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Research Of Structural Feature And Structural Evolution In The Hailar-tamtsag Basin

Posted on:2012-04-08Degree:DoctorType:Dissertation
Country:ChinaCandidate:J L ChenFull Text:PDF
GTID:1110330338468139Subject:Structural geology
Abstract/Summary:PDF Full Text Request
The Hailar-Tamtsag Basin was a LateMesozoic-Paleogene basin, with the basement being Hercynides. The boundary faults to control the basin developing of NE- and NNE-strikings created in EarlyCretaceous, and overprinted by later deformations.The correlation of the strata is the most difficult problem to the researching downfaulted basin. The main reason that the seismic reflection horizons traced in different delves in the Hailar-Tamtsag basin are inconsistent is the lack of the comparison standard of regional seismic strata. The seismic stratigraphic contrast standard is a bottleneck that plagued the oil and gas exploration in Wuerxun depression. Seismic reflection termination type is an important sign to identify the seismic reflector and the unconformity interface on the seismic reflection profile. It includes onlap,downlap,toplap and truncation. In the light of contributing factor of the seismic sequence, the tectonic horizon sequence boundary (T02, T04, T3, T 31,T4 and T5 seismic reflection horizon) and depositional horizon sequence boundary (T2,T21 and T22 seismic reflection horizon)can be recognized, and the seismic strata comparison standard of areal structure-strata framework can be built.In order to clarify the origin of foreset body in Memberâ…¡of Upper Zuun- bayan Formation of Hailaer-Tamtsag Basin, the analysis on structural evolution hist- ory and heavy mineral and the interpretation of seismic profile and logging trace were implemented. It is considered that the huge delta is generated under particular structu- ral setting, the faulting activities tend to be rest during sedimentary period of Memberâ…¡of Damoguaihe Formation, overall tilt and subsidence occur in Hailaer-Tamtsag Basin-tilting in northeast and subsiding in southwest, which formed local NNE-SSW trending drainage system, and the sediment source is rich which formed obvious for- eset configuration. The foreset configuration has relatively large scale extension, with obvious toplap and baselap, and can be used as the marker of seismic stratigraphic correlation in Memberâ…¡of Damoguaihe Formation. The strong reconstruction at the end of Yimin Formation sedimentation disrupts the long-axis huge delta formed duri- ng the Memberâ…¡of Damoguaihe Formation, which brings difficulties for identificati- on. Since the foreset feature of delta has directivity in seismic profile, the method of macroscopically tracing huge delta along river trend effectively solved the knotty problem of identifying delta foreset body in seismic profile.During the course of putting up the basin tectonic framework, the use of Contributing Factor Seismic Strata Comparison Standard resolved the difficulty which the tectonic and deposition sequence boundary can not do with thoroughly.Established the seismic stratigraphic contrast standard of regional tectonic stratigraphic framework through the difference analysis of reflecting structure of seismic profiles.Identified four important unconformity surfaces we divide Hailaer-Tamtsag Basin to four structural layer: the fault depression structural layer (Tamulangou and Tongbomiao formation), the fault sag structural layer(Nantun, Damoguaihe and Yimin formation), the sag structural layer(Qingyuangang formation) and the atrophy structural layer(Cenozoic).Through the investigating of coal field outcrop and the interpret and analysis of seismic cross section, we built up the seismic structure elucidation mode, and recognized folding relatedt fault, decollement and alternation, three types of structural belt. Using change-velocity mapping method, the high precision structure map of Hailar-Tamtsag basin have been completed, and based on the above work, the structural feature in the basin are known as belt structure along north to south, and block structure along west to east.Wuerxun depression as control acceping keeping the base earlier to crack , at the same time udergo much stages distinct area structures once more to respond the field of force reconstruction . Pass through to the sunken base composition feature of Wu Erxun and snaps the trap snap that the trap constitutes the straturm architectural feature with snaps the hollow structure straturm,The feature is analysed the comparison, Promulgating the difference constitutes between the straturm structure setup divergence and every the structure particular period stress orientation alternation . According to the structure straturm divides ancient and modern times constitutes the cell .By the analysis study of Wuerxun depression fault patterns, fault state character and fault activity character, through different periods'fault which contral the depression and the synsedimentary faulting identification, we find out that the earlier in Tongbomiao group sediment period west Wuerxun controling fault is formed from north to south directed fault zones, fault zones is formed with many north-east en echelon faults. But in later period, the means Nantun group and Yimin group section 2-3 sediment period, controling fault move to east to be a south-north fault.By the ten structural history sections in Wuerxun depression, revealed different structures'forming process and distortion sequence.Utilizes the rock acoustic wave time difference and the porosity to adapt to is getting near the real degree(depth ) difference but alternation, nner place resumeing in the depression thirty-one wells thickness corrode .Found to denude the preceding basin prototype structure with when denuding The deformation pattern in basin .Use seimic stractigraphy trend method to restore denuding, then restore Tongbomiao group sediment later period and Yimin group sediment later period's origin basin. With the basement of restoring denuded origin sediment thickness map ,we make each surfaces'ancient structure map in different periods , and then set off ancient structure unit.Combining paleogeomorphology and palaeotectonics structural features and take advantage of sedimentary facies, Tongbomiao group and Nantun group tectonic facies can be recognized. Based on analyses of data including coal field outcrop,drilling,seismic,stratigraphy,structural features and and the interpret and analysis of seismic cross section,it is believed that the last stage of Qingyuangang in the Hailar-Tamtsag Basin is the reverse deformation stage. The reverse deformation at the last stage of Qingyuangang makes the reservoir regulated. The tectonic deformation at the last stage not only provides the transport channel for the oil-gas migration, but also creates the trap for the oil-gas accumulation.Based on the seismic profile analysis and the research of tectonic subsidence ce- nter migration, four structural sequence interfaces and four structural layers were ide- ntified in Harlaer-Tamtsag Basin, which was divided into four generation stages and three reconstruction stages from the perspective of construction and reconstruction of basin. The four generation stages include fault depression stage, fault sag stage,sag stage and atrophy stage. The three reconstruction stages include the twisting and deforming stage during the late of Tongbomiao Formation, the twisting and deform- ing stage during the late of Yimin Formation and the reversing and deforming stage during Qingyuangang Formation. The research indicates that Hailaer-Tamtsag Basin has the characteristic of intersection of construction and reconstruction, and this char- acteristic is presented through the whole evolution process.Through the subdivision of reservoir construction and reform feature analysis in Nantun group and Tongbomiao group, raveled the reform characters and evolution rules,reveals the reservoir's style related with structure.It is the result of joint action of palaeotectonics and current tectonic activities to oil and gas migration and accumulation in Wuerxun depression;the tectonic deformation in late Tongbomiao group settled the structural framework of reservoir in Nantun group and Tongbomiao group,and the reservoir in Nantun group and Tongbomiao group be controlled by palaeotectonics that formed this period; palaeotectonics type andantithetic fault type reservoir is the next key exploration target.From the analysis of the structural evolution and synthetical geology, we recognized that the most favourable area for petroleum accumulation are the overlay area of three structural belt and the position valid hydrocarbon, the burial hill of base rock, the palaeostructure formed in late Tongbomiao and the angle disconformity formed in late Tamulangou and Tongbomiao.
Keywords/Search Tags:Structure style, structural sequence, Angle disconformity, structural evolution, fault depression, Wuerxun depression, Hailar-Tamtsag Basin
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