| The research area is located in the Erbaitai block of the Yakela uplift in the northern Tarim Basin,with the Yakela condensate gas reservoir to its west.A series of large-scale oil and gas fields,including Dawanqi,Kela,Yinan,Tuziluo,Dabeiyi,and Dina,have been discovered nearby.The structure is located in the front uplift area of the Kuqa foreland basin.The research interval is the bottom sandstone of the Kumuqiermu Group of the Cretaceous-Paleogene at the Erbaitai block,with a research area of approximately 500square kilometers.Due to the decreasing production of the Yakela gas field,the Erbaitai area,with a similar structural environment to the Yakela gas field,is regarded as a favorable location for the eastward expansion of the Yakela gas field.In order to further clarify the distribution of Cretaceous reservoirs in the Erbaitai area,it is necessary to carry out structural trap interpretation and oil and gas detection to understand the distribution characteristics of the Cretaceous structural trap reservoirs in the research area.In this paper,combined with the previous research ideas and research results,the seismic data,fault interpretation,oil and gas detection,trap distribution and reservoir formation model of the Erbatai area are deeply studied,and the fault characteristics of the Cretaceous system in the study area are analyzed.Based on the comprehensive comparison of multiple seismic attributes,the specific distribution of the fault in the study area is defined,and the structural characteristics are analyzed.The method of oil and gas detection combined with seismic attributes has been comprehensively analyzed and the following achievements and understandings have been obtained:(1)Volume interpretation of seismic data:Seven kinds of seismic body interpretive processing tests including structural smoothing,track gain,iterative gain and dip+azimuth+structure-oriented filtering were carried out.The dip+azimuth+structure-oriented filtering was selected as the seismic interpretation data body,and the non-dip limited minimum coherent body was used as the basis for first-order fault identification and the maximum likelihood body as the basis for second-order fault identification.A fault detection method based on coherence+maximum likelihood fusion was established to identify different levels and types of fractures.The distribution of faults in the study area is defined,and the strike,dip,dip Angle,fault distance and other factors of 60 large and small faults in the Cretaceous system in Erba Tai area are identified and counted.The combination characteristics of faults in the study area are analyzed from the combination characteristics of plane-section.It is considered that the main fault in the Erba Tai area is a north-dipping geese type strike-slip fault formed by left-strike-slip.(2)Oil and gas detection:according to the existing well locations in the study area,seismic inversion calculation is carried out to predict reservoir distribution from a three-dimensional perspective;Five kinds of seismic detection work for oil and gas were carried out,including frequency division attribute and interlayer attribute(root mean square amplitude,instantaneous amplitude,instantaneous frequency and instantaneous phase).Low frequency shadow,root mean square amplitude and instantaneous frequency seismic attribute were selected as reference attributes for oil and gas detection,and oil and gas detection was carried out by combining multiple angles to clarify the reservoir distribution in the study area.The seismic attribute analysis shows that the root-mean-square amplitude of well S8 and the southern part of well S8 shows medium-high amplitude,and the instantaneous frequency decays rapidly.It is considered that the vicinity of well S8 and the southern part of well S8 have good oil and gas bearing properties.(3)Trap characteristics and favorable target evaluation:The distribution and statistics of structural traps were implemented,the accumulation law of the study area was defined,and the favorable trap optimization evaluation was completed.In this study,a total area of 23.2 km~2 of traps were searched.The trap types were mainly structural traps,and the main trap types were anticlines+fault-nose traps,which were formed by two types of contour closure and fault sealing.Most of them were controlled by combination of fault and contour line,and were mainly affected by the wheatai fault.There are also some traps controlled by contour closure or fault sealing alone.On this basis,the structural traps are implemented,and through the combination of oil and gas detection and trap analysis,the structural traps of well S8 and well S8-1H are favorable for oil and gas traps.In this study,through the detailed implementation of the stratigraphic structural characteristics of the Cretaceous in each stage of the study area,the characteristics of regional stratigraphic lithology combination,combined with the analysis of the well drilled in the study area and the Yakra gas reservoir in the adjacent area,the favorable oil-gas intervals and the oil-gas accumulation model of"bidirectional hydrocarbon supply,multi-stage accumulation,fault sand transport,secondary adjustment,and along the belt accumulation"were established.On this basis,targeted trap implementation and optimization are carried out.A total of 12 structural traps in 5 layers,including Yagelem Formation and Shushanhe Formation,which are the main target strata of Cretaceous in Erbatai working area,have been implemented,and the accumulation potential of these traps has been evaluated according to the oil and gas zones in which they are located.This study analyzed and evaluated the oil and gas potential of the two most favorable traps:the well S8 structural trap is an anticlinal structural trap,which is affected by the control of faults.The trap is located at the high point of the anticlinal structure,and the faults around it are mainly NE strike,and mainly distributed within the anticlinal range,which is conducive to oil and gas migration and accumulation.The structural trap of well S8-1is a fault-nose+anticlinal trap with large anticlinal tectonic amplitude and opposite faults,which provides favorable structural conditions for oil and gas accumulation. |
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