JOPC
Advanced Search
Subscription
Email Alert
Home
|
About JOPC
|
Editorial Board
|
Before Submission
|
Subscription
|
Download
|
Publication Ethics
|
Editorial Office
|
Chinese
News
Search in CSB
Adv Search
·
Mourn deeply for the former Chief-editor Professor FENG Zengzhao
·
To readers and anthors
more>>
Office online
·
Online Submission
·
Peer Review
·
Scientific Editor
·
Editor Work
·
Editor-in-chief
Journal online
·
Forthcoming Articles
·
Current Issue
·
Next Issue
·
Browse by Year
·
Browse by Section
·
Archive By Volumn
·
Advanced Search
·
Email Alert
·
Links
·
《Petroleum Science》
·
Periodical Press of CUP
·
China University of Petroleum (Beijing)
·
《Journal of China University of Petroleum(Edition of Natural Science)》
·
《ACTA PETROLOGICA SINICA》
·
《Geology in China》
·
《China Geology》
·
《ACTA GEOCHIMICA》
·
《geochimica》
·
《GEOTECTONICA ET METALLOGENIA》
·
China Geoscience Journal Portal
·
《Bulletin of Mineralogy, Petrology and Geochemistry》
JOPC 2012 Vol.14 Number 1
2012, Vol.14 Num.1
Online: 2012-02-01
SPECIAL ISSUE ABOUT “Origin of Dolostone and Oil and Gas Reservoir”
LITHOFACIES PALAEOGEOGRAPHY AND SEDIMENTOLOGY
GEOCHEMISTRY AND SEDIMENTARY ENVIRONMENT
PALAEOGEOGRAPHY AND MINERAL RESOURCES
SPECIAL ISSUE ABOUT “Origin of Dolostone and Oil and Gas Reservoir”
1
Mei Mingxiang
Brief introduction of “dolostone problem” in sedimentology according to three scientific ideas
As an important category of carbonate rocks，the forming mechanism and its temporal-spatial distribution feature have been an important researching topic in sedimentology all along.Although lots of models of dolomitization have been proposed and are used to interpret the origin of diversified dolostone，the forming mechanism and process of dolomite have not been simulated and confirmed under experimental conditions，which led to a conundrum in sedimentology，
i.e.
the “dolostone problem”.The formation of dolostone has been simplified as the dolomitization and has been referred as one type of carbonate diagenesis，which represents the first advance of scientific concept.On the basis of the excellent preservation of the primary sedimentary fabrics for the Precambrian dolostone，the change from the previous assumption that the Precambrian dolostone could be primary precipitates to an important concept of the mimetic dolomitization means the second advance of scientific concept.The third advance of scientific concept for dolomite and dolomitization，should refer to the model of microbial dolomitization resulted from the understanding of that microbes can help to dolomitization.Seeking these important advancements will be very meaningful to further understand the progresses of the studies of the “dolostone problem” in sedimentology.
