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High Resolution Sequence Stratigraphy And Reservoir Characteristics Of Yanchang Formation, Upper Triassic Series In Changwu Area, Ordos Basin

Posted on:2010-10-27Degree:MasterType:Thesis
Country:ChinaCandidate:X C ZhaoFull Text:PDF
GTID:2120360278460539Subject:Structural geology
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Ordos basin is the secondary Petroliferous basin which located at the middle zone of sedimentary basin in China ,which was affected by the east Pacific tectonic process and the southwest Tethys-Himalayas tectomic process.While it is one of the large inland basin of abundant energy and mineral source of Mesozoic in the east of our country.And it was preserved integrally.The Yanchang Formation of Triassic is not only researched early ,but also the first obtain oil gas strata of the basin.For a number of years ,i t is the primary target of oil and gas exploration.In Changwu area of Ordos basin,the thickness of Yanchang formation generally had appeared that the western was thin but the eastern was thick,and that the northern was thin but the southern was thick.However,the partition and contrast of Yanchang formation followed and searched K0-K9 primary markers and two pieces of assistant marker which was Zhangjiatan shale in the bottom of chang7 and Lijiapan shale in the bottom of chang9 where the Yanchang formation distributing was more steady in research area;the same time,adding sedimentary cycle and Lithology combination of characteristics,the stratum could be divided into five section and ten pieces of member from bottom to top in study area.Through the multidisciplinary analyses of sedimentary structures,vertical secessions of log information,characteristics of rocks and minerals,this thesis distinguish and measure off sedimentay facies and sedimentary systems of Yanchang formation in Triassic.The thesis expatiated the sedimentary system and the sedimentary microfacies of target formation,from bottom to top of Yangchang formation,the sedimentary from delta depositional system change into lake depositional system to delta depositional system.The delta depositional system is made of delta plain,delta front and prodelta; Distributary channel,mouth bar and far dams are mainly microfacies of delta depositional system.Shore dams and shallow lake-semi-deep lake mud are maily microfacies of delta depositional system.Based on the studying of the characteristics of depositional systems,constructed the pattern of deposition.Through outcrops and drilling-logging date's comprehensive analysis and summarized the proper makers of stratigraphic division,this thesis researched the high-resolution sequence stratigraphy of Yanchang formation in the Changwu area of Ordos Basin, and built the high resolution sequence stratigraphic framework of Yangchang formation.Consequently,one super long-term sequence cycle was indentified,and then,subdivided into 4 long-term sequence cycle and 22 middle-term sequence cycle respectively. On the basis of the above research, using middle-term sequence cycle as mapping units,sequence-lithofacies paleographic map and high resolution sequence stratigraphy correlating map were accomplished.The study of reservoir lithology indicated that there were three main types of rocks in study area:debris-feldspar sandstone,feldspar-debris sandstone and a small number of feldspar sandstone;middle medium and fine grained sandstone is the primary reservoir,the sandbodies have bad component maturity,the date are less than 1.0.The grain of sandstones have good separation and middling psephicity,hypo-arris or subrounded,the relation between grains is line or point-contact.In Yanchang formation,the filling among sandstones are mainly matrix clay and carbonate cement;and then iron calcite and iron dolomite are mainly carbonate cement.The these comprehensive studied the types and characteristics of the diagennsis affecting the reservoir sand body and think the diagegesis included mechanial compaction,compact dissolution,agglutination and dissolution,whiches strongly effected the reservoir performance and evoution of porosity.The pore are made of intergranular pore (include intergranular pore which formed by solution and diagenesis),induced pore(include feldspar soluted pore,debris soluted pore,casting pore and matrix soluted pore),micropore and microcrack.Intergranular pore are primary,which account for a half and soluted intergranular por of sandstone is followed by.Based on there studies mentioned above,the thesis delimited the advantageous sandbody distribution in Sequence stratigraphic framework.The sandbody which developed in chang7,chang8 and chang10 reservoir were the best advantageous sandbody in Yanchang formation,Changwu area.
Keywords/Search Tags:Changwu area, Yanchang Formation, Sedimentary System, High Resolution Sequence Stratigraphy, Reservoir property
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