Study On Building Velocity Field Based On Seismic Inversion And Attributes Fusion Of The Igneous Rocks In H6-RP Area

Currently, the study for igneous rocks in the world mainly focus on igneous oiland gas reservoirs, but relatively only few researches have been done for the sampleigneous rock body. The study area named Halahatang region locates in Tarim Basin,and there are hundreds of exploratory wells have been deployed in this area, whichcommonly drill with igneous rocks in Permian. It’s very difficult to implementlow-amplitude traps and lithologic traps due to the severe change in igneous lithologyand thickness, irregularities and unevenness of velocity, which severely impedes theprocess of this region’s oil and gas exploration.Firstly, in this paper, the geological research about eruption phases of Permianigneous rock in Halahatang area is referred, which indicates that there were threemain volcanic activity times in this area and there were different volcanic typesformed during each time. Then analyzing and processing the logging data of H6-RParea, in which the environmental correction for density by multivariate fitting formulaand the standardized processing of sonic and density via dimensional histogramstatistic are carried out. On this basis, Gardner coefficients are estimated from thoselogs with density curves and result in a good imitative effect. In addition, logscrossplot and quantitative statistics of parameters have also been made which couldbetterly distinguish basalt, dacite and tuff the three igneous rock types.In the aspect of seismic attributes, this paper selects several seismic attributesthat are sensitive to igneous rocks and analyzes them combined with the geologicaldata. On that basis, conducting multiple attributes fusion research, in which themultiple attribute superimposed display indicates the structure information and theattribute ratio is more prominent for lithology identification, and both of them havebeen achieved. In terms of seismic inversion, constrained sparse spike inversion(CSSI) and geostatistical inversion are used to study igneous, and finally bothinversion methods get the wave impedance of Permian igneous rock. Through thewave impedance section, slice and geological data’s contrast, the effect of theconstrained sparse pulse inversion is better, which could get more in line with thegeological characteristics. The three phases of volcanic eruption divided by waveimpedance slices correspond well with the geological research.At last, on the base of wave impedance inversion in front, we realize thetransformation between impedance and velocity on account of the good linear relationship between wave impedance and p-wave velocity, and combined withGardner coefficient estimation. The error analysis shows that the transformed velocityfield from wave impedance has a high precision, which has reached the requirementof practical production.In conclusion, on the basis of previous studies, we have carried out detailedresearches on HLHT Permian igneous rock using seismic inversion, seismic attributeand multi-attribute fusion technology with a combination of seismic, logging andgeological data. Ultimately we could identify the development characteristics anddistribution regularity of igneous rock, and an accurate velocity field is established,which would guide variable speed mapping and make a strong groundwork to carryout the accuracy of trap.