2012 Vol. 14 (1): 1-12 [
Abstract
] (
2026
) [
HTML
1KB] [
PDF
8657KB] (
808
)
13
Qiang Zitong, Zeng Deming, Wang Xingzhi, Wu Shijiu
Isotopic geochemical characteristics of oolitic bank dolostones in the Lower Triassic Feixianguan Formation in northeastern Sichuan Province
A shallow marine carbonate rock sequence with shale and evaporate developed in the Lower Triassic Feixianguan Formation in northeastern Sichuan Province.The edge of carbonate platform commonly developed some oolitic banks，which are dolomitized.The Feixianguan Formation which are formed by oolitic bank dolostone is the most important gas reservoir in northeastern Sichuan Province. Some researchers considered them as the origin of mixing for fresh water and sea water，the others make up them into model for dolomitization by seepage-reflux.The Feixianguan oolitic bank dolostone included stable isotopic oxygen composition of -6.73‰～-3.65‰(PDB)（-10.81‰ in Luojiazhai area），the average is -4.89‰(PDB)，stable isotopic carbon composition of +0.57‰～+3.00‰(PDB)，for matrix and vug-filling saddle dolomite and bright dolomite cement，stable isotopic strontium composition of 0.70735～0.70800 for
87
Sr/
86
Sr rate.These data about oolitic bank dolostone indicate that the dolomitization was formed in the buried condition.After measuring fluid inclusion homogenization temperature，dolomitization temperature and isotopic oxygen of dolomite are known，and then the isotopic oxygen composition of dolomitizing fluid can be calculated(
δ
18
O
dol
-
δ
18
O
water
=［3.2×10
6
T
-2
］-1.5，from Friedman and ONeil (1977)). The average is about +4‰ (SMOW).According to the positive covariance between fluid isotopic oxygen and carbon composition and fluid salinity during evaporation of seawater，fluid
δ
D can be calculated.It is about +25‰(SMOW).The measurement of fluid inclusion salinity suggest that dolomitizing fluid is a brines，which is about several times of seawater.Dolomitizing temperature changes from 90 ℃ to 130 ℃.As far as our knowledge goes，stable isotopic O and C composition of the Lower Triassic oolitic bank dolostone is similar to these of the uppermost Permian reef dolostone.Therefore，it is possible that their dolomitizing fluids are identified source.However，the reason for this conclusion needs to be perfected in the future.
2012 Vol. 14 (1): 13-20 [
Abstract
] (
2081
) [
HTML
1KB] [
PDF
1378KB] (
861
)
21
Qiao Zhanfeng, Shen Anjiang, Zheng Jianfeng, Hu Jie, Wu Xingning, Lu Junming
Classification and origin of the Lower Ordovician dolostone in Tarim Basin
Dolostone of the Lower Ordovician in the Tarim Basin is the most practical exploration target.In this paper，based on the Early Ordovician of tectonic，sedimentary，and palaeoclimate setting of the Tarim Basin，considering the former classifications of dolostone according to the structure，the Lower Ordovician dolostone of the Tarim Basin according to the development and occurrence has been classified as: scattered dolomite in limestone，mottled dolomite in limestone，bedded dolostone，and dolostone related to faults，and the content of dolomite in strata decreases upward.Four dolostones have different features of lithology and occurrence，and they can occur superposably.Features of lithology，geochemistry and occurrence of scattered，mottled dolomite in limestone have revealed their origin of shallow burial dolomitization，and bedded dolostone and dolostone related to faults are formed during moderate-deep burial dolomitization.Their origin and occurrence diversity are controlled by the changes of seawater level，seawater property，and burial environment.Dolostone related to faults，which constitutes important reservoirs，appear to be related closely to the faults in origin and/or in occurrence.Furthermore，it is concluded that the burial dolomitization failed to exert the constructive effects on the formation of dolostone reservoir，while the dissolution caused by migration of fluids in late periods is the main origin.
2012 Vol. 14 (1): 21-32 [
Abstract
] (
2315
) [
HTML
1KB] [
PDF
7445KB] (
720
)
33
Liu Ling, Zhu Jingquan, You Xuelian, He Kai
Sedimentary microfacies of the Middle-Upper Cambrian dolostone in Keping area，Tarim Basin
A set of complete Cambrian dolostone strata was found in Penglaiba section of Keping area，Tarim Basin.Through the detailed field measurements，lithological description，samples collection and slices observation under microscope， an integrated Cambrian stratigraphic column was compiled and analysis of sedimentary facies of these strata were conducted.One kind of facies was identified in the study area：Carbonate platform facies，which can be divided into three subfacies including open platform，restricted platform and evaporative platform.These subfacies include two microfacies respectively.Open platform includes open tidal flat and particles beach;restricted platform includes restricted tidal flat and lagoon;evaporative platform includes evaporative tidal flat and salt lake.The subfacies and microfacies were analyzed，and three facies models were established: Open platform model，restricted platform model and evaporative platform model.The microfacies of these three kinds of platforms turned to be interactivly deposited showing some rhythms.The vertical evolution of the sedimentary environment of the Cambrian in the study area reflects the relative sea-level changes as rising-falling-rising tendency.
