Oil And Gas Accumulation Law Of Fuyu Reservoir In Wolitun Area Of Anda Depression

Reservoir-forming regularity of Fuyu reservoir in Wolitun area of Anda sag is an important condition for Daqing Oilfield to determine reserves abundance more comprehensively and realize economic and effective utilization.Based on the analysis of structural evolution and sedimentary system,combined with the analysis of hydrocarbon source rocks,reservoirs,hydrocarbon migration paths and preservation conditions,the types of reservoirs are classified,the regularity of hydrocarbon accumulation is clarified,the main controlling factors of hydrocarbon accumulation are established,and the favorable targets of the study area are predicted.Firstly,on the premise of confirming the three-dimensional seismic interpretation,the post-stack seismic inversion of Fuyu reservoir in Anda area is carried out by using the StatMod MC method to improve the vertical and horizontal resolution of sand body.The spatial distribution characteristics of sand bodies in Fuyu reservoir in Anda area are described in detail,and the quantitative reservoir prediction in Anda area is completed.Based on the analysis of seismic data and well data,the single well facies,connecting well facies and seismic facies in the study area are depicted,and the distribution law of reservoir characteristics in Fuyu reservoir is summarized.Secondly,through the study of structural characteristics and the analysis of sedimentary evolution characteristics,the distribution of oil and gas in Wolitun area is determined.Combined with the analysis of laboratory data,the hydrocarbon accumulation conditions in the study area are summarized.The results show that:(1)The sandstone layer of Fuyu reservoir in Anda area has the characteristics of large number and thin thickness,and the sandstone bodies are staggered and overlapped in plane,and the source control is realized.From the north,the sedimentary facies belt controls the reservoir development degree,and the sand body has the characteristics of thin thickness,poor continuity,strip-like,relatively uneven reservoir development and strong heterogeneity;the sand body also has incomplete development conditions from the longitudinal angle,and the reservoir physical properties of Fuyu reservoir are mostly low porosity and low permeability;2)Because of the development of faults in the study area,traps and fault facies are formed mostly.According to the role and complexity of faults in traps,Guan can be divided into five types: single fault barrier trap,cross fault barrier trap,fault block trap,fault anticline trap and multi-fault complex trap.Finally,through the analysis of hydrocarbon source rocks,hydrocarbon migration andtrap preservation conditions,the main controlling factors of reservoir formation in Wolitun area of Anda depression are summarized as follows:(1)structural pattern controls hydrocarbon generation trough and hydrocarbon migration and accumulation range;(2)hydrocarbon supply pattern controls hydrocarbon migration and accumulation horizon and favorable supply direction;(3)reverse fault footwall and transition position at the edge of fault-intensive zone controls oil migration.The migration path(4)Good reservoir control oil filling horizon.