The Research And Application Of Seismic Prediction Methods For The Reservoir Under Strong Shield

Ordovician Ma51-5 in the area of TaBaMiao is main gas-reservoir of Lower Paleozoic and there exists typical dolomite in some area.The reservoir is influenced by a series of upper-Paleozoic coal seams.The existence of coal seams results in the strong reflection on the seismic profile,which makes the reflection information of oil(gas)bed difficult to identify and increases the difficulty for reservoir prediction.In this area,the kind of reservoir space is variable,the caves develop coincidently and makes up complex allocation relation,which make the seismic data low main frequency and low resolution.The crack of research area is mainly tiny crack and has small density and has high filling extent.The reservoir of this area is low-porosity and low-permeability,and the lateral heterogeneity is strong,which make the seismic attribute lose the effect.So,the exploration and development of this area confronts with a lot of problems,has strong challenge and has important theoretical research value and scientific research value.After literature research home and abroad,firstly,this paper introduces the signal time-frequency technology and decomposition reconstruction technology.This paper analyzes the matching pursuit and MP-WVD,then analyzes signal reconstruction method using compressed sensing as well as how to solve this question using Bregman linear optimization method.According to the problem in this research area,this paper proposes MP constrained by horizon and wavelet to strip the strong shield.This method can decrease the processing time.By the way,this paper achieves three methods of improving the resolution.The first one is spectral whitening processing based on GST.The second one is time-changing wavelet spectrum simulation to improve the resolution base on GST.The third one is sparse pulse reflection coefficient spectrum inversion method based on compressed sensing.Former two methods can enhance the frequency of signal partly and improve the resolution of seismic profile.The last one can achieve great effect to improve the resolution in model test,but the real seismic data processing needs further analysis and research.After processing the strong shield caused by coal seams,this paper uses the attribute analysis to identify the effect.The attribute analysis shows that Variance Cube(Coherence Cube)can indicate the cave abnormality.Influenced by accuracy,the result of Ant Volume is not obvious and the specific application needs the knowledge of geology and well-logging.The carbonate fractured-cave type gas reservoir has high absorption and attenuation for the frequency of seismic signal,so the analysis of time-frequency feature and attenuation can indicate the location of reservoir.Because of the coal seams,the constrained sparse spike inversion is affected greatly.After striping the coal seams,the inversion gets better.