石油实验地质

2012, 34(2)

Abstract(329) PDF-CN(358)

Abstract:

2012, 34(2): 108-108. doi: 10.11781/sysydz201202108

Abstract(2180) PDF-CN(873)

Abstract:

Evaluation and prediction of shale gas sweet spots：a case study in Jurassic of Jiannan area Sichuan Basin

Zhou Dehua, Jiao Fangzheng

2012, 34(2): 109-114. doi: 10.11781/sysydz201202109

Abstract(6215) PDF-CN(3017)

Abstract:
The evaluation system,critical steps and key parameters for shale gas sweet spots were discussed in this paper.A case study was carried out in Jurassic of Jiannan area of the Sichuan Basin.By means of the evaluation system,the geologic features of sweet spots in shale gas reservoirs were analyzed,the distribution pattern of sweet spots were predicted,and the arrangement of exploration wells were put forward,resulting in good effects.It was concluded as followed.1) Different from conventional petroleum evaluation,the evaluation and explorationof unconventional shale gas demanded an unconventional approach combining geology with engineering.Geology,geochemistry,petroleum engineering,lithomechanics and petrophysics all contributed to the evaluation.2) The success of long-distance horizontal fracturing in well Jianye HF-1 proved good potential for shale gas exploration in Jurassic of Jiannan area.3) The maps of shale thickness,ω(TOC),R_o and burial depth might guide shale gas sweet spots exploration.

Accumulation system for shale gas from Upper Ordovician to Lower Silurian in Sichuan Basin and surrounding areas

Nie Haikuan, Bao Shujing, Gao Bo, Bian Ruikang, Zhang Jinchuan

2012, 34(2): 115-119. doi: 10.11781/sysydz201202115

Abstract(4171) PDF-CN(2521)

Abstract:
Shale sedimentary time,feature,evolution history,present tectonic location,tectonic feature,residual condition,distribution,burial depth and gas content were discussed in this paper.The accumulation system for shale gas from the Upper Ordovician to the Lower Silurian in the Sichuan Basin and the surrounding areas was divided into 7 accumulation systems,including the southern and southeastern Sichuan,the northern Guizhou,the eastern Chongqing,the western Hunan and Hubei,Longmen Mountain,Micang Mountain-Daba Mountain,and the central Sichuan.Shale thickness,organic carbon content,maturity and gas content in each accumulation system were analyzed.The accumulation systems were evaluated at 4 levels as followed: strategic breakthrough,expansion,preparation and perspective area.Exploration targets were also pointed out.

Characteristics of strike-slip fault and its controlling on oil in Shuntuoguole region, middle Tarim Basin

Ma Qingyou, Sha Xuguang, Li Yulan, Zhu Xiuxiang, Yang Suju, Li Huili

2012, 34(2): 120-124. doi: 10.11781/sysydz201202120

Abstract(5345) PDF-CN(1993)

Abstract:
Based on the detailed interpretation of 3D seismic data from Shuntuoguole region in the middle Tarim Basin,the Shuntuo No.1 strike-slip fault was identified,and its structural characteristics,active periods,genesis and influences on reservoir were also studied.The structural styles of the Shuntuo No.1 strike-slip fault included extensional linear structure,negative flower structure,en-echelon tension normal fault,dolphin and riband effects,etc.Its main active time lasted from the end of Silurian to the Early Devonian.At the end of Caledonian,the Altym Island Arch compressed severely from the southeast and acted on the northeast-trending weak zone of basement,resulting in the northeast-trending strike-slip fault.Recent studies have proved that low-amplitude anticline traps related to the northeast-trending strike-slip fault are favorable oil-and-gas exploration targets of Silurian in Shuntuoguole region of the middle Tarim Basin.

Diagenesis of Devonian Donghetang sandstones in Bachu Uplift, Tarim Basin

Li Jianjiao, Cao Zicheng, Yue Yong

2012, 34(2): 125-128. doi: 10.11781/sysydz201202125

Abstract(3817) PDF-CN(1564)

Abstract:
The thin sections of Devonian Donghetang sandstones from several typical wells in Bachu-Maigaiti area of the Tarim Basin were observed.In the Donghetang Formation,quartz was in high content while feldspar and lithic ranged from 1% to 4%,standing for high maturity.The main diagenetic effects included compaction,cementation,dissolution (dissolving) and so on.Devonian Donghetang sandstones were during the middle and late stages of diagenesis.Few primary pores and fissures were found.Epidiagenetic dissolution and burial dissolution dissolved a variety of soluble and carbonate rocks,resulting in intragranular dissolved pores,moldic pores and enlarged dissolved pores.However,since the process of diagenesis was superimposed in the study area,the improvement of reservoir was limited and the physical property of Devonian Donghetang Formation was poor.

