石油实验地质

2011, 33(3)

Abstract(282) PDF-CN(311)

Abstract:

Types and characteristics of shale gas reservoir：A case study of Lower Paleozoic in and around Sichuan Basin

Nie Haikuan, Zhang Jinchuan

2011, 33(3): 219-225. doi: 10.11781/sysydz201103219

Abstract(3624) PDF-CN(1344)

Abstract:
Through field observation,slice,SEM and X-ray diffraction analyses of 41 black shale samples from the Lower Cambrian and the Upper Ordovician-Lower Silurian in and around the Sichuan Basin,the characteristics of reservoir,fracture and pore of shale were studied.There are mainly 2 types of shale gas reservoir:fracture and pore.According to the features of shale gas reservoir,the control of fracture on gas accumulation as well as the nature of fracture,the generation of fracture is classified into 5 degrees:giant,large,medium,small and microfracture.Pores include organic matter(bitumen) pore and/or kerogen network,mineral pores(mineral specific surface,inner,intercrystalline,corrosional and complex-based ones) as well as the pores between organic matter and minerals.Different fracture type,fracture scale,pore type and pore size have different control on shale storage and produce capacity.Pores serve room for gas storage in shale and determine storage capacity.Fractures work as pathways for gas migration in shale reservoir and determine produce capacity.Due to the low porosity and permeability of shale matrix,the generation scales of fracture control the quality of shale gas reservoir.

Petroleum geology and exploration in Colombia

Liu Yaming, Zhang Chunlei

2011, 33(3): 226-232. doi: 10.11781/sysydz201103226

Abstract(3253) PDF-CN(1388)

Abstract:
With rich oil and gas resources,Colombia is the 4th major petroleum producer in South America and attracts much attention.Guided by petroleum geology theory,the characteristics of petroleum geology and the principles of petroleum distribution have been studied,and the exploration potential has been summarized.Colombia is characterized by complex structure,various types of basin,complete sedimentary strata,excellent source rock,good reservoir-cap combination and various types of trap.Oil and gas are concentrated in several basins.Heavy oil and conventional oil are distinctive on plane view.Petroleum accumulation is controlled by source rock,migration pathway and reservoir-cap combination.The eastern tectonic zone,foreland basins,the Tertiary,structural traps and conventional oil and gas are the exploration focuses in the future.The studies provide a reference for the exploration and development of oil and gas in Colombia.

Paleostructural evolution of Lower-Middle Ordovician top and its relationship with hydrocarbon in Tahe Oil Field

Zhang Xiaobing, Lü Haitao, Zhao Xikui, Li Kun, He Jianjun

2011, 33(3): 233-238. doi: 10.11781/sysydz201103233

Abstract(3974) PDF-CN(1013)

Abstract:
Ordovician is the main hydrocarbon producing reservoir in the Tahe Oil Field.Studies of tectonic evolution and paleostructures indicated that the Middle—Lower Ordovician top was a nose-like convex to the northeast during the 2nd phase of Caledonian Movement.The highest point located around the present Luntai Fracture.During the early Hercynian period,structure axial changed to NNW.From the late Hercynian to the early Himalayan,the study area was a rectangular convex composed of NW and NE oriented slopes and the structure axial was to the northeast.From the late Himalayan till now,influenced by the western stress effect and the regional warping,the southern axial remained unchanged,yet the northern axial changed from west to east,and the highest point migrated from north to south.Tectonic,karst and diagenesis effects during the middle and late Caledonian provided room for the first hydrocarbon accumulation in the Tahe Oil Field.Tectonic movements during the early Hercynian destroyed the original reservoirs and heavy oil reservoirs were formed in some region,providing reservoir room for oil-and-gas filling during the late Hercynian.Since Indosinian,accumulation system of the study area has been adjusting.

Formation of volcanic reservoir and its controlling on accumulation in Changling Fault Depression

Xu Hongjie, Lu Jianlin, Yu Wenxiu, Wang Baohua

2011, 33(3): 239-243. doi: 10.11781/sysydz201103239

Abstract(2610) PDF-CN(928)

Abstract:
In the Changling Fault Depression,volcanic rock formation is very thick.There are various types and facies of rock.Reservoirs are well-developed.The storage capacity of volcanic reservoir is not restricted by burial depth.It is favorable for reservoir in deep fault depression,characterized by high porosity and low permeability or low porosity and high permeability.Reservoir space is mainly composed of bubble pore,solution pore,fissure and their combination.Fissures improve the seepage ability of reservoir."Double porosities and double permeabilities" is the main reservoir type.Some reservoirs have homogeneous porosity and permeability.The formation of good volcanic reservoir is controlled by multiple factors.Favorable facies belt is the foundation.Tectonic movement is the key.Weathering leaching and dissolving also play important roles.The volcanic reservoirs near to the high position of tectonic fault are favorable for accumulation.

