Browsing by Subject "Seismic Inversion"
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Item Facies and Porosity Distribution by the Integration of Rockphysics Analysis and Seismic Inversion in Siliciclastic Reservoirs(2014-12-15) Palacios Serrano, Diego GSeismic inversion approach has been applied with a moderate success in some siliciclastic reservoirs in Oriente Basin characterized by their prominent lateral facies variations. Different types of facies with different geological and petrophysical characteristics can produce similar response in seismic velocities. Based on this fact, inversion results such as P-Impedance, S-Impedance, Vp/Vs., Poisson ratio and other derived elastic parameters can be misinterpreted leading to locating faked prolific zones in areas where facies do not have enough quality to be considered productive. In order to achieve this objective, rock physics analysis is used to tie the seismic inversion results to the geological and petrophysical rock characteristics. The Sun model has proven to characterize successfully the seismic response of carbonate and siliciclastics rocks and infer geological, depositional, diagenetical and petro physical characteristics from sonic logs and seismic data. Using the compressional frame flexibility factor (?k) and the shear frame flexibility factor (?u) derived from this model, it is possible in this thesis to successfully correlate geological, depositional and diagenetical characteristics to the seismic response using well log and core data from two siliciclastic reservoirs in Oriente Basin. ?k and ?s factors characterize the pore structure influence to the variability of the compressibility and shear sonic velocities respectively in rocks. For these siliciclastic reservoirs, which present a prominent lateral variation in facies related to their depositional process, different ranges of ?k factor values represent different kind of facies. Values of ?k between 2 and 6 in ?U? sandstone reservoir and values of ?k higher than 6 in ?Hollin? sandstone reservoir are closely correlated to the best quality facies. According to the integrated rock physical, petrophysical and geological analysis in well locations, clean massive sandstones with fine to medium grain size and moderately sorting are represented by this ?k value interval. Using simultaneous inversion results and the assumption previously mentioned, volumes of porosity and ?k are inverted from seismic data. Spatial distribution of the ?k values in the inverted volume correlates well with a previous sedimentological interpretation study using core data descriptions. Finally, using porosity and values of ?k, the discrimination of the best quality facies is performed. As a final result, new prospective zones are visualized taking into account the structural characteristics and facies distribution obtained by this integrated analysis.Item Rock Physics-Based Carbonate Reservoir Pore Type Evaluation by Combining Geological, Petrophysical and Seismic Data(2012-07-16) Dou, QifengPore type variations account for complex velocity-porosity relationship and intensive permeability heterogeneity and consequently low oil and gas recovery in carbonate reservoir. However, it is a challenge for geologist and geophysicist to quantitatively estimate the influences of pore type complexity on velocity variation at a given porosity and porosity-permeability relationship. A new rock physics-based integrated approach in this study was proposed to quantitatively characterize the diversity of pore types and its influences on wave propagation in carbonate reservoir. Based on above knowledge, permeability prediction accuracy from petrophysical data can be improved compared to conventional approach. Two carbonate reservoirs with different reservoir features, one is a shallow carbonate reservoir with average high porosity (>10%) and another one is a supper-deep carbonate reservoir with average low porosity (<5%), are used to test the proposed approach. Paleokarst is a major event to complicate carbonate reservoir pore structure. Because of limited data and lack of appropriate study methods, it is a difficulty to characterize subsurface paleokarst 3D distribution and estimate its influences on reservoir heterogeneity. A method by integrated seismic characterization is applied to delineate a complex subsurface paleokarst system in the Upper San Andres Formation, Permian basin, West Texas. Meanwhile, the complex paleokarst system is explained by using a carbonate platform hydrological model, similar to modern marine hydrological environments within carbonate islands. How to evaluate carbonate reservoir permeability heterogeneity from 3D seismic data has been a dream for reservoir geoscientists, which is a key factor to optimize reservoir development strategy and enhance reservoir recovery. A two-step seismic inversions approach by integrating angle-stack seismic data and rock physics model is proposed to characterize pore-types complexity and further to identify the relative high permeability gas-bearing zones in low porosity reservoir (< 5%) using ChangXing super-deep carbonate reservoir as an example. Compared to the conventional permeability calculation method by best-fit function between porosity and permeability, the results in this study demonstrate that gas zones and non-gas zones in low porosity reservoir can be differentiated by using above integrated permeability characterization method.