GeochemicalcharacteristicsoftheUpperTriassicBagongFormationmudstonesinEasternQiangtangBasinanditspetroleumgeologicalsignificance/2022,46(2):1-12

WANG Zhongwei1,2, XIAO Yang1,2, ZHAN Wangzhong3, YU Fei4

( 1.SchoolofGeoscienceandTechnology,SouthwestPetroleumUniversity,Chengdu,Sichuan610500,China; 2.QiangtangInstituteofSedimentaryBasin,SouthwestPetroleumUniversity,Chengdu,Sichuan610500,China; 3.ChengduCenterofChinaGeologicalSurvey,Chengdu,Sichuan610081,China; 4.SoutheastSichuanGeologicalGroup,ChongqingBureauofGeologyandMineralsExploration,Chongqing400038,China)

Abstract: The Upper Triassic black mudstones are considered to be one of the most significant hydrocarbon source rocks in the Qiangtang Basin, but its quality and hydrocarbon generation potential is obviously different. The organic and elemental geochemical characteristics of the Upper Triassic turbidite mudstones from the Dongqu Section have been studied to estimate their petroleum potential and discuss their depositional conditions. The result shows that the Bagong Formation black mudstones from the Dongqu Section are interpreted as being fair to moderate source rocks. Mixed organic matter sources with land plants and plankton are characterized by type Ⅱ2-Ⅲ kerogen. The organic matter in the mudstones belongs to matured to highly matured evolution and were deposited in the oxic water column, which may be unappropriate for the organic matter preservation. In general, the Upper Triassic Bagong Formation black mudstones from Dongqu Section are of poor hydrocarbon generation potential and mainly in gas generation, which is less than those from the adjacent Quemocuo Section, Eertuolongba Section, and well QZ-7. Based on previous data, we deduced that the Bandaohu-Duogecuoren Areas in the northwest of the study area may have good hydrocarbon generation potential and seem to be the significant target for future oil-gas exploration.

Keywords: characteristics of mudstone; source rocks; hydrocarbon generation potential; turbidity environment; Bagong Formation; Dongqu Section; Upper Triassic; Qiangtang Basin

Sedimentarycharacteristicsandmodelofcoarse-grainedshallow-waterdelta：acasestudyofJurassicSangongheFormationinMobeiArea,JunggarBasin/2022,46(2):13-22

SUN Jing, XUE Jingjing, FEI Liying, SONG Mingxing, JIA Kaifu

(ResearchInstituteofExplorationandDevelopment,XinjiangOilfieldCompany,PetroChina,Karamay,Xinjiang834000,China)

Abstract: Take the Jurassic Sangonghe Formation in Mobei Area, Junggar Basin as the example, the sedimentary characteristics and models of the Jurassic Sangonghe Formation were analyzed based on core data, logging, thin sections, well logs and 3D seismic data. The results show that the coarse-grained shallow water delta deposits, which are mainly coarse and medium-coarse sandstone, are widely developed in the Mobei Area.Two grade slope breaks and three zones controlling sedimentation are developed in the western depression of well Pen 1. Coarse-grained shallow braided river delta-lake system develops in the uplift-slope area, forming two sub-facies of the inner and outer front, which distribute vertically or obliquely along the lakeshore as a whole in the shape of flowers or birds feet. The underwater distributary channel sandbody which are mainly coarse and medium-coarse grained feldspar lithic sandstone is the frontal skeleton. Block and traction flow origin structures are well developed, and their physical properties are relatively good. Multi-stage sand bodies are well developed in the vertical and cut and overlap each other in the lateral, and continuous distribution. Four front underwater distributary channels which are widely distributed and extends far away are developed in the plane near east-west direction. The type is the transgressive-regressive, coarse-grained shallow water delta which has a large area and abundant source supply in wet climate. The results may serve as a reference for deepening exploration and development in the Mobei Area and similar fields in the Junggar Basin.