Sequence stratigraphic division and evolution of Carboniferous in Tarim Basin

Xiao Zhaohui, Wang Zhaoming, Wu Jincai, Jiang Renqi

2011, 33(3): 244-248. doi: 10.11781/sysydz201103244

Abstract(3097) PDF-CN(1017)

Abstract:
Sequence stratigraphic studies have been carried out in the Carboniferous Donghe sandstones in the Tarim Basin based on the theories and methodologies of sequence stratigraphy.An integrated technique for sequence stratigraphic interpretation has been discussed by means of outcrop,drilling and seismic data.The technique can be used to identify sequence boundaries and establish stratigraphic frameworks.Through field outcrop observation,drilling data analyses and seismic profile interpretation,we have identified 6 sequences in the Carboniferous.The Donghe sandstone sequence in Juema-Saike region is a diachronous lithostratigraphic unit including 3 sequences:C-SQ1,C-SQ2 and C-SQ3.The main part of the sequence is equivalent to TST.The sandstones consist of coastal onlap deposits and are the key targets for future explorations.

Sedimentary microfacies of Qingshankou Formaiton, West-Yao block, Yaoyingtai Oil Field, Changling Sag, Songliao Basin

Jiao Lili, Yu Hao, Ren Tao

2011, 33(3): 249-254. doi: 10.11781/sysydz201103249

Abstract(3582) PDF-CN(891)

Abstract:
Based on the studies of core samples and well-logging data from the West-Yao block of the Yaoyingtai Oil Field in the Changling Sag of the Songliao Basin,combined with seismic fine interpretation,guided by sedimentary theory,the types of sedimentary facies of the Qingshankou Formaiton were classified,and the subfacies and microfacies were also divided.15 sandbodies(2-4 m thick each layer) from Q1-Ⅱ and Q2-Ⅳ were described,and the division characteristics of sedimentary microfacies of each sandbody were concluded.The sedimentary microfacies of Q1 and Q2-Ⅳ reservoirs are mainly underwater distributed channels in delta front,and debouch bar was less popular.Channels in each layer overlap each other,yet the channel width is only 200-300 m.The studies of sedimentary microfacies of thin layers are significant for oilfield well arrangement and development performance improvement.

Shallow deepwater channels in Baiyun deepwater region of northern continental slope, South China Sea

Liu Jun, Pang Xiong, Yan Chengzhi, Liu Baojun, Li Yuanping, Hu Lian, Zheng Jinyun

2011, 33(3): 255-259. doi: 10.11781/sysydz201103255

Abstract(1898) PDF-CN(965)

Abstract:
Based on shallow 3D seismic data with high resolution,shallow deepwater channels in the Baiyun deepwater region are studied so as to guide medium and deep explorations with lower seismic resolution.Large amounts of deepwater channels generate in the slope and the slope base of Baiyun Sag.The channels are classified into 3 types:erosional,erosional/aggradational and aggradational.The geometries of deepwater channels change along with gradient.On the upper slope,single deep feeding channel develops.On the gentle slope with restrictive environment,shallow and broad channels stack vertically.On the basin floor with unconfined environment,small channels spread laterally.In plane view,channel shapes may be straight or bended.The vertical changing characteristics of erosional/aggradational channels in the Baiyun Sag are concluded as follows.Grain size decreases upwards.Mastering channels are found at the bottom and leveed channels are found at the top.The explorations of deepwater sandstones are complicated;hence it is necessary to find deepwater sandstones with big thickness and good communication.

Depositional system of lower Nantun Formation in South Tamuchage-South Beier Sag

Ji Youliang, Meng Qi'an, Shan Jingfu, Zhang Ge

2011, 33(3): 260-265. doi: 10.11781/sysydz201103260

Abstract(2020) PDF-CN(958)

Abstract:
Based on the data of core,well drilling,seismic and laboratory chemical analyses,the depositional system of the lower Nantun Formation in the South Tamuchage-South Beier Sag is discussed.Fan-delta,near-shore subwater fan,lake floor fan and lacustrine depositional system characterized by steep slope,near source and multi source account for large scales in the study region.Fan-delta,near-shore subwater fan and deep-lake mud deposits are the most developed sedimentary systems.According to the analyses of seismic facies,seismic features,sandstone contents and heavy minerals,it is discussed in this paper the depositional distribution characteristics of the lower Nantun Formation in the South Tamuchage-South Beier Sag.

