesicular pore, bitum-spherulite pore and molded pore.And both the vesicular pore and bitum-spherulite pore occur in the interior of bituminite and their diameters are of nanometer-scale, which are the direct evidences of hydrocarbon generation from organic matters.Therefore, the development degree of these pores is viewed as one of the indexes for hydrocarbon generation potential assessment of the source rocks. Reference | Related Articles | Metrics | Comments（0）

Select

Waveform-indication-based seismic inversion of carbonate reservoirs:A case study of the Lower-Middle Ordovician in Tahe oilfield,Tarim Basin Han Changcheng, Lin Chengyan, Ren Lihua, Dong Chunmei, Wei Ting Oil & Gas Geology    2017, 38 (4): 822-830.   DOI: 10.11743/ogg20170419 Abstract （234）      PDF（pc） （1522KB）（2398）       Knowledge map    Save Carbonate karst reservoirs of the Lower-Middle Ordovician in Tahe oilfield feature in large burial depth,irregular distribution,complex reservoir types and strong heterogeneity,thus reservoir type identification is always a challenging during oil and gas exploration and development in the area.This paper documented a new impedance inversion method,i.e.waveform-indication-based inversion,based on Bayesian discriminant theory and Markov Chain Monte Carlo sampling algorithm.The method,based on reservoir type identification,seismic reflection characteristics and petrophysical analyses,can be used to optimize sample wells by observing seismic waveform similarities,and establish an initial impedance model by referring to sampling spacing and curve characteristics.The relationship between proposed distribution and prior information is firstly established to achieve efficient sampling of a priori solution space.A Metropolis-Hastings sampling algorithm is then used to sample the posterior probability distribution,so as to obtain the maximum posterior probability solution.The application of the method in identifying the types of the Ordovician karst reservoirs in Tahe Oilfield shows significant improvement of inversion accuracy and a better utilization of horizontal variation of seismic waveforms to reveal effectively the types and spatial and lateral distribution of the reservoirs,and provides fine characterization of the reservoirs. Reference | Related Articles | Metrics | Comments（0）

Select

Characteristics,timing and controlling factors of structural fractures in tight sandstones of the 2nd member of Xujiahe Formation in Jiulong Mountain structure, Sichuan Basin Bai Bin, Zou Caineng, Zhu Rukai, Zhang Jian, Zhang Benjian, Bi Lina Oil & Gas Geology    2012, 33 (4): 526-535.   DOI: 10.11743/ogg20120405 Abstract （1527）      PDF（pc） （698KB）（2391）       Knowledge map    Save Physical properties of tight sands in the 2nd member of Xujiahe Formation in northwestern Sichuan Basin are controlled by structural fractures(SF)formed at different stages.The study on characteristics,timing and controlling factors of the structural fractures can provide useful information for reservoir evaluation and prediction.Identification of cutting relations of the SF on the basis of fracture observation on outcrops,cores and thin sections reveals that the SF can be grouped into NW-SE-trending,NE-trending,NNW-trending,near EW-trending and SEE-trending,of them NW-SE-trending is predominant.At least four stages of SF were identified based on the analysis of the fluid inclusion homogenization temperature of fillings in fractures with different cutting relation and ESR,as well as palaeo-stress data.The first stage is the Late Indosinian,and the SF formed at this stage feature in calcite filling and fluid inclusion homogenization temperature(FIHT)of 84-120℃.The second stage is the Late Yanshanian,and the SF formed at this stage are characterized by quartz filling and FIHT of 72-137℃.The third stage is the Early-middle Himalayan Period and the SF formed at this stage feature in quartz filling,cutting relations with the SF of previous two stags,and FIHT of 153-179℃.The fourth stage is the Late Himalayan Period,and the SF formed in this stage are characterized by coarser calcite fillings with some dolomites and FIHT of 165-190℃.Because of the active tectonic movement during the Indosinian and Himalayan Period,the SF are well developed.The formation and distribution of SF are jointly controlled by tectonic stress and the mechanical property of rocks.Lithic sandstone with high porosity,fine particle and thin layer are favorable for SF development. Reference | Related Articles | Metrics | Comments（0）