Keywords: coarse-grained deposits; shallow-water delta; sedimentary model; Sangonghe Formation; Jurassic; Mobei Area; Junggar Basin

CharacteristicsandsedimentaryenvironmentofstromatolitebiohermsinooliticshoalofZhangxiaFormationinZhucaoyingSection,Qinhuangdao,Hebei/2022,46(2):23-32

ZHU Yidan, QIN Renyue

(SchoolofEarthScienceandResources,ChinaUniversityofGeosciences(Beijing),Beijing100083,China)

Abstract: The Cambrian strata of Zhucaoying Section in Qinhuangdao, Hebei are intact and continuous, and stromatolites are developed in the top of Zhangxia Formation of Miaoling Series. Based on field data and microscopic observation, the characteristics and sedimentary environment of columnar(domal) stromatolites are studied. The results show that stromatolite bioherms and high energy oolitic shoal limestones are developed in the forced regressive system at the top of the Cambrian Zhangxia Formation in Qinhuangdao, Hebei, which are produced in an interactive manner, representing the carbonate deposition during the slow sea level decline in the North China Platform during the Cambrian. The well-preserved filamentous calcified cyanobacteria sheath fossils and window-like fabrics can be found in the dense micrite of the stromatolites from the Zhangxia Formation, suggesting that the stromatolites were formed by the complex calcification of photosynthetic microbial mats or microbial membranes. A small amount of pyrite residue associated with precipitation induced by sulfate reducing bacteria was observed. The results provide an important case for studying the sedimentary environment of Cambrian stromatolites.

Keywords: stromatolitic bioherm; calcified cyanobacteria; microbial carbonate; Zhangxia Formation; Cambrian; Zhucaoying Section; Qinhuangdao

MaincontrollingfactorsofshaleoilenrichmentandoptimizationoffavorableenrichmentintervalsofFengchengFormationinMahuSag/2022,46(2):33-44

LI Xiaohui1,2, JIANG Zhenxue1,2, HUANG Liliang2,3, HE Wenjun3, GAO Zhiye1,2, CHEN Zhixiang1,2, SONG Jia'nan1,2,3, ZHENG Guowei1,2, DUAN Longfei1,2, ZHANG Yuanhao1,2

( 1.StateKeyLaboratoryofPetroleumResourcesandProspecting,ChinaUniversityofPetroleum(Beijing),Beijing102249,China; 2.UnconventionalPetroleumScienceandTechnologyResearchInstitute,ChinaUniversityofPetroleum(Beijing),Beijing102249,China; 3.ResearchInstituteofExplorationandDevelopment,PetroChinaXinjiangOilfieldCompany,Karamay,Xinjiang834000,China)

Abstract: Take Maye 1 Well in Mahu Sag shale Fengcheng Formation as the research object, using core and scanning electron microscope, and the rock pyrolysis, determination of total organic carbon (TOC), gas adsorption, high-pressure mercury injection experiment and whole rock methods of X-ray diffraction, physical property test, research of manasseh lake sag Fengcheng Formation of shale oil enrichment main control factors, forecast Fengcheng Formation of shale oil enrichment zone. The results show that the main controlling factors of shale oil enrichment in Fengcheng Formation in Mahu Sag are of organic matter abundance, porosity, permeability, fracture density and pressure coefficient. Whenw(TOC)>1.30%, porosity is greater than 6.50%, permeability is greater than 1.000×10-3μm2, fracture density is greater than 32 per meter, pressure coefficient is greater than 1.5, shale oil is highly enriched; shale oil enrichment occurs whenw(TOC) is 0.60%-1.30%, porosity is 4.00%-6.50%, permeability is (0.020-1.000) ×10-3μm2, fracture density is 10-32 per meter, and pressure coefficient is 1.2-1.5. Longitudinally, the shale of Fengcheng Formation in Maye 1 Well can be divided into three types: non-enrichment area, enrichment favorable area, high-efficiency enrichment area and six enrichment intervals. The results are of great significance for clarifying the enrichment mechanism of shale oil and guiding shale oil exploration and development.