Dolomitization of Ordovician Majiagou Formation in Sulige region, Ordos Basin

Fu Jinhua, Wang Baoqing, Sun Liuyi, Bao Hongping, Xu Bo

2011, 33(3): 266-273. doi: 10.11781/sysydz201103266

Abstract(2976) PDF-CN(1025)

Abstract:
The Ordovician Majiagou Formation in Sulige region of the Ordos Basin was deposited in hypersaline restricted epicontinental environment.It is mainly composed of carbonate rocks with thin evaporate interbeds.The dolomites are classified into 3 kinds:micrite,fine-medium crystal dolomite,and dolomite filled in pores and fractures.The Na concentrations range from 0 to 2 099×10^-6,the Sr concentrations range from 0 to 70×10^-6,the Mn concentrations range from 0 to 112×10^-6,and the Fe concentrations range from 39 to 86 746×10^-6 in dolomites.The dolomites are characterized with varied Na,low Sr and Mn,and high Fe concentrations.The ¹⁸O values for dolomites range from-16.00‰ to-5.73‰,and the ¹³C values range from -11.46‰ to 1.90‰(PDB).It indicates that carbonate rocks have experienced leaching and burial diagenesis.Most filled dolomites have lower ¹⁸O and ¹³C values than surrounding components,indicating that the former was formed later.The dolomites are characterized with low degrees of order and less stoichiometry.The ⁸⁷Sr/⁸⁶Sr values of dolomites range from 0.707 977±0.000 070 to 0.711 791±0.000 064,most of which are higher than that corresponding to global boundary between middle and upper ordovician.Microbial dolomitization is the reason for dolomite genesis.

Densification of Upper Triassic Xujiahe tight sandstones, Western Sichuan, China

Li Rong, Zhang Di, Zhu Lixia

2011, 33(3): 274-281. doi: 10.11781/sysydz201103274

Abstract(3457) PDF-CN(1023)

Abstract:
Densification process of the Upper Triassic Xujiahe sandstones were described based on petrologic,diagenesis and basin modeling analyses.The diagenetic events that affect reservoir quality mainly include mechanical and chemical compactions,precipitation of carbonate cements,and cementation by quartz.Compaction is the dominant process of porosity loss.Sandstones with high content of quartz,feldspar and carbonate rock fragment exhibit higher mechanical stability.Pervasive mesogenetic carbonate cementation occurs in the calcarenaceous sandstones in T₃x⁴ and the fine-grained sandstones in T₃x² and reservoir quality is significantly deteriorated by extensive carbonate cementation.Open and paleo-high environment is favorable for relatively good reservoir quality.Quartz cements are mainly sourced by the pressure dissolution of detrital quartz and are more abundant in sandstones rich in detrital quartz and illite and poor in carbonate cements and chlorite.Thick and continuous chlorite pore-linings help to preserve porosity by inhibiting pressure dissolution and quartz cementation and thus can be doubly beneficial to the Xujiahe sandstones.

Features of thrust nappe structure in northern South Yellow Sea

Yao Rong, Luo Kaiping, Yang Changqing

2011, 33(3): 282-284. doi: 10.11781/sysydz201103282

Abstract(1872) PDF-CN(993)

Abstract:
In marine formations of the northern South Yellow Sea,thrust nappe took place from NW to SE on Cambrian bottom,Silurian top(or Caledonian tectonic surface) and Upper Permian Longtan Formation coal strata.The thrust nappe structure spread from the Qianliyan Uplift to the southern margin of Laoshan Uplift,mainly in NE or EW direction.According to thrust nappe scale and basement involvement extent,the thrust nappe structure was divided into 3 belts from north to south:root,middle and front.The root located in the Qianliyan Uplift where a huge pre-Sinian thrust(overthrust) napped on the Paleozoic.The middle zone was from the Yantai Depression to the middle of Laoshan Uplift.In this region,imbricate thrusts were found in the Upper Paleozoic.The front zone located in the south of Laoshan Uplift,where detachment structures were found in the Longtan and Qinglong Formations.Analyses of seismic data indicated that thrust nappe movements in the northern South Yellow Sea mainly took place from Indosinian to the early Yanshanian.

