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Sequence stratigraphy and sedimentary facies in the Shahejie formation of the Paleogene in Dongbu sag, Liaohe basin/2015,39(6):1-11

LIU Xiaojing1, XIE Qingbin1,2, XU Xiang1, LI Jun3, WANG Luli1, SONG Yifan1

( 1.DepartmentofGeoscience,ChinaUniversityofPetroleum(Beijing),Beijing102249,China; 2.StateKeyLaboratoryofPetroleumResourcesandProspecting,ChinaUniversityofPetroleum(Beijing),Beijing102249,China; 3.ResearchInstituteofExplorationandDevelopment,LiaoheOilfieldCompany,PetroChina,Panjin,Liaoning124010,China)

Abstract: According to the integrated research on cores, well logs and seismic data, the sequence stratigraphic division and the features of sedimentary facies have been studied comprehensively. We identified three third-order sequence boundaries, thus divided the succession into two third-order sequences in the Shahejie formation. Besides, we identified many kinds of sedimentary facies, such as alluvial fan, fan delta, braided river delta, turbidite fan and lacustrine facies. Based on the study of sequence stratigraphic framework division and depositional bodies, in combination with analyses of cores, logs and sedimentary data, we delineated the sedimentary facies distribution map of two sequences in the Shahejie formation. According to the study of distribution features and evolution laws of sedimentary facies, and the analyses of control factors, the sedimentary facies model of this period was built. In the east steep slope zone of basin, sediments transport in a short distance and develop alluvial fan on land and fan-delta, turbidite fan under water. In the west gentle slope zone of basin, braid river-braid river delta distal sedimentary system is formed because of the relatively far transportation distance of sediments.

sequence stratigraphy; sedimentary facies; sedimentary facies model; Shahejie formation; Paleogene; Dongbu sag; Liaohe basin

Structural characteristics and hydrocarbon accumulation model of Dazhangtuo fault belt in the Banqiao sag/2015,39(6):12-19,110

SONG Fan, SU Nina, LI Hui, HONG Weijun, LU Yunqian, LIU Jiaxing, LIU Xuejia

(SchoolofGeoscienceandTechnologyinChinaUniversityofPetroleum(EastChina),Qingdao,Shandong266580,China)

Abstract: Dazhangtuo fault belt is the largest level Ⅱ fault system of Banqiao sag in the Huanghua depression. It exerts important effect on hydrocarbon distribution and accumulation within the sag. In order to reveal the relationship between the Dazhangtuo fault belt and Cenozonic hydrocarbon accumulation of Banqiao sag, the fault activity, fault structural styles and structural evolution characteristics were systematically researched using the oilfield structural analysis method. Based on comprehensive research of fault passage system and hydrocarbon distribution in two fault walls, the accumulation model of Dazhangtuo fault belt in the Banqiao sag were established. The results show that the Dazhangtuo fault, with vertical installment and planar piecewise activity characteristic, derived a large number of secondary faults. Five kinds of structure style can be identified in the fault belt, mainly including the "ladder" type, the "y" type, the composite "y" type, the "domino" type and the opponent tendency stretch type. The fault activities throughout the Tertiary sedimentary history and the structure evolution have obvious inheritance. The hydrocarbon migration and accumulation are obviously different in the two sets of faults, controlled by the different style of fault structure. And the hydrocarbon gathering units with different genetic types and different reserves abundance formed.

Key words: Banqiao sag; Dazhangtuo fault; fault activity; structural styles; structure evolution; hydrocarbon accumulation

Sedimentary characteristics and sedimentary model of Wei95 block in Mazhai oilfield, Dongpu depression/2015,39(6):20-29,120

YIN Nanxin1,2, LI Cungui3, JIA Yunchao4, LI Zhongchao2, XIONG Yunbin2, ZHANG Wencheng4, WANG Debo2, SUN Li2

( 1.PostdoctoralResearchWorkstationofZhongyuanOilfieldBranch,SINOPEC,Zhengzhou,Henan450018,China; 2.ExplorationandDevelopmentResearchInstitute,ZhongyuanOilfieldBranch,SINOPEC,Puyang,Henan457001,China; 3.DevelopmentandManagementDepartmentofZhongyuanOilfieldBranch,SINOPEC,Puyang,Henan457001,China; 4.OilPlantNo. 3ZhongyuanOilfieldBranch,SINOPEC,Puyang,Henan457000,China)