2012 Vol. 14 (1): 33-43 [
Abstract
] (
2439
) [
HTML
1KB] [
PDF
6856KB] (
787
)
45
Li Hong, Liu Yiqun, Liang Hao, Zhou Xiaohu, Jiao Xin, Liu Hongfu, Yang Rui, Lei Chuan
Origin of lacustrine dolostones of the Middle Permian Lucaogou Formation in Santanghu Basin of Xinjiang
The Santanghu Basin is a small intermountain basin located in northeastern Xinjiang，NW China.The Middle Permian comprises the Wulapo，Jingjingzigou，Lucaogou and Hongyanchi Formations from bottom to top.The Lucaogou Formation was formed of interbeded sedimentary rocks such as dolostone，limestone，black mudstone，shale and detrital rock in lacustrine environment.Two kinds of dolostones were found in this basin.One was named silt-micrite dolostone which contains 70 percent of clay-sized dolomite，30 percent of silt-sized dolomite.The dolomite exhibit weak ordering with degree of 0.48.Morphologically，the dolomite was divided into micro-rhombohedra，xenomorphic crystal，microsphere，and microtubule types under the SEM.Part of the micro-rhombohedra dolomite was ferric dolomite.The other kind of dolostone was named analcime-sanidine dolostone which was composed of fine grained analcime with the granularity of 0.08～0.35mm，micrite potash feldspar(almost sanidine)，micrite dolomite，ankerite，and few coarse crystalline dolomite.This kind of dolomite also showed weak ordering with degree of 0.58.Compared with the dolomites in silt-micrite dolostone，the dolomites in analcime-sanidine dolostone which were almost subhedral rhombohedras under the SEM were characterized as high iron and manganese.The similarities between these two dolostones were that they were poor ordering dolomites，abundant in strontium，and lacking of the evidence in replacement during the buried period.Although these two dolostones were deposited in the similar shallow and semi-deep lake anoxic reduction environment，their differences in composition，trace elements and stable isotopes indicated that they had great diversity in their genesis.The silt-micrite dolostone revealed the features of primary precipitation.The microbe was likely to play a formative role in the precipitation of the microspheroidal and microtubular dolomites.Moreover，the micro-rhombohedrala and xenomorphic dolomites were directly precipitated from lake water.Contrastly，the dolomites in analcime-sanidine dolostone were precipitated by the hydrothermal exhalative processes of the sublacustrine hotsprings.
2012 Vol. 14 (1): 45-58 [
Abstract
] (
2723
) [
HTML
1KB] [
PDF
5158KB] (
1280
)
59
Guo Qiang, Zhong Dakang, Zhang Fangdong, Liu Xingang, Fan Lingxiao, Li Junjun
Origin of the Lower Cretaceous lacustrine dolostones in Baiyinchagan Sag of Erlian Basin，Inner Mongolia
In the Early Cretaceous，there was a set of lacustrine dolostones in the Baiyinchagan Sag with the strong rift extension and high geothermal anomaly.The dolostones were rich in special minerals including ankerite，natrolite，clay sized feldspar (albite,potash feldspar)
etc
.，and were only developed in semi-deep-deep lacustrine facies.The dolostone is controlled by NE-trending synsedimentary faults and distributed mainly in downthrown side of fault zone in northern steep slope zone and southern ramp zone adjacent to the central part in this sag.The lacustrine dolostone is mainly composed of ankerite and paragenetic minerals(natrolite，feldspar，barite，sjogrenite，
etc
.). Its texture can be divided into three types: micrite，microcrystalline and fine-medium grained porphyritic texture（multivariate mineral assemblage).The dolostone also has obvious rock fabric characteristics of hydrothermal sedimentation，including lamellar structure，hydrothermal clastic texture，starrily structure，contemporaneous plastic deformation and net vein structure.Based on the above preliminary analyses, we think that the formation of the lacustrine dolostone is the sedimentation with deep hydrothermal fluids participation，namely hydrothermal sedimentary dolostone.
