Seismic Wave Impedance Inversion And Its Application In Marine Reservoir Prediction In Western Sichuan

Seismic wave impedance inversion is a special seismic processing andinterpretation technology that inverts seismic data to stratum acoustic impedance (orvelocity) information. The technology appeared in the1970s. Wave impedanceinversion technology converts the conventional reflection seismic profile torock-profile. It is a means which contacts geology and geophysics. Wave impedance isa rock physical parameter, so itself can reflect reservoir properties directly. It is animportant parameter which predicts space and condition distribution of the reservoir.This article first introduced the status and development trend of seismic waveimpedance inversion technology. Then the author carried out a detailed study of itsbasic theory in several aspects, including the basic principles, the basic assumptions,classification and analysis of some common seismic wave impedance inversionmethods. The author selected the recursive inversion method and the constrained sparsepulse inversion method specially against the characteristics of western Sichuan Marinereservoir. The author also made a thorough study on their principles, their advantagesand disadvantages and their application fields. This article analyzed the keytechnologies of wave impedance inversion in detail, including the preparation of basicdata, seismic wavelet extraction, well-seismic calibration, wave impedance modelbuilding and quality control in the process of inversion, etc. The author used theconstrained sparse pulse inversion method to invert the3D seismic data in the surveyby InverTrace-plus module in Jason inversion software, so the article focused on theanalysis of the parameters in the inversion process, and it predicted the distributionrange of the reservoir through the inversion results. Finally the article compared theresults of the constrained sparse pulse inversion in Jason and the recursive inversion inStrata and then made an analysis.By theoretical researching and analysis of practical application results, the articlecould draw following conclusions:①In order to guarantee the accuracy of the inversion result, high quality seismicdata and well logging data is indispensable. At the same time we must do a good job for every link such as wavelet extraction, well calibration, model establishment, andso on. We also must modify the parameters repeatedly in the process of the inversionand acquire an inversion result with a high standard of quality control.②Using the wave impedance inversion results, we acquired the generaldistribution of western Sichuan Marine reservoir. In Maantang of the research area,there is a low impedance strip between two high impedance areas, and the strip maybe a favorable reservoir. The geology and the impedance distribution meet thefavorable reservoir conditions at XiaoS1well in Maantang. It is the same as CK1wellin Leikoupo.③Compared the results of constrained sparse pulse inversion and recursiveinversion, constrained sparse pulse inversion has a higher resolution. Seismic waveimpedance inversion methods have different characteristics and applicability, so theymust be selected based on the characteristics of the study area and geologicalproblems to be solved.