Hydrocarbon migration system in complex geological bodies at Chepaizi area,western Junggar Basin

Liu Chuanhu, Wang Xuezhong

2012, 34(2): 129-133. doi: 10.11781/sysydz201202129

Abstract(2791) PDF-CN(1539)

Abstract:
The Chepaizi Arch is a secondary tectonic unit in the western uplift of the Junggar Basin.Two oil fields,Chunguang and Chunfeng,have been discovered,and the proven oil reserves are 6 061?10⁴ t.As to the complex geological bodies in the study area,the framework,driving mechanism and its controlling on petroleum distribution of hydrocarbon migration system have been analyzed.It has been concluded that,in the Chepaizi area which is a typical slope,the Hongche Fault Belt plays the most important role in migration,and the connected matrix sand bodies also work as pathways.Vertical and lateral migrations of big scale are very common,mainly generating structural or lithologic-structural reservoirs.In overlying and erosion belt,unconformities work as the main pathways.Lateral migrations are common,mainly generating stratigraphic or structural-stratigraphic reservoirs.In the higher positions of sand valley,entrenched valley depositional system serves as lateral pathways,resulting in lithologic reservoirs.

Characteristics and significances of carbonate cements in northern Mahai region,northern margin of Qaidam Basin

Sun Guoqiang, Ma Jinye, Wang Haifeng, Chen Ji, Zhang Yongshu, Jia Yanyan, Zhang Shengyin, Shi Ji'an

2012, 34(2): 134-139. doi: 10.11781/sysydz201202134

Abstract(4173) PDF-CN(1413)

Abstract:
Based on lithology,mineralogy and geochemistry,the generation environment and source for carbonate cements in sandstone reservoirs in the lower position of the Paleogene Lower Ganchaigou Formation in the north of the Mahai Uplift which located in the northern margin of the Qaidam Basin were studied systematically.Two types of calcite cements were found,including xenomorphic micrite and hypidiotopic microcrystalline.Their carbon isotope values (δ¹³C) ranged from -7.1‰ to -3.3‰ with the average of -4.9‰,and the oxygen isotope values (δ¹⁸O) ranged from -11.3‰ to -9.6‰ with the average of -10.3‰.The Z-values of paleosalinity ranged from 107.0 to 115.6 and the average value was 112.1.The generation of carbonate cements in sandstone reservoirs in the study area might be related to the decarboxylation of organic matters during the early diagenetic stage.A little organic carbon also participated in the reaction.Diagenetic fluids mainly came from clast and atmospheric freshwater.

Prospecting potential and targets of buried-hill oil and gas reservoirs in Bohai Bay Basin

Li Xin, Yan Weipeng, Cui Zhouqi, Guo Bincheng, Liang Kun, Zhang Tao

2012, 34(2): 140-144. doi: 10.11781/sysydz201202140

Abstract(4778) PDF-CN(1319)

Abstract:
The buried hills in the Bohai Bay Basin have experienced over 40 years'exploration.And based on its exploration course and rules,the buried hill exploration is divided into four stages by ten years,including scale discovery stage,downturn stage,slow discovery stage and new stage.It is indicated from deep resource study that hydrocarbon resource is abundant and buried hill exploration is based on ample resource.It is shown from current situations that buried hill exploration is unbalanced in types,exploration series of strata,depth and degrees,which provides immense prospecting potential.From the exploration practices in Archaean metamorphic rock buried hill in Xinglongtai of the Liaohe Depression and in Wumishan deep buried hill in Niudong of the Jizhong Depression,buried hill exploration will be subsequently conducted in the deeper reservoirs and those below 4 000m will be the hot spots of exploration.The principal type of buried hills varies from weathering crust to internal buried hill.Central sags and swells are the focused exploration targets of internal buried hills.And the exploration presents obvious depression replacement.Attentions are paid on the beaches in the Huanghua Depression and the Liaohe Depression and those areas with low exploration degree.In terms of exploration degree,26 buried-hill zones present higher exploration potential,including Daxing-Gu'an,Shubei-Niuxintuo,Changlu,Wangguantun-Wumaying,Yannan,Bijialing,Haiyue and so on.New discoveries will be surely realized in the exploration of buried hills.