Generation principle of ancient karst in marine carbonate rock hiatus, west of Xuefeng Mountain

Zhang Qingyu, Liang Bin, Chen Hongfeng, Cao Jianwen

2011, 33(3): 285-288. doi: 10.11781/sysydz201103285

Abstract(3012) PDF-CN(915)

Abstract:
During the Caledonian Movement,the Cambrian Niutitang-Sinian Dengying and Upper Cambrian-Ordovician parallel unconformities were found in the west of Xuefeng Mountain.Due to multi-stages of tectonic movements,several regional unconformities were formed in the study area.During different stages,the duration of sedimentary hiatus controlled the generation of carbonate rock karst,and further controlled connectivity.The unconformities seldom outcropped in the study area.Two typical outcrops from field works were studied and the controls of Niutitang-Dengying and Upper Cambrian-Lower Ordovician unconformities on ancient karst were analyzed.

Metamorphic core complex and neighboring basins in Hongzhen, Anhui Province

Fan Xiaolin, Lu Yongde

2011, 33(3): 289-291. doi: 10.11781/sysydz201103289

Abstract(2337) PDF-CN(871)

Abstract:
According to the geophysical analyses of gravity and aeromagnetic anomalies and the characteristic studies of metamorphic core complex in Hongzhen,tectonic genesis models of the Huaining and Wangjiang Basins have been discussed.Basin formation is related to the deep thermal flow in lithosphere and the regional squeezing and uplifting of metamorphic core complex as well as the following extensional tectonic movement.

Study of unresolved complex mixtures in crude oil

Hu Shouzhi, Li Shuifu, Zhang Dongmei, Ma Jun

2011, 33(3): 292-296. doi: 10.11781/sysydz201103292

Abstract(3601) PDF-CN(1059)

Abstract:
Unresolved complex mixtures(UCM) usually refer to hydrocarbons existing in crude oils(especially biodegraded oils).They are difficult to distinguish with normal GC,and include over 250 000 types of compounds.The effective discrimination of UCM may provide new geochemical information for crude oil genesis analysis,production,refinement as well as residual oil pollution evaluation and treatment.Rather than the definition of UCM,it is also discussed in this paper the experiment technology progress and the compound features of UCM as well as the applications in petroleum exploration,deve-lopment and environment protection.The problems in UCM studies and the future targets are also pointed out.

Petroleum accumulation characteristics and favorable exploration directions in Wenchang B Sag and its surrounding areas, Pearl River Mouth Basin

Zhang Yingzhao, Chen Zhihong, Li Xushen, Xu Xinde, Li Qi

2011, 33(3): 297-302. doi: 10.11781/sysydz201103297

Abstract(3107) PDF-CN(1075)

Abstract:
Based on source rock analysis,oil—source correlation and accumulation comprehensive analysis,oil source and accumulation process in the Wenchang B Sag and its surrounding areas were studied.Main source rock and hydrocarbon accumulation features in different regions were illustrated.Main controlling factors of hydrocarbon accumulation and favorable exploration directions were pointed out.Sha-llow lacustrine source rock of the Wenchang Formation in the Wenchang B Sag was the main contributor for accumulation in uplifting region besides the well-known middle—deep lacustrine source rock.At the end of deposition,lacustrine source rock of the Wenchang Formation in the downthrow of southern fault experienced tectonic inversion,resulting in the delay of oil generation and expulsion as well as the multi-stages of oil charging.The downthrow of fault No.3 was also characterized by early oil generation and expulsion as well as multi-stages of oil charging.Favorable lacustrine source rock of the Wenchang Formation,multi-stages of fault activities and sets of reservoir—caprock assemblages worked as the main controlling factors for hydrocarbon accumulation.Favorable exploration directions were pointed out,including the inverse abrupt slope and the middle—deep buried Paleogene of the northern slope in the Wenchang B Sag as well as the first member of Zhujiang Formation in the Qionghai uplift.

