Study On The Method Of Extracting Weak Fault Signals From Seismic Data

In the storage and transportation of underground oil and gas,fault plays a vital role in identifying the shape and distribution of faults,which is an important task in seismic exploration,especially for complex fault block reservoirs in eastern China.In the fault interpretation of seismic data,the manual interpretation method generally has higher precision,but it is susceptible to subjective factors,and the work efficiency is low.The semi-automatic detection algorithm with some fault detection algorithms is not reliable,and the influence of structural complexity and seismic data signal-to-noise ratio is very serious,and need to explain the staff for automatic detection after a large number of modifications and processing.Aiming at the difficult problem of small fault signal detection in an area of Jidong oilfield,this paper studies the extraction method of weak fault in fault block.In this paper,the main content of the weak fault extraction method is divided into the following parts:First,the three-dimensional staggered grid finite difference simulation algorithm is studied,which provides theoretical basis and algorithm support for forward modeling of small and weak fault model.The weak faults in the fault block are detailed analyzed,the small and weak fault model in fault block is established,the weak fault model is simulated by using three-dimensional staggered grid finite difference simulation algorithm,and the fault-related signals in the simulation data are analyzed,and the approximate seismic response characteristics of the type of fault are extracted,It provides a theoretical basis for the identification of small and weak fault signals.Second,the 123 th generation coherent body algorithm and the gradient structure vector method(GST)are explained in detail,and the corresponding coherent body algorithm and gradient structure vector method are used to process the seismic data,and the corresponding attribute bodies are generated to provide data support for the fault automatic tracing.Third,the main principle of the ant colony algorithm is briefly introduced,and some related improved algorithms of the ant colony algorithm are discussed emphatically.Based on the seismic attribute body of the previous part,the seismic attribute body of the target fault block part is extracted separately.The ant colony algorithm is used to track the fault automatically to realize the extraction of fault geometry in weak fault signal.Forth,the fault line is optimized by the weak fault signal in the fault block,including some conventional operations in mathematical morphology,such as expansion,corrosion,open operation,closed operation and thin line,so as to obtain a good continuity,high resolution,reasonable distribution of small and weak fault surface,the final realization of small and weak fault signal extraction.In the full text,the three-dimensional stack data of an area of Jidong oilfield is tightly focused,and the extraction of small and weak fault in the target fault block is realized through stepwise data processing,which verifies the validity of this method.