Influences of diagenetic effects on volcanic rock reservoirs under two different sedimentary environments

Wang Shengpeng, Lin Tong, Sun Ping, Liang Hao, Wang Dongliang, Gou Hongguang

2012, 34(2): 145-152. doi: 10.11781/sysydz201202145

Abstract(4206) PDF-CN(1749)

Abstract:
According to the studies of rock types and reservoir space features of Carboniferous volcanic rocks in the Santanghu Basin,there were two kinds of environments for volcanic rock generation including subaerial and subaqueous in the study area.Based on core description,casting chip,scanning electron microscopy and element analysis,the generation features of volcanic rocks under the two different environments and the corresponding influences on reservoirs were discussed from the aspects of diagenetic effects.It was concluded that different diagenetic effects influenced volcanic reservoirs in different extents.The volcanic rocks which erupted and deposited on land in the study area were severely filled by zeolites and chlorites,and then improved obviously due to weathering and leaching.The extent of weathering and leaching was closely related to the improvement of reservoir.The volcanic reservoirs which deposited under water were improved owing to organic acid erosion.Primary pores were seldom found and a large amount of matrix dissolved holes generated.The generation mechanisms of subaqueous volcanic reservoirs pointed out new areas for explorations in the future.

Characteristics of carbonate reservoirs of Cambrian Loushanguan Formation to the west of Xuefeng Mountain

Li Xubing, Liu An, Zeng Xiongwei, Wang Chuanshang, Bai Yunshan

2012, 34(2): 153-157. doi: 10.11781/sysydz201202153

Abstract(4021) PDF-CN(1677)

Abstract:
The carbonate reservoirs of the Cambrian Loushanguan Formation to the west of Xuefeng Mountain were studied.Two types of reservoirs were identified including oolitic beach and dolomite.Intercrystalline pore,dissolution pore and fracture worked as reservoir room and were usually well connected.The oolitic dolosparites and intraclast dolomites of Loushanguan Formation in Hefeng of Hubei province and Sangzhi and Zhangjiajie of Hunan province were studied.The maximum pore radius of oolitic dolosparite was over 200 μm with the average of 9.61 μm.The pore radius of intraclast dolomite ranged from 100 μm to 200 μm,accounting for 33%.The maximum throat was 81.43 μm and the average was 21.28 μm.The maximum porosity was 10.3% and the average was 3.4%.The maximum permeability was 18.6×10^-3 μm² and the average was 1.4×10^-3 μm².Both porosity and permeability were good and were judged as reservoir of type Ⅱ.The reservoirs of the Cambrian Loushanguan Formation distributed mainly in the tidal flat facies areas to the west of the Cili-Baojing Fault,and had good potential for exploration.

Petroleum geologic characteristics of medium-small continental basins in five provinces in South China

Xu Zhengyu, Yao Genshun, Zhang Ximan, Ma Qinglin, Huang Ling, Cheng Gang, Liao Feiyan, Wang Pengwan

2012, 34(2): 158-166. doi: 10.11781/sysydz201202158

Abstract(4408) PDF-CN(1587)

Abstract:
In 5 provinces (Hainan,Guangdong,Yunnan,Guizhou and Guangxi) in South China,about 63 medium-small continental basins generated from the Late Cretaceous to Cenozoic.6 basin zones and 2 basin generating environments were divided according to tectonic backgrounds.Combined with sedimentary and filling process,4 patterns were concluded.In the east and center of the study area,source rocks generated early (usually during Paleogene) and were featured by big thickness (400-1000,100-900m) and lacustrine mudstones.In the composite and superimposed basins in the west of the study area,source rocks generated late (mainly during Neogene) and were featured by smaller thickness (125-700m) and carbonate mudstones and coal beds.TOC values were high in these basins,but the organic types were complicated and decreased from east to west.The thermal evolution of source rocks also decreased from east to west.The eastern and central basins were during the immature and low-mature stages,and the exploration targets should be focused on immature biogas and low-mature oil.The western basins were during the immature stage,and immature biogas should be explored.As the result of abundant depositional system in these basins,physical property of sandstone reservoirs were fine,usually characterized by mid-high porosity and permeability.What's more,during the fading stage of basin,shallow lacustrine and swamp facies mudstones filled regionally and worked as seal.According to exploration data,petroleum pools in the study area were classified into 4 types including tectonic (mainly in the eastern basins),lithologic (mainly in the western basins),stratigraphic and composite (mainly in the central basins).