Abstract: Es3 subinterval is the main oil-bearing horizon of Wei95 block in Mazhai oilfield. Reservoir is very thick, genesis of sand is very complicated and consequently it is hard to cognize the facies zone. The article analyzed sedimentary characteristic and sedimentology pattern of Es3 low sub-member of Wei95 block. Under the guide of geology and sedimentology, we analyzed the color of mudstone of target zone, rock type and combination, fineness and structure characteristic comprehensively to study the deposition facies. It is concluded that fan-dealta subfacies distributed widely there and the source is from Neihuang uplift in the west. The subfacies is divided into 4 microfacies: underwater distributary channel, channel flanking, sheet sand and inter-channel and we summarized well-log respond mode of each type. From the single-well facies and planar facies of main sand group, we found that multistage fan-delta distributed from northwest to southeast and overlapped mutually. Underwater distributary channel and sheet sand took the majority. Based on the analysis of structure of target area, sedimentary mode of Wei95 block was summarized according to the source direction and distribution characteristic. The result could provide geological reference for further development of the oilfield.

Key words: Dongpu depression; Mazhai oilfield; Wei95 block; Es3 subinterval; fan-delta; sedimentary microfacies; sedimentary mode

Characteristics and main control factors of volcanic gas reservoirs in Yingtai fault depression/2015,39(6):30-37,65

DONG Yisi1, HUANG Wenbiao2, YU Xinghe1, DENG Shouwei3, LU Shuangfang2, SUN Tingting1

( 1.SchoolofEnergyResources,ChinaUniversityofGeosciences(Beijing),Beijing100083,China; 2.InstituteofUnconventionalResourcesandNewEnergy,ChinaUniversityofPetroleum(EastChina),Qingdao,Shandong266580,China; 3.ResearchInstituteofPetroleumExploration&Development,PetroChinaJilinOilfieldCompany,Songyuan,Jilin136200,China)

Abstract: Although the discovery of volcanic gas reservoirs in the southern Songliao basin gained great breakthrough, the poor understanding of gas accumulation rules, compared with the exploration activity, may limit the further development of the deep gas reservoir in Jilin oilfield. Based on the quality and coupling relationship of source rock & reservoir, hydrocarbon migration system, gas reservoir characteristics, analysis on main controlling factors of gas accumulation, the distribution of remaining resources was predicted by summarizing the reservoir forming rules. Study shows that lower generating-upper reservoiring and side generating-side reservoiring types volcanic gas reservoirs was found in Yingtai fault depression. Lower generating-upper reservoiring type is mainly developed in the member 1 of Yingcheng formation in Datun area, and based largely on fault to penetrate source rock and reservoir, which control the distribution of gas reservoir. The side generating-side reservoiring type is mainly developed in Wukeshu area. The key to this kind of gas reservoir accumulation is whether the volcanic reservoir connects directly with side effective source rocks. It is easier to form gas reservoir in contact surface, for not only its large scale, but also its high richness. With the increasing of migration distance of the gas, the scale and richness is reduced gradually. Investigating hydrocarbon accumulation characteristics and main control factors among different kinds of volcanic gas reservoirs will contribute to recognize the distribution of volcanic reservoirs and remaining resources.

Key words: volcanic gas reservoir; main controlling factors; hydrocarbon accumulation rule; favorable area predicting; Yingtai fault depression; Yingcheng formation

Evaluation of the growth characteristics of organic-rich shale in Liaohe depression Es4-Es3 based on logging methods/2015,39(6):38-44,75

SHI Jiayu1,2,3, DING Wenlong1,2,3, ZHAO Wei1,2,3, HE Jianhua1,2,3

( 1.SchoolofEnergyResources,ChinaUniversityofGeosciences,Beijing100083,China; 2.KeyLaboratoryforMarineReservoirEvolutionandHydrocarbonAbundanceMechanism,MinistryofEducation,ChinaUniversityofGeosciences,Beijing100083,China; 3.KeyLaboratoryforShaleGasExploitationandAssessment,MinistryofLandandResources,ChinaUniversityofGeosciences,Beijing100083,China)

Abstract: This paper comprehensively evaluates the growth characteristics of Es4-Es3 organic-rich shale in Liaohe depression, taking Es4-Es3 organic-rich shale in Liaohe depression as the research object, adopting MLR and ΔlgRto qualitatively and quantitatively identify organic-rich shale, from the aspects of vertical development, transverse distribution and plane distribution, etc. This paper points out that the research area shows the feature of wide distribution and continuous thickness, and among them, the average thickness of the lower section Es3 organic-rich shale in western sag is 75 m, and the distribution area of the organic-rich shale that the thickness is over 90 m reaches 210.26 km2, which is the preferred position of shale oil and gas exploration. This paper is of great theoretical and practical significance in natural gas exploration field in the research area or even the Bohai bay area.

