Seismic Identification Method Of Subtle Traps In The Funing Formation At Jinhu Sag,Subei Basin

Based on the stratigraphic division and correlation of the Funing formation in Jinhu sag,the sedimentary and sandbody characteristics are studied.Then combined with the basic features of topography,fracture and so on,development model and accumulation model of subtle traps in different geological settings have been established.The geophysical characteristics of sandstone reservoirs are systematically studied.Through comprehensive reservoir prediction and identification of sand bodies,a specific method for description of subtle traps is summarized,and a number of subtle traps are discovered.Through the study of sedimentary system and sand body modeling,It is found that the type of sand body in E₁f₂³ is mainly residual underwater distributary channel of delta front subfacies and beach sandstone body of coastal shallow lake facies,which is widely distributed in plane and vertical frequent changes.The main microfacies of sand bodies in E₁f³ are underwater distributary channel of delta front subfacies,river mouth bar and distal bar,the main part of sandstone is banded,and the front is mass or flaky.Typical reservoir anatomy of E₁f₂ and E₁f₃ has been carried out.It is considered that E₁f in Jinhu sag has favorable conditions for two types of subtle reservoirs such as lithologic trap and fault-lithologic trap.It is pointed out that the middle-inner slope of Sanhe area and the Longgang area are favorable areas for searching the subtle reservoirs of E₁f.Rock physics analysis and reservoir prediction methods are tested,and E₁f sand body prediction technology is explored.On the basis of defining petrophysical characteristics and sensitive parameters of E₁f₂ and E₁f₃ sandbodies,combining the vertical and lateral characteristics of sand body,it is found that the E₁f₂ beach bars sand body can be effective predicted by comprehensive use of ancient landform restoration,micro structural and attribute analysis.And the channel sand body of E₁f₃ can be effective identified by attributes and inversion.The identification and description of subtle traps in E₁f are carried out.12 subtle traps have been discovered and implemented in E₁f₂₊₃,with the total area are 12.1km² and the taotal trap resources are 904×10⁴t.