Organic petrologic characteristics of hydrocarbon source rocks in Majiang-Kaili area, southeastern Guizhou

Wang Juan, Li Xianqing, Wang Guangli, Yang Yunfeng, Zhao Pei, Kong Longxi

2012, 34(2): 167-172. doi: 10.11781/sysydz201202167

Abstract(4801) PDF-CN(1536)

Abstract:
By means of whole-rock analysis of organic petrology,the maceral composition,hydrocarbon-generating maceral and thermal evolution of organic matter of hydrocarbon source rocks in Majiang-Kaili area of the southeastern Guizhou province have been studied.The source rock samples from this region mainly include 3 types: bitumen-bearing carbonates,mudstones and coals.The maceral contents of these source rocks vary according to their different samples,showing obviously heterogeneity.The total maceral contents (TMC) of the bitumen-bearing carbonates,mudstones and coals are 0.8%-13.6%,1.4%-9.4%,and over 70%,respectively.The hydrogen-rich macerals of these hydrocarbon source rocks are mainly composed of exinite,asphalt group,secondary organic matter and mineral bituminous groundmass.It is suggested that sporinite,liptodetrinite,bitumen and mineral bituminous groundmass are the main hydrocarbon-generating macerals in this region.Thermal evolution level of organic matter in these hydrocarbon source rocks are among the mature and over-mature stage,with the equivalent vitrinite reflectance (R_o) of 0.674%-2.659%.

Features of Mesozoic source rocks and oil-source correlation in southern Ordos Basin

Zhang Yunxia, Chen Chunfang, Song Yanbo, Tao Ye, Li Song

2012, 34(2): 173-177. doi: 10.11781/sysydz201202173

Abstract(4881) PDF-CN(1870)

Abstract:
Based on the studies of carbon isotopes and biomarkers,only one set of effective source rock was identified in Mesozoic in the southern Ordos Basin,that is,dark shale with big thickness deposited in lacustrine environment in the Upper Triassic Yanchang Formation.The source rocks mainly distributed in Qingyang,Zhengning,Zhiluo,Wuqi,Yanchi and Huanxian County.The dark shale in the seventh member of Yanchang Formation was the most favorable source rock in the study area,providing oil and gas for not only itself but also the Fuxian,Yan'an and Zhiluo Formations of Jurassic.With weak structural fluctuation and gentle stratigraphic dip angle (usually below 1°),hydrocarbon had migrated for short distance before accumulating in low-porosity and low-permeability reservoirs.Sand bodies were poorly connected and few fractures worked as vertical migration pathways.Hydrocarbon mainly accumulated in lacustrine depressions or neighboring areas.The results showed that the favorable places for prospecting in the southern Ordos Basin should be the lithologic traps close to the source rocks in Yanchang Formation.

Generation and distribution of thermogenic natural gas hydrates in submarine sediments

Lin Xiaoying, Zeng Jianhui

2012, 34(2): 178-181. doi: 10.11781/sysydz201202178

Abstract(3170) PDF-CN(1614)

Abstract:
With an one-dimensional equipment designed by China University of Petroleum,the simulation of natural gas hydrate generation was carried out using conventional thermogenic natural gas as source and submarine sediment as porous medium.Resistivity method was applied to analyze the generation and distribution of natural gas hydrate in sediment.The results showed that resistivity varied between different positions of sediment.In the middle and lower position,resistivity first increased and then became stable.While in the middle and upper position,resistivity changed like zigzag,that was,decreasing,increasing (or stable),decreasing,increasing and stable.The changes of resistivity indicated the generation and distribution of natural gas hydrate in different positions.The natural gas hydrates in the middle and lower positions had come into being while those in the middle and upper positions were still during the induction and nucleation stages.Influenced by temperature gradient,natural gas hydrates generated slowly and scattered.If gas supplied sufficiently,natural gas hydrates might generate massively in the middle and upper positions.Finally,a hydrate generation and distribution model was established based on the above-mentioned analyses.