Key words: organic-rich shale; growth characteristics; multiple linear regression; ΔlgR; logging methods; Es4-Es3; Liaohe depression

Provenance and sedimentary system research of the third member of Shahejie formation in Beitang sub-sag of Qikou sag/2015,39(6):45-55

TANG Ge, WANG Zhensheng, QIAN Maolu

(ResearchInstituteofExplorationandDevelopment,PetroChinaDagangOilfieldCompany,Tianjin300280,China)

Abstract: In order to determine the exploration target area in Beitang sub-sag of Qikou sag, the provenance and sand body distribution should be identified. Based on the Bouguer gravity anomality as well as palaeo-geomorphology and seismic data, the source amount distribution and the migration direction were analyzed. According to the characteristics of light and heavy minerals, spread scope of different provenances were researched. By studying provenance sand dispersion and sand body distribution, provenance-sedimentary system was constructed. Western and northern provenanc were found in 3rd section of Eogene Shahejie formation(Es3). Six sub sources were divided, including western Gegu, Tanggu, Junliangcheng, as well as northern Hangu, Dashentang and northeast corner of Jiannan source. Among them, Dashentang, Jiannan, Tanggu and Junliangcheng sub source were more intensive, making them the main provenance. Affected by the source system, alluvial fan, braided river delta and far shore water fan sedimentary system can be seen in the north of Beitang sub sag, while the fan delta, far shore water fan system can be found in the west. Various sedimentary systems match each other, forming "full of sand" of Beitang sub-sag. Delta front and far shore subaqueous fan main channel microfacies sandbodies area is the hydrocarbon reservoir forming high quality reservoirs, is the favorable target areas for further oil and gas exploration target area.

Key words: provenance system; sedimentary system; Es3, Beitang sub-sag, Qikou sag

Reservoir characteristics and control factors of sandy debris flow from Chang8 interval, south of Ordos basin/2015,39(6):56-65

JIANG Qi1, DING Xiaoqi1, LIU Xixiang2, REN Qihao1, WANG Youli3

( 1.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,Chengdu,Sichuan610059,China; 2.SchoolofGeoscienceandTechnology,SouthwestPetroleumUniversity,Chengdu,Sichuan610500,China; 3.ChengduCenter,ChinaGeologicalSurvey,Chengdu,Sichuan610081,China)

Abstract: The results of exploration available have showed that Chang8 interval in south of Ordos basin, possesses good exploration potentiality, and multi-port wells have obtained oil flow of industry at present. Analyzing petrological characteristics, physical properties, pore types and main control factors of sandy debris flow of Chang8 reservoir by varieties of methods, such as thin section, SEM, X-ray and CT scan, the results show that sandy debris flow have features that thickness of single layer is small, accumulative thickness is large and poor continuous laterally, not only can it produce alone, but overlapp with turbidity current. Lithic arkose sandstone's reservoir spaces are primarily inter-grain pores, followed by dissolved pores in grains and micropore, under condition of overburden pressure, its high permeability. Feldspar lithic sandstone's reservoir spaces are mainly micropores, then are dissolved pores in grains and inter-grain pores, in addition, throat close under the condition of overburden pressure, permeability decline sharply. Content of plastic rock and matrix are quite different in sandy debris flows, and plastic rock distortion during compaction is the key reason of sandstone densification. In summary, sedimentary environment is the key to the control of the formation of reservoir, compaction and cementation cause the densification, while dissolution and tectonism have main effect on the improvement of physical property.

Key words: sandy debris flow; Chang8 interval; reservoir characteristics; main control factors; Ordos basin

Genetic mechanism of ultra-low permeability reservoir of Chang63gravity flow deposits in B153 block, Huaqing/2015,39(6):66-75

LIU Li, ZHAO Yingcheng, WANG Youjing, LI Jiahong, YAN Linhui, HUI Gang, LIU Chang

(ResearchInstituteofExplorationandDevelopment,CNPC,Beijing100083,China)

Abstract: Based on the comprehensive analysis of core, physical properties, thin section, scanning electron microscopy, X diffraction and other test data, taking the Chang63gravity flow deposits as example, we studied the reservoir characteristics and its controlling factors, in order to figure out the genetic mechanism of ultra-low permeability reservoir. The results indicated that the reservoir is mainly arkose and debris-feldspar sandstone with typical ultra-low permeability; its reservoir spaces are mainly residual primary intergranular pore, followed by secondary solution pores. The reservoir is of poor physical property and strong heterogeneity, and the rock mineral components, sedimentary microfacies and diagenetic evolution are the controlling factors; Strong compaction, chlorite cementation, carbonate cementation and weak dissolution are the key elements leading to the low porosity and low permeability. According to their degree of influence on reservoir physical properties, the low permeability reservoir is divided into three genetic types, including carbonate cementation low permeability reservoir, chlorite cementation-dissolution low permeability reservoir and strong compaction low permeability reservoir. On this basis, in utilization of the porosity reversion method, this study established the densification process of each genetic mechanism and will provide a reliable geological basis for favorable reservoir prediction.

