Study On Trap Types And Distribution Characteristics Of Es₃-Es₄ In Luojia Area

Luojia is an area with abundant resources of oil and gas but also with great difficulty in exploration and development.These difficulties come from the area’s complexity of structure,lithology and unconformity,which lead to scatted strip distribution of oil and many blank gaps between reserve units.Base on the research of Logging data and seismic data,this thesis,by combining different identification and interpretation methods,elaborates the major features of structure-lithological traps and unconformity traps of the Es₃-Es₄ layer in this area,and clarify the distribution features of different trap types and their controlling effects on oil and gas reservoirs.Through further study on the features and distributions of various traps in Luojia area,this thesis provides geological basis and support for further exploration and edge expansion of potential oil reservoirs.Based on the anatomical findings of known reservoirs,there are two major types of traps in the study area:structural-lithologic traps and unconformity traps.The development of tectonic-lithologic traps is controlled by the distribution,characteristics and combinations of sand bodies,faults,roof and floor,while the unconformity traps are mainly affected by the structural characteristics and configuration of overburden,weathered clay layer and underlying layer Relationship control.Through the method of well-seismic combination and seismic attributes,the distribution characteristics of the sand body were anatomically analyzed,and the thickness characteristics and distribution of the sand body in the target layer were clarified:the sand bodies in the target layer were mainly distributed in the middle and upper sub-segments of Es₃ and lower sub-segments of Es₄.In the section,from the bottom to the top of the profile,the thickness of the sand body becomes thinner,the continuity becomes worse,but the number increases;the sand body is distributed along the turbidite channel on the plane,and is cut into blocks by the fault,gradually thinning from north to south,and the number decreases,.Using seismic facies technology and seismic coherence technology to identify and analyze the fault elements,the research shows that the faults in the study area are mainly distributed in two directions:north-north-east and north-west west,and the whole is in a"checkerboard"pattern;through the description of the characteristics of the fault structure,the analysis of the lithological docking relationship on both sides of the fault and the study of fault activity,the characteristics of fault sealing is finally confirmed.The faults in Luojia area have strong activity from the deposition period of Shahejie Formation to the deposition period of Guantao Formation.The opening of the fault is conducive to oil and gas Dredging;during the deposition of the Minghuazhen Formation,fault activity gradually ceased.Among them,faults near east and west,with long extension and poor sand body connection are well sealed,which is conducive to the formation of traps.By combining well point logging interpretation and seismic method,the three-layer structure of unconformity is identified.According to the presence or absence of weathered clay layer and the combination patterns of upper,middle and lower three-layer lithology,a total of two types and 12 sub-types of unconformities are identified,among which the structure type,including the three-layer structure combination style of mudstone-weathered clay layer-limestone and mudstone-weathered clay layer-sandstone unconformity,is more likely to form oil and gas reservoirs.Based on the anatomy of elements,the distribution characteristics of different types of traps were determined.In the near-source slope area,the terrain is slow and there are few faults,mainly developing lithologic traps and structural lithologic traps;in the far-source slope area,the terrain is steep and there are many faults,mainly developing structural lithologic traps and structures Trap;in the uplift area,the terrain becomes slower and there are fewer faults,mainly stratigraphic traps.The Es₃-Es₄Member in the Luojia area as a whole has a stepwise transition from tectonic-lithologic traps to unconformity traps in the direction from north to south.