The Application And Study Of Seismic And Logging Joint Inversion Regarding Tahe 4 Oil-field As The Example

With regard to delicate oil-gas exploration, the results of seismic inversion play a more and more important role in the oil pool description and lateral in oil-gas prediction. The technology can actually reflect underground geological structured and reservoir rock character, and can greatly raise the percentage of drilling hits. The Ordovician carbonate reservoirs of Tahe oilfield are characterized mainly by karstic fissures and vugs, and structural fissures formed by karsticfication and geo-tectonics, and characterized by deep burying and strong heterogeneity. Additionally, because the top strata of Ordovician have been subjected to intensive weathering and denudation, the energy of seismic reflection signals is weak and random and the seismic resolution is low, which multiplies the degree of difficulty in accurately predicting carbonate reservoirs of fissure-vug type. In view of the characteristic of carbonate reservoirs of Tahe oilfield and their difficult point in predicting, on the basis of fully consulting the study result of carbonate reservoirs of fissure-vug type, the thesis uses multiple methods of seismic and logging joint inversion (including Recursive trace inversion, Constrained sparse spike inversion, Seismic characteristic inversion, Random simulation and stochastic inversion; reservoir prediction, etc) to predict reservoirs of this area. In the course of study, the author takes the five-clock-type filter method and the relation of linear calibration in the pretreatment and standard treatment of logging data for ensuring the rationality of reservoir inversion, and takes a detailed research on the principles, key technology and applied conditions of every methods, analyses strong and weak point of every kinds of inversion, and compares applied effectiveness of every inversion methods, so that the optimized inversion method, which is suited to the carbonate reservoirs prediction of the area, is selected. Several points of my understanding are follows:1. The method of Recursive trace inversion uses mainly seismic data, and logging data are not involved in the inversion constraint. The resolution, signal-to-noise and reliability are all dependent on the quality of seismic data themselves. Hence, the seismic noise is sensitive to inversion result and has considerable influence. The width and narrowness of seismic bands can result in the comparative lowering of resolution, which cannot meet the requests of thin reservoir description.2. The method of constrained sparse spike inversion supposes that the reflections coefficients of strata are sparse. A rapid trend-constrained pulse inversion calculation is adopted, using the seismic interpretation horizon and logging-constraint to control the trend and scope of wave impedance. The pulse calculation can obtain the wide-band result. The inversion result is faithful to seismic data and can reflect the lateral change of reservoirs. And the constraint of logging and geology can replenish the component of low and high frequencies. The vertical resolution is heightened comparatively to the conventional seismic data.