2012 Vol. 14 (1): 59-68 [
Abstract
] (
2549
) [
HTML
1KB] [
PDF
4468KB] (
970
)
69
Zhang Jie, Shou Jianfeng, Wen Yingchu, Wang Yigang, Hu Anping
Mechanism of dedolomitization and its rebuilding to reservoir
Dedolomitization is very common in the strata, but it is still in dispute about its formation environment，influencing factors，mechanisms，and the role in reservoir and so on.The recognition marks was analyzed，and detailed classification of dedolomitization from 3 aspects was given: Retaining the original crystal form or not，occurrence mode and forming environment，the manifestation in diagenesis.Dedolomitization can occur in various environments，from the near-surface settings to shallow burial and deep burial environments，even in hypergene deposit and lacustrine environments.The factors influencing dedolomitization mainly include the dolostones chemical constituents and physical properties，degree of order，fluid characters（concentration of SO
2-
4
，Ca/Mg ratio，temperature，pH and partial pressure of CO
2
）and Fe content of the dolostone. Cathodeluminescence and geochemical analysis can be used to study the dedolomitization mechanism in near-surface，mixed seawater and freshwater，burial and other environments.Dedolomitization process can be divided into two steps, including dissolution of dolomite and the precipitation of calcite. Only the first step occurs to form the rhomb-moldic pore; the two steps take place at the same time; only one step happens or the two the two steps take place in different order.Dedolomitization mostly begins from the core of the dolomite or the interface between the core and the rim，because there are deficits during the growth process and the Ca content is high.Dedolomitization can be considered as a kind of process that the Mg
2+
is gradually released.The studies of calcite-dolomite-solution system can help to investigate the transforming condition between calcite and dolomite and the influencing factors.The near-surface dedolomitization is generally relevant to the dissolution of gypsum or anhydrite and the meteoric water of vadose zone and phreatic zone.It is confirmed that the laterally continuous distribution of dedolomitization can indicate unconformity.The study of dedolomitization products can reflect the diagenetic stages and the source of the fluid.Dedolomitization can enlarge the modic pore and inter-crystal pore and improve the reservoir quality，but there is close relationship between the increasing porosity of dedolomitization and latter eluviation.Without the latter leaching，maybe the late burial dedolomitization relevant to calcite precipitation will destroy the primary pores.
2012 Vol. 14 (1): 69-84 [
Abstract
] (
2067
) [
HTML
1KB] [
PDF
3542KB] (
905
)
LITHOFACIES PALAEOGEOGRAPHY AND SEDIMENTOLOGY
85
Li Wenhou, Chen Qiang, Li Zhichao, Wang Ruogu, Wang Yan, Ma Yao
Lithofacies palaeogeography of the Early Paleozoic in Ordos area
A set of marine carbonate rocks interbedded with clastic rock was deposited in the Early Paleozoic in the Ordos area，with huge thickness and various sedimentary types.According to characteristics of sedimentary sequence，petrology，sedimentary structure and palaeontology，four depositional systems can be distinguished in the Lower Paleozoic in the Ordos including coast，carbonate rock platform，platform margin and deepwater slope-trough，which can be subdivided into several subfacies and microfacies.For each facies，its sedimentary characteristics，spatial and temporal distribution were summarized.Based on these studies，the lithofacies palaeogeography maps of the Lower Paleozoic in the Ordos were compiled by each age.The Early Cambrian only formed a set of mud-sand flat and mud-dolostone flat sediments around the southwestern margin of the Ordos land.Followed the marine transgression spread in the Middle Cambrian，the central-eastern part of the Ordos was gradually transformed from sand-mud flat to restricted platform-open platform sediments，and developed platform edge to deepwater trough sediments in the western margin.Since the Late Cambrian marine regression，the central-eastern part of the Ordos was changed to restrictive platform dolostone flat sediments，but the deepwater slope-trough facies was still developed in the western margin.To the Early Ordovician，the main body of the Ordos became a uniform palaeoland with mud-dolostone flat and dolomitic-limestone flat sediments around its southeastern margin.Then a massive transgression in the Middle Ordovician led to an extensive shallow epicontinental deposits in the Ordos.The Northern Shaanxi Depression formed a gypsum salt lake，and developed restrictive platform-open platform sediments outside it.At the late Middle Ordovician，the southwestern margin began to develop platform foreslope-deepwater trough facies sediments.The Late Ordovician Caledonian Movement uplifted the main Ordos as a land，and formed a narrow sea continuing deposit in the southwestern margin of the Ordos.The sedimentary facies was quickly changed from carbonate rock platform to deepwater slope-trough，and developed some reefs in the southern margin of Ordos，indicating the epicontinental marginal rimmed platform deposit.