Keywords: Mahu Sag; Fengcheng Formation; Maye 1 Well; shale oil; shale development characteristics; enrichment main control factors; favorable intervals

Propertiesofdiageneticfluidsystemsandtheirinfluences:takingAheFormationreservoirinYiqikelikeStructuralBeltoftheKuqaDepressionTarimBasinasanexample/2022,46(2):45-57

NI Lingmei1,2, LI Zhong2, GUO Chuntao3, LUO Wei4

( 1.SchoolofCultureandTourism,QujingNormalUniversity,Qujing,Yunnan655011,China; 2.InstituteofGeologyandGeophysics,ChineseAcademyofSciences,Beijing100029,China; 3.DepartmentofGeologicalandEnvironmentalEngineering,ShanxiInstituteofTechnology,Yangquan,Shanxi045000,China; 4.BeijingNationalDaySchool,Beijing100039,China)

Abstract: Based on the data of thin section, scanning electron microscope, X-ray diffraction of clay minerals, formation water and physical property parameters, we systematically analyzed the petrology, diagenesis and formation water of the Lower Jurassic Ahe Formation sandstone in the Yiqikelike Structural Belt of Kuqa Depression, Tarim Basin, combined with the thermal-burial history and the distribution law of fractures and faults of the Ahe Formation in the Yiqikelike Structural Belt, the sealing characteristics of diagenetic fluid, and the oil and gas preservation conditions of the Ahe Formation sandstone reservoirs in the axis and limb of Yiqikelike Anticline are discussed. The results show that volume fraction of authigenic kaolinite in the Ahe Formation sandstone is relatively high in the anticline axis, but relatively low in the limb. The difference of diagenetic evolution sequence between the axis and limb of the Yiqikelike Anticline is about 5 Ma ago. Compared with the anticline limb, the sodium chloride coefficient and desulfurization coefficient in the formation water of Ahe Formation in the anticline axis are higher, and the metamorphic coefficient is lower; the sealing property of diagenetic fluid system of the Ahe Formation sandstone in the anticline axis is weaker than that in the anticline limb, which affects the accumulation of natural gas. The results have great significance for predicting the distribution of oil and gas reservoirs in Yiqikelike Structural Belt.

Keywords: diagenesis; stratum water; fluid systems; Ahe Formation; Yiqikelike Structural Belt; Kuqa Depression; Tarim Basin

Multilevelarchitecturalcharacteristicsofreservoirsandremainingoildistributionofnearshoresubaqueousfan:takingtheLowerCretaceousoillayerofXOilfieldinBongorBasinasanexample/2022,46(2):58-71

FENG Shuo, LIU Qian, PENG Zixiao, FU Chao, LI Sulei, LIU Mingkang

(SchoolofEnergy,ChinaUniversityofGeosciences(Beijing),Beijing100083,China)

Abstract: The sedimentary body of nearshore subaqueous fan developed in continental faulted lake basin has complex structure of thick sand body, and the distribution law of remaining oil is not clear. According to the data of core observation, dense well pattern logging and production performance, the sedimentary sequence of typical thick layer nearshore subaqueous fan of Lower Cretaceous in X Oilfield of Bongor Basin is studied, and the reservoir architecture at different levels and its control effect on the distribution of remaining oil in the sedimentary body are analyzed. The results show that the study area can identify two types of interfaces: sedimentary discontinuity and channel scouring/erosion surface. The architecture unit of nearshore subaqueous fan is divided into seven levels(level 1 to level 7). On the basis of lithofacies division, four types of four level configuration units are identified: distributary channel, inter channel, sheet sand and end channel, and the composite distributary channel is five level architecture unit. The plane distribution characteristics of four-level and five-level architecture units are quantified, and two models of architectural interface interlayer vertical oil control and distributary channel sand body horizontal oil control are proposed. The plane connectivity and interface barrier of architecture units are the main factors controlling oil-water connectivity. The results provide reference and guidance for remaining oil displacement in the later stage of oilfield production.

