Reservoir Classification Evaluation Of The Lower Fault Depression Of Dehui Fault Depression

The Dehui Fault Depression is located in the southern Songliao Basin and is a key exploration area of Jilin Oilfield.Due to the unclear stratigraphic division and unclear control factors of tight gas in this area.In this paper,starting from practical problems,the sequence grid is the main line,and the study of reservoir characteristics is the core;comprehensively using data such as core,logging,logging,seismic and analytical tests,the well-seismic combination is divided into the lower fault depression of Dehui fault depression Strata,clarify the distribution characteristics of strata,and carry out research on reservoir characteristics,and initially establish the reservoir classification evaluation standard of Dehui fault depression.Taking the lower fault depressions of Dehui Fault Depression: Huoshiling Group,Shahezi Group and Yingcheng Group as the key horizons,after logging and seismic response characteristics of the first,second,and third order sequences are clarified,Combined with the deep stratigraphic division scheme of Songliao Basin,the lower fault depression strata is divided into 3 second-order sequences and 8 third-order sequences.The Yingcheng Group is divided into 2 tertiary sequences,and the Shahezi Group and Huoshiling Group are each divided into 3 tertiary sequences.On this basis,single-well and continuous-well comparative profile formation analysis was carried out to summarize the distribution characteristics of the target stratum in the study area.It is clear that the Shahezi Group and Yingcheng Group in the southern part of the lower fault depression in the lower part of the study area are thin and partially missing,and the Huoshiling Group is thicker.The stratum in the north of the rift is intact.Then,the petrological characteristics,distribution characteristics,and reservoir physical characteristics of the target reservoir are carefully evaluated.It is recognized that the lithology of the lower fault depression reservoirs in the Dehui fault depression is mainly feldspar detrital sandstone and debris feldspar sandstone,containing a small amount of feldspar sandstone,and the sortability is medium-good,and the particle contact relationship is linear contact,concave-convex Mainly contact.Through analysis of diagenesis and main diagenetic events,it is clear that the pore evolution of the target layer in the study area is divided into five stages,and the pore types are mainly secondary dissolution pores.Combined with reservoir lithology and physical properties,three types of reservoir evaluation standards have been initially established.This paper is carried out step by step in accordance with a progressive approach to solve the problems of division of strata and unclear reservoir characteristics in the lower part of Dehui fault depression.And on this basis,a reservoir classification standard was established.A more systematic study of the Dehui Fault Depression has laid a good foundation for the subsequent exploration work of the Dehui Fault Depression.