2012 Vol. 14 (1): 85-100 [
Abstract
] (
2242
) [
HTML
1KB] [
PDF
2348KB] (
815
)
101
Liu Xiao, Zhang Yuandong, Zhou Chuanming
Sedimentary characteristics of the Upper Ordovician Wenchang and Yankou Formations in northwestern Zhejiang Province
Based on new collections of fossils from the Upper Ordovician Wenchang，Yankou and Anji Formations in northwestern Zhejiang Province，southeastern China，especially those significant graptolites，the Wenchang Formation is considered to be equivalent to the Yankou Formation，and is largely of Hirnantian Age.In Hirnantian Age，the Gondwana ice sheet，centered in the North Africa，reached its maximum，as evidenced by that more and more glacial deposits(tillites or diamictites)of the age have been reported across the world.The Wenchang and Yankou Formations yield well-developed conglomerates，which are unique in South China and might be related with the glaciation event.Regarding the origination of the conglomerates，there have been some debates and viewpoints from different perspectives.Based on sedimentary studies，these conglomerates display different sedimentary characters and mechanisms among localities and sections in the region.They represent several types of channel depositions in shallow water.A detailed regional lithofacies study of the Wenchang and Yankou Formations in northwestern Zhejiang Province indicates that a Zhe-Wan Basin was developed in the Hirnantian Age，with Cathaysian Land located to its southeast and served as the clastic source.The basin becomes deeper northwestwardly，following the palaeogeographic pattern of pre-Hirnantian.Petrological analysis of the sandstones in the Wenchang and Yankou Formations displays a low compositional maturity along with a low textural maturity，and a provenance of recycled orogenic belt，which indicate a probable sustaining uplift of the Cathaysian Land.The regressional sequence recognized in the Wenchang and Yankou Formations in northwestern Zhejiang Province can be well correlated with that of other continents or regions，such as North Africa，Middle East，U.K.，Sweden and Czech
etc
.
2012 Vol. 14 (1): 101-116 [
Abstract
] (
2887
) [
HTML
1KB] [
PDF
5740KB] (
876
)
GEOCHEMISTRY AND SEDIMENTARY ENVIRONMENT
117
Chen Qiang, Zhang Huiyuan, Li Wenhou, Hao Songli, Liu Zhuo
Characteristics of carbon and oxygen isotopes of the Ordovician carbonate rocks in Ordos and their implication
The Ordos has gigantically thick Paleozoic marine strata.The carbon and oxygen isotopes of the Ordovician carbonate rocks in the Ordos are less modified by post-depositional diagenesis，and thus provide helpful insights into the original ocean.The
δ
13
C values of the Ordovician carbonate rocks in the Ordos range from -7.30‰ to 2.26‰ with a mean value of -0.30‰ and the
δ
18
O varies between -13.14‰ and -1.94‰，averaging at -6.38‰，which indicate the carbon and oxygen isotopes of the Ordovician in the Ordos are comparable to those of the global Ordovician.Spatially，the
δ
13
C shows a decreasing trend，indicating shoaling in water-depth from the western margin of the Ordos，to the southern margin and then to the eastern margin.Temporally，the
δ
13
C gradually increases，showing that sea level rose from the Early to the Late Ordovician，with a significant positive excursion between the Middle and Late Ordovician that is indicated by increase in mean
δ
13
C value from -0.36‰ in the Majiagou Formation to 0.15‰ in the Pingliang Formation and then to 0.68‰ in the Beiguoshan Formation.Sea level change suggested by carbon isotope distribution is consistent with the evolution of sedimentary facies.The positive excursion of carbon isotopes in the Middle and Late Ordovician in the Ordos indicates relative high productivity and organic carbon burial，which is of important petroleum geological significance，reflecting the Pingliang Formation，Wulalike Formation and Beiguoshan Formation in the southwestern margin as the most important and efficient hydrocarbon source rocks of the Lower Paleozoic in the Ordos.