Division of exploration units and its significance in mature exploration region：a case study in Dongying Sag

Xu Xianghua

2011, 33(3): 303-306. doi: 10.11781/sysydz201103303

Abstract(3081) PDF-CN(969)

Abstract:
It is very difficult to explore with structural unit in mature exploration regions.According to exploration and production practices,the concept and the division method of exploration unit in mature region were proposed,and were used to guide geologic study,well arrangement and input-output ana-lysis.In Yanjia-Yong'an region of the northern steep slope of the Dongying Sag,a case study was carried out in the nearshore subaqueous fan lithologic reservoir from the upper Es⁴ to the lower Es³.The relationship between geologic conditions and exploration capabilities was analyzed with "exploration unit".The key problems were pointed out so as to guide exploration and improve efficiency.

Identification of reef in Miocene, south of Qiongdongnan Basin

Zhang Yonggui, Song Zaichao, Zhou Xiaojin, Wu Li, Zhang Xike, Ran Jing

2011, 33(3): 307-309. doi: 10.11781/sysydz201103307

Abstract(3559) PDF-CN(987)

Abstract:
The southern part of the Qiongdongnan Basin was suitable for reef generation when the Meishan Formation deposited during Miocene.Seismic data collected in this region during the past few years have indicated that the Meishan Formation is characterized by typical mound reflection,mainly on ancient uplifts.The formation is flat at the bottom and convex at the top.There is clear boundary between top and bottom.The reflection is strong.Progradational or random reflection exists in the formation,while on the 2 flanks there is onlapping,and on the top there is drape.The wave impendence value is(8-10)×10⁶kg/(m²·s).The formation is regarded as reef according to present studies.Comparisons between reef and mud structure have been carried out based on the studies of regional sedimentary background,mound structure generation location and seismic reflection characteristics,indicating that it is impossible for shale diapire generation in the formation.

Rare gas component measurement with self-designed pretreatment unit and Quadrupole Mass Spectrometer

Tao Cheng, Sun Mingliang, Wang Xiaofeng, Zhou Yu

2011, 33(3): 310-313. doi: 10.11781/sysydz201103310

Abstract(2183) PDF-CN(972)

Abstract:
According to the rare gas component in air,the content of rare gas in sample gas is measured with self-designed pretreatment unit and Quadrupole Mass Spectrometer(QMS).The method is highly sensitive and is accurate in He and Ar analyses.It is applied in rare gas component analyses of natural gas and grouped inclusions in sedimentary rocks.The results satisfy the needs of geology research.

Primary study on relatively preconcentration of trace hydrogen in natural gas

Meng Qingqiang, Tao Cheng, Zhu Dongya, Jin Zhijun, Wang Qiang, Zheng Lunju

2011, 33(3): 314-316. doi: 10.11781/sysydz201103314

Abstract(2239) PDF-CN(895)

Abstract:
A new quantitative preconcentration method for trace hydrogen in natural gas was proposed in this paper so as to deal with the problem of isotopic composition measurement.Based on the differences of chemical and physical properties between different components in natural gas,using cryogenetic trap and vacuum techniques,helium was injected to liquefy the gas components with higher boiling point.In this way,trace hydrogen was concentrated and the concentration degree was calculated.A correspon-ding equipment was designed and produced.Experiments with the mixed gas of standard H₂ and CH₄ as well as trace hydrogen were carried out.It has been proved that,the new method is qualified to concentrate trace hydrogen.The testing error is about ±5‰.It might be a system error,but still remains confirmation.

Quantitative discrimination of hydrocarbon micro-seepage pattern

Yang Jun

2011, 33(3): 317-322. doi: 10.11781/sysydz201103317

Abstract(1500) PDF-CN(872)

Abstract:
Studies of hydrocarbon micro-seepage have indicated that,when reservoir has been formed,oil and gas mainly seep as micro-bubble or with water.Based on isopachous stratigraphic model,a quantitative discrimination coefficient of micro-seepage pattern has been proposed and calculated according to general geological theory.It has been concluded that,1) Due to the changes of geological conditions,the micro-seepage pattern of hydrocarbon in strata is also changing;2) Hydrocarbon usually seeps as micro-bubbles and transfers to water-soluble pattern as it comes closer to earth surface.The 2 pa-tterns result in hydrocarbon abnormality on earth surface while diffusion only forms background field;3) Sealing ability of direct seal,stratigraphic physical property and vertical movable water content are the key factors controlling hydrocarbon micro-seepage pattern.Proposal of the discrimination coefficient is significant for micro-seepage mechanism research.It also settled a foundation for numerical simulation,formation interpretation and evaluation of geochemical field in hydrocarbon chemical exploration.

2011 Vol. 33, No. 3

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