The Research On Characteristics And Mechanism Of Interformational Fault Of Lower-middle Ordovician In Tahe Oilfield,Talimu Basin

The Tarim basin fracture system is of great significance to the formation of carbonate reservoir.The two most important exploration levels of the Tahe oilfield are the Yingshan formation and the Penglaiba formation in Lower-Middle Ordovician.Based on the Yingshan formation and the Penglaiba formation in Lower-Middle Ordovician as the research object,on the theory of sequence stratigraphy,tectonics,etc to guide,on the basis of the drilling and well logging,3D seismic data,seismic attribute analysis as the main technical means,to establish a set of Tahe oilfield backbone fracture and interlaminar fracture development mode,and detailed analysis was carried out on the fracture development mode of all elements.Through geological and seismic data,the detailed explanation of the stratigraphic sequence of the Yingshan formation and the Penglaiba formation in Lower-Middle Ordovician in Tahe oilfield is explained in detail.The Yingshan formation is divided into four fourth-order sequence: Ysq1,Ysq2,Ysq3,Ysq4 and the Penglaiba formation is divided into two fourth-order sequence,one and two sections.By analyzing and comparing the attributes of coherence,curvature,dip attribute and so on more than 10 kinds of seismic attribute,the coherence and curvature attributes are considered to be the best integrated recognition capabilities.The paper studies the characteristics of the profile and plane of fracture,based on the detailed stratigraphic classification and the fine interpretation of fracture.In Tahe oilfield,the planar combined characteristic of the faults in Lower-Middle Ordovician are flat,wild geese,conjugate,etc.,and are mainly composed of large conjugate fractures.The fractographic structure of the fault is divided into two types: flower structure is further classified into seven sub-classes based on the nature of the fracture and fracture and high and steep fracture is be further classified into three sub-types according to the formation of broken strata.At the same time,the research shows that the fault of Tahe oilfield has the characteristics of "three points",namely,zoning,zonality and segmentation.There are five fault zones in the research area,and the eastern and western regions are developed,which is the most concentrated in the middle of the research area.In different positions of the same fault zone,the distance size,the structure style,etc.have different characteristics.Based on the overall understanding of the fault system in Tahe oilfield,the fracture and interlayer fracture development mode in the Lower-Middle Ordovician in Tahe oilfield is established.The structural style of the fault in the upper section of the section is divided into two types: interface termination and interfacial fault.The fracture between the upper layers of the plane is increasing by the bottom-up.The fully developed fault zone is diffused from the north-central part of the research area to the south-central and east west.Through analyzing the sequence interface,lithology,rock thickness and stress field,The Yingshan formation is gradually increasing by the bottom-up mud,and the thickness of the stratum is thinning.The Penglaiba formation has a high level of dolomite,but it is stressed by the greater strata.The research shows that the strength of fracture between the layers is proportional to the strength of the stress field,the content of the dolomite and the mortar,and the thickness of the rock is inversely proportional to the thickness of the rock.