| In recent years,several exploration wells in Shuangyushi area in northwestern Sichuan Basin have been drilling high-yield gas flow in Permian system,which makes Shuangyushi structure belt become the hotspot of exploration in western Sichuan.Due to the problems of Permian system in this area,such as burial depth(more than 7000m),thin reservoir thickness,rapid lateral variation,unclear reservoir seismic response model and difficult prediction of favorable reservoirs,the lack of reservoir prediction methods and poor effects seriously affect the effective exploration of oil and gas.In this thesis,we make comprehensive use of available geological,drilling,logging,and seismic data,focus on the Permian Qixia Formation in Shuangyushi area,explore the effective geological interpretation and reservoir prediction approaches,carry out detailed horizon and fault interpretation,post-stack and pre-stack seismic inversion,reservoir distribution prediction,and reservoir physical properties prediction(e.g.,gas saturation and porosity)to implement the study and research of reservoir prediction.The obtained research results are provided as follows:By making full use of logging,three-dimensional seismic data and combining various methods,such as post-stack amplitude direction decomposition fault prediction(PADD)method,coherent attribute method,and isochronous slicing method,the three-dimensional stratigraphic closure interpretation of Maokou and Qixia formations is carried out and more than 40 faults and 7 traps are identified.The tectonic groups in the work are nearly parallel in the northeast-south direction,and generally have the characteristics of being high in the northeast and low in the southwest.With the combined data of logging and seismic,we attempt to apply seismic forward modeling,attribute extraction,3D geological body sculpting,as well as pre-stack and post-stack seismic inversion approaches to predict the reservoir distribution.The results illustrate that the reservoirs of the work area are striped and distributed in parallel nearly in the northeast-southwest direction.Except for the southeast corner of the work area,the thicker reservoirs are mostly located near the high points of structural traps,which are conducive to the accumulation and storage of oil and gas.Based on the Bayes theorem,we first establish the relationship between seismic parameters and reservoir physical properties parameters,and then we use seismic data to realize the lateral prediction of reservoir physical parameters.The research results indicate that the area with developed pores and high gas saturation in the work area is close to the distribution of the reservoir,which is stripped and nearly parallel.Meanwhile,the pores in the southeast corner of the work area are not well developed and should not be considered as a favorable reservoir.In summary,based on the characteristics of relatively high structure,well-developed reservoir,high porosity,and high gas saturation,the favorable exploration areas are selected and three proposed well areas of Jian 1,Jian 2 and Jian 3 are selected to provide a reference for subsequent exploration and development. |