Key words: ultra-low permeability; gravity flow; genetic mechanism; densification process; B153 block of Huaqing area

Depositional features and pattern of the fourth member of Xujiahe formation in middle and eastern Yuanba area/2015,39(6):76-86

JIA Shuang, XIAO Kaihua, LIU Guoping

(PetroleumExplorationandProductionResearchInstitute,SINOPEC,Beijing100083,China)

Abstract: Elaborate research of sedimentary system and facies has been taken in this analysis, combined with seismic, geology and well logging data. Tectonic background, sedimentary form, sedimentary scale, sedimentary structure and lithology feature from drilling cores are used to identify the sedimentary system. Well logging curves are tied with drilling cores carefully to build up curve models of different microfacies so as to distinguish facies along wells. Distinction of debris component between the middle area and the eastern research area and the distinct sedimentary facies distribution between middle and eastern part of Yuanba area are analyzed to set up the sedimentary pattern. All the above researches indicate the area is dominated by braided river delta rather than fan delta. Facies distribution and evolution reveal that the sedimentary center transported eastward and overall it displayed a trend of regression. The debris component of the middle area is dominated by carbonates while the eastern area is dominated by silicates. In addition, the middle and eastern part have access to different microfacies distribution. These two evident differences between the two parts prove that the deposition is controlled by two distinct sedimentary sources. Thus a bi-source sedimentary pattern should be set up in this area. Because of the prosperity of the fourth member of Xujiahe formation in Yuanba area, making clear its depositional features and facies is beneficial for gas exploration and develop.

Key words: sedimentary feature; sedimentary pattern; sedimentary system; the fourth member of Xujiahe formation; Yuanba area

Reservoir characteristics and controlling factors of Dengying formation in the Anyue-Moxi area of the central of Sichuan basin/2015,39(6):87-94

QIN Zhangjin1,2, LIU Zhiyi1, ZHOU Jiling3

( 1.CollegeofGeoscienceofSouthwestPetroleumUniversity,Chengdu,Sichuan610500,China; 2.PetroChinaSouthwestOilandGasFieldCompanyExplorationDivisions,Chengdu,Sichuan610000,China; 3.CollegeofEnergyResourcesofChengduUniversityofTechnology,Chengdu,Sichuan610059,China)

Abstract: The Sinian Dengying formation of Anyue-Moxi region in the central of Sichuan has the characteristics of having big reservoir thickness and extensive distribution range, showing good exploration prospects. It is difficult to study in region because of the effect of multi-phase tectonic movement and mass denudation of strata. Through collecting and analyzing the core, slice in region, this paper probes into the rock type of Dengying formation reservoir and the characteristic of reservoir space. In addition, studying the physical characteristics of core in region, which reveals the development of reservoir in Sinian Dengying formation of Anyue-Moxi region in the central of Sichuan is controlled by sedimentary facies, tectonic movement and krastfication in paleocrust of weathering. Dissolution and later tectonism determine the reservoir performance, and the growth level of krastfication is the main controlling factor that affects the reservoirs' development in Anyue-Moxi region. The Anyue-Moxi region located between palaeokarst slope and palaeokarst upland, may or may not grow groove and buried platform, which benefits the development of reservoir and oil-gas accumulation, in palaeokarst slope.

Key words: reservoir characteristics; karstification; controlling factors; structural movement; dolomite; Dengying formation; Sichuan basin

Reservoir physical properties and favorable reservoirs in Liushagang formation in Wushi sag/2015,39(6):95-101

YOU Li, ZHAO Zhanjie, LI Cai, WU Shijiu, XU Shouli, LIU Cai

(ZhanjiangBranchofChinaNationalOffshoreOilLimitedCompany,Zhanjiang,Guangdong524057,China)