Keywords: nearshore subaqueous fan; reservoir architecture; architectural interface; remaining oil distribution; Lower Cretaceous; X Oilfield; Bongor Basin

Preservationmechanismandmodelofprimaryporediagenesisindeepreservoirs:takingtheEnpingFormationandWenchangFormationinthesouthofHuizhouSag,PearlRiverMouthBasinasexamples/2022,46(2):72-85

CHANG Siyuan1,2, CHEN Dongxia1,2, WANG Cheng1,2, WANG Qiaochu1,2, LIU Ziyi1,2, WANG Fuwei1,2

( 1.SchoolofEarthSciences,ChinaUniversityofPetroleum(Beijing),Beijing102249,China; 2.StateKeyLaboratoryofOilandGasResourcesandExploration,ChinaUniversityofPetroleum(Beijing),Beijing102249,China)

Abstract: In order to study the formation conditions of deep high-quality reservoirs, taking the Enping Formation and Wenchang Formation in the Southern Huizhou Sag of the Pearl River Mouth Basin as examples, the characteristics of the reservoirs in the study area were analyzed according to the data of rock thin section, cathodoluminescence, scanning electron microscope, reservoir physical properties, and burial history, then to discuss the preservation mechanism and model of primary pore diagenesis in deep reservoirs. The results show that feldspar lithic quartz sandstone is mainly developed in Enping Formation in the Southern Huizhou Sag, and feldspar lithic sandstone is mainly developed in the Wenchang Formation in the Southern Huizhou Sag. The pore types are mainly primary pores, and the porosity ranges from 1.9% to 17.3%, with an average of 13.3%, the permeability is between(0.034-152.683)×10-3μm2, with an average of 18.050×10-3μm2. The preservation of primary pores in the reservoir is controlled by many factors. Among them, the lower geothermal gradient inhibits the compaction, the long-term shallow burial in the early stage and the rapid burial in the later stage make the compaction insufficient, and the differential cementation of carbonate and the early oil and gas charging hinder the compaction and the formation of the reservoir. The cementation in the sand body leads to the widespread development of primary pores in the reservoir. The results provide a basis for establishing a deep exploration and development plan and predicting the horizontal and vertical distribution of high-quality reservoirs.

Keywords: Pearl River Mouth Basin; Huizhou Sag; deep reservoirs; primary pore; diagenesis; preservation mechanism

Calculationmodelofannularpressureininjectionandproductionwellsofundergroundgasstoragerebuiltfromgasreservoiranditsapplication/2022,46(2):86-97

SUI Xiaofeng1, TENG Zhenchao1, JIA Shanpo2, WANG Jianjun3, XU Changfeng4, ZENG Xiangjun5, HE Haijun6

( 1.SchoolofCivilEngineeringandArchitecture,NortheastPetroleumUniversity,Daqing,Heilongjiang163318,China; 2.InstituteofUnconventionalOilandGas,NortheastPetroleumUniversity,Daqing,Heilongjiang163318,China; 3.StateKeyLaboratoryforPerformanceandStructuralSafetyofPetroleumTubularGoodsandEquipmentMaterials,CNPCTubularGoodsResearchInstitute,Xi'an,Shannxi710077,China; 4.HutubiGasStorageOperationArea,CNPCXinjiangOilfieldBranch,Hutubi,Xinjiang831200,China; 5.SchoolofEarthSciences,NortheastPetroleumUniversity,Daqing,Heilongjiang163318,China; 6.HeilongjiangProvincialKeyLaboratoryofOilandGasReservoirStimulation,ResearchInstituteofOilProductionEngineering,DaqingOilfieldCompanyLimited,Daqing,Heilongjiang163453,China)

