The Study Of Detailed Structure And Petrophysics Properties Applied With Seismic Information In Pijia Area Of Songliao Basin

3D seismic data of Pijia Structure in the south of SongliaoBasin was pre-stack migrated. And based on this process, seismicdata in depth domain was interpreted, post-stack reservoir waspredicted.In this paper, for this area, the conventional seismicprocess flow and methods, the basic idea of velocity modeling indepth domain, the principle of pre-stack migration and appliedparameters were introduced.Comparing with old data, in the seismic section of the prestackmigration, images of each main formation of interest areclear, in which the relationship of contact between geologichorizons and faults are distinct, breaking points of smallfaults are distinct, especially the base and internalinformation are clear and locations are dependable. It isconvenient to interpreters to interpret and analyze. At the sametime keeping amplitude seismic data, it is provided reliableinsurance for subsequent reservoir predicting.In the research, a series method of seismic horizonsinterpreting, strata correlating and structural mapping in depthdomain are put forward. For Pijia Area, the structureinterpretation and mapping in depth domain are done. And then,pre-stack reservoir prediction is done. For main formation ofinterest, Formation Denglouku-Formation Shahezi, inversions ofseismic wave impedance, lithology and porosity are well done. The characteristics of reservoir distribution are summarized.Finally, integrating structure interpretation, reservoirprediction and petroleum geological conditions, five zone ofinterest are optimized.Pre-stack migration in depth domain is one of importantcontents of the study. Inclination of structures and the changesof velocity in lateral direction can cause CMP gathers to bedivergent, so layer's velocities to be obtained will bedifficult. Using pre-stack migration, the effects of inclinationof the structures and the lateral change of velocity can beeliminated and the information of the same point reflected withCRP gathers can be obtained. Comparing with pre-stack migrationin depth domain, the sensitivity of the pre-stack migration intime domain is much smaller. It is easily to obtain RMS velocity.Therefore, the RMS velocity could be obtained by means ofrepetition of pre-stack migration in time domain. However, thebest velocity to be obtained from pre-stack migration in timedomain is not exactly the velocity of pre-stack migration. So itmust be processed in detail further through pre-stack migrationin depth domain.Imaging in pre-stack migration of shotpoint in depth domainis much easier to be realized. Kirchhoff pre-stack migration indepth domain is one of the methods of integral migration. Due tothe difficulty of realization( such as the processes of theamplitude of travel time and phases without considering the pathof travel time), that the imaging is limited. Comparing withKirchhoff's , the pre-stack migration of wave equation inshotpoint domain is not sensible anymore of the errors in highfrequency. The trends of velocity is more important than detail, so that the imaging is more easier to be realized in depthdomain.Considering the complexity of fault system and thestructure of the Structure Pijia, through the pre-stackconventional processes and detailed modeling of depth-velocity,it is well done in this area that the 3D seismic data wasmigrated using Fourier's finite difference wave equation withwide angle while the parameters were analyzed and chosencarefully.Post-stack inversion is another important content in thisreaserch.Lateral prediction of reservoir is meant to find out therelationships among the characteristics of lithology,petrophysics and oil and gas saturation, and to build thevarious geophysical responses features of oil, gas and water inthe reservoirs, and that is to say the identification marks ofoil, gas and water on the well log, seismic and seismicvelocity and various seismic attributes. The situation of theoil and gas saturated in this area has been predicted using thepredict module of the integral identification marks. There aremany methods of reservoir prediction. For the features ofdepositional model of continental facies of lakes and inter-bedof sands and mud layer rocks in this area, the lithology andporosity are predicted.In general, the enrichment of oil and gas is mainlydominated with elementary factors of structure, petroleumsources, and the condition of reservoirs and so on. From all ofthe area, the high part of north depression zone is predicted asavailable oil zone, in which the sand sorting, porosity and permeability of the reservoir pretty well approaching oil sourcearea. In the north part of the area, it is apart from the oilsource area, it is interpreted as less available prospect.Analyzing each layers'structure map, it is suggested that thestructure in the high part of the depression approachinggenerating oil source is pretty good prospects. Five respects ofinterest are optimized.