Features and geologic significance of maceral composition of coal-bearing source rocks in Xihu Sag

Qian Menhui, Hou Dujie, Jiang Qigui, Zheng Lunju

2012, 34(2): 182-185. doi: 10.11781/sysydz201202182

Abstract(4604) PDF-CN(1559)

Abstract:
According to the studies of well HY14-1-1,the maceral composition of coal-bearing source rocks in the Xihu Sag was divided into 2 types including type Ⅰ mainly of vitrinite and type Ⅱ mainly of exinite and sapropelinite.The simulations of hydrocarbon generation of the above-mentioned types indicated that the type Ⅰ mainly generated liquid hydrocarbon while the type Ⅱ mainly generated gaseous hydrocarbon.The vertical and horizontal differences between the 2 types of coal-bearing source rocks led to the present distribution of petroleum in the Xihu Sag,that is,oil in the upper formations and gas in the lower formations.

Luo Houyong, Wang Wanchun, Liu Wenhui

2012, 34(2): 186-192. doi: 10.11781/sysydz201202186

Abstract(3662) PDF-CN(1695)

Abstract:
The similarities and differences between simulation experiments on thermochemical sulfate reduction (TSR) and geological observations have been compared.Some results of the TSR simulation experiments are consistent with the natural TSR process in terms of products,reaction temperature,catalysts,etc.; however,there is a big gap between current TSR simulation experiments and actual geological process.Owing to relatively simple reactants,limited experimental time as well as comparatively less catalysts,some complex chain reactions during the actual geological processes fail to occur in the TSR simulation experiments,preventing some of the reactions from achieving the extent of reaction under geological conditions.Therefore,the TSR simulation experiments fail to reproduce the phenomena observed under actual geological conditions.Significant differences exist between simulation experiments and geological observations on the sulfur isotopic fractionations of hydrogen sulphide and the carbon isotopic fractionations of n-alkanes.In order to carry forward the study of TSR reaction mechanisms and dynamics and to efficiently figure out TSR-related geological and geochemical issues,the future TSR simulation experiments should use more complex reactants,systems and all kinds of catalysts.

Studies of 3D reservoir modeling: taking Ordovician carbonate fractured-vuggy reservoirs in Tahe Oil Field as an example

Lu Xinbian, Zhao Min, Hu Xiangyang, Jin Yizhi

2012, 34(2): 193-198. doi: 10.11781/sysydz201202193

Abstract(6684) PDF-CN(5653)

Abstract:
Carbonate fractured-vuggy reservoirs are basically different from clastic or other fracture-pore reservoirs.Karst caves,fractures and corroded pores coexist in the carbonate fractured-vuggy reservoirs and challenge traditional clastic reservoir modeling theories and methods.A new modeling technique based on fractured-vuggy unit has been proposed.It is featured by "5 steps" including the establishments of 5 models: cave distribution,fracture discrete distribution,cave petrophysical parameter,fracture parameter as well as fracture and cave connection.The model illustrates the 3D distribution and features of fractured-vuggy reservoirs and provides theore-tical basement for reservoir exploration.

A new method for analysis of δ¹⁸O and δD in oil-and-gas field water and its application

Tao Cheng, Liu Wenhui, Yang Huamin, Ba Liqiang

2012, 34(2): 199-201. doi: 10.11781/sysydz201202199

Abstract(4168) PDF-CN(1400)

Abstract:
We described a new and simple on-line pyrolysis method for the analysis of δ¹⁸O and δD in oil-and-gas field water by continuous flow EA-IRMS.The sample water was converted into CO and H₂ in glassy carbon tube which was filled with glassy carbon granules at high temperature (1 450℃).And then,CO and H₂ were separated in GC column prior to transferring into the ion source of the Isotope Ratio MS for sequential determination of hydrogen and oxygen isotopes of the sample by magnet switching.This method performed dual measurements of δ¹⁸O and δD from a single sample,and had high efficiency and good productivity.Using this method,we measured some water samples from gas fields in the Sichuan Basin.The results showed that the water of Triassic Xujiahe Formation was the mixture of marine sedimentary and ancient meteoric water.