Abstract: To deal with the pressure in the closed A-annular space caused by temperature and pressure fluctuations during injection and production of gas storage wells, based on the heat-transfer theory, the elastic plane strain theory of tubular strings and the volume compatibility principle, a multi-unit pressure calculation model of annular A considering the inonlinear properties of annulus protection fluid was established. Based on this subsection calculation method, the effect of isothermal compression coefficient and isobaric expansion coefficient of the annular protection fluid, the linear expansion coefficient, elastic modulus and Poisson's ratio of tubing on the annulus pressure were analyzed. The results show that the accuracy of annular pressure prediction can be improved by using subsection computing method. To estimate the annulus pressure without considering the temperature distribution will cause the result to deviate from the actual value, and the higher the temperature, the greater the deviation. The non-linear property of annulus protection fluid has a relatively great impact on annulus pressure, ignoring the change of its properties with temperature will lower the annulus pressure. The pressure calculation model is in good agreement with the on-site monitoring value, which can provide reference for engineering application.

Keywords: underground gas storage rebuilt from gas reservoir; injection-production wells; closed A-annular; annular pressure; subsection computing

Analysisoftheeffectoffloatingplatformmotiononthelateraldynamiccharacteristicsofdeepwaterdrillingriserduringinstallation/2022,46(2):98-106

WANG Yanbin, WANG Jinduo, GAO Deli, XIN Shilin

(KeyLaboratoryforPetroleumEngineeringofMinistryofEducation,ChinaUniversityofPetroleum(Beijing),Beijing102249,China)

Abstract: The mechanical characteristics of deepwater drilling riser during installation have an important impact on its safe and efficient installation. Considering the effect of the dynamic drift of the top floating platform during riser installation, the lateral dynamic characteristic analysis model and control equation during riser installation have been established. The control equation has been numerically solved by the finite difference method, and the effects of the static offset, drift amplitude and drift period of the top floating platform on the lateral dynamic characteristics during riser installation have been discussed. The results show that during the installation of deepwater drilling riser, the maximum value of lateral displacement appears at the bottom of riser, and the maximum value of bending moment and stress appears at the top of riser near the sea surface. In a platform drift period, the maximum lateral displacement at the bottom of the riser occurs at the same time as the maximum bending moment at the top, and the maximum stress at the top lags behind the maximum bending moment at the top. Platform static offset mainly affects the lateral displacement during riser installation, and the static offset and lateral displacement are positively correlated. The amplitude drift of platform is the main factor affecting the lateral dynamic characteristics of riser installation. With the increase of the amplitude drift, the lateral displacement, bending moment and stress of riser increase. The drift period of the platform has little effect on the bending moment, and has no obvious effect on the lateral displacement and stress. This research is of engineering guiding significance for the installation process of deepwater drilling riser.

Keywords: deepwater drilling; riser; installation operation; dynamic characteristics; floating platform; drift motion

Analysisandapplicationofhorizontalwellextensionlimitbasedonsectionalfrictionfactor/2022,46(2):107-116

QIN Lan1, DONG Guochang2, GUO Jianxun2, LI Wei1, LI Zhuolun1, CHEN Zhuo1

( 1.SchoolofPetroleumEngineering,NortheastPetroleumUniversity,Daqing,Heilongjiang163318,China; 2.DrillingTechnologyResearchInstitute,JilinOilfieldBranchofCNPC,Songyuan,Jilin138000,China)

Abstract: The whole borehole is divided into several well sections with different friction factors by using system cluster analysis. Combined with the drill string friction torque model, the simulated annealing algorithm is used to inverse and calculate the optimal value of friction factor of each well section. Based on the sectional friction factor, considering the bearing capacity of the drilling rig, rock crushing conditions, friction conditions, drill string strength conditions and drill string stiffness conditions, the judgment criterion and prediction model of horizontal well extension limit are established. The field application results show that the predicted values of hook load and wellhead torque obtained by the segmented friction factor inversion method have a good correlation with the measured data. The average absolute error values are 3.72% and 3.45% respectively, which are 54.8% and 51.8% higher than the prediction accuracy of the traditional inversion method. With the increase of friction factor, the extension limit of horizontal well decreases obviously. The results can provide a reference for the prediction of extension limit of horizontal wells.

Keywords: horizontal well; extension limit; friction torque; sectional; friction factor; simulated annealing algorithm