Application Research Of Sand Body Prediction Based On Seismic Multi-attribute Fusion Technology

With the continuous consumption of oil and gas resources,the intensity of oil and gas exploration and development has gradually increased,making the processing and interpretation of seismic data more and more onerous.Under the action of formation pressure,oil and gas resources accumulate from source layers to reservoirs along the oil and gas passages.Therefore,the primary goal of seismic exploration is to find favorable reservoirs to develop oil and gas.High-quality oil and gas resource reservoirs need to meet the requirements of high porosity and high permeability.Sandstone is the most popular reservoir among many lithologies.It has high porosity and can store oil and gas well.Since the development of oil and gas exploration and development,the exploration of sandstone reservoirs has always been a vital part.Aiming at the comprehensive prediction of sand bodies,geophysical prospectors have researched and developed a series of mature technologies.In view of the prediction of the spatial distribution of sand bodies and the detection of oil and gas content of sand body reservoirs,research on multi-attribute fusion analysis technology has been carried out.After analyzing the pros and cons of several time-frequency analysis algorithms based on the time-frequency spectrum comparison of the synthesized theoretical signal,the generalized S transform is selected as the basic research technique of this thesis,and then the follow-up work is carried out.It is mainly based on the root mean square amplitude attribute,sweet spot attribute,instantaneous frequency attribute,frequency division coherence technology,time-frequency domain hydrocarbon detection technology,post-stack wave impedance inversion and RGB multi-attribute fusion technology for comprehensive prediction of sand bodies.Through model analysis,comparing the advantages and disadvantages of different algorithms,and then applying them to actual seismic data,the research shows that the method used in this thesis has good applicability for sand body prediction.The main research work carried out in this thesis has the following contents:(1)On the basis of Fourier transform,carry out the research of time-frequency domain algorithm.Mainly study the principles,advantages and disadvantages of Gabor transform,wavelet transform and S transform.Aiming at the time window of S transform cannot be adjusted adaptively,the improvement of the time window function of S transform is carried out,and an improved generalized S transform is obtained.Through time-frequency analysis of the synthesized theoretical signal and comparing the pros and cons of various time-frequency analysis algorithms,the research shows that the generalized S-transform has a better effect.(2)High-resolution data plays an important role in seismic attribute extraction and inversion.At the same time,attributes extracted based on high-resolution seismic data are of great significance to reservoir description.Therefore,deconvolution processing is carried out on the basis of the original seismic data to improve the resolution of seismic sections and the ability to identify thin layers.(3)On the basis of high-resolution data volume,the sand body is finely described by root mean square amplitude attribute,sweet spot attribute and instantaneous frequency attribute;meanwhile,frequency division coherence is mainly used to describe the development degree of seismic fractures,so as to find high-quality reservoirs and depict the boundary characteristics of sand bodies.(4)Due to the cumulative error in the calculation process of a single attribute and the multi-solution of the inversion algorithm,the description of the sand body using a single attribute cannot meet the demand for high-precision characteristics,and the prediction results are unreliable.Therefore,multi-attribute fusion is based on RGB algorithm to jointly describe the spatial distribution characteristics of sand bodies.(5)On the basis of high resolution,through wave impedance inversion and well analysis,the sandstone threshold value is obtained,thus the sand body thickness of the target interval is read,thus accurately revealing the plane distribution characteristics of the target interval sand body.On this basis,the ratio of low-frequency attenuation gradient and high-frequency attenuation gradient is mainly used to detect the oil-gas potential of sand body reservoir,and the comprehensive evaluation of sand body reservoir is carried out by multi parameter.