2012 Vol. 14 (1): 117-124 [
Abstract
] (
2740
) [
HTML
1KB] [
PDF
1251KB] (
864
)
125
Liu Chunlian, Yang Tingting, Wu Jie, Xia Bin, Huang Yi, Zhang Suqing
REE geochemical characteristics of mottled clays of the Late Quaternary in the Pearl River Delta
A layer of mottled clays，sandwiched between the Upper Pleistocene and the Holocene，is widely distributed in the Pearl River Delta area.It was the weathering product of the Upper Pleistocene sediments and mainly formed during the last glacial maximum.Geochemical analysis on three cores（PRD09，PRD16 and PRD17）suggests an apparent change in REE content and fractionation during the weathering.The total REE concentrations of the mottled clays are largely lower than those of underlying sediments.The proximate underlying sediments show a clear enrichment in REE，particularly in HREE.PRD09 and PRD17，subjected to a more intensive weathering，exhibit more enrichment in REE than PRD16 that shows a less weathering intensity.The acidic condition developed in the Pearl River Delta area during the last glacial，which enhanced the mobility of the REE elements.Higher LREE/HREE，（La/Gd)
N
and（La/Yb)
N
values in mottled clays than in underlying sediments were resulted from different mobility and adsorption on clay minerals of LREE and HREE during weathering.It seems that the weathering had less influence on anomaly of Ce and Eu.The mottled clays show slightly more negative Ce and Eu anomaly than underlying sediments.
2012 Vol. 14 (1): 125-132 [
Abstract
] (
2088
) [
HTML
1KB] [
PDF
1179KB] (
672
)
PALAEOGEOGRAPHY AND MINERAL RESOURCES
133
Zang Shibin, Cui Jun, Zheng Yongxian, Xu Wenmei, Wei Jinxing
Analysis of characteristics of low-permeable reservoir with micro-fracture and their origins of the Neogene Youshashan Formation in Nanyishan Oilfield，Qaidam Basin
The reservoir characteristics of the Youshashan Formation of the Neogene in Nanyishan Oilfield were analyzed according to core observation，thin section identification and X-ray diffraction.The lithology of the reservoir can be classified as mudstone，carbonate rocks，sandstone and hunji rock.The clay content of the rock is high and the reservoir properties are complex.Intergranular pores，dissolution pores，micro-pores and micro-fractures are developed，so the reservoir has the characteristics of dual porous media.In general，the physical properties of the Nanyishan reservoir are poor.It is pointed out that the micro-fractures play an important role in the flowing of formation fluids，but micro-pores contribute little to the flowing.The micro-fractures in the reservoir include tectonic micro-fracture，dissolution micro-fracture，and diagenetic micro-fracture.Sandy lamination and argillic or marlaceous lamination are developed alternately in the rock.The unbalanced force，dissolution and shrinkage of reservoir rock during sedimentation and diagenesis resulted in the formation of micro-fractures which improve physical properties of the reservoir.However，compaction and cementation happened simultaneously，which destruct the reservoir properties.The mercury injection curves of the reservoir are composed of two parts: Inclined upward curve and approximately horizontal curve.The tilted curve represents the micro-fracture，and nearly horizontal curve represents micro-pores.Parameters such as threshold pressure and mean pore radius cannot be used to evaluate the reservoir correctly.So，a parameter of effective pore radius is put forward in this paper and can be applied to evaluate the reservoir properly.
2012 Vol. 14 (1): 133-141 [
Abstract
] (
2191
) [
HTML
1KB] [
PDF
3308KB] (
765
)