Abstract: Wushi sag of Beibuwan basin in western south China sea have been confirmed as a sag with rich hydrocarbon. Delta and fan-delta deposition are the main reservoir of the second and third member of Liushagang formation. Reservoir physical properties are high, moderate, low permeability all developing, with strong heterogeneity and different capacity. The reservoir characteristics are revealed by normal physical characteristics, logging interpretation, analysis of rock thin and vitrinite reflectance suppression, XRD. The major controlling factors of reservoir physical properties heterogeneity are analyzed from sedimentary facies and diagenesis. It is determined that sedimentary facies and the sorting are the main control factors of the third member of Liushagang formation reservoir heterogeneity. Underwater distributary channel of greater distant source with good sorting can develop favorable reservoir, sedimentary facies and compaction degree are the main control factors of the second member of Liushagang formation reservoir heterogeneity. The less-compacted areas in the northern are the most favorable, the middle compaction areas are favorable area, the less favorable area the areas with compaction near to strong, which can provide these areas with evaluation and well layout.

Key words: reservoir heterogeneity; sedimentary; diagenesis; favorable reservoir; Wushi sag; Liushagang formation

Optimization of water injection methods and N2flooding for EOR in Tahe fractured-vuggy carbonate reservoir/2015,39(6):102-110

YUAN Dengyu1,2,3, HOU Jirui1,2,3,4, SONG Zhaojie1,2,3, LUO Min1,2,3, ZHENG Zeyu1,2,3, QU Ming1,2,3

( 1.ResearchInstituteofEnhancedOilRecovery,ChinaUniversityofPetroleum(Beijing),Beijing102249,China; 2.BasicTheoryLaboratoryofImprovingOilRecoveryinLowPermeabilityOilfield,TertiaryOilRecoveryKeyLaboratory,CNPC,Beijing102249,China; 3.MOEKeyLaboratoryofPetroleumEngineeringinChinaUniversityofPetroleum,Beijing102249,China; 4.KeyLaboratoryforMarineOilandGasExploitation,SINOPEC,Beijing102249,China)

Abstract: Low initial recovery factor and depleted bottom water supply of Tahe oilfield calls for urgent methods to improve sweep volume and to enhance oil recovery. According to the similarity theory, a three-dimensional fractured-vuggy carbonate reservoir model was developed based on the geological features and production performance of Tahe oilfield. Water injection methods were optimized and nitrogen flooding for EOR was conducted. Results show that among the three water injection methods, intermittent water injection and pulse water injection could achieve a similar oil recovery, 16.39% and 16.48% responsively, which were higher than that of constant water injection 14.05%. Since the total water injection volume of intermittent water injection was less than that of pulse water injection, the former was selected as the more effective water injection method for energy supplement. In addition, for the subsequent N2flooding, the incremental oil recovery of water alternating gas(WAG) flooding 25.92% which was higher than that of continuous nitrogen flooding 23.47%. These results could supply technical support for the high efficiency exploration of carbonate reservoir.

Key words: fractured-vuggy carbonate reservoir; residual oil; swept volume; nitrogen flooding; enhanced oil recovery; Tahe oilfield

Calculation method for fracture pressure of coalbed methane well based on fracture mechanics/2015,39(6):111-120

DONG Zhen1, LIU Yadong2, BAO Qingying1, ZHANG Yi1, CHEN Shanshan1

( 1.ResearchInstituteofExplorationandDevelopment,PetroChina,Langfang,Hebei065007,China; 2.SchoolofResourcesandGeoscience,ChinaUniversityofMiningandTechnology,Xuzhou,Jiangsu221008,China)

Abstract: In order to improve the prediction accuracy of the coalbed methane well(CBM) fracture pressure, the fracture pressure calculation formula of fractured formation is derived by fracture mechanics, the analytical model of fracture pressure in fractured formation is established based on fractal rock mechanics, and a practical calculation method for fracture pressure is obtained. The result shows that the wellbore would be more likely to be fractured along the direction of maximum horizontal stress under non-uniform in-situ stress. The analytical model has expression uniformity with the traditional model and a wider applicability. Coal fracture has fractal characteristics, the fractal effect enhances the ability of rock to hinder crack propagation, the greater the fractal dimension is, the smaller the similarity ratio and the greater the fracture pressure is. The influences of crack length on fracture pressure are different when the crack states are different, when the crack length is small, fracture pressure decreases rapidly with the increase of crack length. After the crack length increases to a certain value, fracture pressure of closed fracture increases with the increase of crack length, fracture pressure of open fracture decreases and tends to constant value with the increase of crack length. Example of 5 CBM wells in Zhengzhuang block shows that the error of this method is less than 10%, fracture pressure is very sensitive to crack length, a reasonable choice of crack length is particularly important to predict fracture pressure accurately.

Key words: fracture pressure; fracture mechanics; fractal geometry; finite element; CBM