Study Of Seismic Prestack Inversion And Reservior Prediction Techniques Applied In Carbonate Gas Reservior

With the increasing demand of energy source and development of exploration, the interested geological condition is becoming more complicated, long with the cost of exploration is steeply rising, the application of geophysical technology has moved to geological comprehensive evaluation no longer focused on structural attitude. Also, as the deepening recognition to geological condition and the development of seismic technology, prestack seismic technology has formed a set of mature pattern including processing and interpretation, which make it possible to predict reservoir and pore fluid qualitatively or even quantitatively. But, how to efficiently transform the abundant information within the seismic data to illustrative delineation of reservoir and pore fluid is always a big challenge in the field of geophysics.Many successful cases have proved that prestack prediction techniques are effective in clastic rock, but few cases in carbonate reservoir. So the importance of the subject mainly focuses on the following aspects: the latest progress of seismic inversion theory, practical rock geophysics techniques, prestack forward modeling, and case studies in reservoir and pore fluid prediction. This study mainly involved with the prediction and identification of fluid property and distribution so as to guid the next plan of exploration.1 Several available simplified equations were compared and analyzed in detail, this may not only provide academic proof for practical application but also use for reference to AVO’development. 2 Based on the achievements of the predecessors, practical technologies of rock physics was carried out and some innovative results were made, such as the allied method for shear velocity estimation, rock physics modeling techniques, the analysis of geophysical parameter sensitive to complex reservoir. The method for prestack forward modeling was set up, and sensitive parameters to pore fluid and seismic attributes were optimized for the interested area.3 The studied techniques and methods were integrated into the preservior prediction and fluid detection, by means of AVO attributes analysis along horizon, crossplot and analysis of P-wave reflectivity, s-wave reflectivity, P-wave and s-wave velocity ratio, poisson ratio reflectivity, along with trace gather dataset, the distribution of biohermal reservoir was made out, which coincided with the drilling tests. This proved these methods were effective and practical. 4 Aimed at the complexity of carbonate reservoir, elastic impedance inversion was used to predict the reservoir and detect the pore fluid, through fine calibration, rock and electrical analysis, elastic physics parameter forward modeling, joint elastic impedance inversion. Practical results proved this set of prestack integrated methods is effective and suitable to hydrocarbon detection for carbonate reservoir.