Quantitative description of high-capacity channels in Gaotaizi Reservior of Honggang Oil Field

Niu Shizhong, Hu Wangshui, Xiong Ping, Wang Wei, Cheng Qun

2012, 34(2): 202-206. doi: 10.11781/sysydz201202202

Abstract(4941) PDF-CN(1751)

Abstract:
In sandstone reservoirs which were during the medium and high water cut stages,high-capacity channels might take place after long terms of water flooding,which made the circulation of water flooding very inefficient,and further reduced exploration efficiency and recovery rate.A case study was carried out in the Gaotaizi Reservoir of the Honggang Oil Field.The influencing factors for the generation of high-capacity channels were studied.Porosity,permeability and water content ratio were chosen as static or dynamic indexes to calculate high-capacity channel parameter by confirming the weight of each index.Based on the above-mentioned modeling indexes,a three-dimensional model for high-capacity channels in the study area was set up so as to illustrate the generation and distribution of high-capacity channels in reservoir and to provide geologic basis for future oilfield development.This new method provided direction for the research on large pores,and was significant for the study of other similar reservoirs.

A new method to calculate sedimentary rates based on Milankovitch Cycles: a case study on middle section of 3rd member of Shahejie Formation in well Niu38, Dongying Sag, Bohai Bay Basin

Xu Wei, Xie Xinong

2012, 34(2): 207-214. doi: 10.11781/sysydz201202207

Abstract(3975) PDF-CN(1934)

Abstract:
A case study was carried out in the middle section of the 3rd member of the Shahejie Formation in well Niu38,Dongying Sag,Bohai Bay Basin.Spectrum analysis and continuous wavelet spectrum of GR log which was closely related to climate change indicated that the target interval was significantly controlled by the eccentricity period of 125 ka corresponding to the thickness of 12.127 m.The filter analysis of this period revealed that about 40 cycles of 125 ka were preserved in the target interval.High-resolution astronomical time scale was established,by means of which the age of the top of the target interval was 33.975 Ma since that of the bottom of the target interval was 38.975 Ma.Based on regional stratigraphic framework,combined with seismic,core and logging data,the Dongying delta was divided into 9 periods named Z1-Z9.According to the sliding window spectrum analysis,the sedimentary rates of the target interval first increased and then decreased as time went by.The sedimentary rate of Z4 reached the maximum (0.127 m/ka) during the most prosperous period of delta prograding.Finally,the duration of each period and more accurate geological age of the interfaces were calculated on the basis of sedimentary rates.

Infra-red emission spectroscopy study of thermal evolution of organic matter bound by clay minerals in muddy hydrocarbon source rocks

Lu Longfei, Cai Jingong, Liu Wenhui, Tenger, Hu Wenxuan

2012, 34(2): 215-222. doi: 10.11781/sysydz201202215

Abstract(4956) PDF-CN(2138)

Abstract:
To examine the thermal evolution of and the influence of organo-clay interaction on organic matter bound by clay minerals in muddy source rocks,we studied the <2μm particle-size fractions extracted from hydrocarbon source rocks in Neocene,Jiyang Depression,eastern China,using infra-red emission spectroscopy(IES).Results show that the vibration peaks of methylene and methyl representing aliphatic chain decrease with the increasing of temperature,and lateral chains are easily to subject to oxidation than main chains.Intensities of vibration peaks attributed to aromatic compounds vary respectively,some peaks such as 798,779 and 750cm^-1 decrease with the increasing of temperature,but the reverse to other peaks.Vibration peaks such as 1 600 and 3 030cm^-1 do not occur until 250℃ and increase first and decrease subsequently,while aromaticity factor increases progressively,showing a clear aromatization process.Also,carboxylic acids interact with interlayer hydrated actions of clay minerals through hydrogen bond,making carboxylic acids much stabile and thus suppressing their thermal evolution.IES study reveals that organic matter bound by clay minerals generates hydrocarbon mainly through aromatization of aliphatic compound,which is a quite useful method for source rocks thermal evolution study.

2012 Vol. 34, No. 2

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